COMPOSITIONS AND METHODS RELATIVE TO IGM MEMORY B CELLS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62/684,882 filed June 14, 2018, the contents of which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[0002] The present disclosure relates to the isolation of antigen-specific memory B cells and compositions and methods related to and derived therefrom.

BACKGROUND

[0003] Memory B cells (MBCs) induced by vaccine or infection are critical components of a protective humoral response. MBCs can persist for long periods of time and rapidly respond to subsequent infection through the production of antibody secreting cells, formation of new germinal centers (GCs) and repopulation of the memory pool (Tarlinton and Good-Jacobson, 2013). Classically defined MBCs express class-switched, somatically hypermutated B cell receptors (BCRs) after undergoing a GC reaction. These cells produce high affinity antibodies within days of a secondary challenge, making them the gold standard for vaccine development. It is now recognized that diverse MBC subsets exist in both mice and humans (Dogan et al, 2009; Klein et al., 1997; Obukhanych and Nussenzweig, 2006; Pape et al., 2011; Seifert et al, 2015).

[0004] Technical advances in tracking antigen-specific B cells have revealed that MBCs are heterogeneous. They have been shown to express either isotype switched or unswitched BCRs that have undergone various degrees of somatic hypermutation (Kaji et al., 2012; Pape et al., 2011; Toyama et al., 2002). MBC subsets also exhibit varied expression of surface markers associated with T cell interactions such as CD73, CD80 and PDL2, revealing varied developmental histories and receptor ligand

interactions (Anderson et al, 2007; Taylor et al., 20l2b; Tomayko et al, 2010). Importantly, these phenotypically different MBC subsets have also been associated with functional heterogeneity, although different studies have led to different conclusions. Some studies have demonstrated that unswitched MBCs preferentially enter GCs, while switched MBCs preferentially form plasmablasts (Benson et al, 2009; Dogan et al, 2009; Pape et al, 2011; Seifert et al, 2015). Other studies have shown instead that unswitched MBCs rapidly generate plasmablasts upon secondary challenge whereas switched MBCs preferentially re-enter GCs (McHeyzer-Williams et al., 2015). SUMMARY OF THE INVENTION

[0005] As described herein, IgM antibodies exert a dramatic protective benefit not predicted by previous observations. Specifically, while it is generally accepted in the art that early IgM responses can promote partial early immune protection, essentially all models of adaptive immunity propose that high- affinity IgG antibodies comprise the major protective component of the humoral response. In contrast, the data described herein support the opposite, in that the data shows, completely unexpectedly, that IgM antibodies can exert an even greater protective effect, which depending on the pathogen or tumor antigen can allow for markedly greater clinical benefits. While a very high-affinity IgG vs. IgM memory -derived IgM antibodies were not directly compared, the K _D studies described herein strongly indicate that, regardless of IgG affinity, the additional benefits rendered by IgM avidity will lead to a greater protective effect even in that scenario.

[0006] The data described herein also demonstrate that IgM antibodies can exert this very strong protective benefit despite having many fewer somatic mutations compared to IgG antibodies. Without wishing to be bound or limited by theory, this latter fact could reflect higher affinity of the germline IgM that triggers generation of an IgM memory B cell. As described herein, despite the lower affinity, IgM antibodies can outperform high-affinity IgG.

[0007] Furthermore, while it is generally accepted in the art concept that pentameric or heptameric IgM molecules exhibit higher avidity compared to monomeric IgM, no one has directly assessed and compared the relative KD of IgM and IgG antibodies having the same binding site against a target protective antigen. As described herein, the data demonstrate a vast difference in KD that was entirely unexpected, indicating that the role of avidity is vastly underappreciated.

[0008] The discovery that memory B cell antigen receptor IgM constructs have exceptionally low dissociation constants despite having relatively low levels of somatic mutation illuminates some new perspectives. One of these is that antigen-binding polypeptide constructs of this kind are less likely to themselves be antigenic when introduced to a human, relative to constructs including more somatically mutated antigen binding domains. Thus, antibody constructs of this kind will potentially be tolerated for repeat or long term dosage better than constructs based upon more somatically mutated binding domains. Until it was realized that such constructs with limited somatic mutation would efficiently bind target antigen, this benefit could not be realized.

[0009] Thus, in one embodiment, provided herein is a screening method in which memory B cells are panned from a biological sample for binding to an antigen of interest, followed by the cloning of heavy and light chain IgM memory B cell receptor antigen-binding domains from the bound cells. This approach reliably provides antigen-binding domains from IgM memory B cells that specifically bind the antigen of interest with high affinity. Polypeptide constructs generated from the cloned antigen-binding domains have low somatic mutation, on the order of 8 or fewer, e.g., 7 or fewer, 6 or fewer, 5 or fewer, 4 or fewer, or even 3 or fewer somatic mutations and have high affinity, specific binding to the antigen of interest, but provoke less anti -immunoglobulin immune response in a human subject relative to constructs using more highly somatically mutated antigen binding domains. Such constructs can, for example, be repeatedly administered for therapy, with a reduced likelihood of provoking an anti immunoglobulin immune response. It is also contemplated that antigen binding domains derived from antigen-specific B cells expressing IgM may be more easily tolerized for therapeutic purposes than those isolated B cells expressing IgG.

[0010] In another aspect, it is recognized herein that not only will IgM antigen-binding domains isolated from memory B cells be less immunogenic, but, given the high affinity binding of recombinant constructs including multimers of these binding domains, e.g., in an IgM format, a broader range of high affinity, antigen specific IgM polypeptide constructs with lower somatic mutation is available than previously achievable. In particular, while the memory B cell IgM antigen receptors may have reduced affinity relative to more somatically mutated antigen binding domains isolated from IgG’s, the finding herein that memory B cell IgM antigen receptors bind with surprisingly lower KD’S than one might expect even when an anticipated decrease in KD via avidity for the multimeric binding domains is considered, means that memory B cell IgM antigen-binding domains provide a considerably broader range source of antigen-specific binding constructs than previously appreciated. Thus, provided herein are libraries of memory B cell IgM antigen receptors with a greater proportion, e.g., at least 10% greater, 20% greater, 30% greater, 40% greater, 50% greater, 60% greater, 70% greater, 80% greater, 90% greater, 100% greater, 2-old, 5-fold, lO-fold, 50-fold, or lOO-fold or more greater proportion of antigen- specific binding domains that provide high affinity binding than a library based upon antibody binding domains from a class-switched B cell population. It is also specifically contemplated that the more native/less somatically mutated or modified an antigen binding domain is, the more its core activity will be preserved.

[0011] In another aspect, it is possible, given the techniques described herein, to isolate antigen binding polypeptides that have a native B cell IgM antigen receptor. By isolating naive B cells, e.g., by selecting a CD19+, CD27-, IgD+ B cell population and cloning the IgM antigen receptor coding sequences, a library of native B cell IgM antigen receptor molecules can be generated. When these are expressed as a recombinant IgM as described herein, high affinity antigen-binding domains substantially without somatic mutation can be prepared. This library can be expressed and panned for binding to an antigen of interest in order to isolate the IgM antigen receptors that bind the antigen of interest. When these are expressed as a recombinant IgM as described herein, high affinity antigen-binding domains substantially without somatic mutation can be prepared. [0012] In another aspect, provided herein are nucleic acid constructs encoding an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds an antigen of interest, in an IgM isotype acceptor antibody framework. In one embodiment, a nucleic acid construct is provided that encodes a light chain antigen binding domain from a memory B cell IgM antigen receptor, a light chain constant domain, a heavy chain antigen binding domain from a memory B cell IgM antigen receptor and a heavy chain constant domain. In one embodiment, the heavy chain and light chain constant domains are IgM constant domains. The antigen-binding domains encoded by such constructs have 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, or even 3 or fewer somatic mutations.

[0013] In another aspect, provided herein are nucleic acid constructs encoding an antigen-binding domain isolated from an IgM native B cell receptor that specifically binds an antigen of interest, in an IgM isotype acceptor antibody framework. In one embodiment, a nucleic acid construct is provided that encodes a light chain antigen binding domain from a native B cell IgM antigen receptor, a light chain constant domain, a heavy chain antigen binding domain from a native B cell IgM antigen receptor and a heavy chain constant domain. In one embodiment, the heavy chain and light chain constant domains are IgM constant domains. The antigen-binding domains encoded by such constructs have substantially no somatic mutation. By substantially no is meant 1 or fewer somatic mutations. A naive B cell would have no somatic mutations in the V regions; without wishing to be limited by theory, somatic mutations found in isolates prepared from naive B cells identified on the basis of a CD19+, CD27-, IgD+ surface marker profile would likely arise from contaminating non-naive B cells in the preparation.

[0014] In one aspect, described herein is a recombinant antigen-binding polypeptide comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds an antigen of interest, in an IgM isotype acceptor antibody framework.

[0015] In one embodiment, the antigen-binding domain has 8 or fewer somatic mutations relative to a naive B cell receptor.

[0016] In another embodiment, the recombinant antigen-binding polypeptide has a Kd for the antigen of interest of 10 ¹⁰ M or below.

[0017] In another embodiment, the recombinant antigen-binding polypeptide has a Kd for the antigen of interest of 10 ¹¹ M or below.

[0018] In another embodiment, the recombinant antigen-binding polypeptide has a Kd for the antigen of interest of 10 ¹² M or below.

[0019] In some embodiments, the recombinant antigen-binding polypeptide comprises human antigen-binding and constant domains.

[0020] In some aspects, described herein is a recombinant polypeptide construct comprising an antigen-binding unit comprising heavy and light chain variable domains of a B cell receptor of a naive B cell, and an IgM heavy chain constant domain. [0021] In one embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a plurality of IgM isotype antigen binding units. In some embodiments, the construct comprises a plurality of antigen binding units.

[0022] In some embodiments, the construct comprises five or seven antigen binding units.

[0023] In some embodiments, the recombinant polypeptide construct comprises a J chain sequence.

[0024] In some embodiments, the recombinant polypeptide is an antigen expressed by a pathogen, or a tumor antigen.

[0025] In some aspects, described herein is a recombinant antigen-binding polypeptide construct comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds a. Plasmodium antigen, in an IgM isotype acceptor antibody framework.

[0026] In one embodiment, the recombinant antigen-binding polypeptide construct described herein comprises variable domain complementarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74; a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

i. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

j. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO:

112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

k. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

1. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154.

[00027] In another embodiment, the CDRs are grafted into an IgM acceptor antibody framework.

[00028] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgM antigen-binding units.

[00029] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises five or six IgM antigen-binding units.

[00030] In another aspect, described herein is a recombinant antigen-binding polypeptide construct

comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds a Plasmodium antigen, in an IgG isotype acceptor antibody framework.

[00031] In one embodiment, the recombinant antigen-binding polypeptide construct comprises variable domain complementarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain

CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain

CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34;

g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

i. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

j . a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

k. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain

CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

l. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and m. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154.

[00032] In another embodiment, the CDRs are grafted into an IgG acceptor antibody framework.

[00033] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgG antigen-binding units.

[00034] In another embodiment, the recombinant antigen-binding polypeptide construct comprises five or six IgG antigen-binding units.

[00035] In another aspect, described herein is a recombinant antigen-binding polypeptide construct

comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds a Plasmodium falciparum merozoite surface protein 1 (MSP-l) polypeptide.

[00036] In one embodiment, the recombinant antigen-binding polypeptide construct comprises CDRs

selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134.

[00037] In another embodiment, the CDRs are grafted into an IgM acceptor antibody framework.

[00038] In another embodiment, the CDRs are grafted into an IgG acceptor antibody framework.

[00039] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgM antigen-binding units.

[00040] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises five or six IgM antigen-binding units.

[00041] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgG antigen-binding units.

[00042] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises five or six IgG antigen-binding units.

[00043] In another aspect, described herein is a recombinant antigen-binding polypeptide construct

comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds Plasmodium falciparum apical membrane antigen 1 (AMA) polypeptide.

[00044] In one embodiment, the recombinant antigen-binding polypeptide construct comprises CDRs

selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154.

[00045] In another embodiment, the CDRs are grafted into an IgM acceptor antibody framework. [00046] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgM antigen-binding units.

[00047] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises five or six IgM antigen-binding units.

[00048] In another embodiment, the CDRs are grafted into an IgG acceptor antibody framework.

[00049] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgG antigen-binding units.

[00050] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises five or six IgG antigen-binding units.

[00051] In another aspect, described herein is a recombinant antigen-binding polypeptide construct

comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds Plasmodium falciparum circumsporozoite protein (CSP).

[00052] In another embodiment, the CDRs are grafted into an IgM acceptor antibody framework.

[00053] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgM antigen-binding units.

[00054] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises five or six IgM antigen-binding units.

[00055] In another embodiment, the CDRs are grafted into an IgG acceptor antibody framework.

[00056] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgG antigen-binding units.

[00057] In another embodiment, the recombinant antigen-binding polypeptide construct described herein comprises five or six IgG antigen-binding units.

[00058] In another aspect, described herein is a recombinant Plasmodium falciparum antigen-binding

polypeptide construct comprising heterologous CDRs grafted into an IgM acceptor antibody framework.

[00059] In one embodiment, the recombinant antigen-binding polypeptide described herein specifically binds to Plasmodium falciparum MSP-l, AMA, or CSP.

[00060] In another embodiment, the CDRs are selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34;

g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

i. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

j . a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

k. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

l. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

m. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154.

[00061] In another aspect, described herein is a multimeric IgG construct comprising five or six IgG antigen binding units that specifically binds an antigen of interest, wherein the heavy chain of each IgG antigen binding unit has a leucine to a cysteine mutation in the C _H 2 domain at the position corresponding to L309 of the wild-type human IgG of SEQ ID NO: 180, and wherein the heavy chain of each IgG antigen-binding unit comprises an IgM tail piece.

[00062] In one embodiment, the IgG is IgGl, IgG2, IgG3, or IgG4.

[00063] In another embodiment, the IgM tail piece comprises the amino acid sequence of SEQ ID NO: 155 (PTLYNV SLVMSDTAGTCY) .

[00064] In another embodiment, each IgG moiety comprises CDRs isolated from a memory B cell receptor that specifically binds an antigen of interest.

[00065] In another embodiment, the antigen of interest is an antigen of a pathogen.

[00066] In another embodiment, the antigen of interest is a Plasmodium falciparum antigen.

[00067] In another embodiment, the Plasmodium falciparum antigen is MSP-l, AMA, or CSP. [00068] In another embodiment, the antigen of interest is a tumor antigen.

[00069] In another embodiment, the multimeric IgG construct described herein comprises an MSP- 1 -specific CDR selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134.

[00070] In another embodiment, the multimeric IgG construct comprises an AMA-specific CDR selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154. [00071] In another aspect, described herein is a method of isolating memory B cells that specifically bind an antigen of interest, the method comprises:

a. contacting a biological sample containing memory B cells from a subject having had prior exposure to the antigen of interest with the antigen of interest or a portion thereof, wherein the antigen of interest is immobilized on a solid support;

b. separating a population of antigen-bound cells from non-antigen-bound cells of step (a); and c. isolating cells expressing CD21, CD27, and IgM from the population antigen-bound cells.

[00072] In one embodiment, the biological sample is a blood sample.

[00073] In another embodiment, the subject has had an infection with or is currently infected with a

pathogen that comprises or expresses the antigen of interest.

[00074] In another embodiment, prior to step (a), a biological sample is obtained from a subject.

[00075] In another embodiment, the isolating step (c) comprises flow cytometry.

[00076] In another embodiment, step (c) optionally comprises isolating cells expressing a plasmablast marker.

[00077] In another embodiment, the plasmablast marker is B220 or CD138.

[00078] In another aspect, described herein is a method of making an antibody construct comprising an antigen-binding domain from a memory B cell and that specifically binds to an antigen of interest, the method comprising:

a. isolating a population of IgM expressing memory B cells from a biological sample according to the methods described herein;

b. amplifying heavy chain and light chain variable domain sequences from the memory B cell population of step (a);

c. ligating heavy chain variable domain sequences amplified in step (b) into a heavy chain

expression vector sequence and ligating light chain variable domain sequences amplified in step (b) into a light chain expression vector sequence;

d. introducing one or more vectors encoding heavy chain and light chain expression vector

sequences of step (c) to a cell and culturing the cell under conditions that permit expression of antibody polypeptides from the expression vector sequences;

e. contacting antibody polypeptides expressed by the cell with an antigen of interest; and f. isolating antibodies that bind to the antigen of interest, thereby making an antibody construct comprising an antigen-binding domain from a memory B cell and that specifically binds to an antigen of interest.

[00073] In one embodiment, the method further comprises prior to step (a), a step of vaccinating a subject and obtaining a biological sample. [00074] In another embodiment, step (e) comprises contacting antibody polypeptides with the antigen of interest immobilized on a solid support

[00075] In another embodiment, the method further comprises prior to step (e), collecting cell culture

medium from cells of step (d).

[00076] In another aspect, described herein is an antibody composition produced by any one of the methods described herein.

[00077] In another aspect, described herein is a method of treating or preventing a disease or disorder, the method comprising administering a recombinant antigen-binding polypeptide construct described herein, or a cell expressing such a polypeptide, or a vector encoding such a polypeptide to a subject in need thereof.

[00078] In one embodiment, the subject is a human.

[00079] In another embodiment, the disease or disorder is an infectious disease.

[00080] In another embodiment, the infectious disease is a parasitic infectious disease.

[00081] In another embodiment, the disease or disorder is cancer.

[00082] In another embodiment, the administering comprises intravenous administration.

[00083] In another aspect, described herein is a method of immunizing a subject against a pathogen, the method comprising: administering a recombinant antigen-binding polypeptide construct described herein, or a cell expressing such a polypeptide construct, or a vector encoding such a polypeptide construct to an individual in need thereof.

[00084] In one embodiment, the administering comprises intravenous administration.

[00085] In another embodiment, the subject is a human.

[00086] In another embodiment, the pathogen is a parasite, bacteria, fungus, virus, or prion.

[00087] In another embodiment, the parasite is selected from the group consisting of: Plasmodium

falciparum, Plasmodium chabaudi chabaudi, Plasmodium vivax, ox Plasmodium berghei.

[00088] In another embodiment, the bacteria is selected from the group consisting of: E. coli, Psuedomonas aeruginosa, M. tuberculosis, Group B Streptococcus, Streptococcus epidermidis, Streptococcus pneumoniae, Haemophilus influenzae, Bacillus anthracis, Erysipelothrix rhusiopathiae, Klebsiella pneumoniae, Brucella abortus, Nocadia brasiliensis, Borrelia hermsii, and Borrelia burgdorferi.

[0089] Also provided herein are methods of sorting antigen-specific IgM memory B cells

comprising: contacting a biological sample obtained from a subject having had prior exposure to an antigen of interest with an agent comprising the antigen or a portion thereof; and sorting a cell population comprising IgM memory B cells based on binding to the agent comprising the antigen.

[0090] In some embodiments of these methods and all such methods described herein, the method further comprises sorting the population comprising antigen-specific IgM memory B cells using an agent specific for CD21, an agent specific for CD27, an agent specific for IgM isotype, or any combination thereof to isolate a population of IgM memory B cells specific for the antigen.

[0091] In some embodiments of these methods and all such methods described herein, the agent comprising the antigen comprises a multimer of the antigen. In some embodiments, the agent comprising the antigen comprises a dimer, trimer or tetramer of the antigen.

[0092] In some embodiments of these methods and all such methods described herein, the antigen is from an infectious organism.

[0093] In some embodiments of these methods and all such methods described herein, the method further comprises one or more steps of sequencing one or more B cell receptors (BCRs) of the cell population comprising IgM memory B cells.

[0094] In some embodiments of these methods and all such methods described herein, the method further comprises one or more steps of cloning the one or more BCRs, or antigen binding domains thereof, and expressing the one or more BCRs or antigen-binding domains thereof as one or more recombinant antigen-binding polypeptides.

[0095] In some embodiments of these methods and all such methods described herein, the biological sample comprises a blood sample.

[0096] Provided herein, in some aspects, are recombinant cells producing an antigen-binding polypeptide comprising a variable heavy chain immunoglobulin sequence, a variable light chain immunoglobulin sequence, or both, from an IgM memory B cell obtained using any of the methods described herein.

[0097] In some aspects, provided herein are recombinant antigen-binding polypeptides isolated from a recombinant cell as described herein.

[0098] In some aspects, provided herein are recombinant antigen-binding polypeptides comprising an antigen-binding domain of an IgM memory B cell receptor.

[0099] In some embodiments of these aspects and all such aspects described herein, the antigen binding domain comprises a variable light chain sequence, a variable heavy chain sequence, or both.

[00100] In some embodiments of these aspects and all such aspects described herein, the IgM memory B cell receptor antigen-binding domain is comprised in a non-IgM isotype antibody framework. In some embodiments, the non-IgM isotype antibody framework is an IgG antibody framework.

[00101] In some embodiments of these aspects and all such aspects described herein, the IgM memory B cell receptor antigen-binding domain is a human IgM memory B cell receptor antigen binding domain.

[00102] In some embodiments of these aspects and all such aspects described herein, the IgM memory B cell is CD21+CD27+. In some embodiments of these aspects and all such aspects described herein, the recombinant antigen-binding polypeptide comprises an scFv polypeptide, a single-domain antibody construct, a chimeric antibody construct or a bispecific antibody construct.

[00103] In some embodiments of these aspects and all such aspects described herein, the polypeptide binds its antigen with a KD of 10 ⁶ nM or lower.

[00104] In some embodiments of these aspects and all such aspects described herein, the variable light chain immunoglobulin sequence, variable heavy chain immunoglobulin sequence, or both has one or more somatic mutations relative to a variable heavy chain immunoglobulin sequence or variable light chain immunoglobulin sequence from a naive B cell. In some embodiments, the variable light chain sequence, variable heavy chain sequence, or both has one to eight somatic mutations relative to a variable heavy chain sequence or variable light chain sequence from a naive B cell. In some

embodiments, the antigen-binding domain of the IgM memory B cell receptor has fewer than 5 somatic mutations.

[00105] In some embodiments of these aspects and all such aspects described herein, the IgM memory B cell receptor antigen-binding domain specifically binds an antigen comprised or expressed by an infectious organism. In some embodiments, the infectious organism is a blood-borne pathogen. In some embodiments, the infectious organism is a virus, a bacterium, a fungus or a parasite. In some embodiments, the infectious organism is P. falciparum. In some embodiments, the antigen is P.

falciparum merozoite surface protein 1 (MSP1) or apical membrane antigen 1 (AMA).

[00106] In some embodiments of these aspects and all such aspects described herein, the IgM memory B cell receptor antigen-binding domain specifically binds a tumor antigen.

[00107] Provided herein, in some aspects, are compositions comprising a population of antigen- specific IgM memory B cells bound via their B cell receptors to antigen immobilized on a solid support.

[00108] In some embodiments of these aspects and all such aspects described herein, the antigen immobilized on the solid support comprises a multimer construct comprising the antigen. In some embodiments, the multimer construct comprises a dimer, trimer or tetramer of the antigen.

[00109] In some embodiments of these aspects and all such aspects described herein, the antigen is an antigen expressed by an infectious organism. In some embodiments, the infectious organism is a blood-bome pathogen. In some embodiments, the infectious organism is a virus, a bacterium, a fungus or a parasite. In some embodiments, the infectious organism is P. falciparum. In some embodiments, the antigen is P. falciparum merozoite surface protein 1 (MSP1) or apical membrane antigen 1 (AMA).

[00110] In some embodiments of these aspects and all such aspects described herein, the IgM memory B cell receptor antigen-binding domain specifically binds a tumor antigen.

[00111] In some aspects, provided herein are populations of at least 100 recombinant antigen-binding molecules, each comprising an antigen-binding domain of an IgM memory B cell receptor, and each binding its antigen with a KD of 10 ⁶ nM or lower. [00112] In some embodiments of these aspects and all such aspects described herein, the average frequency of somatic mutation is eight or fewer per molecule. In some embodiments, the average frequency of somatic mutation is five or fewer per molecule.

[00113] In some embodiments of these aspects and all such aspects described herein, the population binds the same antigen.

[00114] In some embodiments of these aspects and all such aspects described herein, the antigen is an antigen expressed or comprised by an infectious organism. In some embodiments, the infectious organism is a blood-bome pathogen. In some embodiments, the infectious organism is a virus, a bacterium, a fungus, or a parasite. In some embodiments, the infectious organism is P. falciparum. In some embodiments, the antigen is P. falciparum merozoite surface protein 1 (MSP1) or apical membrane antigen 1 (AMA).

[00115] In some aspects, provided herein are pharmaceutical compositions comprising any of the compositions described herein and a pharmaceutically acceptable carrier.

[00116] In some aspects, provided herein are vaccine compositions comprising a composition as described herein.

[00117] In some aspects, provided herein are methods of treating a subject in need of treatment for a disease caused by an infectious organism comprising administering a composition comprising an antigen-binding polypeptide as described herein to the subject, wherein the antigen-binding polypeptide specifically binds an antigen comprised by the infectious organism.

[00118] In some aspects, provided herein are methods of reducing the likelihood of contracting a disease caused by an infectious organism comprising administering to an individual at risk of contracting the disease a composition comprising an antigen-binding polypeptide as described herein to the subject, wherein the antigen-binding polypeptide specifically binds an antigen comprised by the infectious organism.

[00119] In some aspects, provided herein are methods of treating a subject in need of treatment for a tumor that expresses a tumor antigen comprising administering a composition comprising an antigen binding polypeptide as described herein to the subject, wherein the antigen-binding polypeptide specifically binds the tumor antigen.

[00120] Provided herein, in some aspects, are methods of sorting Plasmodium- specific IgM memory B cells (MBCs), comprising: generating B cell tetramers specific for blood or liver stage Plasmodium antigens; providing the B cell tetramers to a biological sample obtained from a subject infected with malaria; and sorting the Plasmodium- specific IgM MBCs based on binding to the tetramers.

[00121] In some embodiments of these aspects and all such aspects described herein, the method further comprises one or more steps of sequencing the Plasmodium- specific IgM MBC B cell receptors (BCRs). [00122] In some embodiments of these aspects and all such aspects described herein, the method further comprises one or more steps of cloning the BCRs and expressing the BCRs as recombinant antibodies.

[00123] In some embodiments of these aspects and all such aspects described herein, the subject is a mammal. In some embodiments, the subject is a human.

[00124] In some aspects, provided herein are isolated or recombinant antibody-producing B-cells produced by using any of the methods described herein. In some aspects, provided herein are recombinant antibodies produced from the isolated or recombinant antibody-producing B-cell.

[00125] In some aspects, provided herein are recombinant antibodies comprising a variable region from Plasmodium- specific memory B cells and an immunoglobulin heavy chain isotype. In some embodiments, the recombinant antibody is for the treatment of or protection from malaria infection in a subject. In some embodiments, the recombinant antibody is for vaccination against malaria. In some embodiments, the recombinant antibody is for the treatment of multi-drug resistant malaria. In some aspects, provided herein are pharmaceutical composition comprising such recombinant antibodies.

[00126] Provided herein, in some aspects, are methods of treating malaria infection in a subject, comprising administering a therapeutically effective amount of a recombinant antibody as described herein. In some embodiments of these aspects and all such aspects described herein, the subject is a mammal. In some embodiments, the subject is immunocompromised.

[00127] Provided herein, in some aspects, are methods of treating multi-drug resistant malaria in a subject, comprising administering a therapeutically effective amount of a recombinant antibody as described herein. In some embodiments of these aspects and all such aspects described herein, the subject is a mammal. In some embodiments, the subject is a human. In some embodiments, the subject is immunocompromised.

[00128] Provided herein, in some aspects, are methods of preventing malaria infection in a subject, comprising administering a pharmaceutically effective amount of a recombinant antibody as described herein. In some embodiments of these aspects and all such aspects described herein, the subject is a mammal. In some embodiments, the subject is a human. In some embodiments, the subject is immunocompromised.

[00129] In some embodiments of these aspects and all such aspects described herein, the recombinant antibody is administered in an amount effective to provide short-term protection against a malaria infection. In some embodiments, the short-term protection is at least about 2 months. In some embodiments, the short-term protection is at least about 3 months.

[00130] Provided herein, in some aspects, are methods for assessing an effective vaccine strategy for malaria infection in a subject comprising: generating B cell tetramers specific for blood or liver stage Plasmodium antigens; providing the B cell tetramers to a biological sample obtained from the subject; and sorting or enumerating the Plasmodium- specific IgM MBCs based on binding to the tetramers. In some embodiments of these aspects and all such aspects described herein, the method further comprises a step of sequencing the Plasmodium- specific IgM MBC B cell receptors (BCRs). In some embodiments of these aspects and all such aspects described herein, the subject is a mammal. In some embodiments, the subject is a human. In some embodiments, the subject is immunocompromised.

[00131] In some aspects, provided herein are recombinant antibodies comprising a variable region from a Plasmodium- specific memory B cell and an IgG or IgM isotype acceptor antibody framework or scaffold.

[00132] Provided herein, in some aspects, are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen apical membrane antigen 1 (AMA) and comprises heavy chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain

CDR2 having the amino acid sequence of SEQ ID NO: 108; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109;

g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain

CDR2 having the amino acid sequence of SEQ ID NO: 138; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; and

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain

CDR2 having the amino acid sequence of SEQ ID NO: 148; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149. [00133] Provided herein, in some aspects, are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen apical membrane antigen 1 (AMA) and comprises light chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34;

b. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

c. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

d. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

e. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

f. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

g. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

h. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154.

[00054] Provided herein, in some aspects, are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen apical membrane antigen 1 (AMA) and comprises heavy and light chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154.

[00055] Provided herein, in some aspects, are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen Merozoite Surface Protein 1 (MSP1) and comprises heavy chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; and

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129.

[0056] Provided herein, in some aspects, are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen Merozoite Surface Protein 1 (MSP1) and comprises light chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74;

b. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94;

c. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104; d. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124; and

e. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134.

[0057] Provided herein, in some aspects, are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen Merozoite Surface Protein 1 (MSP1) and comprises heavy and light chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94; c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104; d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124; and

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134.

[00134] In some aspects, described herein are methods of sorting Plasmodium-s Qcifc IgM memory B cells (MBCs), including the steps of: generating B cell tetramers specific for blood or liver stage

Plasmodium antigens; providing the B cell tetramers to a biological sample obtained from a subject infected with malaria; and sorting the Plasmodium-specific IgM MBCs based on binding to the tetramers.

In some embodiments, the method further includes a step of sequencing the Plasmodium-specific IgM

MBC B cell receptors (BCRs). In some embodiments, the method further includes a step of cloning the BCRs and expressing the BCRs as recombinant antibodies.

[00135] In other aspects, described herein are isolated or recombinant antibody-producing B-cells produced by the aforementioned method. In some embodiments, described herein are recombinant antibodies produced from the isolated or recombinant antibody-producing B-cell.

[00136] In other aspects, described herein are recombinant antibodies, including a variable region from Plasmodium- specific memory B cells and any heavy chain isotype. In some embodiments, the recombinant antibodies are for the treatment of or protection from malaria infection in a subject. In some embodiments, the recombinant antibodies are for vaccination against malaria. In some embodiments, the recombinant antibodies are for the treatment of multi-drug resistant malaria.

[00137] In other aspects, provided herein are pharmaceutical compositions comprising any of the aforementioned recombinant antibodies.

[00138] In other aspects, provided herein are methods of treating or preventing malaria infection in a subject by administering a therapeutically effective amount of any of the aforementioned recombinant antibodies. In some embodiments, the malaria infection is a multi -drug resistant malaria infection. In some embodiments, the recombinant antibody provides short-term protection against a malaria infection.

In some embodiments, the short-term protection is at least about 2 months, or at least about 3 months.

[00139] In other aspects, provided herein are methods for assessing an effective vaccine strategy for malaria infection in a subject, including: generating B cell tetramers specific for blood or liver stage Plasmodium antigens; providing the B cell tetramers to a biological sample obtained from the subject;

and sorting the Plasmodium-specific IgM MBCs based on binding to the tetramers. In some

embodiments, the method further includes a step of sequencing the Plasmodium- specific IgM MBC B cell receptors (BCRs).

[00140] In some embodiments of the aspects described herein, the subject is a mammal. Preferably, the subject is a human. In some embodiments of the aspects described herein, the subject is

immunocompromised.

[00141] Amino acids can be grouped according to similarities in the properties of their side chains (in A. L. Lehninger, in Biochemistry, second ed., pp. 73-75, Worth Publishers, New York (1975)): (1) non-polar: Ala (A), Val (V), Leu (L), He (I), Pro (P), Phe (F), Trp (W), Met (M); (2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn (N), Gln (Q); (3) acidic: Asp (D), Glu (E); (4) basic: Lys (K), Arg (R), His (H). Alternatively, naturally occurring residues can be divided into groups based on common side-chain properties: (1) hydrophobic: Norleucine, Met, Ala, Val, Leu, Ile; (2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln; (3) acidic: Asp, Glu; (4) basic: His, Lys, Arg; (5) residues that influence chain orientation: Gly, Pro; (6) aromatic: Trp, Tyr, Phe. Non-conservative substitutions will entail exchanging a member of one of these classes for another class. Particular conservative substitutions include, for example; Ala into Gly or into Ser; Arg into Lys; Asn into Gln or into His; Asp into Glu; Cys into Ser; Gln into Asn; Glu into Asp; Gly into Ala or into Pro; His into Asn or into Gln; Ile into Leu or into Val; Leu into Ile or into Val; Lys into Arg, into Gln or into Glu; Met into Leu, into Tyr or into Ile; Phe into Met, into Leu or into Tyr; Ser into Thr; Thr into Ser; Trp into Tyr; Tyr into Trp; and/or Phe into Val, into Ile or into Leu.

[00142] As to amino acid sequences (e.g., SEQ ID NOs: 1-187), one of ordinary skill will recognize that individual substitutions, deletions or additions to a nucleic acid, peptide, polypeptide, or protein sequence which alters a single amino acid or a small percentage of amino acids in the encoded sequence is a “conservatively modified variant" where the alteration results in the substitution of an amino acid with a chemically similar amino acid and retains the desired activity of the polypeptide (e.g., the antigen-binding polypeptide described herein). Such conservatively modified variants are in addition to and do not exclude polymorphic variants, interspecies homologs, and alleles consistent with the disclosure.

[00143] A given amino acid can be replaced by a residue having similar physiochemical characteristics, e.g., substituting one aliphatic residue for another (such as Ile, Val, Leu, or Ala for one another), or substitution of one polar residue for another (such as between Lys and Arg; Glu and Asp; or Gln and Asn). Other such conservative substitutions, e.g., substitutions of entire regions having similar hydrophobicity characteristics, are well known. Polypeptides comprising conservative amino acid substitutions can be tested in any one of the assays described herein to confirm that a desired activity, e.g. ligand-mediated receptor activity and specificity of a native or reference polypeptide is retained.

BRIEF DESCRIPTION OF THE DRAWINGS

[00144] FIGs. 1A-1B. show human Plasmodium- specific IgM and IgG memory B cells (MBCs) are somatically hypermutated. FIG. 1A shows the flow cytometry sorting strategy of CDl9 ⁺ B Cells co positive for pfMSPl/AMAl (left), followed by flow cytometry sorting of CD27+ and CD21+ B cells (middle), the remaining B cells were then sorted for IgG+ and IgM+ (right). FIG. IB shows somatic hypermutation (SHM) frequencies for the V _H chain (left), V _k chain (middle), and V, chain (right) for IgM and IgG positive MBCs. Individual % frequencies are shown; solid lines represent the median for each data set. *** P< 0.05, ns is not significant. [00145] FIGs. 2A-2B show the expression of recombinant B cell receptors (BCRs) as IgGl reveals specificity and that both IgM and IgG clones bind with high affinity to plasmodium-specific antigens. Merozoite Surface Protein 1 (MSP-l) specific antibodies are shown (FIG. 2A, left) and apical membrane antigen 1 (APA1) antibodies are shown (FIG. 2B, right). Graphs plot the optical density at 450nm absorbance against antibody (mAh) dilution concentrations.

[00146] FIGs. 3A-3B demonstrate antibodies are pentamers/hexamers by cryoEM that bind protein and parasites. FIG. 3A shows negative stain electron microscopy of IgG and IgM pentamer and hexamers (i). Enlarged images of the hexamers and pentamers of IgM are shown in (ii-iv). FIG. 3B shows immunohistochemistry images of MSP-l IgG controls (left), novel IgM (middle), and DAPI stained image (right).

[00147] FIG. 4 shows that IgG purification. SDS-PAGE (4-20%) protein gel analysis of purified IgG -003 in the reduced and non-reduced forms (+/-). Both proteins are obtained through transient transfection of 293T cells. IgG is purified using protein-G column.

[00148] FIG. 5 shows IgM purification. SDS-PAGE (4-20%) protein gel analysis of purified IgM-003 in the reduced and non-reduced forms (+/-). IgM is concentrated from harvested cell culture supernatant using 100K MWCO concentrator. The heavy chain of IgM appears to have two glycosylation forms.

[00149] FIG. 6 shows negative stain electron microscopy of IgG-003 pentamers and hexamers. IgG- 003 was diluted to 0.01 mg/mL and 0.02 mg/mL, respectively, in 20 mM Tris-HCl, pH 7.9. Diluted samples were applied to glow-discharged carbon-coated grids and stained with 0.7% uranyl formate, then imaged on a Morgagni microscope (FEI co.) operating at 100 kV. Images were collected at 22,000X magnification on an Orius SC1000 CCD camera (Gatan, Inc.). Scale bar for top image is 50nm.

[00150] FIG. 7 demonstrates negative stain electron microscopy of IgM-003. The method described in Fig. 6 was repeated for IgM-003. Scale bar for top image is 50nm and lOnm for the enlarged images of pentamers and hexamers.

[00151] FIGs. 8A-8B show representative plots of the avidity of IgG and IgM dissociation rates using a label free analysis system (Octet). FIG. 8A represents IgG avidity at l .5625nm, 3T25nm, 6.25nm, l2.5nm, 25nm, 50nm, and lOOnm over time (seconds). FIG. 8B represents IgM avidity at 0.78 l25nm, l .5625nm, 3T25nm, 6.25nm, l2.5nm, 25nm, and 50nm over time (seconds).

[00152] FIGs. 9A-9C demonstrate the method of determining if Plasmodium-specific IgM protects from infection in vivo. FIG. 9A shows the structure of P. berhei MSP1 protein 1-19 (Pb-pbMl9, top, grey regions) and P. berhei with the P. falciparum MSP1 protein (pb-PfMl9, bottom, red regions) FIG. 9B demonstrates FITC and rhodamine expression by wild-type P. berhei (Pbwt), pb-PfMl9 with rhodamine expression only, and Pb-pbMl9. FIG. 9C describes the experimental method of delivery of control IgM, anti-MSPl IgM and anti -MSP 1 IgG to murine animals for a 3 -day period following infection w ith P. berghei with P. falciparum MSP1-19 (Pb-PfMl9). [00153] FIG. 10 shows murine percentage survival after P. bergei infection following administration of 500 pg of control IgM or anti-MSPl-l9 delivered IP daily for 3 days (day 1-3). Control animals died within 10 days of infection by acute lethal malaria. Anti -MSP 1 treated mice survived past 10 days post infection with Pb-Pf l9.

[00154] FIG. 11 demonstrates that IgM treated mice are protected from acute infection. Percent survival for animals treated with control IgM (dashed line), MSP1 IgM (solid line), and MSP1 IgG (dotted line) up to 20 days post-infection with P. bergei (top left). Percentage parasitemia up to 10 days post-infection with P. bergei following treatment with control IgM, MSP1 IgM, and MSP1 IgG (top right). Temperature of animals post-infection with P. bergei following treatment with IgM, MSP1 IgM, and MSP1 IgG (bottom left). Animal mass (grams, g) post-infection following treatment with IgM,

MSP1 IgM, and MSP1 IgG. T-tests with multiple comparisons correction: * for Ctrl IgM, *** for IgG vs MSP IgM

[00155] FIG. 12 shows flow cytometry of Pseudomonas- specific B cells after immunization positive for IgM, IgD, and exotoxin A tetramer in naive mice (top) and 8 days post immunization (bottom).

[00156] FIG. 13 demonstrates flow cytometry of Pseudomonas- specific B cells after immunization expressing IgD (left), IgG (middle), and IgM (right) that were also co-positive for CD73 and CD80 in naive mice (top) and 8 days post immunization (bottom).

[00157] FIG. 14 demonstrates the protective IgM responses as demonstrated by mAh

transfer/neutralization and/or related studies. Recent work shows that secreted IgM can also activate complement at mucosal surfaces.

[00158] FIG. 15 shows that healthy human adult subjects possess IgM+ memory B cells specific for tetanus toxoid C fragment (TTCF), a component of the tetanus vaccine.

[00159] FIGs. 16A-16C shows a schematic representation of the strategy used to convert IgGl monomers to IgG multimers. FIG. 16A shows IgGl, FIG. 16B shows IgGl with L309C mutation and IgM tail piece (ptp) added, FIG. 16C shows a IgGl hexamer. Disulfide bridges are indicated as gray lines.

[00160] FIG. 17 shows SDS-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of MSP19 specific multimer IgGl (m-IgG-003) after purification by protein G affinity column.

[00161] FIG. 18 demonstrates the structural analysis of monomer and multimer IgGls.

[00162] FIG. 19 demonstrates ELISA (enzyme-linked immunosorbent assay) analysis of monomer and corresponding multimer IgGls binding to MSP1-19 protein.

[00163] FIG. 20 shows IFA (Indirect Immunofluorescence Assay) analysis of IgGl multimer (m- IgG-003) binding to malaria parasites (merozoites).

DETAILED DESCRIPTION [00164] IgM ⁺ and IgD ⁺ memory B cells (MBCs) are unique populations of cells with distinct phenotypic, functional and survival properties. The studies described herein demonstrate that antigen-specific IgM ⁺ MBCs express high affinity, somatically hypermutated B cell receptors (BCRs) and rapidly respond to produce antibodies prior to IgG ⁺ MBCs.

[00165] In addition, as shown herein, IgM ⁺ MBCs are high affinity, rapid, plastic, early responders that can initiate the secondary response. Accordingly, antigen-specific IgM+ MBCs and antibodies and antigen binding fragments derived from these cells have significant therapeutic applications in vaccine strategies and treatment of infectious diseases and other indications, including cancer.

[00166] Humoral immunity comprises pre-existing antibodies expressed by long-lived plasma cells and rapidly reactive memory B cells (MBC). Recent studies of MBC development and function after protein immunization have uncovered significant MBC heterogeneity. To clarify functional roles for distinct MBC subsets during infection, the compositions and methods described herein are in part, focused on the protozoan parasitic disease, malaria. Despite some progress, malaria remains difficult to prevent by vaccination. The knowledge gained from the studies described herein in regard to malaria is applicable for memory B cell-derived compositions and methods permitting the targeting of any of a wide range of additional antigens. That is, while the studies described herein focus on malaria as an example of an intractable vaccine target, the methods described herein are applicable to the isolation of memory B cell- derived antigen-binding polypeptide constructs specific for essentially any antigen.

[00167] In the malaria model described herein, in the working examples, tetramers were generated that identify Plasmodium-specific MBCs in both humans and mice. Long-lived murine Plasmodium-specific MBCs were found to be made up of three populations: a somatically hypermutated IgM+ subset, a somatically hypermutated IgG+ MBC subset, and an unmutated IgD+ MBC population. Rechallenge experiments revealed that high affinity, somatically hypermutated Plasmodium-specific IgM+ MBCs proliferated and gave rise to antibody secreting cells that dominated the early secondary response to parasite rechallenge. IgM+ MBCs also gave rise to T cell-dependent IgM+ and IgG+B220+CD l38+ plasmablasts or T cell-independent B220-CD138+ IgM+ plasma cells. Thus, even in competition with IgG+ MBCs, IgM+ MBCs are rapid, plastic, early responders to a secondary Plasmodium rechallenge and thus are novel targets for vaccine strategies.

[00168] B cells play a critical role in immune protection to the blood stage of Plasmodium infection. The protective role for antibody was first demonstrated via passive transfer of hyperimmune

immunoglobulin from adults to parasitemic children (Cohen et ah, 1961), resulting in a dramatic decrease in blood stage parasitemia. Prior to the methods and compositions provided herein, little was known, about the cellular source of Plasmodium- specific antibodies, largely due to a lack of tools to analyze

Plasmodium- specific B cells. Therefore, B cell tetramers specific for the blood stage Plasmodium antigen, Merozoite Surface Protein 1 (MSP1) were generated as described herein, in the working examples. MSP1 is a key surface protein expressed by the parasite and is required for erythrocyte invasion (Kadekoppala and Holder, 2010).

Memory B cells

[00169] Generally, B cells function in the humoral immunity of the adaptive immune system to secrete antibodies during an immune response to a pathogen to prevent infections and disease. B cells collectively refer to a subset of lymphocytes having an antigen-specific receptor termed an immunoglobulin or B cell receptor. Mature B cells differentiate into plasma cells, which produce antibodies, and memory B cells. A "B cell progenitor" is a cell that can develop into a mature B cell. B cell progenitors include stem cells, early pro-B cells, late pro-B cells, large pre-B cells, small pre-B cells, and immature B cells and transitional B cells. Immature B cells can develop into mature B cells, which can produce immunoglobulins (e.g., IgA, IgG or IgM). Mature B cells have acquired surface IgM and IgD, are capable of responding to antigen, and express characteristic markers such as CD21 and CD23 (CD23 ^hl CD2l ^hl cells). Common biological sources of B cells and B cell progenitors include bone marrow, peripheral blood, spleen and lymph nodes.

[00170] B cells that encounter antigen for the first time are known as "naive" B cells and have cell- surface IgM and IgD expression. A mature plasma cell secretes immunoglobulins in response to a specific antigen. A memory B cell is a B cell that initiates a unique differentiation program and also undergoes affinity selection and somatic hypermutation (with or without isotype switching) that is generally found during a secondary immune response (a subsequent antigen exposure following a primary exposure), but can also be detected during a primary antigen response. The development of memory B cells typically takes place in germinal centers (GC) of lymphoid follicles where antigen-driven lymphocytes undergo somatic hypermutation and affinity selection. Typically, memory B cells also express high affinity antigen-specific immunoglobulin (B cell receptor) on their cell surface. Further, memory B cells generally express cell- surface CD27 and CD20 as well.

[00171] Memory B cells, differentiate following contact with an antigen to allow for a rapid response to that antigen when the antigen is presented in a secondary immune response. IgM+ memory B cells are part of a germinal center reaction where mature B cells proliferate, differentiate, and mutate their antibody genes or undergo immunoglobulin isotype switching during an immune response to permit a rapid and antigen- specific immune response.

[00172] In some aspects, provided herein are memory B-cells isolated by any of the methods described herein, that express a B cell receptor that specifically binds an antigen of interest.

[00173] To exemplify, described herein are enrichment techniques that permit the direct ex vivo visualization of rare Plasmodium-specific MBCs in malaria infected humans and mice. Detailed analyses of MSP 1+ MBC formation and function in the rodent model of malaria, Plasmodium chabaudi, were then performed. Both isotype-switched and unswitched MBCs emerged early in infection and persisted for at least one year. MSP1+ MBCs were composed of three distinct subsets including: classically defined, somatically hypermutated, high affinity IgG+ MBCs; an IgM ^lo " IgD'" ⁸¹ ' population that resembled naive B cells; and a third IgM ^hlgh IgD ^low MBC population that expressed somatically hypermutated BCRs that exhibit equivalent affinity to their IgG+ MBC counterparts. In response to various doses of malaria rechallenge, the majority of newly formed antibody-secreting cells (ASCs) were somatically hypermutated IgM+ cells, despite IgM+ MBCs being at a numerical disadvantage at the time of challenge. Furthermore, IgM+ MBCs produced both IgM and IgG antibody in response to rechallenge, thereby also contributing to the IgG+ antibody response two days later. Collectively, these studies demonstrate that Plasmodium- specific IgM+ MBCs are high affinity, pluripotent early responders to malaria rechallenge that can provide a critical stop gap until IgG antibodies are generated and can be used in the development of more effective vaccine strategies. These results are applicable across the spectrum of antigens, whether derived from pathogens (e.g., bacteria, viruses, fungi, protozoa, etc.) or, for example, from tumor antigens.

[00174] Accordingly, provided herein, in some aspects are methods of isolating or sorting antigen- specific IgM memory B cells (MBCs) comprising: (i) contacting a biological sample obtained from a subject having had prior exposure to an antigen of interest with an agent comprising the antigen or a portion thereof; and (ii) isolating or sorting a cell population comprising IgM MBCs based on binding of the BCRs on the MBC surface to the agent comprising the antigen. The high affinity, antigen-specific IgM binding domain from such IgM MBCs can be used to prepare, for example, high affinity recombinant antibodies or antigen binding polypeptide constructs for therapeutic and/or diagnostic purposes, as described herein.

[00175] As shown herein, antigen-specific IgM memory B cells are a subset of B cells expressing antigen-specific, high affinity IgM molecules. The term“antigen-specific IgM memory B cells”, as used herein, refers to a sub-population of B cells expressing cell-surface IgM that are high affinity for an antigen, have undergone somatic hypermutation, and can rapidly respond to antigen challenge to produce antibodies. Cell-surface expression molecules such as CD21, CD27, or both CD21 and CD27 can also be used to identify such MBCs. Other cell-surface molecules that can be used to identify such MBCs include CD73, CD80, or both CD73 and CD80. Memory B cells (MBCs), generally can refer to IgM memory B cells or any other type of memory B cell (MBC).

[00176] As shown herein, one way of identifying IgM memory B cells having cell-surface IgM specific for an antigen of interest, is to use a multimeric form of the antigen of interest, i.e., multimeric antigen complexes, in order to increase the binding avidity of the memory B cells having antigen-specific, cell-surface IgM. Accordingly, in some embodiments of the aspects described herein, the agent comprising an antigen refers to a multimer comprising two or more monomer units of an antigen of interest, /. e. , a dimer, a trimer, a tetramer, a pentamer, etc. In some embodiments of the aspects described herein, the agent comprising an antigen refers to a multimer comprising four monomer units of an antigen of interest, i.e., a tetramer. A“tetramer,” as used herein, refers to an agent comprised of four monomer units each comprising all or a portion of the antigen of interest. Such tetramer agents enable sensitive identification and isolation of IgM memory B cells specific for the antigen of interest by flow cytometry, or other methods known in the art, despite their low frequency.

[00177] Subjects from which IgM memory B cells can be derived or isolated for use in the compositions and methods described herein include any subject that can be exposed to an antigen of interest and from whom IgM memory B cells can subsequently be identified and isolated. Accordingly, in some embodiments, a "subject" refers to a mammal, including, but not limited to, a human or non-human mammal, such as a rodent, including mice and rats, bovine, equine, canine, ovine, feline, or non-human primate. In some embodiments of these aspects and all such aspects described herein, the subject is a human. The term “patient” can be used interchangeably with subject in the compositions and methods described herein.

[00178] In order to obtain memory B cells expressing an IgM or IgG receptor directed to an antigen of interest, the subject from which such memory B cells are derived should have had a primary infection with or been previously exposed to a sufficient amount of the infectious organism from which the antigen of interest or portion thereof is derived, or, alternatively, been exposed to (e.g., vaccinated with) the antigen of interest so as to have generated a memory B cell response or memory B cell population. In regard to a biological sample being obtained from“a subject having had prior exposure to an antigen of interest,” such a subject has previously or currently been exposed to the antigen of interest or infected with an infectious organism or pathogen known to express an antigen of interest. For example, in the case of malarial infections, a subject previously having had malaria or having been exposed to P. falciparum is one who has had prior exposure to any antigen expressed or produced by P . falciparum, such as MSP1 or AMA, such that a population of memory B cells was generated in the subject. Alternatively, it is contemplated that MBCs expressing high affinity BCRs for an antigen of interest can be induced by, for example, administering an antigen of interest, e.g., a specific polypeptide or other antigenic fragment, to a subject. Such a subject would have had prior exposure to the antigen of interest, as defined herein.

[00179] Biological samples, as used herein, refer to any biological sample obtained from a subject from which B cells or B cell progenitor cells can be isolated and include bone marrow, spleen, lymph node, blood, e.g., peripheral blood, tissue biopsies or samples, surgical specimens, fine needle aspirates, autopsy material, and the like. In some embodiments of the aspects described herein, a biological sample refers to a sample isolated from a subject, such as a peripheral blood sample, which is then further processed, for example, by cell sorting (e.g., magnetic sorting and/or FACS), to obtain a population of antigen-specific IgM memory B cells. In other embodiments of the aspects described herein, a biological sample comprising IgM memory B cells refers to an in vitro or ex vivo culture of expanded antigen- specific IgM memory B cells. Such a sample is enriched for antigen-specific IgM memory B cells relative to the proportion of such cells that might occure in, e.g., a blood sample from a subject exposed to the antigen. [00180] In some embodiments of the aspects described herein, the biological sample comprises a peripheral blood sample. In some embodiments of the aspects described herein, the methods comprise sorting the population comprising IgM MBCs using a combination of agents specific for CD21, CD27, and IgM isotype to isolate a population of IgM MBCs.

[00181] In some aspects, provided herein are antigen-binding polypeptide constructs or recombinant antibodies produced or derived from memory B-cells isolated as described herein.

Antigen-binding polypeptides and antibodies

[00182] In one aspect, described herein is a recombinant antigen-binding polypeptide construct comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds an antigen of interest, in an IgM isotype acceptor antibody framework or scaffold.

[00183] The antigen-binding domain will generally comprise both a variable heavy chain polypeptide and a variable light chain polypeptide, but it is contemplated that the antigen-binding domain can comprise only a V _H domain polypeptide or only a V _L domain polypeptide, so long as such domain specifically binds to the antigen of interest.

[00184] The term "antigen-binding polypeptide" refers to a polypeptide that specifically binds to a desired antigen of interest and that is an Ig-like protein comprising one or more of the antigen binding domains described herein linked to a linker or an immunoglobulin constant domain. A binding protein can be, in some embodiments, a dual variable domain (DVD-Ig) binding protein. In one embodiment, an antigen-binding polypeptide comprises CDRs of a B cell or antigen receptor in a framework that permits specific binding to the antigen.

[00185] As used herein, the term“antigen binding domain”, refers to the portion of a B cell receptor, an antibody or antigen binding fragment thereof that physically contacts and provides specific binding to an antigen (e.g., antigen of interest). An antigen binding domain most often comprises V _H and V _L polypeptide sequences. The V _H and V _L polypeptide sequences can be on separate polypeptides for example, in an IgG or IgM format, or they can be parts of a single polypeptide for example, in an ScFv construct (i.e. wherein the V _L and V _H polypeptides are joined by a linker polypeptide).

[00186] A "linker polypeptide" comprises two or more amino acid residues joined by peptide bonds and are used to link one or more antigen binding portions. Such linker polypeptides are well known in the art (see e.g., Holliger et al. (1993) Proc. Natl. Acad. Sci. USA 90: 6444-6448; Poljak (1994) Structure 2:

1121-1123). The length at of the linker peptide or polypeptide can be important for determining whether two domains such as a V _H and V _L domain can interact to form a functional molecule (e.g., a functional antigen-binding domain). Linker length necessary to permit V _H and V _L polypeptide sequences to form an antigen-binding domain are known to those of skill in the art. [00187] As used herein, the term“IgM antigen binding unit” refers to an antibody or antigen-binding polypeptide construct which comprises two light chains and two IgM heavy chains. It should be understood that an IgM antigen-binding unit is typically bivalent (i.e., it has two antigen binding domains). An IgM antigen binding unit has the capacity to multimerize via interactions between heavy chains, including heavy chain tailpiece interactions. The IgM heavy chain is a mu (m) heavy chain.

[00188] As used herein, the term“IgG antigen binding unit” refers to an antibody or antigen-binding polypeptide construct which comprises two light chains and two IgG heavy chains. It should be understood that an IgG antigen-binding unit is typically bivalent (i.e., it has two antigen binding domains). IgG has a gamma (g) heavy chain. An IgG typically has two antigen-binding domains.

[00189] In some embodiments, the antigen-binding domain comprises variable heavy chain and variable light chain amino acid sequences from the IgM memory B cell. In some embodiments, described herein is a recombinant polypeptide construct comprising an antigen-binding unit comprising heavy and light chain variable domains of a B cell receptor of a naive B cell, and an IgM heavy chain constant domain.

[00190] An immunoglobulin constant domain refers to a heavy or light chain constant domain. Human IgG heavy chain and light chain constant domain amino acid sequences are known in the art, ( e.g ., see SEQ ID NO: 197, 198, 199 and 200 of US Application 2016/0200813, which is incorporated herein in its entirety by reference for representative examples). In various embodiments, the binding proteins and antibodies disclosed herein can comprise any of the constant domains of SEQ ID NO: 197, 198, 199 and 200 of US Application 2016/0200813. See also, Kabat et al, Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991), which describes heavy and light chain sequences for various isotype classes and subtypes of antibodies.

[00191] As known to those of skill in the art, the term "antibody" broadly refers to any

immunoglobulin (Ig) molecule and immunologically active portions of immunoglobulin molecules (i.e., molecules that contain an antigen binding site that immunospecifically bind an antigen) comprised of four polypeptide chains, two heavy (H) chains and two light (L) chains, or any functional fragment, mutant, variant, or derivation thereof, which retains the essential epitope binding features of an Ig molecule. Such mutant, variant, or derivative antibody formats are known in the art. Non-limiting embodiments of such are discussed below, and include but are not limited to a variety of forms, including full length antibodies and antigen-binding portions thereof; including, for example, an immunoglobulin molecule, a monoclonal antibody, a chimeric antibody, a CDR-grafted antibody, a human antibody, a humanized antibody, a single chain antibody, a Fab, a F(ab'), a F(ab')2, a Fv antibody, fragments produced by a Fab expression library, a disulfide linked Fv, a scFv, a single domain antibody (dAb), a diabody, a multispecific antibody, a dual specific antibody, an anti-idiotypic antibody, a bispecific antibody, a functionally active epitope binding fragment thereof, bifunctional hybrid antibodies (e.g., Fanzavecchia et al., Eur. J. Immunol. 17, 105 (1987)) and single chains ( e.g ., Huston et al., Proc. Natl. Acad. Sci. U.S.A., 85, 5879-5883 (1988) and Bird et al., Science 242, 423-426 (1988), Brinkman et al. mAbs Vol 9, No. 2, 182-212 (2017), which are incorporated herein by reference in their entirety) and/or antigen-binding fragments of any of the above (See, generally, Hood et al., Immunology, Benjamin, N.Y., 2ND ed. (1984), Harlow and Lane, Antibodies. A Laboratory Manual, Cold Spring Harbor Laboratory (1988) and Hunkapiller and Hood, Nature, 323, 15- 16 (1986), which are incorporated herein by reference). Antibodies also refer to immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, i.e., molecules that contain antigen or target binding sites or "antigen-binding fragments."

[00192] The antibody or immunoglobulin molecules described herein can be of any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgGl, IgG2, IgG3, IgG4, IgAl and IgA2) or subclass of immunoglobulin molecule, as is understood by one of skill in the art. Furthermore, in humans, the light chain can be a kappa chain or a lambda chain. As shown herein, high affinity CDRs from IgM+ memory B cells can be used to construct or derive other recombinant antibodies or polypeptide constructs having those CDRs, but different class types, for example.

[00193] Any IgM provides a framework or scaffold from which the CDRs can be removed or replaced with CDRs from another antibody, whether they are from an IgM or other isotype (e.g., IgA, IgD, IgE, or IgG). The IgM isotype acceptor antibody framework can be derived from any species (e.g, mammalian). Furthermore, the IgM isotype acceptor antibody framework can be multimeric, and approaches that generate multimeric IgG are also described herein.

[00194] As used herein, the term“IgM isotype acceptor antibody framework,” refers to the heavy and light chain constant domains of an IgM, onto which heterologous V _H , V _L , and/or CDRs from a V _H and/or V _L can be or have been grafted. It should be understood that an IgM isotype acceptor antibody framework permits multimerization into, for example, a pentameric or hexameric configuration. The IgM isotype acceptor antibody framework can be thought of as a scaffold for heterologous antigen binding domains or CDRs thereof.

[00195] As understood by those of skill in the art, in a full-length antibody, each heavy chain is comprised of a heavy chain variable domain (abbreviated herein as HCVR or V _H ) and a heavy chain constant region. The heavy chain constant region is comprised of three domains: CM, C _H 2, and C _H 3. Each light chain is comprised of a light chain variable domain (abbreviated herein LCVR as V _L ) and a light chain constant region. The light chain constant region is comprised of one domain, C _L . The V _H and V _L regions can be further subdivided into regions of hypervariability, termed complementarity determining regions (CDRs), interspersed with regions that are more conserved regions, termed framework regions (FR). Each V _H and V _L is composed of three CDRs and four FRs, arranged from amino-terminus to carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. This structure is well-known to those skilled in the art. In naturally occurring antibodies and in many antigen-binding polypeptide constructs, the chains are usually linked to one another via disulfide bonds.

[00196] As used herein, the term "Complementarity Determining Regions" ("CDRs"), i.e., CDR1, CDR2, and CDR3) refers to the amino acid residues of a heavy or light chain variable domain the presence of which are necessary for specific antigen binding. Each variable domain typically has three CDR regions identified as CDR1, CDR2 and CDR3. Each complementarity determining region can comprise amino acid residues from a "complementarity determining region" as defined by Rabat (i.e., about residues 24-34 (Ll), 50-56 (L2) and 89-97 (L3) in the light chain variable domain and 31-35 (Hl), 50-65 (H2) and 95-102 (H3) in the heavy chain variable domain; Rabat et ah, Sequences of Proteins of Immunological Interest,

5th Ed. Public Health Service, National Institutes of Health, Bethesda, Md. (1991)) and/or those residues from a "hypervariable loop" (i.e., about residues 26-32 (Ll), 50-52 (L2) and 91-96 (L3) in the light chain variable domain and 26-32 (Hl), 53-55 (H2) and 96-101 (H3) in the heavy chain variable domain; Chothia and Lesk J. Mol. Biol. 196:901-917 (1987)). In some instances, a complementarity determining region can include amino acids from both a CDR region defined according to Rabat and a hypervariable loop. The term "CDR set" as used herein refers to a group of three CDRs that occur in a single heavy or light chain variable region capable of binding the antigen. The exact boundaries of these CDRs have been defined differently according to different systems. The system described by Rabat (Rabat et al, Sequences of Proteins of Immunological Interest (National Institutes ofHealth, Bethesda, Md. (1987) and (1991)) not only provides an unambiguous residue numbering system applicable to any variable region of an antibody, but also provides precise residue boundaries defining the three CDRs. These CDRs may be referred to as Rabat CDRs. Chothia and coworkers (Chothia & Lesk, J. Mol. Biol, 196:901-917 (1987) and Chothia et al., Nature 342:877-883 (1989)) found that certain sub-portions within Rabat CDRs adopt nearly identical peptide backbone conformations, in spite of great diversity at the level of amino acid sequence. These sub portions were designated as Ll, L2 and L3 or Hl, H2 and H3 where the "L" and the "H" designates the light chain and the heavy chains regions, respectively. These regions may be referred to as Chothia CDRs, which have boundaries that overlap with Rabat CDRs. Other boundaries defining CDRs overlapping with the Rabat CDRs have been described by Padlan (FASEB). 9: 133-139 (1995)) and MacCallum (J Mol Biol 262(5):732-45 (1996)). Still other CDR boundary definitions may not strictly follow one of the above systems, but will nonetheless overlap with the Rabat CDRs, although they may be shortened or lengthened in light of prediction or experimental findings that particular residues or groups of residues or even entire CDRs do not significantly impact antigen binding. CDRs can also be described as comprising amino acid residues from a "complementarity determining region" as defined by the IMGT, in some embodiments.

The compositions and methods used herein may utilize CDRs defined according to any of these systems, although preferred embodiments use IMGT defined CDRs. Nonetheless, the boundaries of the CDRs are clear in reference to either of these numbering conventions. [00197] An immunoglobulin constant (C) domain refers to a heavy (C _H ) or light (C _L ) chain constant domain. Murine and human IgG heavy chain and light chain constant domain amino acid sequences are known in the art. With respect to the heavy chain, in some embodiments of the aspects described herein, the heavy chain of an antibody described herein can comprise an alpha (a), delta (D), epsilon (s), gamma (g) or mu (m) heavy chain. Non-limiting examples of human constant region sequences have been described in the art, e.g., see U.S. Pat. No. 5,693,780 and Kabat E A et al., (1991) supra.

[00198] The mu (m) heavy chain of IgM is a protein of about 576 amino acids, and includes a variable domain (V _H ) of about 110 amino acids, four distinct constant region domains (Cpl, Cp2, Cp3, Cp4, each -110 amino acids) and a“tailpiece” of -20 amino acids.

[00199] As used herein, the terms "donor" and "donor antibody" refer to an antibody providing one or more CDRs. In an exemplary embodiment, the donor antibody is an antibody from a species different from the antibody from which the framework regions are obtained or derived. In some embodiments, the donor antibody is of a different isotype than the acceptor antibody. In the context of a humanized antibody, the term "donor antibody" refers to a non-human antibody providing one or more CDRs.

[00200] As used herein, the terms "acceptor" and "acceptor antibody" refer to the antibody providing or nucleic acid sequence encoding at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or 100% of the amino acid sequences of one or more of the framework regions. In some embodiments, the term "acceptor" refers to the antibody amino acid providing or nucleic acid sequence encoding the constant region(s). In yet another embodiment, the term "acceptor" refers to the antibody amino acid providing or nucleic acid sequence encoding one or more of the framework regions and the constant region(s). In a specific embodiment, the term "acceptor" refers to a human antibody amino acid or nucleic acid sequence that provides or encodes at least 80%, preferably, at least 85%, at least 90%, at least 95%, at least 98%, or 100% of the amino acid sequences of one or more of the framework regions. In accordance with this embodiment, an acceptor may contain at least 1, at least 2, at least 3, least 4, at least 5, or at least 10 amino acid residues that does (do) not occur at one or more specific positions of a human antibody. An acceptor framework region and/or acceptor constant region(s) may be, e.g., derived or obtained from a germline antibody gene, a mature antibody gene, a functional antibody (e.g., antibodies well known in the art, antibodies in development, or antibodies commercially available).

[00201] Human heavy chain and light chain acceptor sequences are known in the art. In some embodiments, the human heavy chain and light chain acceptor sequences are selected from the sequences listed from V-base (found on the worldwide web at vbase.mrc-cpe.cam.ac.uk/) or from IMGT™ the international IMMUNOGENETICS INFORMATION SYSTEM™ (found on the worldwide web at imgt.cines.fr/textes/IMGTrepertoire/LocusGenes/). In another embodiment of the technology disclosed herein, the human heavy chain and light chain acceptor sequences are selected from the sequences described in Table 3 and Table 4 of U.S. Patent Publication No. 2011/0280800, incorporated by reference herein in their entireties.

[00202] In some embodiments of any of the aspects, the recombinant polypeptides and antibodies described herein comprise an IgM CM domain sequence of IMGT Accession: X14940, K01307, X57331, AC254827.

[00203] In some embodiments of any of the aspects, the recombinant polypeptides and antibodies described herein comprise an IgM C _H 2 domain sequence of IMGT Accession: X14940, K01308, K01309, X57331, and/or AC254827.

[00204] In some embodiments of any of the aspects, the recombinant polypeptides and antibodies described herein comprise an IgM C _H 3 domain sequence of IMGT Accession: V00561, X14940, K01309, X57331, and/or AC254827.

[00205] In some embodiments of any of the aspects, the recombinant polypeptides and antibodies described herein comprise an IgM C _H 4 domain sequence of IMGT Accession: J00260, X14940, X57331, and/or AC254827.

[00206] In addition to the IgM constant domains, multimeric IgM comprises a J chain and an IgM tail piece that permit formation of pentamers and hexamers.

[00207] As used herein, the term“J chain” refers to a 137 residue polypeptide, encoded by the IGJ gene that allows for joining of the pentameric immunoglobulin structures. Sequences for the human IGJ gene are known in the art, for example, (IGMT Accesion: J00256, X86355, M25625, AJ879487). The J chain establishes the disulfide bridges between IgM antibodies to form multimeric structures such as pentamers. See, for example, S0rensen et al. International Immunology, (2000), Pages 19-27, which is incorporated herein in its entirety for the structural requirements for incorporation of J chain into human IgM and IgA isotypes. It should be noted that the native hexameric IgM never contains a J chain; pentameric IgM can be formed so as to include or not include J chain.

[00208] In some embodiments, a recombinant antigen-binding polypeptide construct described herein comprises a J chain sequence.

[00209] As used herein, the term“IgM tail piece” refers to an 18-amino acid extension on the C-terminal constant domain of the IgM antibody. The tailpiece includes a cysteine residue that forms a disulfide bond between heavy chains to permit formation of an IgM multimer (e.g., pentamers or hexamers of IgM). In IgM, specifically, two additional cysteine residues in the heavy chain (Cys4l4) and (Cys337) are availabile fo linking heavy chains in the multimer as well. It should be noted that IgA also has a secretory tailpiece that is homologous with the IgM tailpiece by 11 of the 18 amino acids. Deletion of the IgM tailpiece prevents formation of polymeric IgMs. Alternatively, cells expressing a tailpiece grafted onto the C-terminus of a gamma (g) heavy chain (i.e., of IgG), can permit the formation of a mulimeric IgG. [00210] As used herein, the term "germline antibody gene" or "germline antibody gene fragment" refers to immunoglobulin-encoding nucleic acid sequence encoded by non-lymphoid cells that have not undergone the maturation process that leads to genetic rearrangement and mutation for expression of a particular immunoglobulin. (See, e.g., Shapiro et al. (2002) Crit. Rev. Immunol. 22(3): 183-200; Marchalonis et al. (2001) Adv. Exp. Med. Biol. 484: 13-30). One of the advantages provided by embodiments that use germline antibody sequences, e.g., for one or more constant domains, stems from the recognition that germline antibody genes are more likely than mature antibody genes to conserve essential amino acid sequence structures characteristic of individuals in the species, hence less likely to be recognized as from a foreign source when used therapeutically in that species.

[00211] As used herein, the term "key" residues refers to certain residues within the variable domain that have more impact on the binding specificity and/or affinity of an antibody, in particular a humanized antibody, than others. A key residue includes, but is not limited to, one or more of the following: a residue that is adjacent to a CDR, a potential glycosylation site (can be either N- or O-glycosylation site), a rare residue, a residue capable of interacting with the antigen, a residue capable of interacting with a CDR, a canonical residue, a contact residue between heavy chain variable domain and light chain variable domain, a residue within the Vernier zone, and a residue in the region that overlaps between the Chothia definition of a variable heavy chain CDR/and the Rabat definition of the first heavy chain framework.

[00212] In some embodiments, a recombinant antigen-binding polypeptide construct described herein comprises human antigen-binding and constant domains.

[00213] The term "humanized antibody" refers to antibodies that comprise heavy and light chain variable domain sequences from a non-human species (e.g., a mouse) but in which at least a portion of the VH and/or VL sequence has been altered to be more "human-like", i.e., more similar to human germline variable sequences. Accordingly, "humanized" antibodies are a form of a chimeric antibody, that are engineered or designed to comprise minimal sequence derived from non-human immunoglobulin. For the most part, humanized antibodies are human immunoglobulins (recipient or acceptor antibody) in which residues from a hypervariable region of the recipient are replaced by residues from a hypervariable region of a non-human species (donor antibody) such as mouse, rat, rabbit or nonhuman primate having the desired specificity, affinity, and capacity. In some instances, Fv framework region (FR) residues of the human immunoglobulin are replaced by corresponding non-human residues. Furthermore, humanized antibodies can comprise residues which are not found in the recipient antibody or in the donor antibody. These modifications are made to further refine antibody performance. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable loops correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin sequence. The humanized antibody optionally also will comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details, see Jones et al, Nature 321:522-525 (1986); Riechmann et al, Nature 332:323-329 (1988); and Presta, Curr. Op. Struct. Biol. 2:593-596 (1992). As used herein, a“composite human antibody” or“deimmunized antibody” are specific types of engineered or humanized antibodies designed to reduce or eliminate T cell epitopes from the variable domains.

[00214] The compositions and methods described herein can, in some embodiments, comprise “antigen-binding fragments” or“antigen-binding portions” of an antibody. The term "antigen-binding fragment" of an antibody refers to one or more fragments of an antibody that retain the ability to specifically bind to an antigen. Antigen-binding functions of an antibody can be performed by fragments of a f ill-length antibody. Such antibody fragment embodiments may also be incorporated in bispecific, dual specific, or multi-specific formats such as a dual variable domain (DVD-Ig) format; specifically binding to two or more different antigens. Non-limiting examples of antigen-binding fragments encompassed within the term "antigen-binding portion" of an antibody include (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL, and C’H 1 domains; (ii) a F(ab')2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and C’H 1 domains; (iv) a Fv fragment consisting of the VL and VH domains of a single arm of an antibody, (v) a dAb fragment (Ward et al. (1989) Nature, 341: 544-546; PCT Publication No. WO 90/05144), which comprises a single variable domain; and (vi) an isolated complementarity determining region (CDR). Furthermore, although the two domains of the Fv fragment, VL and VH, are coded for by separate genes, they can be joined, using recombinant methods, by a synthetic linker that enables them to be made as a single protein chain in which the VL and VH regions pair to form monovalent molecules (known as single chain Fv (scFv); see, for example, Bird et al. (1988) Science 242: 423-426; and Huston et al. (1988) Proc. Natl. Acad. Sci. USA 85: 5879-5883). Such single chain antibodies are also intended to be encompassed within the term "antigen-binding portion" of an antibody. Other forms of single chain antibodies, such as diabodies are also encompassed. Diabodies are bivalent, bispecific antibodies in which VH and VL domains are expressed on a single polypeptide chain, but using a linker that is too short to allow for pairing between the two domains on the same chain, thereby forcing the domains to pair with complementary domains of another chain and creating two antigen binding sites (see, for example, Holliger et al. (1993) Proc. Natl. Acad. Sci. USA 90: 6444-6448; Poljak (1994) Structure 2: 1121-1123); Kontermann and Dubel eds., Antibody Engineering, Springer-Verlag,

N.Y. (2001), p. 790 (ISBN 3-540-41354-5). In addition, single chain antibodies also include "linear antibodies" comprising a pair of tandem Fv segments (V _H -C _H l-V _H -C _H l) which, together with

complementary light chain polypeptides, form a pair of antigen binding regions (Zapata et al. (1995) Protein Eng. 8(10): 1057-1062; and U.S. Pat. No. 5,641,870).

[00215] The term "Fc region" is used to define the C-terminal region of an immunoglobulin heavy chain, which may be generated by papain digestion of an intact antibody. The Fc region may be a native sequence Fc region or a variant Fc region. The Fc region of an immunoglobulin generally comprises two constant domains, a C _H 2 domain, and a C _H 3 domain, and optionally comprises a CH4 domain.

Replacements of amino acid residues in the Fc portion to alter antibody effector function are known in the art (U.S. Pat. Nos. 5,648,260 and 5,624,821). The Fc portion of an antibody mediates several important effector functions, for example, cytokine induction, antibody-dependent cell cytotoxicity (ADCC), phagocytosis, complement dependent cytotoxicity (CDC), and half-life/clearance rate of antibody and antigen-antibody complexes. In some cases, these effector functions are desirable for therapeutic antibody but in other cases might be unnecessary or even deleterious, depending on the therapeutic objectives.

Certain human IgG isotypes, particularly IgGl and IgG3, mediate ADCC and CDC via binding to Fey receptors and complement Clq, respectively. Neonatal Fc receptors (FcRn) are the critical components determining the circulating half-life of antibodies. In still another embodiment at least one amino acid residue is replaced in the constant region of the antibody, for example the Fc region of the antibody, such that effector functions of the antibody are altered.

[00216] The DNA sequences encoding the antibodies or antigen-binding fragments that specifically bind an antigen of interest described herein, e.g., antibodies or antigen-binding fragments specifically binding a malarial or other antigen of interest, can also be modified, for example, by substituting the coding sequence for human heavy- and light-chain constant domains or framework regions in place of the homologous murine sequences (U.S. Pat. No. 4,816,567; Morrison, et al, Proc. Natl. Acad. Sci. USA, 81:6851 (1984)), or by covalently joining to the immunoglobulin coding sequence all or part of the coding sequence for a non-immunoglobulin polypeptide, as also described elsewhere herein.

[00217] Such non-immunoglobulin polypeptides can be substituted for the constant domains of an antibody, or they can be substituted for the variable domains of one antigen-binding site of an antibody to create a chimeric bivalent antibody comprising one antigen- binding site having specificity for one antigen of interest and another antigen- binding site having specificity for a different antigen of interest.

[00218] The term "homology" or“homologous” as used herein refers to sequence similarity between two peptides or between two nucleic acid molecules. Homology can be determined by comparing a position in each sequence which may be aligned for purposes of comparison. When an equivalent position in the compared sequences is occupied by the same base or amino acid, then the molecules are identical at that position; when the equivalent site occupied by the same or a similar amino acid residue (e.g., similar in steric and/or electronic nature), then the molecules can be referred to as homologous (similar) at that position. Expression as a percentage of homology refers to a function of the number of identical or similar amino acids at positions shared by the compared sequences. A sequence which is "unrelated" or "non- homologous" shares less than 40% identity. Determination of homologs of the genes or peptides described herein may be easily ascertained by the skilled artisan. [00219] The sequences provided here can be modified, comprise conservative amino acid substitutions, or have additional amino acids that can improve targeting or efficacy of the composition described herein. In some embodiments of any of the aspects, the first polypeptide has an amino acid sequence with at least 99% homology to the second polypeptide. In some embodiments of any of the aspects, the third polypeptide has an amino acid sequence with at least 99% homology to the fourth polypeptide. In some embodiments of any of the aspects, the first polypeptide has an amino acid sequence that is non-homologous to the second polypeptide. In some embodiments of any of the aspects, the third polypeptide has an amino acid sequence that is non-homologous to the fourth polypeptide. In some embodiments of any of the aspects, the first or second polypeptide has an amino acid sequence that is non-homologous to the third and/or fourth polypeptides.

[00220] The term "conservative substitution," when describing a polypeptide, refers to a change in the amino acid composition of the polypeptide that does not substantially alter the polypeptide's activity, fore examples, a conservative substitution refers to substituting an amino acid residue for a different amino acid residue that has similar chemical properties. Conservative amino acid substitutions include replacement of a leucine with an isoleucine or valine, an aspartate with a glutamate, or a threonine with a serine.

"Conservative amino acid substitutions" result from replacing one amino acid with another having similar structural and/or chemical properties, such as the replacement of a leucine with an isoleucine or valine, an aspartate with a glutamate, or a threonine with a serine. Thus, a "conservative substitution" of a particular amino acid sequence refers to substitution of those amino acids that are not critical for polypeptide activity or substitution of amino acids with other amino acids having similar properties (e.g., acidic, basic, positively or negatively charged, polar or non-polar, etc.) such that the substitution of even critical amino acids does not substantially alter activity. Conservative substitution tables providing functionally similar amino acids are well known in the art. For example, the following six groups each contain amino acids that are conservative substitutions for one another: 1) Alanine (A), Serine (S), Threonine (T); 2) Aspartic acid (D), Glutamic acid (E); 3) Asparagine (N), Glutamine (Q); 4) Arginine (R), Lysine (K); 5) Isoleucine (I),

Leucine (L), Methionine (M), Valine (V); and 6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W). (See also Creighton, Proteins, W. H. Freeman and Company (1984).) In addition, individual substitutions, deletions or additions that alter, add or delete a single amino acid or a small percentage of amino acids in an encoded sequence are also "conservative substitutions." Insertions or deletions are typically in the range of about 1 to 5 amino acids.

[00221] Memory B cell receptor antigen-binding domains isolated as described herein are readily isolated from a human (e.g., through use of a human blood sample). Nonetheless, if also desired, memory B cell antigen binding domains can be isolated from non-human sources. Thus, also provided herein, in some aspects, are humanized antibodies and antigen-binding fragments for use in the compositions and methods described herein. Humanized forms of non-human (e.g., murine) antibodies refer to chimeric antibodies that contain minimal sequence derived from non-human immunoglobulin. For the most part, humanized antibodies are human immunoglobulins (recipient antibody) in which residues from a hypervariable region of the recipient are replaced by residues from a hypervariable region of a non-human species (donor antibody) such as mouse, rat, rabbit or nonhuman primate having the desired specificity, affinity, and capacity. In some embodiments, Fv framework region (FR) residues of the human immunoglobulin can be replaced by corresponding non-human residues. Furthermore, humanized antibodies can comprise residues that are not found in the recipient antibody or in the donor antibody. These modifications are made to further refine antibody performance. In general, a humanized antibody can comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the hypervariable loops correspond to those of a non-human immunoglobulin and all or substantially all of the FR regions are those of a human immunoglobulin sequence. The humanized antibody optionally also can comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. For further details, see Jones et al, Nature 321:522-525 (1986); Riechmann et al, Nature 332:323-329 (1988); and Presta, Curr.

Op. Struct. Biol. 2:593-596 (1992).

[00222] A humanized antibody has one or more amino acid residues introduced into it from a source which is non-human. These non-human amino acid residues are often referred to as "import" residues, which are typically taken from an "import" variable domain. Humanization can be essentially performed following the method of Winter and co-workers (Jones et al., Nature, 321:522-525 (1986); Riechmann et al., Nature, 332:323-327 (1988); Verhoeyen et al, Science, 239: 1534-1536 (1988)), by substituting rodent CDRs or CDR sequences for the corresponding sequences of a human antibody. Accordingly, such humanized antibodies are chimeric antibodies (U.S. Pat. No. 4,816,567) where substantially less than an intact human variable domain has been substituted by the corresponding sequence from a non-human species. In practice, humanized antibodies are typically human antibodies in which some CDR residues and possibly some FR residues are substituted by residues from analogous sites in rodent antibodies.

[00223] While applicable to the variable domains and CDRs of any B cell receptor expressed by an MBC, CDRs of murine MBCs exemplified herein can be used to generate humanized antibody constructs. Accordingly, in some embodiments, humanized antibodies comprising one or more variable domains comprising one or more CDRs encoded by the variable heavy chain sequences of SEQ ID NOs: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 23, and/or one or more CDRs encoded by the variable light chain sequences of SEQ ID NOs: 2, 4, 6, 8, 10, 12, 14, 16, 19, 20, 22, and 24, are provided. Accordingly, in some embodiments of the aspects provided herein, the CDR sequences encoded by the variable heavy chain sequences of SEQ ID NOs: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 23, and/or the CDRs encoded by the variable light sequences of SEQ ID NOs: 2, 4, 6, 8, 10, 12, 14, 16, 19, 20, 22, and 24 can be used to generate, for example, CDR-grafted, chimeric, humanized, or composite human antibodies or antigen-binding fragments, as described elsewhere herein. As understood by one of ordinary skill in the art, any variant, CDR-grafted, chimeric, humanized, or composite antibodies or antigen-binding fragments derived from any of these sequences will maintain the ability to immunospecifically bind the antigen of interest, such that the variant, CDR-grafted, chimeric, humanized, or composite antibody or antigen-binding fragment thereof has at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% , at least 100%, or any amount greater than the binding affinity to the antigen of interest relative to the original antibody from which it is derived.

[00224] In some embodiments of the aspects described herein, the antigen-binding construct, antibody or antigen-binding fragment thereof comprises one, two, three, or four of the framework regions of a heavy chain variable region sequence which is at least 75%, 80%, 85%, 90%, 95% or 100% identical to one, two, three or four of the framework regions of the heavy chain variable region sequence from which it is derived. In some embodiments of the aspects described herein, the heavy chain variable framework region that is derived from said amino acid sequence consists of said amino acid sequence but for the presence of up to 10 amino acid substitutions, deletions, and/or insertions, preferably up to 10 amino acid substitutions. In some embodiments of the aspects described herein, the heavy chain variable framework region that is derived from said amino acid sequence consists of said amino acid sequence with 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 amino acid residues being substituted for an amino acid found in an analogous position in a corresponding non human, primate, or human heavy chain variable framework region. In some embodiments of the aspects described herein, the the antigen-binding construct, antibody or antigen-binding fragment further comprises one, two, three or all four VH framework regions derived from the VH of a human or primate antibody. The primate or human heavy chain framework region of the antibody selected for use with the heavy chain CDR sequences described herein, can have, for example, at least 70% identity with a heavy chain framework region of the non-human parent antibody. Preferably, the primate or human antibody selected can have the same or substantially the same number of amino acids in its heavy chain complementarity determining regions encoded by the variable heavy chain sequences of SEQ ID NOs: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 23. In some embodiments of the aspects described herein, the primate or human heavy chain framework region amino acid residues are from a natural primate or human antibody heavy chain framework region having at least 75% identity, at least 80% identity, at least 85% identity (or more) with the heavy chain framework regions of any of the antibodies described herein. In specific embodiments, the the antigen binding construct, antibody or antigen-binding fragment further comprises one, two, three or all four VH framework regions derived from a human heavy chain variable subfamily (e.g., one of subfamilies 1 to 7).

[00225] In some such embodiments of the aspects described herein, the the antigen-binding construct, antibody or antigen-binding fragment thereof comprises one, two, three or four of the framework regions of a light chain variable region sequence which is at least 75%, 80%, 85%, 90%, 95%, or 100% identical to one, two, three or four of the framework regions of the light chain variable region sequence from which it is derived. In some embodiments of the aspects described herein, the light chain variable framework region that is derived from said amino acid sequence consists of said amino acid sequence but for the presence of up to 10 amino acid substitutions, deletions, and/or insertions, preferably up to 10 amino acid substitutions. In some embodiments of the aspects described herein, the light chain variable framework region that is derived from said amino acid sequence consists of said amino acid sequence with 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 amino acid residues being substituted for an amino acid found in an analogous position in a

corresponding non-human, primate, or human light chain variable framework region. In some embodiments of the aspects described herein, the the antigen-binding construct, antibody or antigen-binding fragment further comprises one, two, three or all four VL framework regions derived from the VL of a human or primate antibody. The primate or human light chain framework region of the antibody selected for use with the light chain CDR sequences described herein, can have, for example, at least 70% identity with a light chain framework region of the non-human parent antibody. The primate or human antibody selected can have the same or substantially the same number of amino acids in its light chain CDRs to that of the light chain complementarity determining regions encoded by the variable light chain sequences of SEQ ID NOs: 2, 4, 6, 8, 10, 12, 14, 16, 19, 20, 22, and 24. In some embodiments of the aspects described herein, the primate or human light chain framework region amino acid residues are from a natural primate or human antibody light chain framework region having at least 75% identity, at least 80% identity, at least 85% identity (or more) with the light chain framework regions of any of the the antigen-binding constructs or antibodies described herein. In some embodiments, the the antigen-binding construct, antibody or antigen binding fragment further comprises one, two, three or all four VL framework regions derived from a human light chain variable kappa subfamily. In some embodiments, the the antigen-binding construct, antibody or antigen-binding fragment further comprises one, two, three or all four VL framework regions derived from a human light chain variable lambda subfamily.

[00226] In some embodiments of the aspects described herein, the position of one or more CDRs along the VH (e.g., CDR1, CDR2, or CDR3) and/or VL (e.g., CDR1, CDR2, or CDR3) region of an the antigen binding construct or antibody described herein can vary, i.e., be shorter or longer, by one, two, three, four, five, or six amino acid positions so long as immunospecific binding to the antigen of interest is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody or B cell receptor from which it is derived). For example, in some embodiments, the position defining a CDR can vary, i.e., be shorter or longer, by shifting the N-terminal and/or C-terminal boundary of the CDR by one, two, three, four, five, or six amino acids, relative to the CDR position of any one of the antibodies described herein, so long as immunospecific binding to the antigen of interest is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody from which it is derived). In other embodiments, the length of one or more CDRs along the VH (e.g., CDR1, CDR2, or CDR3) and/or VL (e.g., CDR1, CDR2, or CDR3) region of an antibody described herein can vary (e.g., be shorter or longer) by one, two, three, four, five, or more amino acids, so long as immunospecific binding to the antigen of interest is maintained (e.g., substantially maintained, for example, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95% of the binding of the original antibody or B cell receptor from which it is derived).

[00227] In some embodiments of the aspects described herein, one, two or more mutations (e.g. , amino acid substitutions) are introduced into the Fc region of an antibody described herein or an antigen-binding fragment thereof (e.g., C _H domain (residues 231-340 of human IgGl) and/or C _H 3 domain (residues 341- 447 of human IgGl) and/or the hinge region, with numbering according to the Kabat numbering system (e.g., the EU index in Kabat)) to increase or decrease the affinity of the antibody for an Fc receptor (e.g., an activated Fc receptor) on the surface of an effector cell or to alter one or more functional properties of the antibody, such as serum half-life, complement fixation, Fc receptor binding and/or antigen-dependent cellular cytotoxicity.

[00228] Mutations in the Fc region of an antibody or fragment thereof that decrease or increase the affinity of an antibody for an Fc receptor and techniques for introducing such mutations into the Fc receptor or fragment thereof are known to one of skill in the art. Examples of mutations in the Fc receptor of an antibody that can be made to alter the affinity of the antibody for an Fc receptor are described in, e.g., Smith P et al., (2012) PNAS 109: 6181-6186, U.S. Pat. No. 6,737,056, and International Publication Nos. WO 02/060919; WO 98/23289; and WO 97/34631, which are incorporated herein by reference.

[00229] In some embodiments of the aspects described herein, one, two or more mutations (e.g. , amino acid substitutions) are introduced into the hinge region of the Fc region (CH 1 domain) such that the number of cysteine residues in the hinge region are altered (e.g., increased or decreased) as described in, e. g _; U.S. Pat. No. 5,677,425. The number of cysteine residues in the hinge region of the CM domain can be altered to, e.g., facilitate assembly of the light and heavy chains, or to alter (e.g., increase or decrease) the stability of the antigen-binding construct or antibody.

[00230] The term“CDR-grafted antibody” refers to antibodies which comprise heavy and light chain variable region sequences from one antigen-binding domain, but in which the sequences of one or more of the CDR regions of VH and/or VL are replaced with CDR sequences of another antigen-binding domain, such as antibodies having human heavy and light chain variable regions in which one or more of the human CDRs (e.g., CDR3) has been replaced with mouse CDR sequences. CDR-grafted antibodies described herein comprise heavy and light chain variable region sequences from a human antibody wherein one or more of the CDR regions of VH and/or VL are replaced with CDR sequences of a B cell receptor, such as a memory B cell receptor, such as an IgM memory B cell receptor. Grafting can put one or more non-human CDRs, e.g., encoded by the variable heavy chain sequences of SEQ ID NOs: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 23, and/or one or more CDRs encoded by the variable light chain sequences of SEQ ID NOs: 2, 4, 6, 8, 10, 12, 14, 16, 19, 20, 22, and 24 into an antigen-binding construct or antibody described herein. [00231] In some embodiments of these aspects and all such aspects described herein, the memory B cell receptor (e.g., IgM MBC) antigen-binding domain is a human IgM memory B cell receptor antigen binding domain. For example, provided herein are amino acid sequences for heavy chain antigen binding domains derived from malarial antigen-specific human IgM memory B cells (SEQ ID NOs: 26, 36, 46, 56, 66, 76, 86, 96, 106, 116, 126, 136, and 146) and amino acid sequences for light chain antigen binding domains derived from malarial antigen-specific human IgM memory B cells (SEQ ID NOs: 31, 41, 51, 61, 71, 81, 91, 101, 111, 121, 131, 141, and 151).

[00232] In some embodiments of these aspects and all such aspects described herein, the IgM memory B cell is CD21+CD27+.

[00233] In some embodiments of these aspects the recombinant antibody has an IgM isotype framework.

[00234] In other embodiments, the recombinant antibody has a non-IgM isotype framework.

[00235] In some embodiments of these aspects and all such aspects described herein, the recombinant antigen-binding polypeptide construct comprises an scFv polypeptide, a single-domain antibody construct, a chimeric antibody construct or a bispecific antibody construct, each including CDRs or an antigen binding domain derived from a memory B cell, (e.g., an IgM memory B cell).

[00236] In some embodiments of these aspects and all such aspects described herein, the polypeptide binds its antigen with a K _D of 10 ⁷ M or lower, 10 ⁸ M or lower, 10 ⁹ M or lower, 10 ¹⁰ M or lower, 10 ¹¹ M or lower, 10 ¹² M or lower.

[00237] As shown herein, sequencing of receptors derived from IgM+ memory B cells demonstrates that these cells, like conventional IgG+ memory B cells, undergo somatic hypermutation in their variable heavy and light chains relative to germline variable heavy and light chains sequences.

[00238] As known to those of skill in the art,“somatic hypermutation” is a cellular mechanism by which B cell receptors are further diversified to increase affinity of a B cell receptor for its cognate antigen.

Somatic hypermutation involves a programmed process of introducing point mutations into the variable regions of immunoglobulin genes, thereby increasing antibody diversity, and then using further positive selection to select antibodies that bind with higher affinity to the antigen. Somatic hypermutation has been estimated to expand the ultimate scope of antibody diversity 10 to lOO-fold or more. Typically, an antigen binding domain derived from an IgM memory B cell receptor for use in the compositions and methods described herein has undergone at least one or more, at least two or more, at least three or more, at least four or more, at least five or more, at least six or more, at least seven or more, but less than eight, somatic hypermutations relative to germline variable heavy and light chains sequences. Typically, an antigen binding domain derived from an IgM memory B cell receptor for use in the compositions and methods described herein has undergone fewer than five somatic hypermutations, . e.. between one to five somatic hypermutations, between one to four somatic hypermutations, and between one to three somatic

hypermutations. [00239] In some embodiments of these aspects and all such aspects described herein, the variable light chain immunoglobulin sequence, variable heavy chain immunoglobulin sequence, or both has one or more somatic mutations relative to a variable heavy chain immunoglobulin sequence or variable light chain immunoglobulin sequence from a naive B cell.

[00240] In some embodiments of these aspects and all such aspects described herein, the variable light chain sequence, variable heavy chain sequence, or both has one to eight somatic mutations relative to a variable heavy chain sequence or variable light chain sequence from a naive B cell.

[00241] In some embodiments of these aspects and all such aspects described herein, the memory B cell receptor antigen-binding domain (e.g., an IgM MBC receptor antigen-binding domain) specifically binds an antigen comprised or expressed by an infectious organism. In some embodiments of these aspects and all such aspects described herein, the infectious organism is a blood-bome pathogen. In some embodiments of these aspects and all such aspects described herein, the infectious organism is a virus, a bacterium, a fungus or a parasite. In some embodiments of these aspects and all such aspects described herein, the infectious organism is P. falciparum.

[00242] Provided herein, in some aspects are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen AMA and comprise heavy chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy

chain CDR2 having the amino acid sequence of SEQ ID NO: 108; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; and

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149.

[00243] In some aspects, provided herein are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen AMA and comprise light chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34;

b. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

c. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

d. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

e. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

f. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

g. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

h. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154. [00244] In some aspects, provided herein are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen AMA and comprise heavy and light chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84;

f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114;

g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154.

[00245] Provided herein, in some aspects are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen MSP 1 and comprise heavy chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; and

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; and a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; [00246] In some aspects, provided herein are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen MSP 1 and comprise light chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74;

b. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94;

c. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104;

d. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124; and

e. a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134;

[00247] In some aspects, provided herein are recombinant antibodies or antigen-binding fragments thereof that specifically bind to the malarial antigen MSP 1 and comprise heavy and light chain complimentarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74;

b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94;

c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104;

d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy

chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124;

e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy

chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134.

[00248] In one embodiment, the CDRs are grafted into an IgM acceptor antibody framework. In another embodiment, the CDRs are grafted into an IgG acceptor antibody framework. In some embodiments, the recombinant antigen-binding polypeptide construct described herein comprises a multimer of IgM antigen-binding units or a multimer of IgG antigen-binding units.

[00249] In some embodiments, the recombinant antigen-binding polypeptide construct described herein comprises five or six IgM antigen-binding units.

Methods of treating disease

[00250] Antigen-binding polypeptide constructs and antibodies described herein can be used, for example, for the treatment or prevention of diseases, including for example, infectious disease and/or cancer. Thus in some embodiments, a subject suffering from or diagnosed with a disease (e.g., infectious disease or cancer), can be administered an antigen-binding polypeptide construct or antibody as described herein to therby treat the disease or disorder. Administration comprises administering the antigen-binding polypeptide construct or antibody directly or, for example administering a cell that produces and expresses the construct or administering a vector encoding the construct under control of sequence elements that provide its expression upon entry or introduction to the cell. [00251] In other embodiments, a subject at rick of developing a disease (e.g., infectious disease or cancer), can be administered a composition described herein to either limit the extent of disease or, preferably, to prevent the establishment of the disease.

[00252] Treatment of prevention of infactious disease using the constructs described herein can be thought of, in one regard, as passive immunization, i.e.. providing antibody or antibody-like constructs that circulate and can bind to an antigen expressing or an infecting pathogen and thereby targeting it for killing or inactivation. In such instances, the binding of the construct as described herein to an antigen expressed by a pathogen can, for example, interfere with cellular entry of an intracellular pathogen, e.g., a virus or a microbe such as a malaria pathogen. Alternatively, the construct can interfere with growth or replication of a pathogen due to a sheer number of construct molecule binding to the pathogen, or as a further alternative, due to activation of immune pathways, e.g., the complement cascade or antibody-mediated recruitment of other immune effector cells. In this context,“prevention” of an infectious disease means that a productive infection is limited to an extent that disease symptoms are substantially reduced (e.g., by 90% or more relative to non-treatment) or do not occur at all following exposure of the treated individual to the pathogen. Unless cells or a vector encoding a construct as described herein are administered so as to permit continued expression or delivery of the construct, it is anticipated that lasting prevention can require repeated administration.

[00253] Treatment of an established infectious disease can also be effected using constructs as described herein that bind an antigen expressed by or on the pathogen. In such instances, the constructs can inhibit further growth or replication of the pathogen, e.g., by interfering with pathogen cellular function due to the number of construct molecules binding to the pathogen surface, and/or by interfering with the entry of additional pathogen organisms to their target cells, and/or by recruiting or activating additional immune functions or effector cells (e.g., complement activation, effector T cell recruitment, activation, etc.). In general, any approach that slow the growth or proliferation of a pathogenic organism permits more time for the host immune system to effectively attach the pathogen.

[00254] Treatment of cancer via administration of a construct as described herein that targets one or more tumor antigens can involve as non-limiting examples, recruitment of cytotoxic T cells or NK cells to the site of construct-provoked inflammatory signaling. In such instances, it is preferred that the construct comprise antibody constant domain motifs or sequences that interact with immune system components that mediate such signaling effective for provoking antibody-dependent cellular cytotoxicity, e.g., Fc sequences that interact with Fc-receptor bearing immune cells can be included or a construct. Antibody Fc domains and modifications to them that increase or otherwith modulate interaction with Fc receptors and cells that express them are known to those of ordinary skill in the art.

[00255] In some aspects, described herein is a method of treating or preventing a disease or disorder, the method comprises: administering a recombinant antigen-binding polypeptide construct described herein, or a cell expressing such a polypeptide, or a vector encoding such a polypeptide to a subject in need thereof.

[00256] In some aspects, provided herein are methods of treating a subject in need of treatment for a disease caused by an infectious organism, the method comprising administering an antigen-binding compositions as described herein, wherein the antigen-binding polypeptide of the composition specifically binds an antigen comprised by the infectious organism.

[00257] In some aspects, provided herein are methods reducing the likelihood of contracting a disease caused by an infectious organism, the method comprising administering to an individual at risk of contracting the disease an antigen-binding composition as described herein, wherein the antigen-binding polypeptide specifically binds an antigen comprised by the infectious organism.

[00258] In some embodiments of these aspects and all such aspects described herein, the recombinant antibody described herein is for the treatment of or protection from malaria infection in a subject.

[00259] In some aspects, provided herein are methods of treating malaria infection in a subject, comprising administering a therapeutically effective amount of any a recombinant antibody as described herein.

[00260] In some aspects, provided herein are methods of treating multi -drug resistant malaria in a subject, comprising administering a therapeutically effective amount of a recombinant antibody as described herein.

[00261] In another aspect, described herein is a method of immunizing a subject against a pathogen, the method comprising: administering a recombinant antigen-binding polypeptide construct described herein, or a cell expressing such a polypeptide construct, or a vector encoding such a polypeptide construct to an individual in need thereof.

[00262] In some embodiments of these aspects and all such aspects described herein, the

recombinant antibody or polypeptides described herein are for vaccination against malaria. In some embodiments of these aspects and all such aspects described herein, the recombinant antibody is for the treatment of multi -drug resistant malaria.

[00263] An“infectious organism” refers to any organism, particularly microscopic organisms, that can infect a subject and lead to an infectious disease or disorder. Examples of infectious organisms or pathogens include, but are not limited to, viruses, bacteria, protozoa, mycoplasma, and fungi. Infectious diseases can impact any bodily system, be acute (short-acting) or chronic/persistent (long-acting), occur with or without fever, strike any age group, and overlap with other infectious organisms.

[00264] As used herein, the term“pathogen” refers to an organism that causes a disease or disorder in a subject. For example, pathogens include but are not limited to viruses, fungi, bacteria, parasites and other infectious organisms or molecules therefrom, as well as taxonomically related macroscopic organisms within the categories algae, fungi, yeast, protozoa, or the like. In some embodiments, the pathogen is a human pathogen.

[00265] The compositions and methods described herein are useful against persistent infections, in some embodiments. A "persistent infection," as used herein, refers to an infection in which the infectious agent (such as a virus, mycoplasma, bacterium, parasite, or fungus) is not cleared or eliminated from the infected host, even after the induction of an immune response. Persistent infections can be chronic infections, latent infections, or slow infections. A“latent infection” is characterized by the lack of demonstrable infectious virus between episodes of recurrent disease.“Chronic infection” is characterized by the continued presence of infectious virus following the primary infection and can include chronic or recurrent disease.“Slow infection” is characterized by a prolonged incubation period followed by progressive disease. Unlike latent and chronic infections, slow infection may not begin with an acute period of viral multiplication. While acute infections are relatively brief (lasting a few days to a few weeks) and resolved from the body by the immune system, persistent infections can last for example, for months, years, or even a lifetime. These infections may also recur frequently over a long period of time, involving stages of silent and productive infection without cell killing or even producing excessive damage to the host cells. Persistent infections often involve stages of both silent and productive infection without rapidly killing or even producing excessive damage of the host cells. During persistent viral infections, the viral genome can be either stably integrated into the cellular DNA or maintained episomally. Persistent infection occurs with viruses such as human T-Cell leukemia viruses, Epstein-Barr virus, cytomegalovirus, herpesviruses, varicella-zoster virus, measles, papovaviruses, prions, hepatitis viruses, adenoviruses, parvoviruses and papillomaviruses, among others.

[00266] Causative infectious agents for persistent infections can be detected in the host (such as inside specific cells of infected individuals) even after the immune response has resolved, using standard techniques. Mammals are diagnosed as having a persistent infection according to any standard method known in the art and described, for example, in U.S. Pat. Nos. 6,368,832, 6,579,854, and 6,808,710 and U.S. Patent Application Publication Nos. 20040137577, 20030232323, 20030166531, 20030064380, 20030044768, 20030039653, 20020164600, 20020160000, 20020110836, 20020107363, and

20020106730, all of which are hereby incorporated by reference in their entireties.

[00267] As used herein, a“parasitic infection” refers to any infection caused by a parasite. A parasitic infection as described herein can be caused by any parasite currently known, or yet to be discovered that results in a pathogenic disease. Exemplary parasites include, but are not limited to, malaria ( Plasmodium ), roundworms (nematodes), tapeworms (cestodes), flukes (trematodes), Cooperia, their species, or any other parasite known in the art. A parasitic infection can be treated with, for example, a deworming agent or antibiotics. [00268] As used herein,“malarial infection” refers to infection of a host subject caused by Plasmodium. Malaria is a mosquito-bome infectious disease that affects mammalian subjects and causes symptoms such as fever, tiredness, vomiting, yellowing of the skin, seizures, coma, and can be lethal. The disease is spread by mosquito saliva that upon contact with a host subject, permits the transfer of parasites such as Plasmodium into the host subject’s blood. Several medications are available to prevent malaria such as sulfadoxine/pyrimethamine. However, no effective vaccine for malaria exists. Non-limiting examples of treatments for malaria include chloroquine, hydroxychloroquine, amodiaquine,

pyrimethamine, proguanil, sulfonamids, mefloquine, atovaquone, primaquine, and derivatives therof.

However, the parasites can be resistant to these treatments and cause forms of drug resistant malarial infections.

[00269] In some embodiments, the compositions and methods described herein are contemplated for use against other infectious organisms, i. e. , when the antigen of interest comprises an antigen of interest derived from other infectious organisms, such as protozoan parasites. Other infectious organisms, such as protozoan parasites, include Plasmodium falciparum, exemplified herein, Shistosoma mansoni,

Trypanosoma cruzi, Trichinella spiralis, Strongyloides ratti, and Toxoplasma gondii, among others. Thus, in some embodiments, the compositions and methods described herein are contemplated for use against infections caused by Plasmodium falciparum, Shistosoma mansoni, Trypanosoma cruzi, Trichinella spiralis, and Strongyloides ratti, among others.

[00270] As used herein, the term” Plasmodium” refers to a genus of parasites described herein that affect a host subject by growing within vertebrate tissues and enter the blood stream. The Plasmodium destroy the red blood cells of the host subject. The genus Plasmodium consists of over 200 species known in the art. Non-limiting examples of Plasmodium include Plasmodium falciparum, Plasmodium chahaudi chahaudi, Plasmodium yoelii, Plasmodium vivax, and Plasmodium herghei.

[00271] As used herein, a“viral infection” refers to any infection caused by a virus. A viral infection as described herein can be caused by any virus type currently known, or yet to be discovered that results in a pathogenic disease. Exemplary viruses include, but are not limited to, coronavirus, respiratory syncytial virus, bovine diarrhea virus, rabies virus, Herpes virus, retrovirus, lentivirus, or any other virus known in the art.

[00272] In some embodiments, the compositions and methods described herein are contemplated for use against viral infections, i.e. , when the antigen of interest comprises a viral antigen of interest. Non-limiting examples of infectious viruses include: Retroviridae (for example, HIV); Picornaviridae (for example, polio viruses, hepatitis A virus; enteroviruses, human coxsackie viruses, rhinoviruses, echoviruses); Calciviridae (such as strains that cause gastroenteritis); Togaviridae (for example, equine encephalitis viruses, rubella viruses); Flaviridae (for example, dengue viruses, encephalitis viruses, yellow fever viruses, West Nile virus, Zika virus); Coronaviridae (for example, coronaviruses); Rhabdoviridae (for example, vesicular stomatitis viruses, rabies viruses); Filoviridae (for example, ebola viruses); Paramyxoviridae (for example, parainfluenza viruses, mumps virus, measles virus, respiratory syncytial virus); Orthomyxoviridae (for example, influenza viruses); Bungaviridae (for example, Hantaan viruses, bunga viruses, phleboviruses and Nairo viruses); Arena viridae (hemorrhagic fever viruses); Reoviridae (e.g., reoviruses, orbiviurses and rotaviruses); Birnaviridae; Hepadnaviridae (Hepatitis B virus); Parvoviridae (parvoviruses); Papovaviridae (papilloma viruses, polyoma viruses); Adenoviridae (most adenoviruses); Herpesviridae (herpes simplex virus (HSV) 1 and HSV-2, varicella zoster virus, cytomegalovirus (CMV), herpes viruses); Poxviridae (variola viruses, vaccinia viruses, pox viruses); and Iridoviridae (such as African swine fever virus); and unclassified viruses (for example, the etiological agents of Spongiform encephalopathies, the agent of delta hepatitis (thought to be a defective satellite of hepatitis B virus), the agents of non -A, non-B hepatitis (class l=intemally transmitted; class 2=parenterally transmitted (i.e.. Hepatitis C); Norwalk and related viruses, and astroviruses). Some viral diseases occur after immunosuppression due to re-activation of viruses already present in the recipient. Examples of persistent viral infections include, but are not limited to,

cytomegalovirus (CMV) pneumonia, enteritis and retinitis; Epstein-Barr virus (EBV) lymphoproliferative disease; chicken pox/shingles (caused by varicella zoster virus, VZV); HSV-l and -2 mucositis; HSV-6 encephalitis, BK-virus hemorrhagic cystitis; viral influenza; pneumonia from respiratory syncytial virus (RSV); AIDS (caused by HIV); and hepatitis A, B or C. In some embodiments, the compositions and methods described herein are contemplated for use against viral infections caused by enteroviruses, Flaviridae, for example, dengue viruses, encephalitis viruses, yellow fever viruses, West Nile virus, Zika and virus; Filoviridae, for example, ebola viruses; Orthomyxoviridae, for example, influenza viruses; Arena viridae, for example, hemorrhagic fever viruses; and Reoviridae, e.g., reoviruses, orbiviurses and rotaviruses.

[00273] As used herein, a“bacterial infection” refers to any infection caused by a bacterium. A bacterial infection as described herein can be caused by any bacteria type currently known, or yet to be discovered that results in a pathogenic disease. Pathogenic bacteria and diseases are well known in the art.

[00274] In some embodiments, the compositions and methods described herein are contemplated for use against bacterial infections, i.e., when the antigen of interest comprises an antigen of interest derived from bacteria. Non-limiting examples of infectious bacteria include: E. coli, Psuedomonas aeruginosa, Helicobacter pyloris, Borelia burgdorferi, Legionella pneumophilia, Mycobacteria sps (such as. M.

tuberculosis, M. avium, M. intracellulare, M. kansaii, M. gordonae), Staphylococcus aureus, Neisseria gonorrhoeae, Neisseria meningitidis, Listeria monocytogenes, Streptococcus pyogenes (Group A

Streptococcus), Streptococcus agalactiae (Group B Streptococcus), Streptococcus (viridans group), Streptococcus faecalis, Streptococcus epidermidis, Streptococcus bovis, Streptococcus (anaerobic sps.), Streptococcus pneumoniae, pathogenic Campylobacter sp., Enterococcus sp., Haemophilus influenzae, Bacillus anthracis, corynebacterium diphtheriae, corynebacterium sp., Erysipelothrix rhusiopathiae, Clostridium perfringers, Clostridium tetani, Enterobacter aerogenes, Klebsiella pneumoniae, Brucella abortus, Pasteurella multocida, Bacteroides sp., Fusobacterium nucleatum, Streptobacillus moniliformis, Treponema pallidium, Treponema pertenue, Leptospira, Nocadia brasiliensis, Borrelia hermsii, Borrelia burgdorferi, and Actinomyces israelii. In some embodiments, the compositions and methods described herein are contemplated for use against bacterial infections caused by E. coli, Psuedomonas aeruginosa,

M. tuberculosis, Group B Streptococcus, Streptococcus epidermidis, Streptococcus pneumoniae,

Haemophilus influenzae, Bacillus anthracis, Erysipelothrix rhusiopathiae, Klebsiella pneumoniae,

Brucella abortus, Nocadia brasiliensis, Borrelia hermsii, and Borrelia burgdorferi.

[00275] As used herein, a“fungal infection” refers to any infection caused by a fungus. A fungal infection as described herein can be caused by any fungi currently known, or yet to be discovered that results in a pathogenic disease. A fungal infection can be treated with antifungals, for example, fluconazole, ketoconazole, or amphotericin B.

[00276] In some embodiments, the compositions and methods described herein are contemplated for use against fungal infections, i.e., when the antigen of interest comprises an antigen of interest derived from a fungus. Non-limiting examples of fungal infections include but are not limited to: aspergillosis; thrush (caused by Candida albicans),· cryptococcosis (caused by Cryptococcus),· and histoplasmosis. Thus, infectious fungi include, but are not limited to, Cryptococcus neoformans, Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis , Pneumocystis carinii, Chlamydia trachomatis, and Candida albicans. In some embodiments, the compositions and methods described herein are contemplated for use against fungal infections caused by Candida albicans, Cryptococcus neoformans, and Pneumocystis carinii.

Methods of treating cancer

[00277] As introduced above, in some aspects, provided herein are methods of treating a subject in need of treatment for a tumor that expresses a tumor antigen, the method comprising administering an antigen binding composition as described herein to the subject, wherein the antigen-binding polypeptide of the composition specifically binds the tumor antigen.

[00278] As used herein, the term“cancer” refers to a hyperproliferation of cells that exhibit a loss of normal cellular control that results in unregulated growth, lack of differentiation, local tissue invasion, and metastasis. The methods and compositions described herein can be used for the treatment of solid tumors ( e.g ., cancer) or non-solid tumors, such as leukemia, blood cell cancers, and the like. Solid tumors can be found in bones, muscles, the brain, or organs, and can be sarcomas or carinomas. Where the methods and compositions described herein can overcome barriers of tumor treatment, including, but not limited to barriers to treatment or inhibition of metastases, it is contemplated that aspects of the technology described herein can be used to treat all types of solid and non-solid tumor cancers, including cancers not listed in the instant specification. The compositions and methods described herein, without limitation, include methods of treating cancer, methods of inhibiting metastases, and methods of inducing an anti-tumor immune response.

Examples of Surface Antigens

[00279] Infectious organisms can express a number of surface antigens, including but not limied to antigens that relate to their ability to infect a host subject and proliferate. The surface antigens described herein can be used, for example, to detect the organism’s presence in a host subject, produce antibodies to the surface antigens, or identify novel antigens to generate new therapeutics for infection.

[00280] Examples of Plasmodium surface antigens of particular use in the methods described herein include merozoite surface protein-l (MSP1), apical membrane antigen 1 (AMA1), and circumsporozoite protein (CSP). As used herein, the terms“merozoite surface protein 1” or“MSP1” or“MSP-l” or“MSP1 polypeptide” are used interchangeably to refer to the MSP1 surface polypeptide expressed on parasites ( e.g Plasmodium).

[00281] MSP1 is a key surface protein expressed by the parasite and is required for erythrocyte invasion. See for example, Kadekoppala and Holder, 2010 which is incorporated herein by reference in its entirety. Amino acid sequences for MSP1 are known in the art, for example, Plasmodium falciparum (UnitProt Accession: P19598, SEQ ID NO: 186). Antibodies generated by a host or subject against the l9kD C-terminus region of MSP 1 potently inhibit erythrocyte invasion and animals actively, or passively, immunized against MSP1 are protected against subsequent infection (Blackman et ah, 1990;

Hirunpetcharat et ah, 1997; Moss et ah, 2012). Furthermore, the acquisition of both IgG and IgM antibodies against the MSP 1 C-terminus have been associated with the development of clinical immunity (al-Yaman et al, 1996; Arama et al, 2015; Branch et ah, 1998; Dodoo et ah, 2008; Riley et ah, 1992).

[00282] Another example of a surface antigen expressed on a parasite or pathogen is apical membrane antigen 1 (AMA). As used herein, the terms“apical membrane antigen 1 (AMA)” or“AMA” or“AMA1” or“AMA polypeptide” can be used interchangeably to refer to the AMA surface polypeptide expressed on parasite (e.g., Plasmodium). The AMA polypeptide is a 66kDa polypeptide that is transported to the Plasmodium cell surface prior to the schizont stage of malarial infection. Genomic and amino acid sequences for AMA are known in the art, for example, Plasmodium falciparum (NCBI Gene ID: 810891 and GenBank: CAB97194.1, SEQ ID NO: 187).

[00283] Accordingly, also provided herein, in some aspects, are recombinant cells producing a surface antigen-binding polypeptide comprising a variable heavy chain immunoglobulin sequence, a variable light chain immunoglobulin sequence, or both, from an IgM memory B cell obtained using any of the methods described herein.

[00284] In some aspects, provided herein are recombinant surface antigen-binding polypeptides produced by recombinant cells as described herein. [00285] In some embodiments of these aspects and all such aspects described herein, the antigen is a blood stage malaria surface antigen or a sporozoite stage surface antigen. In some such embodiments, the blood stage malaria surface antigen or sporozoite stage surface antigen is selected from P. falciparum merozoite surface protein 1 (MSP1), AMA, and CSP (circumsporozoite protein).

[00286] In some embodiments of these aspects and all such aspects described herein, the IgM memory B cell receptor antigen-binding domain specifically binds a tumor antigen.

[00287] Tumor antigens are generally polypeptides or other antigens expressed on the surface of a tumor cell. Tumor antigens are generally experienced to a greater extent on a tumor cell than or corresponding non-tumor tissues. Many tumor antigens confer a growth advantage on the tumor cell, e.g., endothelial growth factor receptor (EGFR). EGFR is a growth factor receptor often overexpressed by tumors that render the tumor cells sensitive to small concentrations of the growth factor-mutated, e.g., constituitively active forms of such receptors are also known to by tumor antigens. Non-limiting examples of tumor antigens to which an IgM memory B cell receptor antigen-binding domain can specifically bind include Acute myelogenous leukemia Wilms tumor 1 (WT1), preferentially expressed antigen of melanoma (PRAME), PR1, proteinase 3, elastase, cathepsin G, Chronic myelogenous WT1, Myelodysplastic syndrome WT1, Acute lymphoblastic leukemia PRAME, Chronic lymphocytic leukemia Survivin, Non-Hodgkin's lymphoma Survivin, Multiple myeloma New York esophagus 1 (NY-Esol), Malignant melanoma MAGE, MART-l/Melan-A, Tyrosinase, GP100, Breast cancer WT1, Lung cancer WT1, Prostate-specific antigen (PSA), prostatic acid phosphatase, (PAP) Carcinoembryonic antigen (CEA), mucins (e.g., MUC-l), and Renal cell carcinoma (RCC) Fibroblast growth factor 5 (FGF-5).

[00288] In some embodiments of these aspects and all such aspects described herein, the multimer construct comprises a dimer, trimer, or tetramer of the antigen.

Methods of isolating and making IgM memory B cells and antigen-binding polypeptides

[00289] Described herein is a method of isolating memory B cells that specifically bind an antigen of interest, the method comprises: (a) contacting a biological sample containing memory B cells from a subject having had prior exposure to the antigen of interest with the antigen of interest or a portion thereof, wherein the antigen of interest is immobilized on a solid support; (b) separating a population of antigen-bound cells from non-antigen-bound cells of step (a); and (c) isolating cells expressing CD21, CD27, and IgM from the population antigen-bound cells.

[00290] In some embodiments, prior to contacting step (a), a biological sample is obtained from a subject. In some embodiments, the biological sample is a blood sample.

[00291] As used herein, the term“contacting” when used in reference to a cell or organ, encompasses both introducing or administering the composition or pathogen or antigen described herein, an agent, surface, hormone, etc. to the cell, tissue, or organ in a manner that permits physical contact of the cell with the composition, antigen, agent, surface, hormone etc., and/or introducing an element, such as a genetic construct or vector, that permits the expression of the compositions described herein by a cell or population thereof.

[00292] In some embodiments, the isolating step (c) comprises flow cytometry. Methods of flow cytometry are known in the art. See, for example, Malleret et al., Sci Rep (2011); Robbiani et al, Cell (2015), which are incorporated herein by reference in their entirety. In some embodiments, step (c) further comprises isolating cells expressing a plasmablast marker. In some embodiments, the plasmablast marker is B220 or CD138.

[00293] As used herein, a“plasmablast” refers to B cells that have differentiated into an immature plasma cell. These cells will eventually produce large volumes of antibodies in response to an antigen. Plasmablasts are capable of rapid division and are capable of internalizing antigens and presenting them to T cells. The IgM+ MBCs described herein can give rise to T cell-dependent IgM+ and

IgG+B220+CDl38+ plasmablasts or T cell-independent B220-CD138+ IgM+ plasma cells.

[00294] In another aspect, described herein is a method of making an antibody construct comprising an antigen-binding domain from a memory B cell and that specifically binds to an antigen of interest, the method comprises: (a) isolating a population of IgM expressing memory B cells from a biological sample as described herein; (b) amplifying heavy chain and light chain variable domain sequences from the memory B cell population of step (a); (c) ligating heavy chain variable domain sequences amplified in step (b) into a heavy chain expression vector sequence and ligating light chain variable domain sequences amplified in step (b) into a light chain expression vector sequence; (d) introducing one or more vectors encoding heavy chain and light chain expression vector sequences of step (c) to a cell and culturing the cell under conditions that permit expression of antibody polypeptides from the expression vector sequences; (e) contacting antibody polypeptides expressed by the cell with an antigen of interest; and (f) isolating antibodies that bind to the antigen of interest, thereby making an antibody construct comprising an antigen-binding domain from a memory B cell and that specifically binds to an antigen of interest.

[00295] In some embodiments, the method further comprises, prior to step (a), a step of immunizing a subject and obtaining a biological sample.

[00296] In some embodiments, the method further comprises, prior to step (e), collecting cell culture medium from cells of step (d).

[00297] In some embodiments, step (e) comprises contacting antibody polypeptides with the antigen of interest immobilized on a solid support.

[00298] The antigen-binding polypeptides and antibody constructs described herein can be expressed in a vector (e.g., an expression vector). The term "vector", as used herein, refers to a nucleic acid construct designed for delivery to a host cell or for transfer between different host cells. As used herein, a vector can be viral or non-viral. The term“vector” encompasses any genetic element that is capable of replication when associated with the proper control elements and that can transfer gene sequences to cells. A vector can include, but is not limited to, a cloning vector, an expression vector, a plasmid, phage, transposon, cosmid, artificial chromosome, virus, virion, etc.

[00299] As used herein, the term“viral vector" refers to a nucleic acid vector construct that includes at least one element of viral origin and has the capacity to be packaged into a viral vector particle. The viral vector can contain a nucleic acid encoding a polypeptide as described herein in place of non-essential viral genes. The vector and/or particle may be utilized for the purpose of transferring nucleic acids into cells either in vitro or in vivo. Numerous forms of viral vectors are known in the art.

[00300] As used herein, the term "expression vector" refers to a vector that directs expression of an RNA or polypeptide (e.g., the antigen-binding polypeptide constructs described herein) from nucleic acid sequences contained therein linked to transcriptional regulatory sequences on the vector. The sequences expressed will often, but not necessarily, be heterologous to the cell. An expression vector may comprise additional elements, for example, the expression vector may have two replication systems, thus allowing it to be maintained in two organisms, for example in human cells for expression and in a prokaryotic host for cloning and amplification. The term "expression" refers to the cellular processes involved in producing RNA and proteins and as appropriate, secreting proteins, including where applicable, but not limited to, for example, transcription, transcript processing, translation and protein folding, modification and processing. "Expression products" include RNA transcribed from a gene, and polypeptides obtained by translation of mRNA transcribed from a gene. The term "gene" means the nucleic acid sequence which is transcribed (DNA) to RNA in vitro or in vivo when operably linked to appropriate regulatory sequences. The gene may or may not include regions preceding and following the coding region, e.g. 5’ untranslated (5’UTR) or "leader" sequences and 3’ UTR or "trailer" sequences, as well as intervening sequences (introns) between individual coding segments (exons).

[00301] Integrating vectors have their delivered RNA/DNA permanently incorporated into the host cell chromosomes. Non-integrating vectors remain episomal which means the nucleic acid contained therein is never integrated into the host cell chromosomes. Examples of integrating vectors include retroviral vectors, lentiviral vectors, hybrid adenoviral vectors, and herpes simplex viral vector.

[00302] One example of a non-integrative vector is a non-integrative viral vector. Non-integrative viral vectors eliminate the risks posed by integrative retroviruses, as they do not incorporate their genome into the host DNA. One example is the Epstein Barr oriP/Nuclear Antigen- 1 (“EBNAl”) vector, which is capable of limited self-replication and known to function in mammalian cells. As containing two elements from Epstein-Barr virus, oriP and EBNAl, binding of the EBNAl protein to the virus replicon region oriP maintains a relatively long-term episomal presence of plasmids in mammalian cells. This particular feature of the oriP/EBNAl vector makes it ideal for generation of integration-free host cells. Other non-integrative viral vectors include adenoviral vectors and the adeno-associated viral (AAV) vectors. [00303] Another non-integrative viral vector is RNA Sendai viral vector, which can produce protein without entering the nucleus of an infected cell. The F-deficient Sendai virus vector remains in the cytoplasm of infected cells for a few passages, but is diluted out quickly and completely lost after several passages (e.g., 10 passages).

[00304] Another example of a non-integrative vector is a minicircle vector. Minicircle vectors are circularized vectors in which the plasmid backbone has been released leaving only the eukaryotic promoter and cDNA(s) that are to be expressed.

[00305] In some embodiments, the antigen-binding polypeptide constructs described herein are encoded by one vector. In some embodiments, the antigen-binding polypeptide construct described herein is encoded by multiple vectors (e.g., heavy or light chains in seperated vectors). Without limitation, multiple expression vectors can be used and expressed to make the antigen-binding polypeptide construct or antibody contructs comprising an antigen-binding domains as described herein from a memory B cell.

[00306] In some aspects, provided herein are methods of sorting Plasmodium- specific IgM memory B cells (MBCs), comprising: contacting a biological sample obtained from a subject infected with or having been vaccinated against malaria with a tetramer comprising a Plasmodium antigen; and sorting a cell population comprising Plasmodium- specific IgM MBCs based on binding to the tetramer.

[00307] In some embodiments of these aspects and all such aspects described herein, the method further comprises generating tetramers comprising blood or liver stage Plasmodium antigens prior to the contacting step. Non-limiting examples of such blood or liver stage Plasmodium antigens include MSP-l, CSP, and AMA.

[00308] In some embodiments of the aspects described herein, the methods further comprise a step of sequencing one or more BCRs, or at least the antigen-binding domains thereof, expressed by the cell population comprising IgM MBCs. In some embodiments of these aspects and all such aspects described herein, the methods further comprise a step of sequencing Plasmodium- specific IgM MBC BCRs.

Methods of sequencing are known in the art. See, for example, Schwartz et al. J Immunol (2015), which is incorporated herein by reference in its entirety.

[00309] In some embodiments of the aspects described herein, the methods further comprise a step of cloning the one or more BCRs and expressing the one or more BCRs as recombinant antibodies or antigen-binding fragments thereof. See, for example, Tiller et al. J Immunol Methods (2009), which is incorporated herein by reference in its entirety.

[00310] Provided herein, in some aspects, are populations comprising at least 100 recombinant antigen binding molecules, each comprising an antigen-binding domain of an IgM memory B cell receptor, and each binding its antigen with a K _D of 10 ⁷ nM or lower. The recombinant antigen-binding molecules of the population can be derived from BCR antigen-binding sequences of a population of antigen-specific MBCs isolated as described herein. In some embodiments, the average frequency of somatic mutation is eight or fewer per molecule for the population. In some embodiments, the average frequency of somatic mutation is five or fewer per molecule for the population. In some embodiments, the population binds the same antigen. In some embodiments, the population binds the same antigen, but different epitopes on the same antigen.

[00311] Provided herein, in some aspects, are compositions comprising a population of antigen- specific IgM memory B cells bound via their B cell receptors to antigen immobilized on a solid support.

[00312] A " solid support" for use in immobilizing, restraining, or capturing a population of antigen- specific IgM memory B cells can be any suitable solid support to which an antigen of interest can be attached or bound, and includes, for example, glass (e.g., a glass slide), plastic, chips, pins, filters, beads (e.g., magnetic beads, polystyrene beads, etc.), paper, membrane (e.g., nylon, nitrocellulose,

polyvinybdene fluoride (PVDF), etc.), fiber bundles, or any other suitable substrate. The antigen of interest generally can be immobilized or restrained on the solid support via covalent or noncovalent interactions (e.g., ionic bonds, hydrophobic interactions, hydrogen bonds, Van der Waals forces, dipole- dipole bonds).

[00313] In some embodiments of these aspects and all such aspects described herein, the antigen immobilized on the solid support comprises a multimer construct comprising the antigen.

[00314] In some embodiment of any of these aspects and all such aspects described herein, the compositions described herein selectively bind the antigen of interest. Methods of measuring binding of a polypeptide to an antigen are known in the art (e.g., ELISA or ELISPOT assays).

[00315] The terms“selectively binds,”“specifically binds,” or“specific for” refer, with respect to an antigen of interest, such as MSP1, or apical membrane antigen 1 (AMA), or tetanus toxoid C fragment (TTCF) among others, to the preferential association of an IgM memory B cell, in whole or part, with a cell or tissue bearing that antigen, or an epitope thereof, and not to cells or tissues or samples lacking that antigen, with a KD of 10 ⁵ M (10000 nM) or less, e.g., 10 ⁶ M or less, 10 ⁷ M or less, 10 ⁸ M or less, 10 ⁹ M or less, 10 ¹⁰ M or less, 10 ¹¹ M or less, or 10 ¹² M or less. It is, of course, recognized that a certain degree of non-specific interaction can occur between a molecule and a non-target cell or tissue. Nevertheless, specific binding can be distinguished as mediated through specific recognition of the antigen. Specific binding results in a much stronger association between the agent comprising an antigen of interest and IgM memory B cells specific for the antigen, or a portion thereof, than between the agent and IgM memory B cells lacking such specificity. Specific binding typically results in greater than 2-fold, such as greater than 5-fold, greater than lO-fold, or greater than lOO-fold increase in binding of an IgM memory B cell specific for that antigen of interest to a cell or tissue bearing it, as compared to a cell or tissue lacking it. Specificity of binding can be assayed, for example, by competition assays using the antigen of interest, in comparison to competition with one or more unrelated or different antigens. A variety of immunoassay formats are appropriate for selecting agents, such as multimers, like tetramers, antibodies, or other ligands that specifically bind a given IgM memory B cell. Specific binding can be influenced by, for example, the affinity and avidity of the polypeptide agent and the concentration of polypeptide agent. The person of ordinary skill in the art can determine appropriate conditions under which the agents described herein selectively bind the IgM memory B cells using any suitable methods, such as titration of an agent in a suitable cell binding assay.

[00316] The term "KD" (also "Kd"), as used herein, refers to the "equilibrium dissociation constant", and refers to the value obtained in a titration measurement at equilibrium, or by dividing the dissociation rate constant (Koff) by the association rate constant (Kon). The association rate constant (Kon), the dissociation rate constant (Koff), and the equilibrium dissociation constant (KD are used to represent the binding affinity of a binding protein to an antigen. Methods for determining association and dissociation rate constants are well known in the art. Fluorescence -based techniques offer high sensitivity and the ability to examine samples in physiological buffers at equilibrium. Other experimental approaches and instruments such as a BIAcore™. (biomolecular interaction analysis) assay can also be used (e.g., instrument available from BIAcore International AB, a GE Healthcare company, Uppsala, Sweden) to determine dissociateion kinetics and measure KD. Additionally, a KinExA™ (Kinetic Exclusion Assay) assay, available from Sapidyne Instruments (Boise, Id.) can also be used. See also, Bee et al. PLOS One. (2013), Bee et al. PLOS One. (2012), Drake et al Anal Biochem (2004), and Landry et al. J Immunol Methods (2015), which are incorporated herein by reference in their entirety.

[00317] As demonstrated herein, antigen-specific IgM memory B cells are a sub-population of B cells expressing cell-surface IgM that are high affinity, have undergone limited somatic hypermutation, and can rapidly respond, upon subsequent exposure to the same antigen, to produce high-affinity, secreted antibodies. Upon isolation and cloning of such antigen-specific IgM memory B cells, high affinity sequences corresponding to variable heavy and variable light chain sequences, as well as corresponding CDRs, can be obtained and used to generate novel antigen-binding constructs, antibodies and antigenbinding fragments thereof, and recombinant cells that produce such novel antigen-binding constructs, antibodies and antigen-binding fragments thereof. Antigen-specific IgM antibodies selected for cloning and sequencing typically have a high binding affinity for the antigen of interest, for example, typically having a KD value between 10 ⁷ M to 10 ¹⁰ M, or better.

Pharmaceutical Compositions and Methods of Treatment

[00318] In some aspects, provided herein are pharmaceutical compositions comprising any of the antigen-binding constructs, antibodies, antigen-binding polypeptides, or BCR-derived compositions described herein, and a pharmaceutically acceptable carrier. Provided herein, in some aspects, are pharmaceutical compositions comprises any of the antigen-binding constructs or recombinant antibodies described herein. [00319] In some aspects, provided herein are vaccine compositions comprising any of the compositions described herein.

[00320] A vaccine composition can be used, for example, to protect or treat an organism against disease. The terms“immunize” and“vaccinate” tend to be used interchangeably in the field. However, in reference to the administration of recombinant antigen-binding polypeptide constructs as described herein to provide protection against disease, e.g., infectious disease caused by a pathogen that expresses the antigen recognized by the recombinant antigen-binding polypeptide construct, it should be understood that the term “immunize” refers to the passive protection conferred by the administered construct. While the

administered antigen-binding construct may recruit or promote components of the immune system, it is not administered to raise an antibody response against the antigen.

[00321] For the clinical use of the methods described herein, administration of antigen-binding constructs or antibodies or antigen-binding fragments thereof described herein can include formulation into pharmaceutical compositions or pharmaceutical formulations for parenteral administration, e.g., intravenous; mucosal, e.g., intranasal; ocular, or other mode of administration. In some embodiments, the antigen-binding polypeptide constructs, antibodies or antigen-binding fragments thereof described herein can be administered along with any pharmaceutically acceptable carrier compound, material, or composition which results in an effective treatment in the subject. Thus, a pharmaceutical formulation for use in the methods described herein can contain antigen-binding polypeptide constructs, antibodies or antigen-binding fragments thereof as described herein in combination with one or more pharmaceutically acceptable ingredients.

[00322] The phrase“pharmaceutically acceptable" refers to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio. The phrase "pharmaceutically acceptable carrier" as used herein means a pharmaceutically acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, solvent, media, encapsulating material, manufacturing aid (e.g., lubricant, talc magnesium, calcium or zinc stearate, or steric acid), or solvent encapsulating material, involved in maintaining the stability, solubility, or activity of, an antibody or antigen-binding fragment thereof. Each carrier must be "acceptable" in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient. The terms "excipient", "carrier", "pharmaceutically acceptable carrier" or the like are used interchangeably herein.

[00323] The antigen-binding polypeptide constructs, antibodies or antigen-binding fragments thereof described herein can be specially formulated for administration of the compound to a subject in solid, liquid or gel form, including those adapted for the following: (1) parenteral administration, for example, by subcutaneous, intramuscular, intravenous or epidural injection as, for example, a sterile solution or suspension, or sustained-release formulation; (2) transdermally; or (3) transmucosally. Additionally, an antigen-binding polypeptide construct, antibody or antigen-binding fragment thereof can be implanted into a patient or injected using a drug delivery system. See, for example, Urquhart, et al, Ann. Rev. Pharmacol. Toxicol. 24: 199-236 (1984); Lewis, ed. "Controlled Release of Pesticides and Pharmaceuticals" (Plenum Press, New York, 1981); U.S. Pat. No. 3,773,919; and U.S. Pat. No. 35 3,270,960.

[00324] Therapeutic formulations of the antigen-binding constructs or antibodies or antigen-binding fragments thereof described herein can be prepared for storage by mixing the antibodies or antigen-binding fragments having the desired degree of purity with optional pharmaceutically acceptable carriers, excipients or stabilizers (Remington's Pharmaceutical Sciences l6th edition, Osol, A. Ed. (1980)), in the form of lyophilized formulations or aqueous solutions. Acceptable carriers, excipients, or stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid and methionine; preservatives (such as

octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride, benzethonium chloride; phenol, butyl or benzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3-pentanol; and m-cresol); low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, histidine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugars such as sucrose, mannitol, trehalose or sorbitol; salt-forming counter-ions such as sodium; metal complexes (e.g. Zn-protein complexes); and/or non-ionic surfactants such as TWEEN™, PLURONICS™or polyethylene glycol (PEG). Exemplary lyophilized antigen-binding polypeptide construct, antibody formulations are described in WO 97/04801, expressly incorporated herein by reference.

[00325] Optionally, but preferably, the formulations comprising the compositions described herein contain a pharmaceutically acceptable salt, typically, e.g., sodium chloride, and preferably at about physiological concentrations. Optionally, the formulations of the invention can contain a pharmaceutically acceptable preservative. In some embodiments the preservative concentration ranges from 0.1 to 2.0%, typically v/v. Suitable preservatives include those known in the pharmaceutical arts. Benzyl alcohol, phenol, m-cresol, methylparaben, and propylparaben are examples of preservatives. Optionally, the formulations of the invention can include a pharmaceutically acceptable surfactant at a concentration of 0.005 to 0.02%.

[00326] The therapeutic formulations of the compositions comprising antibodies and antigen-binding fragments thereof described herein can also contain more than one active compound as necessary for the particular indication being treated, preferably those with complementary activities that do not adversely affect each other. Alternatively, the composition can comprise a cytotoxic agent, cytokine, or growth inhibitory agent, for example. Such molecules are suitably present in combination in amounts that are effective for the purpose intended.

[00327] The active ingredients of the therapeutic formulations of the compositions comprising antibodies or antigen-binding fragments described herein can also be entrapped in microcapsules prepared, for example, by coacervation techniques or by interfacial polymerization, for example,

hydroxymethylcellulose or gelatin-microcapsules and poly-(methylmethacylate) microcapsules, respectively, in colloidal drug delivery systems (for example, liposomes, albumin microspheres, microemulsions, nano-particles and nanocapsules) or in macroemulsions. Such techniques are disclosed in Remington's Pharmaceutical Sciences l6th edition, Osol, A. Ed. (1980).

[00328] In some embodiments, sustained-release preparations can be used. Suitable examples of sustained-release preparations include semipermeable matrices of solid hydrophobic polymers containing antigen-binding polypeptide constructs, the antibodies or antigen-binding fragments in which the matrices are in the form of shaped articles, e.g., fdms, or microcapsule. Examples of sustained-release matrices include polyesters, hydrogels (for example, poly(2-hydroxyethyl-methacrylate), or poly(vinylalcohol)), polylactides (U.S. Pat. No. 3,773,919), copolymers of L-glutamic acid and y ethyl-L-glutamate, non- degradable ethylene-vinyl acetate, degradable lactic acid-glycolic acid copolymers such as the LUPRON DEPOT™ (injectable microspheres composed of lactic acid-glycolic acid copolymer and leuprolide acetate), and poly-D-(-)-3-hydroxybutyric acid. While polymers such as ethylene -vinyl acetate and lactic acid- glycolic acid enable release of molecules for over 100 days, certain hydrogels release proteins for shorter time periods. When encapsulated antigen-binding polypeptide constructs, antibodies remain in the body for a long time, they can denature or aggregate as a result of exposure to moisture at 37°C, resulting in a loss of biological activity and possible changes in immunogenicity. Rational strategies can be devised for stabilization depending on the mechanism involved. For example, if the aggregation mechanism is discovered to be intermolecular S— S bond formation through thio-disulfide interchange, stabilization can be achieved by modifying sulfhydryl residues, lyophilizing from acidic solutions, controlling moisture content, using appropriate additives, and developing specific polymer matrix compositions.

[00329] The therapeutic formulations to be used for in vivo administration, such as parenteral administration, in the methods described herein can be sterile, which is readily accomplished by filtration through sterile filtration membranes, or other methods known to those of skill in the art.

[00330] Antigen-binding polypeptide construct, antibodies and antigen-binding fragments thereof, are formulated, dosed, and administered in a fashion consistent with good medical practice. Factors for consideration in this context include the particular disorder being treated, the particular subject being treated, the clinical condition of the individual subject, the cause of the disorder, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to medical practitioners. The "therapeutically effective amount" of the antibodies and antigen-binding fragments thereof to be administered are governed by such considerations, and refers to the minimum amount necessary to ameliorate, treat, or stabilize an infection, the cancer; to increase the time until progression (duration of progression free survival) or to treat or prevent the occurrence or recurrence of an infection or tumor. The antigen-binding polypeptide constructs, antibodies and antigen-binding fragments thereof are optionally formulated, in some embodiments, with one or more additional therapeutic agents currently used to prevent or treat the infection, for example. The effective amount of such other agents depends on the amount of antibodies and antigen-binding fragments thereof present in the formulation, the type of disorder or treatment, and other factors discussed above. These are generally used in the same dosages and with administration routes as used herein before or about from 1 to 99% of the heretofore employed dosages.

[00331] The dosage ranges for the therapeutic agents depend upon the potency, and encompass amounts large enough to produce the desired effect. The dosage should not be so large as to cause unacceptable adverse side effects. Generally, the dosage will vary with the age, condition, and sex of the patient and can be determined by one of skill in the art. The dosage can also be adjusted by the individual physician in the event of any complication. In some embodiments, the dosage ranges from 0.001 mg/kg body weight to 100 mg/kg body weight. In some embodiments, the dose range is from 5 pg/kg body weight to 100 pg/kg body weight. Alternatively, the dose range can be titrated to maintain serum levels between 1 pg/mL and 1000 pg/mL. For systemic administration, subjects can be administered a therapeutic amount, such as, e.g., 0.1 mg/kg, 0.5 mg/kg, 1.0 mg/kg, 2.0 mg/kg, 2.5 mg/kg, 5 mg/kg, 7.5 mg/kg, 10 mg/kg, 15 mg/kg, 20 mg/kg,

25 mg/kg, 30 mg/kg, 40 mg/kg, 50 mg/kg, or more. These doses can be administered by one or more separate administrations, or by continuous infusion. For repeated administrations over several days or longer, depending on the condition, the treatment is sustained until, for example, the cancer is treated, as measured by the methods described above or known in the art. However, other dosage regimens can be useful.

[00332] The term“effective amount" as used herein refers to the amount of an antibody or antigen binding fragment thereof needed to alleviate at least one or more symptom of the disease or disorder, and relates to a sufficient amount of pharmacological composition to provide the desired effect, e.g., reduce an infectious organism or tumor load or reduce pathology or any symptom associated with or caused by the infectious organism or tumor load. The term "therapeutically effective amount" therefore refers to an amount of an antibody or antigen-binding fragment thereof using the methods as disclosed herein, that is sufficient to effect a particular effect when administered to a typical subject. An effective amount as used herein would also include an amount sufficient to delay the development of a symptom of the disease, alter the course of a symptom disease (for example but not limited to, slow the progression of a symptom of the disease), or reverse a symptom of the disease. Thus, it is not possible to specify the exact“effective amount." However, for any given case, an appropriate“effective amount" can be determined by one of ordinary skill in the art using only routine experimentation. [00333] Effective amounts, toxicity, and therapeutic efficacy can be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., for determining the LD50 (the dose lethal to 50% of the population) and the ED50 (the dose therapeutically effective in 50% of the population). The dosage can vary depending upon the dosage form employed and the route of administration utilized.

The dose ratio between toxic and therapeutic effects is the therapeutic index and can be expressed as the ratio LD50/ED50. Compositions and methods that exhibit large therapeutic indices are preferred. A therapeutically effective dose can be estimated initially from cell culture assays. Also, a dose can be formulated in animal models to achieve a circulating plasma concentration range that includes the IC50 (i-e., the concentration of the antibody or antigen-binding fragment thereof), which achieves a half-maximal inhibition of symptoms) as determined in cell culture, or in an appropriate animal model. Levels in plasma can be measured, for example, by high performance liquid chromatography. The effects of any particular dosage can be monitored by a suitable bioassay. The dosage can be determined by a physician and adjusted, as necessary, to suit observed effects of the treatment.

[00334] The recombinant antigen-binding polypeptide constructs comprising an antigen-binding domain of an IgM memory B cell receptor as described herein can be administered to a subject in need thereof by any appropriate route which results in an effective treatment in the subject. As used herein, the terms “administering," and“introducing" are used interchangeably and refer to the placement of an antigen binding polypeptide construct, antibody or antigen-binding fragment thereof into a subject by a method or route which results in at least partial localization of such agents at a desired site, such as a site of infection or cancer, such that a desired effect(s) is produced. An antigen-binding polypeptide construct, antibody or antigen-binding fragment thereof can be administered to a subject by any mode of administration that delivers the agent systemically or to a desired surface or target, and can include, but is not limited to, injection, infusion, instillation, and inhalation administration. To the extent that antigen-binding polypeptide constructs, antibodies or antigen-binding fragments thereof can be protected from inactivation in the gut, oral administration forms are also contemplated.“Injection” includes, without limitation, intravenous, intramuscular, intra-arterial, intrathecal, intraventricular, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, sub capsular, subarachnoid, intraspinal, intracerebro spinal, and intrastemal injection and infusion.

[00335] The phrases“parenteral administration" and“administered parenterally” as used herein, refer to modes of administration other than enteral and topical administration, usually by injection. The phrases “systemic administration,"“administered systemically",“peripheral administration" and“administered peripherally" as used herein refer to the administration of a therapeutic agent other than directly into a target site, tissue, or organ, such as a tumor site, such that it enters the subject’s circulatory system and, thus, is subject to metabolism and other like processes. In other embodiments, the antibody or antigen-binding fragment thereof is administered locally, e.g. , by direct injections, when the disorder or location of the infection permits, and the injections can be repeated periodically.

[00336] As used herein, the terms "treat," "treatment," "treating," or "amelioration" refer to therapeutic treatments, wherein the object is to reverse, alleviate, ameliorate, inhibit, slow down or stop the progression or severity of a condition associated with, a disease or disorder. The term "treating" includes reducing or alleviating at least one adverse effect or symptom of a condition, disease or disorder associated with an infection or a cancer. Treatment is generally "effective" if one or more symptoms or clinical markers are reduced. Alternatively, treatment is "effective" if the progression of a disease is reduced or halted. That is, "treatment" includes not just the improvement of symptoms or markers, but also a cessation or at least slowing of progress or worsening of symptoms that would be expected in absence of treatment. Beneficial or desired clinical results include, but are not limited to, alleviation of one or more symptom(s), diminishment of extent of disease, stabilized (i.e., not worsening) state of disease, delay or slowing of disease progression, amelioration or palliation of the disease state, and remission (whether partial or total), whether detectable or undetectable. The term "treatment" of a disease also includes providing relief from the symptoms or side-effects of the disease (including palliative treatment).

[00337] As used herein "preventing" or "prevention" refers to any methodology where the disease state does not occur due to the actions of the methodology (such as, for example, administration of a composition or construct as described herein). In one aspect, it is understood that prevention can also mean that the disease is not established to the extent that occurs in untreated controls. Accordingly, prevention of a disease encompasses a reduction in the likelihood that a subject can develop the disease, relative to an untreated subject (e.g. a subject who is not treated with the methods or compositions described herein).

[00338] The duration of a therapy using the methods described herein will continue for as long as medically indicated or until a desired therapeutic effect (e.g., those described herein) is achieved. In certain embodiments, the administration of the antigen-binding polypeptide construct, antibody or antigen-binding fragment described herein is continued for 1 month, 2 months, 4 months, 6 months, 8 months, 10 months, 1 year, 2 years, 3 years, 4 years, 5 years, 10 years, 20 years, or for a period of years up to the lifetime of the subject.

[00339] As will be appreciated by one of skill in the art, appropriate dosing regimens for a given composition can comprise a single administration/immunization or multiple ones. Subsequent doses may be given repeatedly at time periods, for example, about two weeks or greater up through the entirety of a subject's life, e.g., to provide a sustained preventative effect. Subsequent doses can be spaced, for example, about two weeks, about three weeks, about four weeks, about one month, about two months, about three months, about four months, about five months, about six months, about seven months, about eight months, about nine months, about ten months, about eleven months, or about one year after a primary immunization. [00340] The precise dose to be employed in the formulation will also depend on the route of administration and should be decided according to the judgment of the practitioner and each patient's circumstances. Ultimately, the practitioner or physician will decide the amount of protein or vaccine composition to administer to particular subjects.

[00341] In some embodiments of these methods and all such methods described herein, the antigen binding polypeptide construct, recombinant antibody is administered in an amount effective to provide short-term protection against a malaria infection.

[00342] As used herein,“short-term protection” refers to protection from an infection, such as a malarial infection, lasting at least about 2 weeks, at least about 1 month, at least about 6 weeks, at least about 2 months, at least about 3 months, at least about 4 months, at least about 5 months, at least about 6 months, at least about 7 months, at least about 8 months, at least about 9 months, at least about 10 months, at least about 11 months, or at least about 12 months. Such protection can involve repeated dosing.

[00343] "Alleviating a symptom of a persistent infection" is ameliorating any condition or symptom associated with the persistent infection. Alternatively, alleviating a symptom of a persistent infection can involve reducing the infectious microbial (such as viral, bacterial, fungal or parasitic) load in the subject relative to such load in an untreated control. As compared with an equivalent untreated control, such reduction or degree of prevention is at least 5%, 10%, 20%, 40%, 50%, 60%, 80%, 90%, 95%, or 100% as measured by any standard technique. Desirably, the persistent infection is completely cleared as detected by any standard method known in the art, in which case the persistent infection is considered to have been treated. A patient who is being treated for a persistent infection is one who a medical practitioner has diagnosed as having such a condition. Diagnosis may be by any suitable means. Diagnosis and monitoring may involve, for example, detecting the level of microbial load in a biological sample (for example, a tissue biopsy, blood test, or urine test), detecting the level of a surrogate marker of the microbial infection in a biological sample, detecting symptoms associated with persistent infections, or detecting immune cells involved in the immune response typical of persistent infections (for example, detection of antigen specific T cells that are anergic and/or functionally impaired). A patient in whom the development of a persistent infection is being prevented may or may not have received such a diagnosis. One in the art will understand that these patients may have been subjected to the same standard tests as described above or may have been identified, without examination, as one at high risk due to the presence of one or more risk factors (such as family history or exposure to infectious agent).

[00344] For the treatment of diseases, as described herein, the appropriate dosage of an antibody or antigen-binding fragment thereof will depend on the type of disease to be treated, as defined above, the severity and course of the disease, whether the antigen-binding polypeptide construct, antibody or antigen binding fragment thereof is administered for preventive or therapeutic purposes, previous therapeutic indications, the subject's clinical history and response to the antigen-binding polypeptide construct, antibody or antigen-binding fragment thereof , and the discretion of the attending physician. The antigen-binding polypeptide construct, antibody or antigen-binding fragment thereof is suitably administered to the subject at one time or over a series of treatments. In a combination therapy regimen, the antigen-binding polypeptide construct, antibody or antigen-binding fragment thereof and the one or more additional therapeutic agents described herein are administered in a therapeutically effective or synergistic amount. As used herein, a therapeutically effective amount is such that co-administration of an antigen-binding polypeptide construct, antibody or antigen-binding fragment thereof and one or more other therapeutic agents, or administration of a composition described herein, results in reduction or inhibition of a disease or disorder as described herein. A therapeutically synergistic amount is that amount of an antigen-binding polypeptide construct, antibody or antigen-binding fragment thereof and one or more other therapeutic agents necessary to synergistically or significantly reduce or eliminate conditions or symptoms associated with a particular disease. In some cases, the antigen-binding polypeptide construct, antibody or antigen-binding fragment thereof can be co administered with one or more additional therapeutically effective agents to give an additive effect resulting in a significantly reduction or elimination of conditions or symptoms associated with a particular disease, but with a much reduced toxicity profile due to lower dosages of one or more of the additional

therapeutically effective agents.

Exemplary Antigen-Specific IgM Memory B cell Clone Sequences

[00345] Provided herein as SEQ ID NOs: 1-154 are nucleotide and corresponding amino acid sequences, and heavy and light chain CDR amino acid sequences sequenced from malarial antigen-specific memory B cell clones for MSP 1 and AMA obtained using the methods described herein.

[00346] Clone B6-3P1 uses a V _H IMGT of IGHVl-64*0l, a J _H IMGT of IGHJ4*0l and has a V _H light chain nucleotide sequence of:

CAGGTGCAGCTGCAGCAGCCTGGGGCTGAGCTGGTAAAGCCTGGGGCTTCAGTGAAGTTG TCCTGCAAGGCTTCTGGC TACACTTTCATCAACTACTGGATGCACTGGGTGAAGCAGAGGCCTGGACAAGGCCTTGAG TGGATTGGAATGATTCAT C C T AAAAGT G GT AG C AC T AAC T T C AAT GAGAAGT T C AAGAG C AAG G C C AC AC T GAC T GT AGAC AAAT C C T C C AG C AC A GCCTACATGCAAGTCAGCAGCCTGACATCTGAGGACTCTGCGGTCTATTATTGTGCAAAG GAAGTCATGGACTACTGG GGTCAAGGAACCTCAGTCACCGTCTCCTCAG (SEQ ID NO: 1).

[00347] Clone B6-3P1 uses a V _K IMGT of IGKV8-24*0l, a J _K IMGT of IGKJ2*0land has a V _K light chain nucleotide sequence of:

GACATTGTGATGACTCAGTCTCCATCCTCCCTGGCTATGTCAGTAGGACAGAAGGTCACT ATGAACTGCAAGTCCAGT CAGAG C C T T T T AAAT AGT AGAAAT C AAAAGAAT TTTTTGGCCTGGTAC C AAC AGAAAC C AG GAC AGT C T C C T AAAC T T CTGGTATACTTTGCATCCACTAGGGACTCTGGGGTCCCTGATCGCTTCATAGGCAGTGGA TCTGGGACAGATTTCACT CTTACCATCAGCAGTGTGCAGGCTGAAGACCTGGCAGATTACTTCTGTCAGCAACATTAT AGCACTCCGTACACGTTC GGAG G G G G GAC C AAG C T G GAAAT AAAAC (SEQ ID NO: 2). [00348] Clone Dl-3Pluses a V _H IMGT of IGHV3-6*0l, a J _H IMGT of IGHJ4*0l and has a V _H light chain nucleotide sequence of:

GATGTACAGCTTCAGGAGTCAGGACCTGGCCTCGTGAAACCTTCTCAGTCTCTGTCTCTC ACCTGTTCTGTCATTGGT TATTCCATCACCAGTGGTTATTACTGGAACTGGGTCCGGCAGTTTCCAGGAAACAAACTG GAATGGATGTCCTACATA AAC T AC GAT G GT AAC AAT AAC T AC AAC CCTTCTCT C AAAAAT C GAAT C T C CAT C AC T C GT GAC AC AT C T AAGAAC C AG TTTTTCCTGAAGTTGAATTCTGTGACTACTGAGGACACAGCCACATATTACTGTGCAAGA GGGAGGTTTCCTTATGCT TTGGACTACTGGGGTCAAGGAACCTCAGTCACCGTCTCCTCAG (SEQ ID NO: 3).

[00349] Clone Dl-3Pluses a V _K IMGT of IGKVl2-46*0l, a J _K IMGT of IGKJl*0land has a V _K light chain nucleotide sequence of:

GACATCCAGATGACTCAGTCTCCAGCCTCCCTATCTGTCTCTGTGGGAGAAACTGTCACC ATCACATGTCGAGCAAGT GAGAAT AT T T AC AGT AAT T T AG CAT G GT AT C AG C AGAAAC AG G GAAAAT C T C C T C AG CTCCTGGTC TAT GAAAC AAC A AAGTTAAGAGATGGTGTGTCATCAAGGTTCAGTGGCAGTGGATCAGGCACACAGTATTTC CTCAAGATCAACAACCTG CAGTCTGAAGATTTTGGGAGTTATTACTGTCAACATTTTTGGGGGAGTCCGTGGACGTTC GGTGGGGGCACCAAGCTG GAAAT CAAAC (SEQ ID NO: 4).

[00350] Clone D5-3Pluses a V _H IMGT of IGHVl0-3*0l, a J _H IMGT of IGHJ3*0l and has a V _H light chain nucleotide sequence of:

GAGGTGCAGCTGGTGGAGTCTGGTGGAGGATTGGTGCAGCCTAAAGGATCATTGAAACTC TCATGTGCCGCCTCTGGT TTCACCTTCAATACCTATGCCATGCACTGGGTCCGCCAGGCTCCAGGAAAGGGTTTGGAA TGGGTTGCTCGCATAAGA AGT AAAAGT AGT AAT T AT GCAACAT AT T AT GC C GAT T CAGT GAAAGACAGAT T CAC CAT CT C CAGAGAT GAT T CACAA AGCAT GCT CTAT CT GCAAAT GAAC AAC C T GAAAAC T GAG GAC AC AG C CAT GTATTACT GT GT GAGAGAGAGTT GGGAC CTCTGGTTTGCTTACTGGGGCCAAGGGACTCTGGTCACTGTCTCTGCA (SEQ ID NO: 5).

[00351] Clone D5-3Pluses a V _K IMGT of IGKV8-27*0l, a J _K IMGT of IGKJl*0land has a VK light chain nucleotide sequence of:

AACATTAT GAT GACACAGT CGCCAT CAT CT CT GGCT GT GT CT GCAGGAGAAAAGGT CACTAT GAGCT GTAAGT CCAGT CAAAGTGTTTTATACAGTTCAAATCAGAAGAACTACTTGGCCTGGTACCAGCAGAAACCA GGGCAGTCTCCTAAATTG CTGATCTACTGGGCATCCACTAGGGAATCTGGTGTCCCTGATCGCTTCACAGGCAGTGGA TCTGGGACAGATTTTACT CTTACCATCAGCAGTGTACAAGCTGAAGACCTGGCAGTTTATTACTGTCATCAATACCTC TCCTCGTGGACGTTCGGT GGAG G CAC C AAG C T G GAAAT CAAAC (SEQ ID NO: 6).

[00352] Clone B2-3P3 uses a V _H IMGT of IGHVl-l8*0l, a J _H IMGT of IGHJ2*0l and has a V _H light chain nucleotide sequence of:

GAGGTGCAGCTGCAGCAGTCTGGACCTGAGCTGGTGAAGCCTGGGGCTTCAGTGAAGATA CCCTGCAAGGCTTCTGGA T AC AC AT T CAC T GAC T AC AAC AT G GAC T G G GT GAAG C AGAG C CAT G GAAAGAG C C T T GAGT G GAT T G GAGAT AT T AAT CCTAACAATGGTGGTACTATCTACAACCAGAAGTTCAAGGGCAAGGCCACATTGACTGTA GACAAGTCCTCCAGCACA GC C T AC AT G GAG C T C C G C AG C C T GAC AT C T GAG GAC AC T G CAGT C TAT T AC T GT G C AAGAAG GAGAT T AC GAC GT GAG GGGGACTTTGACTACTGGGGCCAAGGCACCACTCTCACAGTCTCCTCA (SEQ ID NO: 7).

[00353] Clone B2-3P3 uses a V _K IMGT of IGKV6-l5*0l, a J _K IMGT of IGKJ2*0land has a VK light chain nucleotide sequence of: GACATTGTGATGACTCAGTCTCAAAAATTCATGTCCACATCAGTAGGAGACAGGGTCAGC GTCACCTGCAAGGCCAGT

CAGAAT GT GAAT AC T AAT GT AG C C T G GT AT C AAC AGAAAC C AG G G C AAT C T C C T AAAG C AC T GAT TTACTCGG CAT C C TTCCGGTACAGTGGAGTCCCTGATCGCTTCACAGGCAGTGGATCTGGGACAGATTTCACT CTCACCATCAGCAATGTG CAGTCTGAAGACTTGGCAGAGTATTTCTGTCAGCAATATAACAGCTATCCTCTCACGTTC GGAGGGGGGACCAAGCTG GAAATAAAAC (SEQ ID NO: 8).

[00354] Clone C3-3P3 uses a V _H IMGT of IGHV3-6*0l, a J _H IMGT of IGHJ4*0l and has a VH light chain nucleotide sequence of:

GATGTACAGCTTCAGGAGTCAGGACCTGGCCTCGTGAAACCTTCTCAGTCTCTGTCTCTC ACCTGCTCTGTCACTGGC TACTCCATCACCAGTGGTTATTACTGGAACTGGATCCGGCAGTTTCCAGGAAACAAACTG GAATGGATGGGCTACATA AG C T AC GAT G GT AG C AAT AAC T AC AAC C CAT C T C T C AAAAAT C GAAT C T C CAT C AC T C GT GAC AC AT C T AAGAAC C AG TTTTTCCTGAAGTTGAATTCTGTGACTACTGAGGACACAGCCACATATTACTGTGCAAGA GGGAAGGGATCCTATGCT ATGGACTACTGGGGTCAAGGAACCTCAGTCACCGTCTCCTCAG (SEQ ID NO: 9).

[00355] Clone C3-3P3 uses a V _K IMGT of IGKVl2-46*0l, a J _K IMGT of IGKJ4*0land has a VK light chain nucleotide sequence of:

GACATCCAGATGACTCAGTCTCCAGCCTCCCTATCTGTATCTGTGGGAGAAACTGTCACC ATCACATGTCGAGCAAGT GAGAAT AT T T AC AGT AAT T T AG CAT G GT AT C AG C AGAAAC AG G GAAAAT C T C C T C AG CTCCTGGTC TAT GT T G C AAC A AACTTAGCAGATGGTGTGCCATCAAGGTTCAGTGGCAGTGGATCAGGCACACAGTATTCC CTCAAGATCAACAGCCTG CAGTCTGAAGATTTTGGGAGTTATTACTGTCAACATTTTTGGGGTACTCCATTCACGTTC GGCTCGGGGACAAAGTTG GAAATAAAAC (SEQ ID NO: 10).

[00356] Clone A 1 -3P3 uses a V _H IMGT of IGHV 1 -77* 01 , a J _H IMGT of IGHJ2* 01 and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGAAGCAGTCTGGAGCTGAGCTGGTGAAGCCTGGGGCTTCAGTGAAGATG TCCTGCAAGGCTTCTGGC T AC AC C T T C AC T GAC T AC T AT AT AAAC T G GT T GAAAC AGAG G C C T G GAC AG G G C C T T GAGT G GAT T G GAAAGAT T G GT C C T G GAAGT GGTAGTACTTAC T AC AAT GAGAAGT T C AAG GAC AAG G C C AC AC T GAC T G C AGAC AAAT C C T C C AG C AC A GC C T AC AT G C AG C T C AG C AG C C T GAC AT C T GAG GAC T C T G C AGT C TAT T T C T GT AC AAGAAC C T AC TAT AGT AAT T AC TTTGACTACTGGGGCCAAGGCACCACTCTCACAGTCTCCTCAG (SEQ ID NO: 11).

[00357] Clone A1-3P3 uses a V _K IMGT of IGKV6-32*0l, a J _K IMGT of IGKJ2*0land has a VK light chain nucleotide sequence of:

AGTATTGTGATGACCCAGACTCCCAAATTCCTGCTTGTATCAGCAGGAGACAGGGTTACC ATAACCTGCAAGGCCAGT CAGAGTGTGAATAATAATGTAGCTTGGTACCAACAGAAGCCAGGGCAGTCTCCTAAACTG CTGATATTTTATGCATCC AATCGCTACACTGGAGTCCCTGATCGCTTCACTGGCAGTGGATATGGGACGGATTTCACC TTCACCATCAACACTGTG CAGGCTGAAGACCTGGCAGTTTATTTCTGTCAGCAGGATTATAGTTCTCCGAACACGTTC GGAGGGGGGACCAAGCTG GAAATAAAAC (SEQ ID NO: 12).

[00358] Clone F1-3P3 uses a V _H IMGT of IGHVl-64*0l, a J _H IMGT of IGHJ2*0l and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGCAGCAGCCTGGGGCTGAACTGGTGAAGCCTGGGGCTTCAGTGAAGTTG TCCTGTAAGGCTTCTGGC TACACTTTCACCTTCTACTGGATGCACTGGGTGAAGCAGAGGCCTGGACAAGGCCTTGAG TGGATTGGAATGATTCAT CCTAATAGT GGTAGTACTAACTACAAT GAGAAGTT CAAGAGCAAGGCCACACT GACT GTAGACAAAT CCT CCAGCACA GCCTACATGCAACTCAGCAGCCTGACATCTGAGGACTCTGCGGTCTATTACTGTGCAAGA GGGGGGGACTTTGACTAC TGGGGCCAAGGCACCACTCTCACAGTCTCCTCAG (SEQ ID NO: 13).

[00359] Clone F1-3P3 uses a V _K IMGT of IGKV3-2*0l, a J _K IMGT of IGKJl*0land has a VK light chain nucleotide sequence of:

GACATTGTGCTGACCCAATCTCCACCTTCTTTGGCTGTGTCTCTAGGGCAGAGGGCCACC ATCTCCTGCAGAGCCAGC GAAAGT GT T GAT AAT T T T G G CAT T AAT T T TAT GAAC T G GT T C C AAC AGAAAC C AG GAC AG C C AC C C AAAC T C C T CAT C TATGCTGCATCCAACCAAGGATCCGGGGTCCCTGCCAGGTTTAGTGGCAGTGGGTCTGGG ACAGACTTCAGCCTCAAC ATCCATCCTATGGAGGAGGATGATACTGCAATGTATTTCTGTCAGCAAAGTAAGGAGGTT CCTCGGACGTTCGGTGGA GG C AC C AAG C T G GAAAT C AAAC (SEQ ID NO: 14).

[00360] Clone F5-3P3 uses a V _H IMGT of IGHV3-6*0l, a J _H IMGT of IGHJ4*0l and has a VH light chain nucleotide sequence of:

GATGTACAGCTTCAGGAGTCAGGACCTGGCCTCGTGAAACCTTCTCAGTCTCTGTCTCTC ACCTGCTCTGTCACTGGC TACTCCATCACCAGTGGTTATTACTGGAACTGGATCCGGCAGTTTCCAGGAAACAACCTG GAATGGATGGGCTACATA AAC T AC GAT G GT AG C AAT AAC T AC AAT CCTTCTCT C AAAAAT C GAAT C T C CAT C AC T C GT GAC AC AT C T AAGAAC C AG TTTTTCCTGAAGTTGAATTCTGTGACTAGTGAGGACACAGGCACGTATTACTGTGCAAGA GGGGCCTACAATAGTAAC TGGGGGGGTGCTATGGACTGCTGGGGTCAAGGAACCTCAGTCACCGTCTCCTCAG (SEQ ID NO: 15).

[00361] Clone F5-3P3 uses a V _K IMGT of IGKVl2-46*0l, a J _K IMGT of IGKJl*0land has a VK light chain nucleotide sequence of:

GACATCCAGATGACTCAGTCTCCAGCCTCCCTATCTGTATCTGTGGGAGAAATTGTCACC ATCACATGTCGAGCAAGT GAGAAT AT T T AC AGT AAT T T AG CAT G GT AT C AG C AGAAAC AG G GAAAAT C T C C T C AC CTCCTGGTC TAT G C T G C AAC A AAGTTAGCAGCTGGTGTGCCATCAAGGTTCAGTGGCAGTGGATCAGGCACGCAGTATTCC CTCAAGATCAACAGCCTG CAGTCTGAAGATTTTGGGAGTTATTACTGTCAACATTTTTGGGGTATTCCCCCGACGTTC GGTGGAGGCACCAAGCTG

GAAAT CAAAC (SEQ ID NO: 16).

[00362] Clone A3-1P2 uses a V _H IMGT of IGHVl-64*0l, a J _H IMGT of IGHJ2*0l and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGCAGCAGCCTGGGGCTGAGCTGGTAAAGCCAGGGGCTTCAGTGAAGTTG TCCTGCAGGGCTTCTGGC TACACTTTCACCAGCTACTGGATGCACTGGGTGAAGCAGAGGCCTGGACAAGGCCTTGAG TGGATTGGAATGATTCAT CCTAAAAGTGGTAGTATTAATTACAATGAGAAGTTCAAGAGCAAGGCCACACTGACTGTA GACAAATCCTCCAGCACA GCCTACATGCAACTCAGCAGCCTGACATCTGAGGACTCTGCGGTCTATTACTGTGCAAGA GGTGGGGACTTTGACTAC TGGGGCCAGGGCACCACTCTCACAGTCTCCTCAG (SEQ ID NO: 17).

[00363] Clone A3-1P2 uses a V _K IMGT of IGKV3-2*0l, a J _K IMGT of IGKJl*0land has a VK light chain nucleotide sequence of:

GACATTGTGCTGACCCAATCTCCAGCTTCTTTGGCTGTGTCTCTAGGGCAGAGGGCCACC ATCTCCTGCAGAGCCAGC GAAAGT GT T GAT AAT TAT G G CAT T AGT T T TAT GAAC T G GT T C C AAC AGAAAC C AG GAC AG C C AC C CAAAC T C C T CAT C TATGCTGCATCCAACCAAGGATCCGGGGTCCCTGCCAGGTTTAGTGGCAGTGGGTCTGGG ACAGATTTCAGCCTCAAC ATCCATCCTATGGAGGAGGATGATACTGCAATGTATTTCTGTCAGCAAAGTAGGGAAATT CCTCGGACGTTCGGTGGA

GG C AC C AAG C T G GAAAT CAAAC (SEQ ID NO: 18). [00364] Clone B3-1P2 uses a V _H IMGT of IGHV3-6*0l, a J _H IMGT of IGHJ4*0l and has a VH light chain nucleotide sequence of:

GATGTACAGCTTCAGGAGTCAGGACCTGGCCTCGTGAAACCTTCTCAGTCTCTGTCTCTC ACCTGCTCTGTCACTGGC TACTCCATCACCAGTGGTTATTACTGGAACTGGATCCGGCAGTTTCCAGGAAACAAACTG GAATGGATGGGCTACATA AG C T AC GAT G GT AG C AAT AAC T AC AAC C CAT C T C T C AAAAAT C GAAT C T C CAT C AC T C GT GAC AC AT C T AAGAAC C AG TTTTTCCTGAAGTTGAATTCTGTGACTACTGAGGACACAGCCACATATTACTGTGCAAGG GAAAGTCCGGGCTACTAT GCTATGGACTACTGGGGTCAAGGAACCTCAGTCACCGTCTCCTCAG (SEQ ID NO: 19).

[00365] Clone B3-1P2 uses a V _K IMGT of IGKVl2-46*0l, a J _K IMGT of IGKJ5*0land has a VK light chain nucleotide sequence of:

GACATCCAGATGACTCAGTCTCCAGCCTCCCTATCTGTATCTGTGGGAGAAACTGTCACC ATCACATGTCGAGCAAGT GAGAAT AT T T AC AGT AAT T T AG CAT G GT AT C AG C AGAAAC AG G GAAAAT C T C C T C AG CTCCTGGTC TAT G C T G C AAC A AACTTAGCAGATGGTGTGCCATCAAGGTTCAGTGGCAGTGGATCAGGCACACAGTATTCC CTCAAGATCAACAGCCTG CAGTCTGAAGATTTTGGGAGTTATTACTGTCAACATTTTTGGGGTACTCCGTTCACGTTC GGTGCTGGGACCAAGCTG GAGCTGAAAC (SEQ ID NO: 20).

[00366] Clone B2-1P2 uses a V _H IMGT of IGHVl-64*0l, a J _H IMGT of IGHJ2*0l and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGCAGCAGCCTGGGGCTGAGCTGGTAAAGCCTGGGGCTTCAGTGAAGTTG TCCTGCAAGGCTTCTGGC TACACTTTCACCAGCTACTGGATGCACTGGGTGAAGCAGAGGCCTGGACAAGGCCTTGAG TGGATTGGAATGATTCAT CCTAATAGT GGTAGTACTAACTACAAT GAGAAGTT CAAGAGCAAGGCCACACT GACT GTAGACAAAT CCT CCAGCACA GCCTACATGCAACTCAGCAGCCTGACATCTGAGGACTCTGCGGTCTATTACTGTGCAAGA GGAGGTGACTTTGACTAC TGGGGCCAAGGCACCACTCTCACAGTCTCCTCAG (SEQ ID NO: 21).

[00367] Clone B2-1P2 uses a V _K IMGT of IGKV3-2*0l, a J _K IMGT of IGKJl*0land has a VK light chain nucleotide sequence of:

GACATTGTGCTGACCCAATCTCCAGCTTCTTTGGCTGTGTCTCTAGGGCAGAGGGCCACC ATCTCCTGCAGAGCCAGC GAAAGT GT T GAT AAT TAT G G CAT T AGT T T TAT GAAC T G GT T C C AAC AGAAAC C AG GAC AG C C AC C C AAAC T C C T CAT C TATGCTGCATCCAACCAAGGATCCGGGGTCCCTGCCAGGTTTAGTGGCAGTGGGTCTGGG ACAGACTTCAGCCTCAAC ATCCATCCTATGGAGGAGGATGATACTGCAATGTATTTCTGTCAGCAAAGTAAGGAGGTT CCTCGGACGTTCGGTGGA GG C AC C AAG C T G GAAAT C AAAC (SEQ ID NO: 22).

[00368] Clone A6B-1P2 uses a V _H IMGT of IGHV3-6*0l, a J _H IMGT of IGHJ2*0l and has a VH light chain nucleotide sequence of:

GATGTACAGCTTCAGGAGTCAGGACCTGGCCTCGTGAAACCTTCTCAGTCTCTGTCTCTC ACCTGCTCTGTCACTGGC TACTCCATCACCAGTGGTTATTACTGGAACTGGATCCGGCAGTTTCCAGGAAACAAACTG GAATGGATGGGCTACATA AG C T AC GAT G GT AG C AAT AAC T AC AAC C CAT C T C T C AAAAAT C GAAT C T C CAT C AC T C GT GAC AC AT C T AAGAAC C AG TTTTTCCT GAAGT T GAAT T C T GT GAC TACT GAG GAC AC AG C C AC AT AT T AC T GT G C AAGAGAGAC T G G GAC GAG GT AC TTTGACTACTGGGGCCAAGGCACCACTCTCACAGTCTCCTCAG (SEQ ID NO: 23).

[00369] Clone A6B-1P2 uses a V _K IMGT of IGKVl2-46*0l, a J _K IMGT of IGKJ2*0land has a VK light chain nucleotide sequence of: GACATCCAGATGACTCAGTCTCCAGCCTCCCTATCTGTATCTGTGGGAGAAACTGTCACC ATCACATGTCGAGCAAGT

GAGAATATTTACAGTAATTTAGCATGGTATCAGCAGAAACAGGGAAAATCTCCTCAG CTCCTGGTCTATGCTGCAACA AACTTAGCAGATGGTGTGCCATCAAGGTTCAGTGGCAGTGGATCAGGCACACAGTATTCC CTCAAGATCAACAGCCTG CAGTCTGAAGATTTTGGGAGTTATTACTGTCAACATTTTTGGGGTACTCCGTACACGTTC GGAGGGGGGACCAAGCTG GAAATAAAAC (SEQ ID NO: 24).

[00370] Human malaria antigen AMA-specific IgM clone A8P1-A1 uses a V _H IMGT of IGHV4- 31*03, a J _H IMGT of IGHJ3*02 and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCACAGACCCTGTCCCTC ACCTGCACTGTCTCTGGT GGCTCCATCAGCAGTAGTGGTTACTACTGGAGCTGGATCCGCCAGCACCCAGCGAAGGGC CTGGAGTGGATTGGGTAC ATCTATTACAGTGGGAGCACCTATCACAACCCGTCCCTCAAGAGTCGAGTTACCATATCA GTAGGCACGTCTAAGAAC CAGTTCTCCCTGAAGCTGAGCTCTGTGACTGCCGCGGA (SEQ ID NO: 25).

[00371] The amino acid sequence of the V _H domain of AMA-specific IgM clone A8P1-A1 corresponding to SEQ ID NO: 25 is:

QVQLQESGPGLVKPSQTLSLTCTVSGGSISSSGYYWSWIRQHPAKGLEWIGYIYYSGSTY HNPSLKSRVTISVGTSKN QFSLKLSSVTAADTAVYYCARGYFSGTYSGAFDIWGQGTMVTVSS (SEQ ID NO: 26).

[00372] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 26 according to the IMGT sequence numbering is: GGSISSSGYY (SEQ ID NO: 27). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 26 according to the IMGT sequence numbering is: IYYSGST (SEQ ID NO: 28). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 26 according to the IMGT sequence numbering is: ARGYFSGTYSGAFDI (SEQ ID NO: 29)

[00373] Human malaria antigen AMA-specific IgM clone A8P1-A1 uses a V, IMGT of IGLV2-23*0l and IGLV2-23*03, a IMGT of IGLJ3*02 and has a VL light chain nucleotide sequence of:

CAGTCTGCCCTGACTCAGCCTGCCTCCGTGTCTGGGTCTCCTGGACAGTCGATCACCATC TCCTGCACTGGAACCAGC AGTGATGTTGGGAGTTATAACCTTGTCTCCTGGTACCAACAGCACCCAGGCAAAGCCCCC AAACTCATGGTTTATGAG GGCAGTAAACGGCCCTCAGGGCTTTCTAATCGCTTCTCTGGCTCCAAGTCTGGCAACACG GCCTCCCTGACAATCTCT GGGCTCCAGGCTGAAGACGAGGCTGATTATTACTGCTGCTCATATGCAGGTAGTAGCACT TGGGTGTTCGGCGGAGGG ACCAAACT (SEQ ID NO: 30).

[00374] The amino acid sequence of the V _L domain of AMA-specific IgM clone A8P1-A1 corresponding to SEQ ID NO: 30 is:

QSALTQPASVSGSPGQSITISCTGTSSDVGSYNLVSWYQQHPGKAPKLMVYEGSKRPSGL SNRFSGSKSGNTASLTIS GLQAEDEADYYCCSYAGSSTWVFGGGTKLTVL (SEQ ID NO: 31).

[00375] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _L domain of SEQ ID NO: 31 according to the IMGT sequence numbering is: SSDVGSYNL (SEQ ID NO: 32). The amino acid sequence of the CDR2 of the V _L domain of SEQ ID NO: 31 according to the IMGT sequence numbering is: EGS (SEQ ID NO: 33). The amino acid sequence of the CDR3 of the VL domain of SEQ ID NO: 31 according to the IMGT sequence numbering is: CSYAGSSTWV (SEQ ID NO: 34).

[00376] Human malaria antigen AMA-specific IgM clone A8P1-B1 uses a VH IMGT of IGHV3- 11*01, a JH IMGT of IGHJ4*02 and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGGTGGAGTCTGGGGGAGGCTTGGTCAAGCCTGGAGGGTCCCTGAGACTC TCCTGTGCAGCCTCTGGA TTCACCTTCAGTGACTACTACATGAGCTGGATCCGCCAGGCTCCAGGGAAGGGGCTGGAG TGGATTTCATACATTAGT AGTAGTGGTAGTACCATATACTACGGAGACTCTGTGAAGGGCCGATTCACCATCTCCAGG GACAACGCCAAGAACTCA CT GT AT C T AC AAAT GAAC AG C C T GAGAG C C GAG GAC A (SEQ ID NO: 35).

[00377] The amino acid sequence of the VH domain of AMA-specific IgM clone A8P1-B1

corresponding to SEQ ID NO: 35 is:

QVQLVESGGGLVKPGGSLRLSCAASGFTFSDYYMSWI RQAPGKGLEWI SYI S S SGSTIYYGDSVKGRFTI SRDNAKNS L YLQMN S L RAE DT AVY Y CARE RG S G S YWVD YW GQ GT L VT V S S (SEQ ID NO: 36).

[00378] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VH domain of SEQ ID NO: 36 according to the IMGT sequence numbering is: GFTFSDYY (SEQ ID NO: 37). The amino acid sequence of the CDR2 of the VH domain of SEQ ID NO: 36 according to the IMGT sequence numbering is: ISSSGSTI (SEQ ID NO: 38). The amino acid sequence of the CDR3 of the VH domain of SEQ ID NO: 36 according to the IMGT sequence numbering is: ARERGSGSYWVDY (SEQ ID NO: 39).

[00379] Human malaria antigen AMA-specific IgM clone A8P1-B1 uses a V, IMGT of IGLV4-69*0l, a Jx IMGT of IGLJ2*0l and IGLJ3*0l and has a VL light chain nucleotide sequence of:

CAGCTTGTGCTGACTCAATCGCCCTCTGCCTCTGCCTCCCTGGGAGCCTCGGTCAAGCTC ACCTGCACTCTGAGCAGT

GGGCACAGCAACTACGCCATCGCATGGCATCAGCAGCAGCCAGAGAAGGGCCCTCGG TGCTTGATGAAGGTTAACAGT

GATGGCAGCCACAGCAAGGGGGACGGGATTCCTGATCGCTTCTCAGGCTCCAGCTCT GGGGCTGAGCGCTACCTCACC

ATCTCCAGCCTCCAGTCTGAGGATGAGGCTGACTATTACTGTCAGACCTGGACCACT GGCATTCGGGTATTCGGCGGA

GGGA (SEQ ID NO: 40)

[00380] The amino acid sequence of the VL domain of AMA-specific IgM clone A8P1-B 1

corresponding to SEQ ID NO: 40 is:

QLVLTQS PSASASLGASVKLTCTLS SGHSNYAIAWHQQQPEKGPRCLMKWSDGSHSKGDGI PDRFSGS S SGAERYLT I S SLQSEDEADYYCQTWTTGI RVFGGGTKLTVL (SEQ ID NO: 41).

[00381] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VL domain of SEQ ID NO: 41 according to the IMGT sequence numbering is: SGHSNYA (SEQ ID NO: 42). The amino acid sequence of the CDR2 of the VL domain of SEQ ID NO: 41 according to the IMGT sequence numbering is: VNSDGSH (SEQ ID NO: 43). The amino acid sequence of the CDR3 of the VL domain of SEQ ID NO: 41 according to the IMGT sequence numbering is: QTWTTGIRV (SEQ ID NO: 44). [00382] Human malaria antigen AMA-specific IgM clone A8P1-B10 uses a V _H IMGT of IGHV3- 15*01, a J _H IMGT of IGHJ4*02 and has a VH light chain nucleotide sequence of:

GAGGTGCAGCTGGTGGAGTCTGGGGGAGGCTTGGTAAAGCCTGGGGGGTCCCTTAGACTC TCCTGTGTTGCCTCTGGA TTCACTTTCGATAACGCCTGGATGAGCTGGGTCCGCCAGGCTCCAGGGAAGGGGCTGGAG TGGGTTGGCCGTATTAAA AGTAAAAGTGATGGTGTGACAACGGACTACGCCGCACACGTGAAAGGCAGATTCACGATC TCAAGAGACGAATCAAAA AC T C C T C TAT AT C T G C AAAT GAAC AG C C T GAGAG (SEQ ID NO: 45).

[00383] The amino acid sequence of the V _H domain of AMA-specific IgM clone A8P1-B10 corresponding to SEQ ID NO: 45 is:

EVQLVESGGGLVKPGGSLRLSCVASGFTFDNAWMSWVRQAPGKGLEWVGRI KSKSDGVTTDYAAHVKGRFTI SRDESK TPLYLQMNSLRVEDTAMYYCTTGGNQYS FFDSWGRGTLVTVS S (SEQ ID NO: 46).

[00384] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 46 according to the IMGT sequence numbering is: GFTFDNAW (SEQ ID NO:

47). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 46 according to the IMGT sequence numbering is: IKSKSDGVTT (SEQ ID NO: 48). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 46 according to the IMGT sequence numbering is: TTGGNQYSFFDS (SEQ ID NO: 49).

[00385] Human malaria antigen AMA-specific IgM clone A8P1-B10 uses a V, IMGT of IGLV3-9*0l, a IMGT of IGLJ2*0l and IGLJ3*0l and has a VL light chain nucleotide sequence of:

TCCTATGAGCTGACACAGCCACTCTCAGTGTCAGTGGCCCTGGGACAGACGGCCAAGATT ACCTGTGGGGGAGACAAC

ATTGGAAGAAAGAATGTGCACTGGTACCAGCAGAAGCCAGGCCAGGCCCCTGTCTTG GTCATCTATAAGGATCGCTAC

CGGCCCTCTGGGATCCCTGAGCGATTCTCTGGCTCCAACTCGGGGAACACGGCCACC CTGACCATCAACAGAGCCCAA

GGCGGGGATGACGCTGACTATTTCTGTCAGGTGTGGGACAGTAGCGCTGCGGGGGTC CTATTCGGCGGAGGGACCAAG

CT (SEQ ID NO: 50)

[00386] The amino acid sequence of the V _L domain of AMA-specific IgM clone A8P1-B10 corresponding to SEQ ID NO: 50 is:

SYELTQPLSVSVALGQTAKITCGGDNI GRKNVHWYQQKPGQAPVLVIYKDRYRPSGI PERFSGSNSGNTATLTINRAQ GGDDADYFCQVWDS SAAGVLFGGGTKLTVL (SEQ ID NO: 51).

[00387] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _L domain of SEQ ID NO: 51 according to the IMGT sequence numbering is: NIGRKN (SEQ ID NO: 52). The amino acid sequence of the CDR2 of the V _L domain of SEQ ID NO: 51 according to the IMGT sequence numbering is: KDR (SEQ ID NO: 53). The amino acid sequence of the CDR3 of the V _L domain of SEQ ID NO: 51 according to the IMGT sequence numbering is: QVWDSSAAGVL (SEQ ID NO: 54).

[00388] Human malaria antigen AMA-specific IgG clone A8P1-D10 uses a V _H IMGT of IGHV4- 59*01 and IGHV4-59*08, a J _H IMGT of IGHJ4*02 and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCC CTCACCTGCAGTGTCTCTGGT

GACTCCATCAATTTTTACTACTGGAACTGGATCCGGCAGTCCCCAGGGAAGGGACTG GAGTGGATTGCGTATGTGTCT AACCGTGGTGACAGTACGAAGTATAACCCCTCACTCGAGAGTCGAGTCACCATTTCAAGA GAGCCGTCCAAGCGCCAG TCCTCCCTGAAACTGAACTCTGTGACCGCCGCGGACAC (SEQ ID NO: 55).

[00389] The amino acid sequence of the VH domain of AMA-specific IgG clone A8P1-D10

corresponding to SEQ ID NO: 55 is:

QVQLQESGPGLVKPSETLSLTCSVSGDS INFYYWNWI RQS PGKGLEWIAYVSNRGDSTKYNPSLESRVTI SREPSKRQ SSLKLNSVTAADTAVYYCALWS SYFRGYFDYWGQGI LVTVS S (SEQ ID NO: 56).

[00390] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VH domain of SEQ ID NO: 56 according to the IMGT sequence numbering is: GDSINFYYW (SEQ ID NO: 57). The amino acid sequence of the CDR2 of the VH domain of SEQ ID NO: 56 according to the IMGT sequence numbering is: SNRGDST (SEQ ID NO: 58). The amino acid sequence of the CDR3 of the VH domain of SEQ ID NO: 56 according to the IMGT sequence numbering is: ALWSSYFRGYFDY (SEQ ID NO: 59).

[00391] Human malaria antigen AMA-specific IgG clone A8P1-D10 uses a V _K IMGT of IGKV3- 15*01, a J _K IMGT of IGKJ3*0l and has a VL light chain nucleotide sequence of:

GAAATAGTGATGACGCAGTCTCCAGCCACCCTGTCTGTGTCTCCAGGGGAAAGAGTCACC CTCTCCTGCAGGGCCAGT

CAGAGTGTGAGCACCAATTTAGCCTGGTACCAGCAGAGGCCTGGCCAGGCTCCCAGG CTCCTCATCTATGCTTCTTCC

ACCAGGGCCACTGGTATCCCAGCCAGGTTCAGTGGCGGTGGGTCTGGGACAGAGTTC ACTCTCACCATCAGCAGCCTG

CAGTCTGAAGATTTTGCAGTTTATTACTGTCAGCAGTATGGTCACTGGCCTCCTTAC ACTTTCGGCCCTGGGACCAAA

GTGGA (SEQ ID NO: 60).

[00392] The amino acid sequence of the VL domain of AMA-specific IgG clone A8P1-D10

corresponding to SEQ ID NO: 60 is:

EIVMTQS PATLSVS PGERVTLSCRASQSVSTNLAWYQQRPGQAPRLLIYAS STRATGI PARFSGGGSGTEFTLTI S SL QSEDFAVYYCQQYGHWPPYTFGPGTKVDI K (SEQ ID NO: 61).

[00393] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VL domain of SEQ ID NO: 61 according to the IMGT sequence numbering is: QSVSTN (SEQ ID NO: 62).

The amino acid sequence of the CDR2 of the VL domain of SEQ ID NO: 61 according to the IMGT sequence numbering is: ASS (SEQ ID NO: 63). The amino acid sequence of the CDR3 of the VL domain of SEQ ID NO: 61 according to the IMGT sequence numbering is: QQYGHWPPYT (SEQ ID NO: 64).

[00394] Human malaria antigen MSP 1 -specific IgM clone A8P2-B7 uses a VH IMGT of IGHV4-

34*0land IGHV4-34*02, a JH IMGT of IGHJ4*0l and IGHJ4*02 and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTACAGCAGTGGGGCGCAGGACTGTTGAAGCCTTCGGAGACCCTGTCCCTC ACGTGCGCTGTCTATGGT GGGTCCTTCAGTGGTTACTACTGGACTTGGATCCGCCAGCCCCCAGGGAAGGGACTGGAG TGGATTGGAGAAATCAAT AATAGT GGAAAAAC CAACT ACAAC C C GT C CCTCAAAAGT C GAGT C AG CAT T T CAAT AGACAC GT C CAAGAAC CAGT T T

TCCCTGAAGGTGACTTCTGTGACCGCCGCGGACACAGC (SEQ ID NO: 65). [00395] The amino acid sequence of the V _H domain of MSP l-specific IgM clone A8P2-B7 corresponding to SEQ ID NO: 65 is:

QVQLQQWGAGLLKP S ETLS LTCAVYGGS FS GYYWTWI RQP PGKGLEWI GEINNS GKTNYNP S LKS RVS I S I DT S KNQF SLKVT SVTAADTAVYYCARGPQQHLEP P FDYWGHGTLVTVS S (SEQ ID NO: 66).

[00396] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 66 according to the IMGT sequence numbering is: GGSFSGYY (SEQ ID NO: 67). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 66 according to the IMGT sequence numbering is: INNSGKT (SEQ ID NO: 68). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 66 according to the IMGT sequence numbering is: ARGPQQHLEPPFDY (SEQ ID NO: 69).

[00397] Human malaria antigen MSP 1 -specific IgM clone A8P2-B7 uses a V, IMGT of IGLV1-

47*01, a Jx IMGT of IGLJ3*02 and has a VL light chain nucleotide sequence of:

CAGTCTGTGCTGACTCAGCCACCCTCAGCGTCTGGGACCCCCGGGCAAAGGGTCACCATC TCTTGTTCTGGAAGCAAC

TCCAACATCGCGACTAATTATGTGTGCTGGTACCAGCAATACCCAGGAACGGCCCCC AAACCCCTCATCTACAGGACT

GATCAGCGGCCCTCAGGGGTCCCTGACCGATTCTCTGGCTCCAAGTCTGGCACCTCA GCCTCCCTGGCCATCAGTGGG

CTCCGGTCCGAGGATGAGGCTGATTATTATTGTGCAACATGGGATGACAGCCTGAGT GCCTGGGTGTTCGGCGGAGGG

ACCA (SEQ ID NO: 70).

[00398] The amino acid sequence of the V _L domain of MSP 1 -specific IgM clone A8P2-B7

corresponding to SEQ ID NO: 70 is:

QSVLTQP P SAS GT PGQRVT I S CS GSNSNIATNYVCWYQQYPGTAPKPLI YRTDQRP S GVPDRFS GS KS GT SAS LAI S G LRS EDEADYYCATWDDS LSAWVFGGGTKLTVL (SEQ ID NO: 71).

[00399] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _L domain of SEQ ID NO: 71 according to the IMGT sequence numbering is: NSNIATNY (SEQ ID NO: 72). The amino acid sequence of the CDR2 of the V _L domain of SEQ ID NO: 71 according to the IMGT sequence numbering is: RTD (SEQ ID NO: 73). The amino acid sequence of the CDR3 of the V _L domain of SEQ ID NO: 71 according to the IMGT sequence numbering is: ATWDDSLSAWV (SEQ ID NO: 74).

[00400] Human malaria antigen AMA-specific IgM clone A8P2-E5 uses a V _H IMGT of IGHVl-8*02, a J _H IMGT of IGHJ6*03 and has a VH light chain nucleotide sequence of:

CAGGTTCAGCTGGTGCAGTCTGGGACTGAAGTGAGGGAGCCTGGGGCCTCAGTGAAGGTC TCCTGCAAGGCTTCTGGA T AC AC C T T C AC C AAC TAT GAT AT C AAC T G G GT G C GAC AG G C C AC AG GAC AAG G G C T T GAGT G G GT G G GAT G GAT GAAC C C T AAT AGT G GT GAGAC AG G C TAT G C AC AG GAGT T C C AG G G C AGAAT C AC CAT T AC T AG G GAC AC C T C C AT AAG C AC A AT T T AC AT G GAGT T GAG C AG C C T GAC AT C T GAG GAC AC G G C C GT AT AT TACTGTGC C AG (SEQ ID NO: 75).

[00401] The amino acid sequence of the V _H domain of AMA-specific IgM clone A8P2-E5

corresponding to SEQ ID NO: 75 is:

QVQLVQS GTEVREPGASVKVS CKAS GYT FTNYDINWVRQATGQGLEWVGWMNPNS GETGYAQEFQGRI T I TRDT S I ST I YMELS S LT S EDTAVYY CARGGFCT ST S CYYHYMDVWGKGTTVTVS S (SEQ ID NO: 76). [00402] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 76 according to the IMGT sequence numbering is: GYTFTNYD (SEQ ID NO: 77). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 76 according to the IMGT sequence numbering is: MNPNSGET (SEQ ID NO: 78). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 76 according to the IMGT sequence numbering is: ARGGFCTSTSCYYHYMDV (SEQ ID NO: 79)

[00403] Human malaria antigen AMA-specific IgM clone A8P2-E5 uses a V _K IMGT of IGKVl-5*03, a J _K IMGT of IGKJ2*0l and has a VL light chain nucleotide sequence of:

GACATCCAGATGACCCAGTCTCCTTCCACCCTGTCTGCATCTGTAGGAGACAGAGTCACC ATCACTTGTCGGGCCAGT CAGAGTGTTAATAGCTGGTTGGCCTGGTATCAGCAGAAACCAGGGAAAGCCCCTAAGGTC CTGATCTATAAGGCAACT AGTTTAGAAAGTGGGGTCCCATCAAGGTTCAGCGGCAGTGAATCTGGGACAGAATTCACT CTCACCATCAGCAGCCTG CAGGCTGATGATTTTGCAACTTATTACTGCCAACAGTATAATGATTTTCCGTACACTTTT GGCCGGGGGACCAAGCTG GAGATCAAAC (SEQ ID NO: 80).

[00404] The amino acid sequence of the V _L domain of AMA-specific IgM clone A8P2-E5

corresponding to SEQ ID NO: 80 is:

DIQMTQS PSTLSASVGDRVTITCRASQSWSWLAWYQQKPGKAPKVLIYKATSLESGVPSRFSGSESG TEFTLTI S SL QADDFATYYCQQYNDFPYTFGRGTKLEI K (SEQ ID NO: 81).

[00405] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _L domain of SEQ ID NO: 81 according to the IMGT sequence numbering is: QSVNSW (SEQ ID NO: 82). The amino acid sequence of the CDR2 of the V _L domain of SEQ ID NO: 81 according to the IMGT sequence numbering is: KAT (SEQ ID NO: 83). The amino acid sequence of the CDR3 of the V _L domain of SEQ ID NO: 81 according to the IMGT sequence numbering is: QQYNDFPYT (SEQ ID NO: 84).

[00406] Human malaria antigen MSP 1 -specific IgM clone A8P2-E6 uses a V _H IMGT of IGHV4-

34*0land IGHV4-34*02, a J _H IMGT of IGHJ4*02 and IGHJ5*02 and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTACAGCAGTGGGGCGCAGGACTGTTGAAGCCTGCGGAGACCCTGTCCCTC ACTTGCGCTGTCTATGGT GGGTCCTTCACTGGTCACTACTGGACCTGGATCCGTCAGCCCCCTGGTAAGGGGCCGGAA TGGATTGGGGAAATCAAT CATCGTGGAGGCACCGACTACAACCCGTCCCTCAAGAGTCGAGTCACCATTTCACTAGAC ACGTCCAAGAACCAGGTG TCCCTGAAACTGAGCGCTGTGACCGCCGTAGACACG (SEQ ID NO: 85).

[00407] The amino acid sequence of the V _H domain of MSP 1 -specific IgM clone A8P2-E6

corresponding to SEQ ID NO: 85 is:

QVQLQQWGAGLLKPAETLSLTCAVYGGS FTGHYWTWI RQPPGKGPEWI GEINHRGGTDYNPSLKSRVTI SLDTSKNQV SLKLSAVTAVDTAVYYCARGHGRYYYSYLDSWAQGTLVTVS S (SEQ ID NO: 86).

[00408] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 86 according to the IMGT sequence numbering is: GGSFTGHY (SEQ ID NO: 87). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 86 according to the IMGT sequence numbering is: INHRGGT (SEQ ID NO: 88). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 86 according to the IMGT sequence numbering is: ARGHGRYYYSYLDS (SEQ ID NO: 89)

[00409] Human malaria antigen MSP 1 -specific IgM clone A8P2-E6 uses a V _K IMGT of IGKVl-5*03, a J _K IMGT of IGKJ2*0l and IGKJ2*02, and has a VL light chain nucleotide sequence of:

GACATCCAGATGACCCAGTCTCCTTCCACCCTGTCTGCAGCTGTAGGAGACCGAGTCACC ATCACTTGCCGGGCCAGT CAGGCTATTAGTCCCTGGGTGGCCTGGTATCAGCAGAAACCAGGGAAAGCCCCTTCACTC CTTATCTATCAGGCGTCT ACTTTACAAAGTGCGGTCCCATTAAGGTTCAGCGGCAGTGGATCTGGGACAGACTTCACT CTCACCATCAGCAGCCTG CAGCCTGAGGATTTTGCAACTTATTTCTGCCAACAGTATGGTCGCTATTCCACTTTTGGC CAGGGGACCAAGCTGGAG ATCAAAC (SEQ ID NO: 90).

[00410] The amino acid sequence of the V _L domain of MSP 1 -specific IgM clone A8P2-E6

corresponding to SEQ ID NO: 90 is:

DIQMTQS PSTLSAAVGDRVTITCRASQAI S PWVAWYQQKPGKAPSLLIYQASTLQSAVPLRFSGSGSGTDFTLTI S SL QPEDFATYFCQQYGRYSTFGQGTKLEI K (SEQ ID NO: 91).

[00411] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _L domain of SEQ ID NO: 91 according to the IMGT sequence numbering is: QAISPW (SEQ ID NO: 92).

The amino acid sequence of the CDR2 of the V _L domain of SEQ ID NO: 91 according to the IMGT sequence numbering is: QAS (SEQ ID NO: 93). The amino acid sequence of the CDR3 of the V _L domain of SEQ ID NO: 91 according to the IMGT sequence numbering is: QQYGRYST (SEQ ID NO: 94).

[00412] Human malaria antigen MSPl-specific IgG clone A8P2-E12 uses a V _H IMGT of IGHV4- 34*01, a J _H IMGT of IGHJ4*02 and IGHJ5*02 and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTACAGCAGTGGGGCGCAGGACTGTTGAAGCCTGCGGAGACCCTGTCCCTC ACCTGCGCTGTCTATGGT GGGTCCTTCACTGGTTACTACTGGACCTGGATCCGTCAGCCCCCTGGTAAGGGGCTGGAA TGGATTGGGGAGATCAAT CATCGTGGAGGCACCGACTACAATCCGTCCCTCAAGAGTCGAGTCACCATTTCTCTTGAC ACGTCCAAGAACCAGGTG TCCCTGAAACTCCGCTCTGCGACCGCCGTAGACACGGC (SEQ ID NO: 95).

[00413] The amino acid sequence of the V _H domain of MSP 1 -specific IgM clone A8P2-E12

corresponding to SEQ ID NO: 95 is:

QVQLQQWGAGLLKPAETLSLTCAVYGGS FTGYYWTWI RQPPGKGLEWI GEINHRGGTDYNPSLKSRVTI SLDTSKNQV SLKLRSATAVDTAVYYCARGHGRYYYSYLNLWAQGTLVTVS S (SEQ ID NO: 96).

[00414] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 96 according to the IMGT sequence numbering is: GGSFTGYY (SEQ ID NO: 97). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 96 according to the IMGT sequence numbering is: INHRGGT (SEQ ID NO: 98). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 96 according to the IMGT sequence numbering is: ARGHGRYYYSYLNL (SEQ ID NO: 99) [00415] Human malaria antigen MSPl-specific IgM clone A8P2-E12 uses a V _K IMGT of IGKV1- 5*03, a J _K IMGT of IGKJ2*0l and IGKJ2*02, and has a VL light chain nucleotide sequence of:

GACATCCAGATGACCCAGTCTCCTTCCACCCTGTCTGCATCTGTAGGAGACAGAGTCACC ATCACTTGCCGGGCCAGT CAGGCTATTAGTCCCTGGTTGGCCTGGTATCAGCAGAAACCAGGGAGAGCCCCTAAACTC CTGATCTATCAGGCGTCC ACTTTACAAAGTGCGGTCCCATCAAGATTCAGCGGCAGTGGATCTGGGACAGAATTCACT CTCACCATCACCAGCCTG CAGCCTGAAGATTTTGCAACTTATTACTGCCAACAGTATGGTCGTTATTCCACTTTTGGC CAGGGGACCAAGCTGGAG ATCAAAC (SEQ ID NO: 100).

[00416] The amino acid sequence of the V _L domain of MSP 1 -specific IgM clone A8P2-E12 corresponding to SEQ ID NO: 100 is:

DIQMTQSPSTLSASVGDRVTITCRASQAISPWLAWYQQKPGRAPKLLIYQASTLQSAVPS RFSGSGSGTEFTLTITSL QPEDFATYYCQQYGRYSTFGQGTKLEIK (SEQ ID NO: 101).

[00417] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _L domain of SEQ ID NO: 101 according to the IMGT sequence numbering is: QAISPW (SEQ ID NO: 102). The amino acid sequence of the CDR2 of the V _L domain of SEQ ID NO: 101 according to the IMGT sequence numbering is: QAS (SEQ ID NO: 103). The amino acid sequence of the CDR3 of the V _L domain of SEQ ID NO: 101 according to the IMGT sequence numbering is: QQYGRYST (SEQ ID NO: 104).

[00418] Human malaria antigen AMA-specific IgM clone A8P3-B5 uses a V _H IMGT of IGHV4- 61*02, a J _H IMGT of IGHJ6*02, and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCACAGACCCTGTCCCTC ACCTGCACTGTCTCTGGT GGCTCCATCAGCAGTGGTAGTTACTACTGGAGCTGGATCCGGCAGCCCGCCGGGAAGGGA CTGGAGTGGATTGGGCGT ATCTATACCAGTGGGAGCACCAACTACAACCCCTCCCTCAAGAGTCGAGTCACCATATCA GTAGACACGTCCAAGAAC CAGTTCTCCCTGAAGCTGAGCTCTGTGACCGCCGCAGA (SEQ ID NO: 105).

[00419] The amino acid sequence of the V _H domain of AMA-specific IgM clone A8P3-B5

corresponding to SEQ ID NO: 105 is:

QVQLQESGPGLVKPSQTLSLTCTVSGGSISSGSYYWSWIRQPAGKGLEWIGRIYTSGSTN YNPSLKSRVTISVDTSKN QFSLKLSSVTAADTAVYYCARVMVRGVIGSYGMDVWGQGTTVTVSS (SEQ ID NO: 106).

[00420] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 106 according to the IMGT sequence numbering is: GGSISSGSYY (SEQ ID NO: 107). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 106 according to the IMGT sequence numbering is: IYTSGST (SEQ ID NO: 108). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 106 according to the IMGT sequence numbering is: ARVMVRGVIGSYGMDV (SEQ ID NO: 109)

[00421] Human malaria antigen AMA-specific IgM clone A8P3-B5 uses a V _L IMGT of IGLV3-2l*02, a J _L IMGT of IGLJ3*02, and has a VL light chain nucleotide sequence of:

TCCTATGTGCTGACTCAGCCACCCTCGGTGTCAGTGGCCCCAGGACAGACGGCCAGGATT ACCTGTGGGGGAAACAAC

ATTGGAAGTAAAAGTGTGCACTGGTACCAGCAGAAGCCAGGCCAGGCCCCTGTGCTG GTCGTCTATGATGATAGCGAC CGGCCCTCAGGGATCCCTGAGCGATTCTCTGGCTCCAACTCTGGGAACACGGCCACCCTG ACCATCAGCAGGGTCGAA

GCCGGGGATGAGGCCGACTATTACTGTCAGGTGTGGGATAGTAGTAGTGATCATGAG GTGTTCGGCGGAGGGACCAAG

(SEQ ID NO: 110)

[00422] The amino acid sequence of the V _L domain of AMA-specific IgM clone A8P3-B5

corresponding to SEQ ID NO: 110 is:

SYVLTQPPSVSVAPGQTARITCGGNNI GSKSVHWYQQKPGQAPVLWYDDSDRPSGI PERFSGSNSGNTATLTI SRVE AGDEADYYCQVWDS S SDHEVFGGGTKLTVL (SEQ ID NO: 111).

[00423] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _L domain of SEQ ID NO: 111 according to the IMGT sequence numbering is: NIGSKS (SEQ ID NO: 112). The amino acid sequence of the CDR2 of the V _L domain of SEQ ID NO: 111 according to the IMGT sequence numbering is: DDS (SEQ ID NO: 113). The amino acid sequence of the CDR3 of the V _L domain of SEQ ID NO: 111 according to the IMGT sequence numbering is: QVWDSSSDHEV (SEQ ID NO: 114).

[00424] Human malaria antigen MSPl-specific IgG clone A8P3-C10 uses a V _H IMGT of IGHV3- 23*01, IGHV3-23*04, and IGHV3-23D*0l, a J _H IMGT of IGHJ4*02, and has a VH light chain nucleotide sequence of:

GAGGTGCAGCTGTTGGAGTCTGGGGGAGCCTTGGTACAGCCTGGGGGGTCCCTGAGACTG TCCTGTGTAACCTCTGGA TTCACCTTTAGCTCCTATGCCATGACCTGGGTCCGCCAGGCTCCAGGGAAGGGGCTGGAA TGGGTCTCAGGTATTAGT TCCGGTGGCTTTATCACATACTACGCAGACTCCGTGAAGGGCCGCTTCACCATCTCCAGA GACAATTCCAAGAACACA GT GT AT T T G C AAAT GAAC AG C C T GAGAG C C GAG GAC AC G (SEQ ID NO: 115).

[00425] The amino acid sequence of the V _H domain of MSP 1 -specific IgG clone A8P3-C10

corresponding to SEQ ID NO: 115 is:

EVQLLESGGALVQPGGSLRLSCVTSGFTFS SYAMTWVRQAPGKGLEWVSGI S SGGFITYYADSVKGRFTI SRDNSKNT VYLQMNSLRAEDTALYYCAKGMGSNIYVGFDYWGQGTLVTVS S (SEQ ID NO: 116).

[00426] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 116 according to the IMGT sequence numbering is: GFTFSSYA (SEQ ID NO: 117). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 116 according to the IMGT sequence numbering is: ISSGGFIT (SEQ ID NO: 118). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 116 according to the IMGT sequence numbering is: AKGMGSNIYVGFDY (SEQ ID NO: 119)

[00427] Human malaria antigen MSPl-specific IgG clone A8P3-C10 uses a V _K IMGT of IGKV3- 20*01, a J _K IMGT of IGKJl*0l, and has a VL light chain nucleotide sequence of:

GAAATTGTGTTGACGCAGTCTCCAGGCACCCTGTCTTTGTCTCCAGGGGAAAGAGCCACC CTCTCCTGCAGGGCCAGT

CAGATTGTAAGCAGCAACTACTTAGCCTGGTACCAGCAGAAACCTGGCCAGGCTCCC AGGCTCCTCATCTTTGGTGCA

TCCAGCAGGGCCACTGGCATCCCAGACAGGTTCAGTGGCAGTGGGTCTGACACAGAC TTCACTCTCACCATCCGCAGA

CTGGAGTCTGAAGATTTTGCAGTGTATTACTGTCACCAGTATGGTAGCTCACCGGGG ACGTTCGGCCAAGGGACCAAG

GTGGA (SEQ ID NO: 120). [00428] The amino acid sequence of the V _L domain of MSP 1 -specific IgG clone A8P3-C10 corresponding to SEQ ID NO: 120 is:

EIVLTQSPGTLSLSPGERATLSCRASQIVSSNYLAWYQQKPGQAPRLLIFGASSRATGIP DRFSGSGSDTDFTLTIRR LESEDFAVYYCHQYGSSPGTFGQGTKVEIK (SEQ ID NO: 121).

[00429] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _L domain of SEQ ID NO: 121 according to the IMGT sequence numbering is: QIVSSNY (SEQ ID NO: 122). The amino acid sequence of the CDR2 of the V _L domain of SEQ ID NO: 121 according to the IMGT sequence numbering is: GAS (SEQ ID NO: 123). The amino acid sequence of the CDR3 of the V _L domain of SEQ ID NO: 121 according to the IMGT sequence numbering is: HQYGSSPGT (SEQ ID NO: 124).

[00430] Human malaria antigen MSP 1 -specific IgM clone A8P3-E4 uses a V _H IMGT of IGHV4-

59*01, a J _H IMGT of IGHJ4*02, and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGGAGACCCTGTCCCTC ACCTGCTCTGTCTCTGGT GGCTCCATCAGTAATTCCTACGTGAGCTGGATCCGGCAGCCCCCAGGGAAGGGACTGGAG TGGATTGGGTATATCTAT TACAGTGGGGGCACCAACTACAACCCCTCCCTTAAGAGTCGAGTCACCATTTCAGTAGAC ACGTCCAAGAACCAGTTC TCCCTGAAGCTGAGCTCCGTGACCGCTGCGGACACGG (SEQ ID NO: 125).

[00431] The amino acid sequence of the V _H domain of MSP 1 -specific IgM clone A8P3-E4

corresponding to SEQ ID NO: 125 is:

QVQLQESGPGLVKPSETLSLTCSVSGGSISNSYVSWIRQPPGKGLEWIGYIYYSGGTNYN PSLKSRVTISVDTSKNQF SLKLSSVTAADTAVYYCARGKIYFDYWGQGTLVTVSS (SEQ ID NO: 126).

[00432] The amino acid sequence of the complementarity determining region 1 or CDR1 of the V _H domain of SEQ ID NO: 126 according to the IMGT sequence numbering is: GGSISNSY (SEQ ID NO: 127). The amino acid sequence of the CDR2 of the V _H domain of SEQ ID NO: 126 according to the IMGT sequence numbering is: IYYSGGT (SEQ ID NO: 128). The amino acid sequence of the CDR3 of the V _H domain of SEQ ID NO: 126 according to the IMGT sequence numbering is: ARGKIYFDY (SEQ ID NO: 129).

[00433] Human malaria antigen MSPl-specific IgM clone A8P3-E4 uses a V _K IMGT of IGKVl-5*03, a J _K IMGT of IGKJl*0l, and has a VL light chain nucleotide sequence of:

GACATCCAGATGACCCAGTCTCCTTCCACCCTGTCTGCATCCGTAGGAGACAGAGTCACC ATCACTTGCCGGGCCAGT CAGAGTATTAGTAGTTGGTTGGCCTGGTATCAGCTGAAACCAGGGAAGGCCCCTAAACTC CTGATTTATAAGGCGTCC AGTTTAGAAAGTGGGGTCCCATCGAGATTCAGCGGCAGTGGATCTGGGACAGAATTCACT CTCACCATCAGCAGCCTG CAGCCTGGTGATTTTGCAACTTATTACTGCCAACAGTATAATAGTTATGCTTTGGCGTTC GGCCAAGGGACCAAGGTG GAGAT (SEQ ID NO: 130).

[00434] The amino acid sequence of the V _L domain of MSP 1 -specific IgM clone A8P3-E4

corresponding to SEQ ID NO: 130 is:

DIQMTQSPSTLSASVGDRVTITCRASQSISSWLAWYQLKPGKAPKLLIYKASSLESGVPS RFSGSGSGTEFTLTISSL QPGDFATYYCQQYNSYALAFGQGTKVEIK (SEQ ID NO: 131). [00435] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VL domain of SEQ ID NO: 131 according to the IMGT sequence numbering is: QSISSW (SEQ ID NO: 132). The amino acid sequence of the CDR2 of the VL domain of SEQ ID NO: 131 according to the IMGT sequence numbering is: KAS (SEQ ID NO: 133). The amino acid sequence of the CDR3 of the VL domain of SEQ ID NO: 131 according to the IMGT sequence numbering is: QQYNSYALA (SEQ ID NO: 134).

[00436] Human malaria antigen AMA-specific IgG clone A8P3-H8 uses a VH IMGT of IGHV4-

39*01, a JH IMGT of IGHJ4*02, and has a VH light chain nucleotide sequence of:

CAGCTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAACCTTCGGAGACCCTGTCCCTC ACCTGCACTGTCTCTGGT GGCTCCATCAGCAGTAGTCTTTACTACTGGGGCTGGATCCGCCAGCCCCCAGGGAAGGGA CTGGAGTGGATTGGGAAT ATCTATTATAGTGGGATCACCTATTACAACCCGTCCCTCACAAGTCGAGTCACCATATCC GTAGACACGTCCAAGGAC CAGTTCTCCCTGAAGCTGAGCTCTGTGACCGTCGCAGACACGGCTGTGTATTACTGTGCG CG (SEQ ID NO: 135).

[00437] The amino acid sequence of the VH domain of AMA-specific IgG clone A8P3-H8

corresponding to SEQ ID NO: 135 is:

QLQLQESGPGLVKPSETLSLTCTVSGGSISSSLYYWGWIRQPPGKGLEWIGNIYYSGITY YNPSLTSRVTISVDTSKD QFSLKLSSVTVADTAVYYCAREILTGDPSVGGDPFDYWGQGTLVTVSS (SEQ ID NO: 136).

[00438] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VH domain of SEQ ID NO: 136 according to the IMGT sequence numbering is: GGSISSSLYY (SEQ ID NO: 137). The amino acid sequence of the CDR2 of the VH domain of SEQ ID NO: 136 according to the IMGT sequence numbering is: IYYSGIT (SEQ ID NO: 138). The amino acid sequence of the CDR3 of the VH domain of SEQ ID NO: 136 according to the IMGT sequence numbering is: AREILTGDPSVGGDPFDY (SEQ ID NO: 139)

[00439] Human malaria antigen AMA-specific IgG clone A8P3-H8 uses a V _L IMGT of IGLVl-5 l*02, a J _L IMGT of IGLJ2*0l and IGLJ3*0l, and has a VL light chain nucleotide sequence of:

CAGTCTGTGCTGACGCAGCCGCCCTCAGTGTCTGCGGCCCCAGGACAGAAGGTCACCATC TCCTGCTCTGGAAGCAGC TCCAACATTGGGAATAATTATGTTTCTTGGTATCGACAACTCCCAGGAACAGCCCCCAAA CTCCTCGTCTATGAAAGT AATAAGCGACCCTCAGGGATTCCTGACCGATTCTCTGGCTCCAAGTCTGCCACGTCAGCC ACCCTGGGCATCACCGGA CTCCAGACTGGGGACGAGGCCGATTATTACTGCGGAACATGGGATACCAGCCTGAGTGCT GTGGTATTCGGCGGAGGG ACCAAACTGACCGTCCTAG (SEQ ID NO: 140).

[00440] The amino acid sequence of the VL domain of AMA-specific IgG clone A8P3-H8

corresponding to SEQ ID NO: 140 is:

QSVLTQPPSVSAAPGQKVTISCSGSSSNIGNNYVSWYRQLPGTAPKLLVYESNKRPSGIP DRFSGSKSATSATLGITG LQTGDEADYYCGTWDTSLSAWFGGGTKLTVL (SEQ ID NO: 141).

[00441] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VL domain of SEQ ID NO: 141 according to the IMGT sequence numbering is: SSNIGNNY (SEQ ID NO: 142). The amino acid sequence of the CDR2 of the VL domain of SEQ ID NO: 141 according to the IMGT sequence numbering is: ESN (SEQ ID NO: 143). The amino acid sequence of the CDR3 of the VL domain of SEQ ID NO: 141 according to the IMGT sequence numbering is: GTWDTSLSAVV (SEQ ID NO: 144).

[00442] Human malaria antigen AMA-specific IgG clone A8P2-G6 uses a VH IMGT of IGHV4-38- 2*02, a JH IMGT of IGHJ4*02, and has a VH light chain nucleotide sequence of:

CAGGTGCAGCTGCAGGAGTCGGGCCCAGGACTGGTGAAGCCTTCGCAGACCCTGTCCCTC ACCTGCACTGTCTCTAAT

TTCCCCATTGCCAGTTCTTACTACTGGAACTGGATCCGCCAGTCGCCAGAAAAGGGA CTGGAATGGATTGGAAGTGTG

TATTTTAGTGGCAGCACCCACTCTAATCCGTCTTTCGCGAGTCGAGTGAGCATGTCG GTGGACACCTCCAAGAGCCAA

TTCACCCTCAAGTTGA

CCTCTCTGTCCGCCGCGGACACA (SEQ ID NO: 145).

[00443] The amino acid sequence of the VH domain of AMA-specific IgG clone A8P2-G6

corresponding to SEQ ID NO: 145 is:

QVQLQES GPGLVKP SQTLS LTCTVSNFP IAS SYYWNWI RQS PEKGLEWI GSVYFS GSTHSNP S FAS RVSMSVDT S KSQ FTLKLT S LSAADTAVYYCAKGDT S RLATNFDDWGPGI QVIVS S (SEQ ID NO: 146).

[00444] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VH domain of SEQ ID NO: 146 according to the IMGT sequence numbering is: NFPIASSYY (SEQ ID NO: 147). The amino acid sequence of the CDR2 of the VH domain of SEQ ID NO: 146 according to the IMGT sequence numbering is: VYFSGST (SEQ ID NO: 148). The amino acid sequence of the CDR3 of the VH domain of SEQ ID NO: 146 according to the IMGT sequence numbering is: AKGDTSRLATNFDD (SEQ ID NO: 149)

[00445] Human malaria antigen AMA-specific IgG clone A8P2-G6 uses a V _K IMGT of IGKV4- 1*01, a J _K IMGT of IGKJ4*0l and IGKJ4*02, and has a VL light chain nucleotide sequence of:

GACATCGTGATGACCCAGTCTCCAGAGACCCTGCCTGTGTCTCTGGGCGAGAGGGCCACC ATCAACTGCAAGTCCAGC CAGAC T C T T T TAT T T AC C T C C AAC AAT AAG GAC TACGTAGCTTGGTAC C AG C AGAAAC C AG GAC AG C C T C C T AAGT T G CTCATTTACTGGGCATCTACCCGGGAATCCGGGGTCCCTGACCGCTTCAGTGGCAGCGGG TCTGGGACAGATTTCACT CTCACCATCAACAGCCTGCAGGCTGAAGATGTGGCGGTTTATTATTGTCAGCAATACCTT ACTACTCCTCTTACCTTC

GGCGGAG (SEQ ID NO: 150).

[00446] The amino acid sequence of the VL domain of AMA-specific IgG clone A8P2-G6

corresponding to SEQ ID NO: 150 is:

DIVMTQS PETLPVS LGERAT INCKS SQTLLFT SNNKDYVAWYQQKPGQP PKLLI YWASTRES GVPDRFS GS GS GTDFT LT INS LQAEDVAVYYCQQYLTT PLT FGGGTKVDI R (SEQ ID NO: 151).

[00447] The amino acid sequence of the complementarity determining region 1 or CDR1 of the VL domain of SEQ ID NO: 151 according to the IMGT sequence numbering is: QTLLFTSNNKDY (SEQ ID NO: 152). The amino acid sequence of the CDR2 of the VL domain of SEQ ID NO: 151 according to the IMGT sequence numbering is: WAS (SEQ ID NO: 153). The amino acid sequence of the CDR3 of the VL domain of SEQ ID NO: 151 according to the IMGT sequence numbering is: QQYLTTPLT (SEQ ID NO: 154). [00448] The amino acid sequence of the IgM tail piece of any IgM or IgG hexamer or tetramer described herein corresponding to SEQ ID NO: 155 is: PTLYNV SLVMSDTAGTCY (SEQ ID NO: 155).

[00449] Additional antibody sequences of recombinant MSPl9-specific monoclonal antibodies and their corresponding multimer IgGls (m-IgG) can be found in Table #29 and SEQ ID NOs: 156-179.

[00450] The reference sequence of the IgG C _H 2 domain described herein corresponding to SEQ ID NO: 180 is:

1 EVQLVESGGG LVKPGGSLRL SCAASGFPFT NAWMNWVRQA PGKGLEWVGH IKGKSDGGTT

61 DYAAPVRGRF TISRDDSKNM LYLQLNSLKT DDTAVYYCTP YTMMGDWGPG TLVTVSSAST

121 KGPSVFPLAP SSKSTSGGTA ALGCLVKDYF PEPVTVSWNS GALTSGVHTF PAVLQSSGLY

181 SLSSWTVPS SSLGTQTYIC NVNHKPSNTK VDKKVEPKSC DKTHTCPPCP APELLGGPSV

241 FLFPPKPKDT LMI SRTPEVT CVWDVSHED PEVKFNWYVD GVEVHNAKTK PREEQYNSTY

301 RWSVLTVLH QDWLNGKEYK CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSRDELTK

361 NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS DGSFFLYSKL TVDKSRWQQG

421 NVFSCSVMHE GLHNHYTQKS LSLSPGK (SEQ ID NO: 180).

[00451] The GenBank Accession number for SEQ ID NO: 180 is GenBank: ARA90393.1. L309 is in bold above.

[00452] The reference sequence of the plasmid encoding the IgG C _H 2 domain described herein corresponding to SEQ ID NO: 181 is:

CCAGCACCTGAACTCCTGGGGGGACCGTCAGTCTTCCTCTTCCCCCCAAAACCCAAGGAC ACCCTCATGATCTCCCGGA CCCCTGAGGTCACATGCGTGGTGGTGGACGTGAGCCACGAAGACCCTGAGGTCAAGTTCA ACTGGTACGTGGACGGCGT GGAGGTGCATAATGCCAAGACAAAGCCGCGGGAGGAGCAGTACAACAGCACGTACCGTGT GGTCAGCGTCCTCACCGTC CTGCACCAGGACTGGCTGAATGGCAAGGAGTACAAGTGCAAGGTCTCCAACAAAGCCCTC CCAGCCCCCATCGAGAAAA CCATCTCCAAAGCCAAA (SEQ ID NO: 181).

[00453] The reference sequence of the plasmid encoding the full length IgGl corresponding to SEQ ID NO: 182 is:

TCGACCAAGGGCCCAAGCGTCTTCCCCCTGGCACCCTCCTCCAAGAGCACCTCTGGGGGC ACAGCGGCCCTGGGCTGCC

TGGTCAAGGACTACTTCCCCGAGCCGGTGACGGTGTCGTGGAACTCAGGCGCCCTGA CCAGCGGCGTGCACACCTTCCC

GGCTGTCCTACAGTCCTCAGGACTCTACTCCCTCAGCAGCGTGGTGACCGTGCCCTC CAGCAGCTTGGGCACCCAGACC

TACATCTGCAACGTGAATCACAAGCCCAGCAACACCAAGGTGGACAAGAGAGTTGAG CCCAAATCTTGTGACAAAAC

TCACACATGCCCACCGTGCCCAGCACCTGAACTCCTGGGGGGACCGTCAGTCTTCCT CTTCCCCCCAAAACCCAAGGAC

ACCCTCATGATCTCCCGGACCCCTGAGGTCACATGCGTGGTGGTGGACGTGAGCCAC GAAGACCCTGAGGTCAAGTTCA

ACTGGTACGTGGACGGCGTGGAGGTGCATAATGCCAAGACAAAGCCGCGGGAGGAGC AGTACAACAGCACGTACCGTGT

GGTCAGCGTCCTCACCGTCCTGCACCAGGACTGGCTGAATGGCAAGGAGTACAAGTG CAAGGTCTCCAACAAAGCCCTC

CCAGCCCCCATCGAGAAAACCATCTCCAAAGCCAAAGGGCAGCCCCGAGAACCACAG GTGTACACCCTGCCCCCATCCC

GGGAGGAGATGACCAAGAACCAGGTCAGCCTGACCTGCCTGGTCAAAGGCTTCTATC CCAGCGACATCGCCGTGGAGTG

GGAGAGCAATGGGCAGCCGGAGAACAACTACAAGACCACGCCTCCCGTGCTGGACTC CGACGGCTCCTTCTTCCTCTAT

AGCAAGCTCACCGTGGACAAGAGCAGGTGGCAGCAGGGGAACGTCTTCTCATGCTCC GTGATGCATGAGGCTCTGCACA

ACCACTACACGCAGAAGAGCCTCTCCCTGTCCCCGGGTAAATGA (SEQ ID NO: 182). [00454] The amino acid sequence of the L309C IgG C _H 2 domain described herein corresponding to SEQ ID NO: 183 is:

1 EVQLVESGGG LVKPGGSLRL SCAASGFPFT NAWMNWVRQA PGKGLEWVGH IKGKSDGGTT

61 DYAAPVRGRF TISRDDSKNM LYLQLNSLKT DDTAVYYCTP YTMMGDWGPG TLVTVSSAST

121 KGPSVFPLAP SSKSTSGGTA ALGCLVKDYF PEPVTVSWNS GALTSGVHTF PAVLQSSGLY

181 SLSSWTVPS SSLGTQTYIC NVNHKPSNTK VDKKVEPKSC DKTHTCPPCP APELLGGPSV

241 FLFPPKPKDT LMI SRTPEVT CVWDVSHED PEVKFNWYVD GVEVHNAKTK PREEQYNSTY

301 RWSVLTVCH QDWLNGKEYK CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSRDELTK

361 NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS DGSFFLYSKL TVDKSRWQQG

421 NVFSCSVMHE GLHNHYTQKS LSLSPGK (SEQ ID NO: 183). C309 is in bold above.

[00455] The reference sequence encoding the human IgGl described herein corresponding to SEQ ID NO: 184 is: GenBank: LT615368.1 (SEQ ID NO: 184).

[00456] The reference amino acid sequence encoding the human IgGl described herein corresponding to SEQ ID NO: 185 is:

1 STKGPSVFPL APSSKSTSGG TAALGCLVKD YFPEPVTVSW NSGALTSGVH TFPAVLQSSG 61 LYSLSSWTV PSSSLGTQTY ICNWHKPSN TKVDKRVEPK SCDKTHTCPP CPAPELLGGP 121 SVFLFPPKPK DTLMISRTPE VTCVWDVSH EDPEVKFNWY VDGVEVHNAK TKPREEQYNS 181 TYRWSVLTV LHQDWLNGKE YKCKVSNKAL PAPIEKTISK AKGQPREPQV YTLPPSREEM 241 TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVL DSDGSFFLYS KLTVDKSRWQ 301 QGNVFSCSVM HEALHNHYTQ KSLSLSPGK ( SEQ ID NO: 185).

[00457] The GenBank accession number for SEQ ID NO: 185 is GenBank: SC094948.1

[00458] The reference amino acid sequence for UnitProt Accession: P 19598, Plasmodium falciparum (isolate ro-33 / Ghana) MSP1 polypeptide corresponding to SEQ ID NO: 186 is:

MKIIFFLCSFLFFIINTQCVTHESYQELVKKLEALEDAVLTGYSLFQKEKMVLKDGANTQ WAKPADAVSTQSAKNPPGATVPSGTASTKGAIRSPGAANPSDDSSDSDAKSYADLKHRV QNYLFTIKELKYPELFDLTNHMLTLCDNIHGFKYLIDGYEEINELLYKLNFYFDLLRAKL NDVCANDYCQIPFNLKIRANELDVLKKLVFGYRKPLDFIKDNVGKMEDYIKKNKTTIANI NELIEGSKKTIDQNKNADNEEGKKKLYQAQYDLFIYNKQLQEAHNLISVLEKRIDTLKKN ENIKKLLEDIDKIKIDAEKPTTGWQILSLRLEKESRHEEKIKEIAKTIKFNIDRLFTDP LELEYYLREKNKKVDVTPKSQDPTKSVQIPKVPYPNGIVYPLPLTDIHNSLAADNDKNSY GDLMNPHTKEKINEKIITDNKERKIFINNIKKQIDLEEKNINHTKEQNKKLLEDYEKSKK DYEELLEKFYEMKFNNNFNKDWDKIFSARYTYNVEKQRYNNKFSSSNNSVYNVQKLKKA LSYLEDYSLRKGISEKDFNHYYTLKTGLEADIKKLTEEIKSSENKILEKNFKGLTHSANA SLEVSDIVKLQVQKVLLIKKIEDLRKIELFLKNAQLKDSIHVPNIYKPQNKPEPYYLIVL KKEVDKLKEFIPKVKDMLKKEQAVLSSITQPLVAASETTEDGGHSTHTLSQSGETEVTEE TEETVGHTTTVTITLPPKEVKWENSIEHKSNDNSQALTKTVYLKKLDEFLTKSYICHKY ILVSNSSMDQKLLEVYNLTPEENELKSCDRLDLLFNIQNNIPAMYSLYDSMNNDLQHLFF ELYQKEMIYYLHKLKEENHIKKLLEEPKQITGTSSTSSPGNTTWTAQSATHSNSQNQQS NASSTNTQNGVAVSSGPAWEESHDPLTVLSISNDLKGIVSLLNLGNKTKVPNPLTISTT EMEKFYENILKIMIPIFNDDIKQFVKSNSKVITGLTETQKNALNDEIKKLKDTLQLSFDL

YNKYKLKLDRLFNKKKELGQDKMQIKKLTLLKEQLESKLNSLNNPHNVLQNFSVFFNKKK

EAEIAETENTLENTKILLKHYKGLVKYYNGESSPLKTLSEVSIQTEDNYANLEKFRV LSK

IDGKLNDNLHLGKKKLSFLSSGLHHLITELKEVIKNKNYTGNSPSENNKKWEALKSY EN

FLPEAKVTTWTPPQPDVTPSPLSVRVSGSSGSTKEETQIPTSGSLLTELQQWQLQNY D

EEDDSLWLPIFGESEDNDEYLDQWTGEAISVTMDNILSGFENEYDVIYLKPLAGVYR S

LKKQIEKNIFTFNLNLNDILNSRLKKRKYFLDVLESDLMQFKHISSNEYIIEDSFKL LNS

EQKNTLLKSYKYIKESVENDIKFAQEGISYYEKVLAKYKDDLESIKKVIKEEKEFPS SPP

TTPPSPAKTDEQKKESKFLPFLTNIETLYNNLWKIDDYLINLKAKINDCNVEKDEAH VK

ITKLSDLKAIDDKIDLFKNPYDFEAIKKLINDDTKKDMLGKLLSTGLVQNFPNTIIS KLI

EGKFQDMLNISQHQCVKKQCPQNSGCFRHLDEREECKCLLNYKQEGDKCVENPNPTC NEN

NGGCDADAKCTEEDSGSNGKKITCECTKPDSYPLFDGIFCSSSNFLGISFLLILMLI LYS

FI (SEQ ID NO: 186)

[00459] The reference amino acid sequence for GenBank CAB97194.1 Plasmodium falciparum AMA polypeptide corresponding to SEQ ID NO: 187 is:

1 LLSAFEFTYM INFGRGQNYW EHPYQNSNVY HPINEHREHP KEYQYPLHQE HTYQQEDSGE

61 DENTLQHAYP IDHEGAEPAP QEQNLFSSIE IVERSNYMGN PWTEYMAKYD IEEVHGSGIR 121 VDLGEDAEVA GTQYRLPSGK CPVFGKGIII ENSNTTFLTP VATENQDLKD GGFAFPPTKP 181 HMSPMTLDDM RLLYKDNEDV KNLDELTLCS RHAGNMIPDN DKNSNYKYPA VYDDKDKKCH 241 ILYIAAQENX GPRYCNKDQS KRNSMFCFRP AKDKSFQXYT YLSKNWDNW EKVCPRKNLE 301 NAKFGLWVDG NCEDIPHWE FSANDLFECN KLVFELSASD QPKQYEQHLT DYEKIKEGFK 361 NKNASMIKSA FLPTGAFKAD RYKSHGKGYN WGNYNTKTQK CEIFNVKPTC LINNSSYIAT 421 TALSHPIEVE HNFPCSLYKD EIKKEIERES KRIKLNDNDD EGNKKIIAPR IFISDDIDSL 481 KCPCDPEMVS NSTCRFFVCK CVERRAEVTS NNEVWKEEY KDEYAD (SEQ ID NO: 187)

Selected definitions

[00460] Unless otherwise defined herein, scientific and technical terms used in connection with the present application shall have the meanings that are commonly understood by those of ordinary skill in the art to which this disclosure belongs. It should be understood that this invention is not limited to the particular methodology, protocols, and reagents, etc., described herein and as such can vary. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention, which is defined solely by the claims. Definitions of common terms in immunology, and molecular biology can be found in The Merck Manual of Diagnosis and Therapy, l9th Edition, published by Merck Sharp & Dohme Corp., 2011 (ISBN 978-0-911910-19-3); Robert S. Porter et al. (eds.), The Encyclopedia of Molecular Cell Biology and Molecular Medicine, published by Blackwell Science Ltd., 1999-2012 (ISBN 9783527600908); and Robert A. Meyers (ed.), Molecular Biology and Biotechnology: a Comprehensive Desk Reference, published by VCH Publishers, Inc., 1995 (ISBN 1- 56081-569-8); Immunology by Wemer Luttmann, published by Elsevier, 2006; Janeway's Immunobiology, Kenneth Murphy, Allan Mowat, Casey Weaver (eds.), Taylor & Francis Limited, 2014 (ISBN 0815345305, 9780815345305); Lewin's Genes XI, published by Jones & Bartlett Publishers, 2014 (ISBN-1449659055); Michael Richard Green and Joseph Sambrook, Molecular Cloning: A Laboratory Manual, 4 ^th ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., USA (2012) (ISBN 1936113414); Davis et al, Basic Methods in Molecular Biology, Elsevier Science Publishing, Inc., New York, USA (2012) (ISBN 044460149X); Laboratory Methods in Enzymology: DNA, Jon Lorsch (ed.) Elsevier, 2013 (ISBN

0124199542); Current Protocols in Molecular Biology (CPMB), Frederick M. Ausubel (ed.), John Wiley and Sons, 2014 (ISBN 047150338X, 9780471503385), Current Protocols in Protein Science (CPPS), John E. Coligan (ed.), John Wiley and Sons, Inc., 2005; and Current Protocols in Immunology (CPI) (John E. Coligan, ADA M Kruisbeek, David H Margulies, Ethan M Shevach, Warren Strobe, (eds.) John Wiley and Sons, Inc., 2003 (ISBN 0471142735, 9780471142737), the contents of which are all incorporated by reference herein in their entireties.

[00461] As used herein, the terms “proteins” and “peptides” and “polypeptides” are used interchangeably herein to designate a series of amino acid residues connected to the other by peptide bonds between the alpha-amino and carboxy groups of adjacent residues. Although“protein” is often used in reference to relatively large polypeptides, and“peptide” is often used in reference to small polypeptides, usage of these terms in the art overlaps and varies. The term“peptide” as used herein refers to peptides, polypeptides, proteins and fragments of proteins, unless otherwise noted. The terms“protein” and“peptide” are used interchangeably herein when referring to a gene product and fragments thereof. Thus, exemplary peptides or proteins include gene products, naturally occurring proteins, homologs, orthologs, paralogs, fragments and other equivalents, variants, fragments, and analogs of the foregoing.

[00462] In regard to antigen-binding polypeptides, antibodies and antigen-binding fragments being specific for an“antigen of interest,” such as an antigen derived from an infectious organism, an "antigen" is a molecule that is bound by a binding site comprised by the variable region of an immunoglobulin- related or derived polypeptide agent, such as an antibody or antibody fragment or BCR, or antigen-binding fragment thereof. Typically, antigens are bound by antibody ligands and are capable of raising or causing an antibody immune response in vivo. An antigen can be a polypeptide, protein, nucleic acid or other molecule. In the case of conventional antibodies and fragments thereof, the binding site as defined by the variable loops (Ll, L2, L3 and Hl, H2, H3) is capable of binding to the antigen. The term "antigenic determinant" refers to an epitope on the antigen recognized by an antigen-binding molecule, and more particularly, by the antigen-binding site of said molecule.

[00463] In some embodiments of the aspects described herein, the antigen of interest is from an infectious organism. [00464] The term "epitope" is a region or portion of an antigen that is bound by a binding protein, and includes any polypeptide determinant capable of specific binding to an immunoglobulin or T-cell receptor. In certain embodiments, epitope determinants include chemically active surface groupings of molecules such as amino acids, sugar side chains, phosphoryl, or sulfonyl, and, in certain embodiments, may have specific three dimensional structural characteristics, and/or specific charge characteristics. An epitope can be determined by obtaining an X-ray crystal structure of an antibody: antigen complex and determining which residues on the antigen are within a specified distance of residues on the antibody of interest, wherein the specified distance is, 5Ά or less, e.g., 5 A, 4A, 3A, 2A, lA or any distance in between. In some embodiments, an "epitope" can be formed on a polypeptide both from contiguous amino acids, or noncontiguous amino acids juxtaposed by tertiary folding of a protein. Epitopes formed from contiguous amino acids are typically retained on exposure to denaturing solvents, whereas epitopes formed by tertiary folding are typically lost on treatment with denaturing solvents. An epitope typically includes at least 3, and more usually, at least 5, about 9, or about 8-10 amino acids in a unique spatial conformation. An "epitope" includes the unit of structure conventionally bound by an immunoglobulin V _H /V _L pair. Epitopes define the minimum binding site for an antibody, and thus represent the target of specificity of an antibody. In the case of a single domain antibody, an epitope represents the unit of structure bound by a variable domain in isolation. The terms "antigenic determinant" and "epitope" can also be used

interchangeably herein. In certain embodiments, epitope determinants include chemically active surface groupings of molecules such as amino acids, sugar side chains, phosphoryl, or sulfonyl, and, in certain embodiments, may have specific three dimensional structural characteristics, and/or specific charge characteristics.

[00465] The phrase“agent comprising the antigen,” in regard to the compositions and methods described herein, refers to any agent comprising all or a part of an antigen of interest to which an IgM memory B cell specific for that antigen of interest specifically binds. Thus, for example, an agent comprising malarial MSP1 (merozoite surface protein 1) is an agent that can be specifically bound by an IgM memory B cell specific for MSP1 or AMA or tetanus toxoid C fragment (TTCF) and not to unrelated polypeptides, such as other malarial antigen. Such agents include, but are not limited to, portions or active fragments thereof of recombinant proteins, fusion proteins, peptides, multimers, tetramers, that specifically bind to the variable region of the cell-surface IgM expressed by an IgM memory B cell.

[00466] As used herein, an“appropriate control” refers to an untreated, otherwise identical cell or population (e.g., a subject who was not administered the composition described herein, or was administered by only a subset of agents provided herein, as compared to a non-control cell).

[00467] As used herein, a“reference level” can refer to one or more parameters or markers as measured for a normal, otherwise unaffected cell population or tissue (e.g., a biological sample obtained from a healthy subject, or a biological sample obtained from the subject at a prior time point, or a biological sample that has not yet been contacted with a pathogen as described herein). For measuring or monitoring therapeutic efficacy, a level determined prior to treatment or earlier in treatment can also provide a reference level for a given parameter or value.

[00468] As used herein, the term“modulates” refers to an effect including increasing or decreasing a given parameter as those terms are defined herein.

[00469] The terms“increased,"“increase,"“increases,” or“enhance" or“activate" are all used herein to generally mean an increase of a property, level, or other parameter by a statistically significant amount; for the avoidance of any doubt, the terms“increased",“increase" or“enhance" or“activate" means an increase of at least 10% as compared to a reference level, for example an increase of at least about 20%, or at least about 30%, or at least about 40%, or at least about 50%, or at least about 60%, or at least about 70%, or at least about 80%, or at least about 90% or up to and including a 100% increase or any increase between 10- 100% as compared to a reference level, or at least about a 2-fold, or at least about a 3 -fold, or at least about a 4-fold, or at least about a 5-fold or at least about a lO-fold increase, at least about a 20-fold increase, at least about a 50-fold increase, at least about a lOO-fold increase, at least about a lOOO-fold increase or more as compared to a reference level. For example, increasing activity can refer to activating a receptor or a signaling pathway (e.g., antibody production or inflammation).

[00470] The terms“decrease”,“reduced”,“reduction”, or“inhibit” are all used herein to mean a decrease or lessening of a property, level, or other parameter by a statistically significant amount. In some embodiments of any of the aspects,“reduce,”“reduction" or“decrease" or“inhibit” typically means a decrease by at least 10% as compared to a reference level (e.g., the absence of a given treatment) and can include, for example, a decrease by at least about 10%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 98%, at least about 99% , or more. As used herein,“reduction” or“inhibition” does not encompass a complete inhibition or reduction as compared to a reference level. “Complete inhibition” is a 100% inhibition as compared to a reference level. A decrease can be preferably down to a level accepted as within the range of normal for an individual without a given disorder.

[00471] As used herein the term "comprising" or "comprises" is used in reference to compositions, methods, and respective component(s) thereof, that are essential to the method or composition, yet open to the inclusion of unspecified elements, whether essential or not.

[00472] As used herein the term "consisting essentially of' refers to those elements required for a given embodiment. The term permits the presence of elements that do not materially affect the basic and novel or functional characteristic(s) of that embodiment. [00473] The term "consisting of' refers to compositions, methods, and respective components thereof as described herein, which are exclusive of any element not recited in that description of the embodiment.

[00474] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus for example, references to "the method" includes one or more methods, and/or steps of the type described herein and/or which will become apparent to those persons skilled in the art upon reading this disclosure and so forth. Similarly, the word "or" is intended to include "and" unless the context clearly indicates otherwise. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosure, suitable methods and materials are described below. The abbreviation, "e.g. " is derived from the Latin exempli gratia, and is used herein to indicate a non-limiting example. Thus, the abbreviation "e.g." is synonymous with the term "for example."

[00475] Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein should be understood as modified in all instances by the term "about." The term "about" when used in connection with percentages can mean±l%.

[00476] The term "statistically significant" or "significantly" refers to statistical significance and generally means a two standard deviation (2SD) difference, above or below a reference value. Additional definitions are provided in the text of individual sections below.

[00477] It should be understood that this invention is not limited to the particular methodology, protocols, and reagents, etc., described herein and as such may vary. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention, which is defined solely by the claims.

[00478] As used herein and in the claims, the singular forms include the plural reference and vice versa unless the context clearly indicates otherwise. The term“or” is inclusive unless modified, for example, by “either.” Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein should be understood as modified in all instances by the term“about.”

[00479] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[00480] It is understood that the foregoing description and the following examples are illustrative only and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments, which will be apparent to those of skill in the art, may be made without departing from the spirit and scope of the present invention. Further, all patents, patent applications, and publications identified are expressly incorporated herein by reference for the purpose of describing and disclosing, for example, the methodologies described in such publications that might be used in connection with the present invention. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents are based on the information available to the applicants and do not constitute any admission as to the correctness of the dates or contents of these documents.

[00481] All patents and other publications identified are expressly incorporated herein by reference for the purpose of describing and disclosing, for example, the methodologies described in such publications that could be used in connection with the present invention. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicants and does not constitute any admission as to the correctness of the dates or contents of these documents.

[00482] Some embodiments of the technology described herein can be defined according to any of the following numbered paragraphs:

1. A recombinant antigen-binding polypeptide construct comprising an antigen-binding domain

isolated from an IgM memory B cell receptor that specifically binds an antigen of interest, in an IgM isotype acceptor antibody framework.

2. The recombinant antigen-binding polypeptide construct of paragraph 1, wherein the antigen-binding domain comprises variable heavy chain and variable light chain amino acid sequences from the IgM memory B cell.

3. The recombinant antigen-binding polypeptide construct of paragraph 1, which comprises a multimer of IgM antigen-binding units.

4. The recombinant antigen-binding polypeptide construct of paragraph 1, wherein the antigen-binding domain has 8 or fewer somatic mutations relative to a naive B cell receptor.

5. The recombinant antigen-binding polypeptide construct of paragraph 1, which has a Kd for the antigen of interest of 10 ¹⁰ M or below.

6. The recombinant antigen-binding polypeptide construct of paragraph 1, which has a Kd for the antigen of interest of 10 ¹¹ M or below.

7. The recombinant antigen-binding polypeptide construct of paragraph 1, which has a Kd for the antigen of interest of 10 ¹² M or below.

8. The recombinant antigen-binding polypeptide construct of paragraph 1, which comprises human antigen-binding and constant domains. A recombinant polypeptide construct comprising an antigen-binding unit comprising heavy and light chain variable domains of a B cell receptor of a naive B cell, and an IgM heavy chain constant domain.

The recombinant polypeptide construct of paragraph 9, wherein the construct comprises a plurality of IgM isotype antigen binding units.

The recombinant polypeptide construct of paragraph 10, wherein the construct comprises five or seven antigen binding units.

The recombinant polypeptide construct of any one of paragraphs 1-11 that comprises a J chain sequence.

The recombinant polypeptide construct of any one of paragraphs 1-12, wherein the antigen is an antigen expressed by a pathogen, or a tumor antigen.

A recombinant antigen-binding polypeptide construct comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds a Plasmodium antigen, in an IgM isotype acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of paragraph 14, comprising variable domain complementarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94; c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104; d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124; e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134; f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34; g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44; h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54; i. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64; j. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84; k. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114; l. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

m. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154. The recombinant antigen-binding polypeptide construct of any one of paragraphs 14-15, wherein the CDRs are grafted into an IgM acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 14-16, which comprises a multimer of IgM antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 14-17, which comprises five or six IgM antigen-binding units.

A recombinant antigen-binding polypeptide construct comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds a Plasmodium antigen, in an IgG isotype acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of paragraph 19, comprising variable domain complementarity determining regions (CDRs) selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94; c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104; d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124; e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134; f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34; g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44; h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54; i. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64; j. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84; k. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114; l. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

m. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154. The recombinant antigen-binding polypeptide construct of any one of paragraphs 19-20, wherein the CDRs are grafted into an IgG acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 19-21, which comprises a multimer of IgG antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 19-22, which comprises five or six IgG antigen-binding units.

A recombinant antigen-binding polypeptide construct comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds a Plasmodium falciparum merozoite surface protein 1 (MSP-l) polypeptide.

The recombinant antigen-binding polypeptide construct of paragraph 24, comprising CDRs selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94; c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104; d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124; e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134. The recombinant antigen-binding polypeptide construct of any one of paragraphs 24-25, wherein the CDRs are grafted into an IgM acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 24-26, wherein the CDRs are grafted into an IgG acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 24-27, which comprises a multimer of IgM antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 24-28, which comprises five or six IgM antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 24, 25, or 27, which comprises a multimer of IgG antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 24, 25, 27, or 30, which comprises five or six IgG antigen-binding units. A recombinant antigen-binding polypeptide construct comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds Plasmodium falciparum apical membrane antigen 1 (AMA) polypeptide.

The recombinant antigen-binding polypeptide construct of paragraph 32, comprising CDRs selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44; c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54; d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64; e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84; f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114; g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154. The recombinant antigen-binding polypeptide construct of any one of paragraphs 32-33, wherein the CDRs are grafted into an IgM acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 32-34, which comprises a multimer of IgM antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 32-35, which comprises five or six IgM antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 32-33, wherein the CDRs are grafted into an IgG acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 32-33 or 37, which comprises a multimer of IgG antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 32, 33, 37 or 38, which comprises five or six IgG antigen-binding units.

A recombinant antigen-binding polypeptide construct comprising an antigen-binding domain isolated from an IgM memory B cell receptor that specifically binds Plasmodium falciparum circumsporozoite protein (CSP).

The recombinant antigen-binding polypeptide construct of paragraph 40, wherein the CDRs are grafted into an IgM acceptor antibody framework.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 40-41, which comprises a multimer of IgM antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 40-42, which comprises five or six IgM antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 40-43, wherein the CDRs are grafted into an IgG acceptor antibody framework. The recombinant antigen-binding polypeptide construct of any one of paragraphs 41 or 44, which comprises a multimer of IgG antigen-binding units.

The recombinant antigen-binding polypeptide construct of any one of paragraphs 41, or 44-45, which comprises five or six IgG antigen-binding units.

A recombinant Plasmodium falciparum antigen-binding polypeptide construct comprising heterologous CDRs grafted into an IgM acceptor antibody framework.

The recombinant antigen-binding polypeptide of paragraph 47, which specifically binds to Plasmodium falciparum MSP-l, AMA, or CSP.

The recombinant antigen-binding polypeptide of paragraph 47 or 48, wherein the CDRs are selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94; c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104; d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124; e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134; f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34; g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44; h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54; i. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64; j. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84; k. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114; l. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

m. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154. A multimeric IgG construct comprising five or six IgG antigen-binding units that specifically binds an antigen of interest, wherein the heavy chain of each IgG antigen-binding unit has a leucine to a cysteine mutation in the C _H 2 domain at the position corresponding to L309 of the wild-type human IgG of SEQ ID NO: 180, and wherein the heavy chain of each IgG antigen-binding unit comprises an IgM tail piece.

The multimeric IgG construct of paragraph 50, wherein the IgG is IgGl, IgG2, IgG3, or IgG4. The multimeric IgG construct of any one of paragraphs 50 or 51, wherein the IgM tail piece comprises the amino acid sequence of SEQ ID NO: 155 (PTLYNVSLVMSDTAGTCY).

The multimeric IgG construct of any one of paragraphs 50-52, wherein each IgG moiety comprises CDRs isolated from a memory B cell receptor that specifically binds an antigen of interest.

The multimeric IgG construct of any one of paragraphs 50-53, wherein the antigen of interest is an antigen of a pathogen.

The multimeric IgG construct of any one of paragraphs 50-54, wherein the antigen of interest is a P. falciparum antigen.

The multimeric IgG construct of paragraph 55, wherein the P. falciparum antigen is MSP-l, AMA, or CSP.

The multimeric IgG construct of any one of paragraphs 50-56, wherein the antigen of interest is a tumor antigen.

The multimeric IgG construct of any one of paragraphs 50-57, comprising an MSP-l -specific CDR selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 67; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 68; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 69; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 72; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 73; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 74; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 87; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 88; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 89; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 92; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 93; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 94; c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 97; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 98; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 99; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 102; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 103; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 104; d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 117; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 118; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 119; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 122; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 123; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 124; e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 127; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 128; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 129; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 132; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 133; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 134. The multimeric IgG construct of any one of paragraphs 50-57, comprising an AMA-specific CDR selected from the group consisting of:

a. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 27; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 28; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 29; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 32; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 33; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 34; b. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 37; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 38; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 39; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 42; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 43; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 44; c. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 47; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 48; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 49; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 52; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 53; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 54; d. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 57; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 58; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 59; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 62; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 63; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 64; e. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 77; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 78; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 79; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 82; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 83; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 84; f. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 107; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 108; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 109; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 112; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 113; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 114; g. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 137; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 138; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 139; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 142; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 143; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 144; and

h. a heavy chain CDR1 having the amino acid sequence of SEQ ID NO: 147; a heavy chain CDR2 having the amino acid sequence of SEQ ID NO: 148; a heavy chain CDR3 having the amino acid sequence of SEQ ID NO: 149; a light chain CDR1 having the amino acid sequence of SEQ ID NO: 152; a light chain CDR2 having the amino acid sequence of SEQ ID NO: 153; and a light chain CDR3 having the amino acid sequence of SEQ ID NO: 154. A method of isolating memory B cells that specifically bind an antigen of interest, the method comprising:

a. contacting a biological sample containing memory B cells from a subject having had prior exposure to the antigen of interest with the antigen of interest or a portion thereof, wherein the antigen of interest is immobilized on a solid support;

b. separating a population of antigen-bound cells from non-antigen-bound cells of step (a); and c. isolating cells expressing CD21, CD27, and IgM from the population antigen-bound cells. The method of paragraph 60, wherein the biological sample is a blood sample. The method of paragraph 60, wherein the subject has had an infection with or is currently infected with a pathogen that comprises or expresses the antigen of interest.

The method of paragraph 60, comprising the step, prior to step (a), of obtaining a biological sample from a subject.

The method of paragraph 60, wherein the isolating step (c) comprises flow cytometry.

The method of paragraph 60, wherein step (c) optionally comprises isolating cells expressing a plasmablast marker.

The method of paragraph 65, wherein the plasmablast marker is B220 or CD138.

A method of making an antibody construct comprising an antigen-binding domain from a memory B cell that specifically binds to an antigen of interest, the method comprising:

a. isolating a population of IgM expressing memory B cells from a biological sample

according to paragraph 60;

b. amplifying heavy chain and light chain variable domain sequences from the memory B cell population of step (a);

c. ligating heavy chain variable domain sequences amplified in step (b) into a heavy chain expression vector sequence and ligating light chain variable domain sequences amplified in step (b) into a light chain expression vector sequence;

d. introducing one or more vectors encoding heavy chain and light chain expression vector sequences of step (c) to a cell and culturing the cell under conditions that permit expression of antibody polypeptides from the expression vector sequences;

e. contacting antibody polypeptides expressed by the cell with an antigen of interest; and f. isolating antibodies that bind to the antigen of interest, thereby making an antibody

construct comprising an antigen-binding domain from a memory B cell and that specifically binds to an antigen of interest.

The method of paragraph 67, further comprising, prior to step (a), a step of vaccinating a subject and obtaining a biological sample.

The method of paragraph 67, wherein step (e) comprises contacting antibody polypeptides with the antigen of interest immobilized on a solid support

The method of paragraph 67, further comprising, prior to step (e), collecting cell culture medium from cells of step (d).

An antibody composition produced by any one of the methods of paragraphs 60-71.

A method of treating or preventing a disease or disorder, the method comprising administering a recombinant antigen-binding polypeptide construct of any one of paragraphs 1-59, or a cell expressing such a polypeptide, or a vector encoding such a polypeptide to a subject in need thereof. The method of paragraph 72, wherein the subject is a human. 74. The method of paragraph 72, wherein the disease or disorder is an infectious disease.

75. The method of paragraph 72, wherein the infectious disease is a parasitic infectious disease.

76. The method of paragraph 72, wherein the disease or disorder is cancer.

77. The method of paragraph 72, wherein the administering comprises intravenous administration.

78. A method of immunizing a subject against a pathogen, the method comprising: administering a recombinant antigen-binding polypeptide construct of any one of paragraphs 1-59, or a cell expressing such a polypeptide construct, or a vector encoding such a polypeptide construct to an individual in need thereof.

79. The method of paragraph 78, wherein the administering comprises intravenous administration.

80. The method of paragraph 78, wherein the subject is a human.

81. The method of paragraph 78, wherein the pathogen is a parasite, bacteria, fungus, virus, or prion.

82. The method of paragraph 81, wherein the parasite is selected from the group consisting of:

Plasmodium falciparum, Plasmodium chabaudi chabaudi, Plasmodium vivax, or Plasmodium berghei.

83. The method of paragraph 81, wherein the bacteria is selected from the group consisting of: E. coli, Psuedomonas aeruginosa, M. tuberculosis, Group B Streptococcus, Streptococcus epidermidis, Streptococcus pneumoniae, Haemophilus influenzae, Bacillus anthracis, Erysipelothrix rhusiopathiae, Klebsiella pneumoniae, Brucella abortus, Nocadia brasiliensis, Borrelia hermsii, and Borrelia burgdorferi.

EXAMPLES

EXAMPLE 1

MSPl-specific B cells expand, differentiate and form memory in response to blood stage malaria infection.

[00483] The direct ex vivo visualization of antigen-specific B cells during infection has been difficult to accomplish due to a lack of tools and techniques to track small populations of B cells. Therefore, techniques used to analyze MBC development in response to protein immunization were developed. While applicable to any desired antigen, the approach is exemplified herein examining MBC

development and function in response to blood stage malaria infection in C57BL/6 mice were adopted. A phycoerythrin (PE)-conjugated B cell tetramer containing the majority of the l9kD C-terminal portion of the MSP 1 protein from P. chabaudi was generated and used with magnetic bead-based enrichment to analyze malaria-specific B cells directly ex vivo throughout all phases of the immune response.

[00484] In all experiments, splenocytes were first stained with a decoy reagent and then with the MSP1 PE tetramer to exclude cells binding other components of the tetramer (Taylor et al, 20l2a). Anti-PE coated magnetic beads were then used to enrich both decoy-specific and MSPl-specific B cells, which were subsequently stained with antibodies for analysis by multiparameter flow cytometry. Antibody panels were based upon gating strategies developed to visualize all stages of mature B2 B cell differentiation. After excluding non-lymphocytes and doublets, Decoy MSPft B cells were identified amongst B220 ⁺ and

B220 ^low CDl38 ⁺ cells (identifying plasmablasts) (data not shown). In uninfected mice, there were

approximately 400 MSPl ⁺ B cells, while 8 days after infection with lxlO ⁶ P.chabaudi iRBCs (Butler et al., 2012), the number of MSPl ⁺ B cells expanded 50 fold to 23,000 cells (data not shown). Control experiments demonstrated that B cells with BCRs specific for hen egg lysozyme (MD4 Rag2 ^~ ' ^~ mice) did not bind the MSP1 tetramer nor were they activated non-specifically by Plasmodium 8 days post-infection after adoptive transfer into a congenic host (data not shown). Thus, rare endogenous MSPl ⁺ B cells that could be identified in naive mice, expanded in an antigen-specific manner, demonstrating the ability to stringently identify and analyze MSPl ⁺ B cells throughout the course of Plasmodium infection.

[00485] Both parasitemia and MSPl ⁺ B cells were quantified in the spleens of individual mice for approximately a year after infection. Parasitemia was measured in blood samples throughout the course of infection using a flow cytometry based assay (Malleret et al, 2011; Robbiani et al, 2015). MSPl ⁺ B cells isolated from spleens of infected mice began to expand by 4 days after infection, peaked 8 days after infection, then sharply contracted, mirroring parasitemia (data not shown). Variations in total MSPl ⁺ B cell numbers continued until day 150, although intracellular staining with the cell cycle marker Ki67 demonstrated that the vast majority (-95%) of MSPl ⁺ B cells at day 100 are quiescent. MSPl ⁺ B cells persisted with a half-life of 221 days that resulted in a population of 3600 cells at 340 days post infection (data not shown). MSPl ⁺ B cells therefore expanded with ascending parasitemia, contracted, and then numbers fluctuated before stabilizing and slowly declining over 350 days. Importantly, these data demonstrated that long-lived, quiescent Plasmodium-specific B cells persisted and can be analyzed well after parasitemia is controlled.

MSPl-specific B cell fates emerge early after infection and MBCs persist

[00486] The heterogeneity of MSPl ⁺ B cells was first assessed during the acute phase of the infection. Gating strategies were designed to distinguish between CDl38 ⁺ plasmablasts (PBs), CD38 ⁺ GL7 ⁺ activated precursors (Taylor et al, 20l2b), CD38 GL7 ⁺ germinal center (GC) B cells, and expanded CD38 ⁺ GL7 MBC populations (data not shown). Within 8 days of infection, multiple fates emerged including a dominant population of MSPl ⁺ CDl38 ⁺ PBs that primarily expressed IgM as measured by flow cytometry and serum ELISA consistent with previous reports (Achtman et al., 2003; Nduati et al., 2010). Several thousand MSPl ⁺ B cells that retained CD38 expression, therefore resembling MBCs, were also present at day 8. The remainder of the population consisted of IgM ⁺ and IgM GL7 ⁺ CD38 ⁺ activated precursors which have been shown to be multipotent and capable of differentiating into GC B cells or MBCs (Taylor et al., 2012). While GC responses were not present at day 8, they began to emerge at day 12, and expanded to a peak of about 15,000

MSP 1 T L71gM IgD CD38 cclls at day 20, at which point numerous IgD germinal centers could also be found in the spleen by immunofluorescent microscopy (data not shown). This was further confirmed by the presence of various sub-classes of MSP 1 -specific IgG ⁺ antibodies measured in the serum (data not shown) .

[00487] To determine which of these early fates persisted into the memory phase of the response, MSPl ⁺ B cells were characterized for approximately a year using similar gating strategies described above (data not shown). Although CDl38 ⁺ PBs initially waned between days 20 to 40, a small, consistently present CDl38 ⁺ population re-emerged around day 85 suggesting that these were splenic plasma cells (PCs), similar to recent work demonstrating that

[00488] PCs emerge after MBCs in response to protein immunization (Bortnick et ak, 2012; Weisel et ak, 2016). These PCs persisted at all timepoints thereafter, were still present at day 340 post infection, and were predominantly IgM ⁺ (data not shown).

[00489] Enrichment techniques also facilitated the visualization of a waning GC response. MSP l ⁺ GC B cells contracted by day 40 post infection and then slowly declined before eventually disappearing around 150 days post infection. Therefore, from day 50 on, the vast majority of the MSPl ⁺ cells were CD38 ⁺ GL7 MBCs that remained for at least 340 days post infection (data not shown). These data demonstrate that well after parasite clearance and termination of the GC reaction, splenic MSPl ⁺ B cells are predominantly comprised of an expanded population of CD38 ⁺ MBCs and a small but persistent CDl38 ⁺ PC population.

Switched and unswitched Plasmodium-specific MBCs can be found in malaria-exposed mice and humans

[00490] It was next important to determine if recently defined MBC subsets that emerge after protein immunization were also present in response to infection. To interrogate the diversity of the MSPl ⁺ MBCs, antibodies specific for IgM and IgD were used to identify“switched” and“unswitched” MSPl ⁺ B cells.

Interestingly, this staining strategy identified three distinct populations of MSPl ⁺ MBCs 100 days after infection: an IgM IgD isotype switched population (referred to as swlg ⁺ ), and two unswitched subsets. One subset was phenotypically IgM ^lo IgD ^M g ^h (referred to as IgD ⁺ ) while the other subset was IgM^IgD ¹⁰ (referred to as IgM ⁺ ) (data not shown). While all three populations persisted for 340 days post infection, at the latest time points IgD ⁺ MBCs stably persisted whereas both the IgM ⁺ and swlg ⁺ MBCs declined (data not shown).

[00491] Because of the persistence of heterogeneous MBCs after malaria infection in mice , whether switched and unswitched P. falciparum-specific MBCs also occur in exposed individuals residing in an endemic area was investigated. Although IgG ⁺ P. falciparum- specific MBCs have been detected by

ELISPOT (Weiss et ak, 2012) in individuals exposed to both high (Ndungu et ak, 2012; Weiss et ak, 2010) and low (Clark et ak, 2012; Ndungu et ak, 2013; Wipasa et ak, 2010) malaria transmission, it is unknown if P. falciparum infection induces antigen-specific unswitched MBCs. Antigen-specific enrichment experiments were therefore performed on peripheral blood mononuclear cells (PBMCs) collected from P falciparum- infected Malian subjects during the malaria season (Crompton et ak, 2008) or malaria-naive U.S. subjects. To enhance the sensitivity of Plasmodium-specific cell detection (less than 20 million PBMC were available in some samples), B cell tetramers were generated using the C-terminal region of MSP 1 and apical membrane antigen 1 (AMA1) from the human P. falciparum ( 3D7) strain. In Mahan subjects, approximately 40% of the P. falciparum-specific B cells in blood were CD2l ⁺ CD27 ⁺ MBCs in keeping with expected frequencies of total MBCs in human blood (Kaminski et ah, 2012; Klein et al, 1998; Tangye and Good, 2007). Furthermore, there was a 6 fold increase in the total number of P. falciparum-specific B cells and a 60-fold increase amongst CD27 ⁺ CD2l ⁺ MBCs compared to uninfected US controls (data not shown). P . falciparum- specific CD27 ⁺ MBCs have been characterized from Mahan samples for their expression of BCR isotype and found that they were comprised of both switched and unswitched cells (data not shown). Thus, heterogeneous populations of Plasmodium-specific MBCs are expanded in both mice and humans.

Murine MSPl-specific MBC subsets are phenotypically and genetically distinct

[00492] To further dissect the unique phenotypic and functional characteristics associated with distinct Plasmodium- specific MBCs, additional studies were performed in mice. Studies have demonstrated that MBC subsets display heterogeneous expression of surface markers associated with T cell interactions including CD73 and CD80 on both switched and unswitched MBCs (Anderson et al., 2007; Tomayko et al., 2010;

Yates et al, 2013). Expression of these proteins was therefore examined on MSPl ⁺ MBCs 100 days post infection. Again, it was found that the division of unswitched MBCs into IgM ⁺ and IgD ⁺ subsets largely accounted for the variability in surface marker expression. -81% of IgM ⁺ MBCs expressed CD73 and CD80, comparable to the -96% of the swlg ⁺ MBCs that expressed both markers, whereas only -8% of IgD ⁺ MBCs expressed CD73 and CD80, comparable to MSPl ⁺ naive B cells (data not shown). Similar to MBC diversity generated by protein immunization, phenotypically diverse Plasmodium- specific IgD ⁺ , IgM ⁺ , and swlg ⁺ MBC subsets develop in response to infection. Additionally, expression of CD73 and CD80 further distinguishes IgM ⁺ and IgD ⁺ MBCs as two distinct, unswitched populations.

[00493] B cell expression of both CD73 and CD80 is associated with expression of activation-induced cytidine deaminase (AID) and, in some cases but not all, germinal center dependence (Anderson et al, 2007; Kaji et al, 2012; Taylor et al., 20l2b; Weisel et al, 2016). Based on these observations, it was tested whether the CD73 ⁺ CD80 ⁺ MSPl ⁺ IgM ⁺ MBCs represented a previously unexplained population of somatically hypermutated, unswitched MBCs identified in other immunization models (Kaji et al, 2012; Pape et al, 2011). To test this, flow cytometric sorting was used to isolate individual MSPl ⁺ CD73 CD80 IgD ⁺ , CD73 ⁺ CD80 ⁺ IgM ⁺ , and CD73 ⁺ CD80 ⁺ swIg ⁺ MBCs or MSPl ⁺ naive B cells. Individual BCRs were sequenced and cloned using previously described methods (Tiller et al., 2009). The relative numbers of somatic hypermutations (SHM) in both light (VH) and light (VL) chain sequences present in individual MBC subsets were calculated after comparison to BCRs from naive MSPl ⁺ B cells, which had no mutations and were identical to germline sequences. While only 3% of IgD ⁺ MBC VH or VL chain sequences showed SHM, 65% of VH and 75% of VL chain sequences of CD73 ⁺ CD80 ⁺ IgM ⁺ cells were mutated with a mean of 3 mutations in both chains (data not shown). swlg ⁺ MBCs were also highly mutated (97%) and displayed significantly more mutations (mean of 8) in both VH and VL chains (data not shown).

[00494] Since increased levels of SHM are associated with an overall increase in BCR affinity (Chan and Brink, 2012), the affinities of IgM ⁺ and swlg ⁺ MBC BCRs were tested. Individual BCR variable region sequences with varying levels of somatic hypermutation from either MSPl ⁺ IgM ⁺ or swlg ⁺ MBC clones were therefore expressed as monoclonal antibodies (mAb), with human IgG constant (Fc) regions to prevent contributions to avidity by oligomerization. Antibodies were then used in dilution assays against MSP1 protein to compare affinity of the various mAbs by ELISA (Kolhatkar et ah, 2015). Importantly, these studies further confirmed the specificity of MSP l-tetramer techniques, as 100% of expressed clones bound MSP1 protein, while the control PC-specific mAb did not (data not shown). Furthermore, despite overall fewer mutations, individual BCRs from IgM ⁺ MBCs showed comparable affinity for the MSP1 protein to swlg ⁺ MBCs (data not shown). These data therefore demonstrate that expression of CD73 and CD80 on both IgM ⁺ and swlg ⁺ MBCs is associated with increased levels of SHM, resulting in similar BCR affinities.

Secondary infection induces the rapid proliferation and differentiation of MSPl-specific MBCs.

[00495] To understand how the MBCs described above function during a secondary infection, mice in the memory phase of the response were rechallenged with iRBCs. Of note, the experimental conditions used were distinct from several previous studies that utilized adoptive transfer of individual MBC populations followed by antigen rechallenge. In intact memory mice, MBC competition for antigen and T cell help, as well as the presence of pre-existing antibodies factor into the overall response, perhaps as they would in repeatedly infected humans. To replicate this, memory mice infected 12-16 weeks prior were left unchallenged or rechallenged with either lxlO ⁷ uninfected RBCs (unRBCs) or iRBCs, and MSPl ⁺ B cells were analyzed 3 or 5 days later. Following rechallenge with iRBCs, but not unRBCs, the total number of MSPl ⁺ B cells expanded significantly on day 3 and continued to increase at day 5 compared to

unchallenged memory mice (data not shown). To ascertain whether these newly formed cells were originating from MBCs or recently formed naive cells, naive mice were also infected with a challenge dose of lxlO ⁷ iRBCs and MSPl ⁺ B cells were quantified and phenotyped. In stark contrast to the logarithmic increase seen in MSPl ⁺ B cells in memory mice after rechallenge, there was no significant increase in the total number of MSPl ⁺ B cells in naive mice at either 3 or 5 days after a primary infection (data not shown).

[00496] It was next determined whether expanded MSPl ⁺ cells in rechallenged memory mice were also differentiated. Phenotypic analyses using gating strategies described above confirmed that MSPl ⁺ B cells in memory mice prior to challenge consisted of both B220 ⁺ CDl38 B cells (consisting primarily of MBCs and a small, waning population of GC B cells) and B220 CDl38 ⁺ PCs (data not shown). Three days after iRBC challenge, a newly formed MSPl ⁺ B220 ⁺ CDl38 ⁺ population emerged and remained expanded at day 5, suggesting these were the product of recently activated MBCs (data not shown). The rapid formation of this population was unique to a memory response as a significant B220 ⁺ CD l38 ⁺ population form in naive mice was not observed three days after the same iRBC challenge (data not shown). Additional quantification of the B220 ⁺ CDl38 B cells and B220 CDl38 ⁺ PCs revealed that these populations also increased in number after rechallenge (data not shown). Together, these data demonstrate that within 3 days of rechallenge, expanded and differentiated MSPl ⁺ B cells form in response to a secondary infection.

[00497] To determine what precursor populations were proliferating to produce expanded populations of MSPl ⁺ B cells, Ki67 expression (which marks actively cycling cells) was compared before and after rechallenge. Prior to challenge, -4% of MSPl ⁺ B cells were Ki67 ⁺ (data not shown). Three days after rechallenge the percentage of Ki67 ⁺ increased to -16% of all MSPl ⁺ B cells and remained restricted to the B220 ⁺ B cells (B220 PCs were Ki67 ) (data not shown). Detailed phenotypic analysis of the Ki67 ⁺ cells revealed that three separate MSP l ⁺ B220 ⁺ populations were proliferating: newly formed B220 ⁺ CDl38 ⁺ plasmablasts (PBs) (-30%), CD38 ⁺ MBCs (-50%) and CD38 ⁺ GL7 ⁺ activated precursors (-20%) (data not shown). Therefore, within three days, some MSPl ⁺ MBCs had already proliferated and differentiated into PBs and CD38 ⁺ GL7 ⁺ activated precursors, but many CD38 ⁺ GL7 MBCs were still proliferating but had not yet differentiated.

[00498] The isotypes of the proliferating cells were also determined to reveal precursor relationships. Surprisingly, the majority of both Ki67 ⁺ PBs three days after rechallenge expressed IgM despite IgM ⁺ MBCs being at a numerical disadvantage to the swlg ⁺ MBCs at this timepoint (data not shown). The activated precursors and MBCs were largely isotype switched (data not shown). In contrast, very few of the MSPl ⁺ IgD ⁺ MBCs were proliferating. These data demonstrate that IgM ⁺ MBCs rapidly respond to secondary infection and make up the majority of the early proliferating plasmablasts.

[00499] To further discern precursor relationships for the IgM ⁺ PBs, BCRs were cloned from the IgM ⁺ B220 ⁺ CDl38 ⁺ PBs 3 days after challenge to look for somatic hypermutation. If the PBs were somatically hypermutated, it would support the idea that these cells were derived from somatically hypermutated IgM ⁺ MBCs as opposed to unmutated IgD ⁺ MBCs. Remarkably, 95% of newly formed IgM+ PB clones (mean mutation of 8) were somatically hypermutated at levels that were comparable to MSPl ⁺ IgM ⁺ MBCs, further establishing a precursor relationship between IgM ⁺ MBCs and newly formed PBs after a secondary infection (data not shown).

The early secondary antibody response is IgM-domin an t

[00500] It was next asked what MSPl ⁺ cells were differentiated antibody secreting cells (ASCs). Again, memory mice were rechallenged and intracellular staining for immunoglobulin light and light chain (Ig) was performed on MSPl ⁺ B cells 3 or 5 days later. In memory mice analyzed prior to challenge, the only ASCs present were -600 B220 CDl38 ⁺ PCs (which represent about 5% of the total cells) (data not shown). Three days after rechallenge, approximately -3000 MSPl ⁺ B cells (about 15%) were now making antibody, split between B220 ⁺ CDl38 ⁺ PBs and B220 CDl38 ⁺ PCs (data not shown). Now, approximately 70% of the MSPl ⁺ Ig ⁺ ASCs were IgM ⁺ , while only about 30% of the ASCs were switched, resulting in significantly more IgM ⁺ ASCs on day 3 than switched ASCs (data not shown). Two days later, on day 5 post challenge, IgM ⁺ ASCs continued to expand, but now there was also a larger, switched antibody-secreting PB pool. Interestingly, the switched PCs stayed relatively stable at all timepoints examined (data not shown).

[00501] To confirm that intracellular antibody staining represented measurable changes of secreted antibody in vivo, MSP 1-19 protein-specific ELISAs were performed on serum samples taken from individual mice before or after challenge. In conjunction with what was observed by flow cytometry, three days after infection MSP 1 -specific IgM antibody expression was significantly increased over pre-challenge levels while IgG antibody expression remained unchanged (data not shown). Two days later however, on day 5, significant increases in MSP 1 -specific IgG antibodies were observed, while IgM antibody levels remained elevated (data not shown). Since it was unclear if these switched PBs arose from swlg ⁺ or IgM ⁺ MBCs, MBCs were additionally sorted two days after rechallenge to look for IgM or IgG expression by ELISPOT after 2 days in culture. This approach revealed that, while swlg ⁺ MBCs could only form IgG ⁺ ASCs, IgM ⁺ MBCs formed both IgM ⁺ and IgG ⁺ ASCs (data not shown). Collectively, these data demonstrate that the secondary response is dominated by early IgM ⁺ antibody expression and later IgG ⁺ antibody expression.

Additionally, these findings demonstrate that IgM ⁺ MBCs are capable of expressing both IgM ⁺ and IgG ⁺ antibodies, highlighting that the IgM ⁺ MBCs are rapid, plastic responders to a secondary infection.

Secondary IgM response is not affected by challenge dose or timing

[00502] One potential cause for the early IgM dominant response after secondary challenge could be high antigen load, which could somehow preferentially activate IgM ⁺ MBCs. Memory mice were therefore challenged with two lower iRBC challenge doses (lxlO ³ and lxlO ⁵ ) prior to MSPl ⁺ B cell analysis 3 days later. Remarkably, in both lower dose challenges, the IgM ⁺ ASC response still dominated the early ASC population and even more dramatically than what was observed at the higher dose challenge (data not shown). This was especially striking given the 2.5-fold numerical disadvantage of IgM ⁺ MBCs compared to swlg ⁺ MBCs 100 days post-challenge (data not shown).

[00503] While this ruled out dose dependent effects, it was also possible that the time of rechallenge influenced the results, for example if a germinal center was ongoing, which was the case for the 12-16 week rechallenge experiments. It was therefore tested whether the presence of an ongoing GC reaction at the time of challenge influenced the early secondary responders. Memory mice 35 weeks post infection, in which the GC reaction had ended and IgM ⁺ and swlg ⁺ MBCs were in equal number (data not shown), were therefore given a secondary challenge with lxlO ⁷ iRBCs and analyzed 3 days later. As seen in mice with an ongoing GC, IgM ⁺ cells were still the predominant early antibody-expressing population data not shown). Together these data indicate that despite variations in infectious dose, the presence or absence of a GC, or shifts in the numerical ratio of IgM ⁺ to swlg ⁺ MBCs, IgM ⁺ MBCs can compete with swlg ⁺ MBCs and are important early responders in a secondary Plasmodium infection. IgM ⁺ MBCs generate both T-independent and T-dependent antibody secreting effectors

[00504] The beter understand the predominant secondary IgM ⁺ memory response, the mechanisms of the early IgM response were interrogated. It was hypothesized that differences in T cell dependence could allow some populations to form faster than others. To test this, mice were treated a CD4 ⁺ T cell depleting antibody (clone GK1.5) for two days prior to rechallenge and formation of PBs and PCs was assessed 3 days later. Strikingly, while MSPl ⁺ PBs did not form in the absence of T cell help, the PCs in the GK1.5 treated animals expanded comparably to those in a T cell replete rechallenged mouse (data not shown). To assess the isotype of the responding T-independent ASCs, intracellular Ig staining was again performed. In mice depleted of T cells, more than 85% of the Ig ⁺ CDl38 ⁺ ASCs expressed IgM ⁺ (data not shown).

Therefore, the formation of both unswitched and switched PBs is T cell dependent, yet predominantly IgM ⁺ expressing PCs can still form in a T cell independent manner. These data therefore indicate that IgM ⁺

MBCs can form two unique ASC populations in two mechanistically distinct ways, again highlighting their plasticity.

[00505] As demonstrated herein, how MBC subsets develop and function in response to infection with a relevant pathogen was studied. To accomplish this, B cell tetramers were generated and enrichment techniques utilized to perform analyses of endogenous Plasmodium- specific B cells in malaria-exposed humans and mice. Importantly, the results presented in these studies highlight the fact that IgM ⁺ and IgD ⁺ MBCs are unique populations of cells with distinct phenotypic, functional and survival properties. Furthermore, these studies emphasize that IgM ⁺ MBCs are not low affinity cells that provide redundancy to IgG ⁺ MBCs. On the contrary, Plasmodium- specific IgM ⁺ MBCs express high affinity, somatically hypermutated BCRs and rapidly respond to produce antibodies prior to IgG ⁺ MBCs, even in competition. Lastly, these studies reveal that a secondary memory response results in the generation of T-dependent plasmablasts and T-independent plasma cells that create multiple layers of antibody secreting cells.

[00506] In many ways, the results described herein reconcile many of the disparate findings from various studies using a variety of protein immunization strategies, BCR transgenics and isolated transfer and rechallenge techniques. Dividing unswitched cells into two populations based on differential expression of IgM and IgD, revealed that IgM ⁺ MBCs were far more similar in phenotype (CD73 and CD80 expression), developmental history (evidence of somatic hypermutation), affinity, survival and function (rapid plasmablast formation) to swlg ⁺ MBCs than the more naive-like IgD ⁺ MBCs. Thus either isotype, as shown by Pape et al. (Pape et al, 2011) or expression of markers associated with somatic hypermutation (Zuccarino-Catania et al, 2014) can predict MBC function, reconciling the findings of these two separate studies. While the IgD ⁺ MBCs were remarkably stable, both the IgM ⁺ and swlg ⁺ subsets persisted with similar, and less stable kinetics as predicted by studies demonstrating a loss of somatically hypermutated B cells overtime (Gitlin et al., 2016). Without wishing to be bound or limited by theory, IgD ⁺ MBCs may represent a durable, expanded memory population that provides a high number of pathogen-specific clones with kinetics similar to naive B cells.

[00507] It was also addressed how distinct antigen-specific MBC subsets respond to a secondary infection in vivo in competition and demonstrate a hierarchy of MBC responsiveness to secondary infection. Surprisingly, at the earliest timepoints, IgM ⁺ MBCs are the dominant producers of ASCs at all doses of rechallenge and timepoints examined. By 5 days post-secondary infection however, IgM antibody production did not continue to increase, while switched PBs began to produce significant amounts of antibody highlighting that this dominance is transient. Therefore unlike previous studies indicating that IgM cells do not readily form PBs perhaps due to their low affinity (Pape et ah, 2011) or form plasmablasts with similar kinetics to IgG ⁺ PBs (Zuccarino-Catania et ah, 2014), as shown herein, IgM ⁺ MBCs are high affinity, rapid, plastic early responders that can initiate the secondary response.

[00508] The results described herein may explain recent data associating the depth and breadth of Plasmodium-specific IgM antibodies with resistance to infection (Arama et ah, 2015). While it was demonstrated that F(ab)s made from IgM ⁺ MBCs are of comparable affinity to those sequenced from IgG ⁺ MBCs, upon pentamerization of IgM antibodies, the IgM ⁺ antibody avidity would be far greater than the IgG antibodies. Moreover, IgM antibodies are important mediators of complement-mediated lysis, which is important for control of blood stage infection (Boyle et ah, 2015). While the importance of IgM antibodies in Plasmodium infection has been shown in murine models (Couper et ah, 2005), additional studies are being performed examining the importance of IgM antibodies in human malaria infection as well as the comparison of Plasmodium- specific IgM ⁺ MBCs found in the murine systems described herein to those identified in malaria-exposed humans.

[00509] Finally, the studies described herein help to clarify long-standing controversies concerning the level of T cell dependence of secondary MBC responses (Kurosaki et ak, 2015). Although many studies in humans and mice have demonstrated T cell-independent activation of MBCs (Bemasconi et ak, 2002;

Richard et ak, 2008; Von Eschen and Rudbach, 1974), later studies suggested MBCs cannot be activated by bystander inflammation (Benson et ak, 2009) or without the help of T cells (Ise et ak, 2014). The results described herein demonstrate that both T-dependent and T-independent processes contribute to a secondary MBC response and support recent studies demonstrating that IgM ⁺ MBCs can be reactivated in a T- independent manner when transferred in isolation into T-cell depleted mice (Zuccarino-Catania et ak, 2014). Specifically, secondary IgM ⁺ and IgG ⁺ PB formation was T-dependent, while the rapid generation of non dividing, antibody-secreting IgM ⁺ PCs was T-independent, raising many questions about the origins of these cells. Without wishing to be bound or limited by theory, the murine somatically hypermutated IgM ⁺ MBCs identified in these studies could be homologous to human IgM ⁺ MBCs that can mediate T-independent IgM ⁺ responses to bacterial infection (Weill et ak, 2009). In conclusion, the studies described herein highlight IgM ⁺ MBCs as a functional, plastic, rapidly responding MBC population that should be targeted by vaccines to prevent disease.

EXPERIMENTAL PROCEDURES

Animals

[00510] 5-8 week old female C57BL/6 and B6.SJL-Ptprc ^a Pepc ^b /BoyJ (CD45. U) mice were used for these experiments. Mice were purchased from The Jackson Laboratory and maintained/bred under specific pathogen free conditions at the University of Washington. MD4-Rag2 mice were provided. All experiments were performed in accordance with the University of Washington Institutional Care and Use Committee guidelines.

Plasmodium Infection

[00511] Plasmodium chabaudi chabaudi (AS) parasites were maintained as frozen blood stocks and passaged through donor mice. Primary mouse infections were initiated by intraperitoneal (i.p.) injection of lxlO ⁶ iRBCs from donor mice. Secondary mouse infections were performed 12-35 weeks after primary infection using a dose of lxlO ⁷ iRBCs injected intravenously (i.v.). In some cases, when indicated, secondary challenges were given at lower doses using either lxlO ³ or lxlO ⁵ iRBCs injected i.v.

Tetramer Production

[00512] For murine studies, recombinant His-tagged C-terminal MSP1 protein (amino acids 4960 to 5301) from P. chabaudi (AS) was produced by Pichia pastoris and purified using a Ni-NTA agarose column as previously described (Ndungu et al, 2009). Purified P.chabaudi MSP1 protein was biotinylated and tetramerized with streptavidin-PE (Prozyme) as previously described (Taylor et al., 20l2a). For human studies, AMA1 protein from P .falciparum (3D7) (provided by Dr. Julian Rayner, Welcome Trust Sanger Institute) and MSP1-19 protein from P.falciparum (3D7) (provided by Dr. Anthony Holder, Francis Crick Institute) were biotinylated and tetramerized as described above. Decoy reagent to gate out non-MSPl ⁺ B cells was made by conjugating SA-PE to AF647 using an AF647 protein labeling kit (ThermoFisher), washing and removing any unbound AF647, and incubating with an excess of an irrelevant biotinylated HIS-tagged protein, similar to what has been previously described (Taylor et al., 20l2a).

Mouse and Human Cell Enrichment and Flow Cytometry

[00513] For murine samples, splenic cell suspensions were prepared and resuspended in 200ul in PBS containing 2% FBS and Fc block (2.4G2) and first incubated with Decoy tetramer at a concentration of 10hM at room temperature for 10 min. MSP 1 -PE tetramer was added at a concentration of 10hM and incubated on ice for 30 min. Cells were washed, incubated with anti-PE magnetic beads for 30 min on ice, and passed over magnetized LS columns (Miltenyi Biotec) to elute the bound cells as previously described (Taylor et al., 20l2a). For human samples, PBMC were similarly stained and enriched using Decoy, PfAMAl and PfMSPl tetramers. All bound cells were stained with surface antibodies followed by intracellular antibody staining when needed. All cells were run on the LSRII (BD) and analyzed using FlowJo software (Treestar).

Single Cell BCR Sequencing and Cloning

[00514] Single MSPl ⁺ MBCs were FACS sorted using an ARIAII into 96-well plates. BCRs were amplified and sequenced from the cDNA of single cells as previously described (Schwartz et al, 2014), with additional IgH primers used (Tiller et al, 2009). Amplified products were cloned and generated mAbs using previously described methods (Schwartz et al., 2014; Tiller et al, 2009).

ELISAs

[00515] Costar 96-well EIA/RIA plates (Fisher Scientific) were coated overnight at 4°C with lOug/ml of MSP 1 protein. Plates were blocked with 2% BSA prior to sample incubation. For serum samples, plates were incubated with serially diluted serum from naive or infected animals. For cloned mAbs, plates were incubated with serially diluted mAbs starting at l0ng/pl. Each sample was plated in duplicate. For serum samples, bound antibodies were detected using either IgM Biotin (11/41), IgG Biotin (Poly4053), IgGl Biotin (A85-1), IgG2c Biotin (5.7), IgG2b Biotin (R123), or IgG3 (R40-82) followed by

Streptavidin-HRP (BD). For mAbs, bound antibodies were detected with mouse anti-human IgG-HRP (SouthemBiotech). Absorbance was measured at 450nm using an IMARK Microplate Reader (Bio-Rad). ELISPOT

[00516] 96 well ELISPOT plates (Millipore) were coated overnight at 4°C with lOug/ml of Ig(H+L) unlabeled antibody (Southern Biotech). Plates were blocked with 10% FBS in complete DMEM (Gibco). MSPl ⁺ MBCs were sorted using a FACSARIA (BD) from memory mice 2 days after rechallenge. Cells of each MBC population were plated onto coated ELISPOT plates and incubated at 37°C for an additional 2.5 days. Cells were washed off and secreted antibodies were detected using either IgM Biotin (11/41) or IgG Biotin (Poly4053) followed by Streptavidin-HRP (BD). Nonspecific (background) spots were determined in wells containing no cells. Spots were developed using AEC substrate (BD) and counted and analyzed using the CTL ELISPOT reader and Immunospot analysis software (Cellular Technology Limited).

Number of spots detected per well were used to calculate spot frequency per lxlO ⁵ total cells.

Depletion of CD4+ T cells

[00517] For depletion of CD4 ⁺ T cells, GK1.5 monoclonal antibody to CD4 (rIgG2b; BioXcell) was used. One and two days prior to secondary challenge, memory mice were given an i.p. injection of 200pg GK1.5 or isotype control diluted in PBS. Efficiency of CD4 ⁺ T cell depletion was monitored by checking blood of mice pre -depletion, day 1 post injection and day of challenge. Depletion was found to be greater than 98% of CD4 ⁺ T cells as assessed by a non-GKl .5 competing anti-CD4 clone, RM4-4.

Statistical Analysis [00518] Unpaired, two-tailed Student’s t tests were applied to determine the statistical significance of the differences between groups with Prism (Graphpad) software. The p-values were considered significant when p < 0.05 (*), p < 0.01 (**), and p < 0.001 (***).

Parasitemia by flow cytometry

[00519] Parasitemia was measured by flow cytometry by staining lul of blood with Terl 19 APC eFluor780 (eBioscience), CD45 APC (BD), Hoechst33342 (Sigma), and Dihydroethidium (Sigma). Giemsa staining of thin blood smears was done in parallel.

Human PBMC samples

[00520] Deidentified Plasmodium- infected PBMC samples are from a cohort in Mali previously described. (Crompton et al., 2008). Uninfected control PBMC are from healthy U.S. adult donors enrolled in NIH protocol #99-CC-0l68. Demographic and travel history data were not available from the anonymous U.S. donors, but prior P .falciparum exposure is unlikely.

Immunofluorescence staining of spleens

[00521] Spleens from infected mice were embedded in OCT and flash frozen. 8um sections were cut and fixed in acetone and then stained with CD4 Biotin (RM4-5), B220 Alexa Fluor 647 (RA3-6B2), and IgD Alexa Fluor 488 (11- 26c.2a). Streptavidin Cy3 (Jackson Immunoresearch) was used as a secondary antibody. Images were acquired using a Nikon Eclipse 90i microscope and NIS Elements BR (Build 738) software was used for the capture of individual images for each channel. Raw TIFF files were imported in Adobe Photoshop for overlay of single channel images and editing.

EXAMPLE 2

Summary for recombinant human malaria specific monoclonal antibodies.

[00522] Plasmodium specific (AMA/MSP1 Tmr-based) FACS sorting yielded 208 (111 IgM and 97 IgG) MBCs from 9 donors (4-39 totals cells/donor). Sequence data was obtained for 168 distinct HC or LCs (from 8/9 donors; 10- 38 per/donor). Full BCRs were cloned for 40 MBCs, 22 IgM and 18 IgG, and these BCRs were derived from 8/9 donors. Recombinant mAbs were expressed from 27 BCR clones, out of which 26 of the 27 expressed. The obtained mAbs were next tested by ELISA, and 20/26 were ELISA-positive for AMA or MSP1 with the positive clones obtained from 8/9 donors, ranging from 2-12 mAbs/donor. Overall yield for BCRs was 40/208 sorted MBCs = 19%, with majority reactive to one of the two malarial antigens used for sorting.

BCR Cloning Methods

[00523] Received nine plates with frozen single cells sorted partially into each plate. Created cDNA libraries using FERMENTAS MAXIMA First Strand Kit. Performed four separate PCR reactions to amplify heavy-gamma, heavy-mu, lambda, and kappa chains. Visualized products on gels. Purified and Sanger sequenced amplicons in forward and reverse. Analysis Methods

[00524] Quality control was performed by trimming all sequence ends with more than 1% chance of error per base. Contigs were created with forward and reverse sequences. All contigs were aligned to the human IMGT database using NCBI IgBLAST. Recorded V and J genes, functionality, and % homology to germline. Exploratory data analysis done in R.

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Weill, J.C., Weller, S., and Reynaud, C.A. (2009). Human marginal zone B cells. Annu Rev

Immunol 27, 267-285.

Weisel, Florian J., Zuccarino-Catania, Griselda V., Chikina, M., and Shlomchik, Mark J. (2016). A Temporal Switch in the Germinal Center Determines Differential Output of Memory B and Plasma Cells. Immunity 44, 116-130

Weiss, G.E., Ndungu, F.M., McKittrick, N., Li, S., Kimani, D., Crompton, P.D., Marsh, K., and Pierce, S.K. (2012). High efficiency human memory B cell assay and its application to studying Plasmodium falciparum-specific memory B cells in natural infections. J Immunol Methods 375, 68-74.

Weiss, G.E., Traore, B., Kayentao, K., Ongoiba, A., Doumbo, S., Doumtabe, D., Kone, Y., Dia, S., Guindo, A., Traore, A., et al. (2010). The Plasmodium falciparum- specific human memory B cell compartment expands gradually with repeated malaria infections. PLoS Pathog 6, el0009l2.

Wipasa, J., Suphavilai, C., Okell, L.C., Cook, J., Corran, P.H., Thaikla, K., Liewsaree, W., Riley, E.M., and Hafalla, J.C. (2010). Long-lived antibody and B Cell memory responses to the human malaria parasites, Plasmodium falciparum and Plasmodium vivax. PLoS Pathog 6, el000770.

Yates, J.L., Racine, R., McBride, K.M., and Winslow, G.M. (2013). T cell-dependent IgM memory B cells generated during bacterial infection are required for IgG responses to antigen challenge. J

Immunol 191, 1240-1249.

Zuccarino-Catania, G.V., Sadanand, S., Weisel, F.J., Tomayko, M.M., Meng, H., Kleinstein, S.H., Good-Jacobson, K.L., and Shlomchik, M.J. (2014). CD80 and PD-L2 define functionally distinct memory B cell subsets that are independent of antibody isotype. Nat Immunol 75, 631637. EXAMPLE 3

IgM memory B cells can be identified post-vaccination and exhibit capacity to bind target antigens with high affinity

[00526] Tetanus vaccine response:

[00527] Rationale and Summary: The ability to identify and track antigen-specific IgM memory B cells following a protective vaccine response would be predicted to permit isolation and cloning of novel protective IgM antibodies. Notably, no previous studies have evaluated human subjects for the presence of antigen-specific, IgM memory B cells following vaccination. Thus, it was determined whether antigen- specific IgM memory B cells could be identified in response to tetanus vaccination, a common, highly effective, protein vaccine.

[00528] TTCF tetramer-binding B cells were enriched from PBMCs collected from healthy adult subjects that were previously vaccinated for tetanus. The top row shows gating for IgM+ CD21+ CD27+ memory B cells within the total B cell pool. The bottom row of FIG. 15 applies the same gates to antigen- specific cells. TTCF-specific cells are primarily CD21+ CD27+, indicating a memory phenotype, and many express IgM. Representative plots from a single donor (of eight) are also shown (FIG. 15).

[00529] These findings shown in FIG. 15 clearly show that Healthy human adult subjects possess IgM+ memory B cells specific for tetanus toxoid C fragment (TTCF), a component of the tetanus vaccine (FIG. 15). Surprisingly, IgM memory B cells remain detectable for years post-vaccination for tetanus.

EXAMPLE 4

Antibody sequences derived from IgG (or IgM) memory B cells can be converted into IgG multimers that exhibit increased binding activity and increased capacity to activate complement

[00530] Rationale and Summary: Antibodies can deploy the complement cascade as a potent effector mechanism. Complement-fixing antibodies are strongly associated with protection from a range of infections including protection from malaria (Boyle et al. 2015; Reiling et al. 2019). While both IgG or IgM antibodies can activate the classical pathway of complement, IgM is much more efficient in triggering this pathway. The Clq complex is comprised of six globular heads arrayed in a hexameric ring structure. Each globular head contains an Fc binding site and concurrent binding of multiple Fc is a key step in triggering complement-dependent cytotoxicity (CDC) (Wang et al. 2016; Ugurlar et al. 2018). IgM exists in either a hexamer or a pentamer conformation. Consistent with the structural constraints for Clq binding, hexamer IgM has a superior ability to interact with Clq and greater complement activating potential (approximately one-log higher compared to IgM pentamers). Because the affinity of a single Clq globular head for immunoglobulin Fc is low (Feinstein et al. 1986; Hughes-Jones et al. 1979), high avidity Clq binding of IgG antibodies requires multimerization of IgG at the site of antigen binding - a process that may not occur for many antigen targets due to surface antigen size, density and fluidity as well as epitope accessibility. To address this issue, several antibody engineering methods have been developed to generate either disulfide- bridged multimeric IgG complexes or facilitate IgG multimerization upon antigen binding through non- covalent protein interface interactions (Smith et al. 1995; Sorensen et al. 1996; Diebolder et al. 2014).

Recent studies show that polymeric IgG is more effective in complement activation than wild-type IgG (Diebolder et al. 2014).

[00531] IgM multimerization occurs through formation of a disulfide bridge between Cp3 (Cys4l4) and C-terminal tail-piece (Cys575). Notably, position 414 in human IgM and position 309 in human IgG are homologous (Sorensen et al. 1996).

[00532] An IgM tail piece of amino acid sequence (PTL YNVSL VMSDTAGTCY) (SEQ ID NO:

155) with 5' and 3' overlap regions for cloning was produced as an ultramer by IDT. Mutation (L309C) and IgM tail piece were introduced into IgG heavy -chain construct (AbVec-hlgGl) by Gibson assembly. Protein expression was carried out by transient transfection of 293T cells using polytheylenimine (PEI).

Cell culture supernatant was collected 6 days after transfection and purified using HiTrap Protein G HP antibody purification column (GE healthcare). Final protein was buffer-exchanged into l x PBS, filter sterilized and stored at -80°C before use.

[00533] Therefore, by utilizing mutation (L309C) and appending an IgM tail piece to C-terminal of candidate IgG heavy chains (FIGs. 16A-16C), IgG mAbs derived from memory B cells that target malaria surface proteins into IgM-like-multimers (FIG. 17 and FIG. 18). The amino acid and gene sequences encoding the IgG reference sequences and the IgG L309C polypeptide sequence are described herein in

SEQ ID NOs: 180-185

[00534] SDS-PAGE analysis (Invitrogen, NuPAGE 4-12% Bis-Tris Gel) was carried out to verify the formation and purity of multimer IgG (FIG. 17). Multimer IgG-003 was generated using the anti-MSP mAb 003 (originally derived from a single, MSP-tetramer binding human memory IgM B cells; expressed an IgG monomer; hIgG-003). Multimer construction introduced the L309C substitution and appending an IgM tail piece to C-terminus of the IgG heavy chain. In the absence of 2-Mercaptoethanol (b-ME), majority of IgGl (>80%) with L309C mutation and m-tail piece forms a polymer that migrates slowly due to large size. After reduction using 2-Mercaptoethanol (b-ME), multimer IgGl is reduced to heavy (HC) and light chains (LC).

[00535] Antibodies were then expressed as described previously and imaged by negative-stain electron microscopy. In contrast to monomer IgGl, multimer IgGl (m-IgGl) proteins mainly form hexamers (FIG. 18).

[00536] Plates were coated with MSP 19 and equal concentrations (based on mass) of monomeric anti- MSP mAb (derived from single memory IgM or IgG B cells; hIgG-003, 008, 010) or multimer-IgG derived from the same mAbs (m-IgG-003, 008, 010) were added at the indicated lO-fold serial dilutions. A non- MSP specific mAb (also derived from a single memory B cell; hIgG-0l2) and its corresponding multimer (m-IgG-0l2) were included as negative controls. Anti-IgG Biotin antibody followed by Streptavidin-HRP was used to detect antibody binding to MSP19. Individual IgGls expressed as multimers exhibited has similar binding affinity (pg/ml) to its corresponding monomer. Based upon the much greater molecular weight of the multimer reagents, these findings imply that at the same molar concentration, the multimer reagents exhibit significantly higher binding affinity compared with each corresponding monomer (FIG.

19).

[00537] These results collectively demonstrate that this approach is feasible and increases antigen binding avidity (FIG. 19) and, by inference, also enhances complement activation.

[00538] Red blood cells (RBCs) were harvested from mice infected with Plasmodium berghei that were previously engineered to express the P. falciparum-specific MSP protein. RBCs were permeabilized and stained with multimeric -IgG (data shown indicate results using m-IgG-003) followed by a fluorescently labelled anti-IgG. Parasites (merozoite stage) were also labelled with an antibody against the Plasmodium protein, BIP, and DAPI which stains their DNA to demonstrate the location of parasite populations within infected RBCs (FIG. 20).

[00539] The engineered multimer IgGl binds to the surface of merozoite during invasion of red blood cell (FIG. 20). These results demonstrate that using this approach, high avidity antibodies derived from IgG memory B cells can be generated that exhibit properties similar to IgM antibodies. Combining the capacity to isolate antigen-specific memory B cells (and to clone and express antibodies from these cells) with IgG multimerization, thereby expands the memory B cell antibody engineering platform described herein for identification and expression of both novel IgM reagents and novel IgG reagents with similar functional properties.

[00540] Antibody sequences of recombinant MSPl9-specific monoclonal antibodies and their corresponding multimer IgGls (m-IgG) can be found in Table #29 and SEQ ID NOs: 156-179.

[00541] References Cited for Examples 3 and 4:

Boyle M.J., Railing L et al. Human Antibodies Fix Complement to Inhibit Plasmodium falciparum Invasion of Erythrocytes and Are Associated with Protection against Malaria. Immunity, 2015, 42, 580-590. PMCID: PMC437225

Diebolder C.A. Complement is activated by IgG hexamers assembled at the cell surface. Science 2014 343, 1260-1263. PMCID: PMC4250092

Feinstein A., Richardson N., Taussig M.J. Immunoglobin flexibility in complement activation. Immunol. Today 1986, 7, 169-174. PMID: 25290202

Hughes- Jones N.C., Gardner B. Reaction between the isolated globular sub-units of the complement component Clq and IgG-complexes. Mol. Immunol. 1979, 9, 697-701. PMID: 119162 Reiimg L.. Boyle M.j et al. Targets of complement-fixing antibodies in protective immunity against malaria in children. Nat. Commun. 2019, 10, 610. PMCID: PMC6363798

Smith, R. L, Coloma, M.J., Morrison, S. L. Addition of a mu-tailpiece to IgG results in polymeric antibodies with enhanced effector functions including complement-mediated cytolysis by IgG4. J. Immunol. 1995, 154, 2226-2236. PMID: 7868896

Sorensen V. et al. Effect of the IgM and IgA secretary tailpieces on polymerization and secretion of IgM and IgG. J Immuno .1996 156, p2858-2865. PMID: 8609405

Ugurlar D. et al. Structures of Cl-IgGi provide insights into how danger pattern recognition

activates complement. Science 2018 359, 794-797. PMID: 29449492

Wang G. et al. Molecular Basis of Assembly and Activation of Complement Component Cl in Complex with Immunoglobulin Gl and Antigen. Mol. Cell 2016, 63, 135-145. PMID: 27320199

SEQUENCE SUMMARY TABUES

Table 1: Variable Heavy Chain Segment Usage by Cell Subset

## V. Segment

## Cell. Subset IGHV1-2 IGHV1-46 IGHV1-69 IGHV1-8 IGHV3-11 IGHV3-15 IGHV3-23 ## IgG MBC 2 0 0 1 0 6 0 ## IgM BC 0 1 1 3 1 1 1 ## V. Segment

## Cell. Subset IGHV3-23D IGHV3-30 IGHV3-30-3 IGHV3-30-5 IGHV3-33 IGHV3-48 ## IgG MBC 1 2 0 1 1 1 ## IgM MBC 0 0 1 0 0 1 ## V. Segment

## Cell. Subset IGHV3-7 IGHV3-74 IGHV3-9 IGHV4-30-4 IGHV4-31 IGHV4-34 ## IgG MBC 0 0 6 2 0 4 ## IgM MBC 1 1 0 0 1 7 ## V. Segment

## Cell. Subset IGHV4-38-2 IGHV4-39 IGHV4-4 IGHV4-59 IGHV4-61 IGHV5-51 ## IgG MBC 3 3 1 2 3 1 ## IgM MBC 2 4 0 1 3 1

Table 2: IgM Cell Subset JH Segment Usage by VH Segment Usage

## D . segment

## V. Segment IGHD1 IGHD3 IGHD4 IGHD4 on IGHD5 IGHD5 IGHD6

## IGHV1-46 0 0 1 0 0 0

## IGHV1-69 0 0 1 0 0 0

## IGHV1-8 0 0 0 0 0 3

## IGHV3-11 0 0 1 0 0 0

## IGHV3-15 0 1 0 0 0 0

## IGHV3-23 0 0 1 0 0 0

## IGHV3-30-3 0 1 0 0 0 0

## IGHV3-48 0 0 1 0 0 0

## IGHV3-7 0 0 0 0 0 1

## IGHV3-74 0 0 0 0 0 1

## IGHV4- 31 0 1 0 0 0 0

## IGHV4- 34 0 3 4 0 0 0

## IGHV4- 38-2 0 0 0 0 2 0

## IGHV4- 39 0 0 1 1 1 1

## IGHV4- 59 0 0 1 0 0 0

## IGHV4-61 0 0 1 0 1 1

## IGHV5- 51 1 0 0 0 0 0

Table 3: IgG Cell Subset JH Segment Usage by VH Segment Usage

## 3. segment

## V. Segment IGHDl IGHD2 IGHD3 IGHD4 IGHD4 on IGHD5 IGHD5 IGHD6

## IGHV1-2 0 0 0 0 0 0 2

## IGHV1-8 0 0 0 1 0 0 0

## IGHV3-15 0 0 0 6 0 0 0

## IGHV3-23D 0 0 0 1 0 0 0 ## IGHV3- 30 0 0 0 2 0 0 0 ## IGHV3-30-5 0 0 0 1 0 0 0

## IGHV3- 33 0 0 1 0 0 0 0 ## IGHV3-48 0 0 0 0 1 0 0 ## IGHV3-9 0 2 0 2 0 1 1 ## IGHV4- 30-4 0 0 0 1 0 1 0 ## IGHV4- 34 0 0 0 1 2 1 0 ## IGHV4- 38-2 0 0 0 3 0 0 0 ## IGHV4- 39 0 0 0 3 0 0 0 ## IGHV4-4 0 0 0 0 0 0 1 ## IGHV4- 59 0 0 0 2 0 0 0 ## IGHV4-61 0 0 0 2 1 0 0 ## IGHV5- 51 1 0 0 0 0 0 0

Table 4: VH Usage by Individual for IgM MBCs

## cDNA. plate

## V. Segment Kali-077 Kali-080 Kali-102 Kali-110 Kali-121 Kali-125

## IGHV1-46 0 0 0 0 0 1

## IGHV1-69 0 1 0 0 0 0

## IGHV1-8 0 1 0 1 1 0

## IGHV3-11 0 0 0 0 1 0

## IGHV3-15 0 0 0 1 0 0

## IGHV3-23 0 0 0 0 1 0

## IGHV3-30-3 0 1 0 0 0 0

## IGHV3-48 0 0 0 0 0 1

## IGHV3-7 1 0 0 0 0 0

## IGHV3-74 0 0 0 0 1 0

## IGHV4- 31 0 0 0 0 1 0

## IGHV4- 34 0 0 4 0 1 0

## IGHV4- 38-2 0 1 0 0 1 0

## IGHV4- 39 1 1 1 1 0 0

## IGHV4- 59 0 0 0 0 0 1

## IGHV4-61 0 2 0 0 0 1

## IGHV5- 51 0 0 0 0 0 0

## cDNA. plate

## V. Segment Kali-147

## IGHV1- 46 0

## IGHV1- 69 0

## IGHV1- 8 0

## IGHV3- 11 0

## IGHV3- 15 0

## IGHV3- 23 0

## IGHV3- 30 -3 0

## IGHV3- 48 0

## IGHV3- 7 0

## IGHV3- 74 0

## IGHV4- 31 0

## IGHV4- 34 2

## IGHV4- 38 -2 0

## IGHV4- 39 0

## IGHV4- 59 0 ## IGHV4-61 0

## IGHV5- 51 1

Table 5: VH Usage by Individual for IgG MBCs

## cDNA. plate

## V. Segment Kali-077 Kali-080 Kali-102 Kali-110 Kali-121 Kali-138

## IGHV1-2 0 0 0 2 0 0

## IGHV1-8 0 1 0 0 0 0

## IGHV3-15 0 0 0 4 2 0

## IGHV3-23D 0 1 0 0 0 0

## IGHV3- 30 0 0 0 0 2 0

## IGHV3-30-5 0 0 0 0 0 0

## IGHV3- 33 0 1 0 0 0 0

## IGHV3-48 0 0 0 1 0 0

## IGHV3-9 0 3 0 0 0 3

## IGHV4- 30-4 0 0 0 0 1 0

## IGHV4- 34 0 0 0 3 0 1

## IGHV4- 38-2 0 0 0 1 0 2

## IGHV4- 39 1 0 0 0 2 0

## IGHV4-4 1 0 0 0 0 0

## IGHV4- 59 0 0 2 0 0 0

## IGHV4-61 0 3 0 0 0 0

## IGHV5- 51 1 0 0 0 0 0

## cDNA. plate

## V. Segment Kali-147

## IGHV1- 2 0

## IGHV1- 8 0

## IGHV3- 15 0

## IGHV3- 23D 0

## IGHV3- 30 0

## IGHV3- 30-5 1

## IGHV3- 33 0

## IGHV3- 48 0

## IGHV3- 9 0

## IGHV4- 30-4 1

## IGHV4- 34 0

## IGHV4- 38-2 0

## IGHV4- 39 0

## IGHV4- 4 0

## IGHV4- 59 0

## IGHV4- 61 0

## IGHV5- 51 0

Table 6: Variable Kappa Chain Segment Usage by Cell Subset

## V. Segment

## Cell. Subset IGKV1-12 IGKV1-39 IGKV1-5 IGKV1-8 IGKV1D-33 IGKV2-28 IGKV2-30

## IgG F1BC 1 0 7 1 1 0 5

## IgN NBC 0 3 4 0 0 1 0

## V. Segment

## Cell. Subset IGKV2D-29 IGKV3-11 IGKV3-15 IGKV3-20 IGKV3D-20 IGKV4-1

Table 7: IgM Cell Subset JK Segment Usage by VK Segment Usage

## D . segment

## V. Segment IGKD1 IGKD2 IGKD3 IGKD4

## IGKV1-39 0 2 1 0

## IGKV1-5 1 2 0 1

## IGKV2-28 0 1 0 0

## IGKV3-11 0 0 0 1

## IGKV3-15 1 0 0 0

## IGKV3-20 1 4 0 0

## IGKV3D-20 0 1 0 0

## IGKV4-1 3 1 0 0

Table 8: IgG Cell Subset JK Segment Usage by VK Segment Usage

## 3. segment

## V. Segment IGKD1 IGKD2 IGKD3 IGKD4 IGKD5

## IGKV1-12 0 0 0 1 0

## IGKV1-5 4 3 0 0 0

## IGKV1-8 1 0 0 0 0

## IGKV1D-33 0 1 0 0 0

## IGKV2-30 0 0 4 0 1

## IGKV2D-29 0 0 0 1 0

## IGKV3-15 1 0 2 0 0

## IGKV3-20 1 1 0 1 1

## IGKV4-1 1 0 0 3 0

Table 9: VK Usage by Individual for IgM MBCs

## cDNA. plate

## V. Segment Kali-080 Kali-102 Kali-110 Kali 121 Kali-125 Kali-138 Kali 147 ## IGKV1-39 1 0 0 0 0 2 0 ## IGKV1-5 0 0 1 1 2 0 0 ## IGKV2-28 0 0 1 0 0 0 0 ## IGKV3-11 1 0 0 0 0 0 0 ## IGKV3-15 0 0 0 0 1 0 0 ## IGKV3-20 0 0 0 3 0 1 1 ## IGKV3D-20 0 0 0 0 0 1 0 ## IGKV4-1 0 3 0 1 0 0 0

Table 10: VK Usage by Individual for IgG MBCs

## cDNA. plate

## V. Segment Kali-077 Kali-080 Kali-102 Kali 110 Kali-121 Kali-138 Kali 147 ## IGKV1-12 1 0 0 0 0 0 0 ## IGKV1-5 0 4 0 3 0 0 0 ## IGKV1-8 0 1 0 0 0 0 0 ## IGKV1D-33 0 0 1 0 0 0 0 ## IGKV2- 30 0 0 0 3 0 0 2 ## IGKV2D-29 0 0 0 0 0 0 1 ## IGKV3-15 0 0 2 0 0 0 1 ## IGKV3-20 1 1 0 0 0 1 1 ## IGKV4-1 0 1 0 0 1 2 0

Table 11: Variable Uambda Chain Segment Usage by Cell Subset

## V. Segment

## Cell. Subset IGLV1-44 IGLV1-47 IGLV1-51 IGLV2-11 IGLV2-14 IGLV2-23 IGLV2-8

Table 13: IgG Cell Subset JU Segment Usage by VU Segment Usage

## 3. segment

## V. Segment IGLD2 on IGLD3 IGLD3

## IGLV1-47 0 1

## IGLV2-14 0 1

## IGLV3-9 2 0

## IGLV4-69 1 0

Table 14: VU Usage by Individual for IgM MBCs

## cDNA. plate

## V. Segment Kali-080 Kali-102 Kali-110 Kali-121 Kali-147

## IGLV1-44 0 1 0 0 1

## IGLV1-47 0 0 0 0 1

## IGLV1-51 1 0 0 0 1

## IGLV2-11 1 0 0 0 0

## IGLV2-23 0 0 0 1 0

## IGLV2-8 0 0 1 0 0 ## IGLV3-21 1 0 0 0 0 ## IGLV4-69 0 0 0 1 0

## IGLV6- 57 0 1 2 0 0

## IGLV8-61 1 0 0 0 0

Table 15: VL Usage by Individual for IgG MBCs

## cDNA. plate

## V. Segment Kali-080 Kali-102 Kali-121

## IGLV1-47 0 1 0

## IGLV2-14 1 0 0

## IGLV3-9 0 0 2

## IGLV4-69 1 0 0

Table 16: Light Chain Usage by Cell Subset

## Cell. Subset

## Chain IgG MBC IgM MBC

## Kappa 27 20

## Lambda 5 14

Table 17: Mutation Rates (%) by Cell Subset and Chain

## # A tibble: 6 x 4

## # Groups: Cell. Subset [?]

## Cell. Subset Chain Count Mean .V. Mutation . Rate

## <fctr> <fctr> <int> <dbl>

## 1 IgG MBC Heavy 40 10.285000

## 2 IgG MBC Kappa 27 6.325926

## 3 IgG MBC Lambda 5 4.740000

## 4 IgM MBC Heavy 31 2.635484

## 5 IgM MBC Kappa 20 2.645000

## 6 IgM MBC Lambda 14 4.007143

Table 18: Mutation Rates (%) by Individual and Cell Subset

## # A tibble: 15 x 5

## # Groups: cDNA. plate [?]

## cDNA. plate Cell. Subset Count Mean .V. Mutation . Rate SD.\ '.Mut . Rate

## <fctr> <fctr> <int> <dbl> <dbl>

## 1 Kali-077 IgG MBC 5 6.06000000 3.5990276

## 2 Kali-077 IgM MBC 2 2.25000000 3.1819805

## 3 Kali-080 IgG MBC 18 7.68333333 2.8226500

## 4 Kali-080 IgM MBC 13 0.07692308 0.2047513

## 5 Kali-102 IgG MBC 6 10.43333333 5.9634442

## 6 Kali-102 IgM MBC 10 2.52000000 1.7806366

## 7 Kali-110 IgG MBC 17 7.91764706 3.1800620

## 8 Kali-110 IgM MBC 8 7.08750000 3.9678845

## 9 Kali-121 IgG MBC 10 7.98000000 3.0684053

## 10 Kali-121 IgM MBC 14 2.28571429 2.0635508 ## 11 Kali-125 IgM MBC 7 3.72857143 2.8726958 ## 12 Kali-138 IgG MBC 9 13.82222222 4.8640975 ## 13 Kali-138 IgM MBC 4 3.40000000 2.4372115 ## 14 Kali-147 IgG MBC 7 5.12857143 3.3179885 ## 15 Kali-147 IgM MBC 7 4.51428571 1.8068652

Table 19: Mutation Rates (%) by Individual and Cell Subset and Chain

## cDNA. plate Chain Cell. Subset Count Mean.V. Mutation. Rate SD.V.Mut . Rate ## 1 Kali-077 Heavy IgG MBC 3 6.86666667 3.8423083 ## 2 Kali-077 Heavy IgM MBC 2 2.25000000 3.1819805 ## 3 Kali-077 Kappa IgG MBC 2 4.85000000 4.1719300 ## 4 Kali-080 Heavy IgG MBC 9 8.74444444 3.1436886 ## 5 Kali-080 Heavy IgM MBC 7 0.04285714 0.1133893 ## 6 Kali-080 Kappa IgG MBC 7 6.78571429 2.3954322 ## 7 Kali-080 Kappa IgM MBC 2 0.00000000 0.0000000 ## 8 Kali-080 Lambda IgG MBC 2 6.05000000 0.9192388 ## 9 Kali-080 Lambda IgM MBC 4 0.17500000 0.3500000 ## 10 Kali-102 Heavy IgG MBC 2 16.20000000 5.2325902 ## 11 Kali-102 Heavy IgM MBC 5 2.66000000 2.2963014 ## 12 Kali-102 Kappa IgG MBC 3 8.93333333 3.7220066 ## 13 Kali-102 Kappa IgM MBC 3 3.16666667 1.1239810 ## 14 Kali-102 Lambda IgG MBC 1 3.40000000 NA ## 15 Kali-102 Lambda IgM MBC 2 1.20000000 0.2828427 ## 16 Kali-110 Heavy IgG MBC 11 8.77272727 3.6003030 ## 17 Kali-110 Heavy IgM MBC 3 5.20000000 2.3895606 ## 18 Kali-110 Kappa IgG MBC 6 6.35000000 1.3707662 ## 19 Kali-110 Kappa IgM MBC 2 3.30000000 0.1414214 ## 20 Kali-110 Lambda IgM MBC 3 11.50000000 0.7000000 ## 21 Kali-121 Heavy IgG MBC 7 9.30000000 2.4785749 ## 22 Kali-121 Heavy IgM MBC 7 2.27142857 2.3178397 ## 23 Kali-121 Kappa IgG MBC 1 6.50000000 NA ## 24 Kali-121 Kappa IgM MBC 5 2.52000000 2.3466998 ## 25 Kali-121 Lambda IgG MBC 2 4.10000000 1.8384776 ## 26 Kali-121 Lambda IgM MBC 2 1.75000000 0.4949747 ## 27 Kali-125 Heavy IgM MBC 4 4.45000000 3.7027017 ## 28 Kali-125 Kappa IgM MBC 3 2.76666667 1.3279056 ## 29 Kali-138 Heavy IgG MBC 6 16.61666667 2.9116433 ## 30 Kali-138 Kappa IgG MBC 3 8.23333333 1.7785762 ## 31 Kali-138 Kappa IgM MBC 4 3.40000000 2.4372115 ## 32 Kali-147 Heavy IgG MBC 2 9.20000000 0.5656854 ## 33 Kali-147 Heavy IgM MBC 3 4.76666667 1.5821926 ## 34 Kali-147 Kappa IgG MBC 5 3.50000000 2.1977261 ## 35 Kali-147 Kappa IgM MBC 1 2.30000000 NA ## 36 Kali-147 Lambda IgM MBC 3 5.00000000 2.0952327

Table 20: Mutation Rates (%) by VH Segment and Individual

## V. Segment cDNA. plate Count Mean .V. Mutation . Rate

## 1 IGHV1-2 Kali-110 2 7.300000

## 2 IGHV1-46 Kali-125 1 9.500000

## 3 IGHV1-69 Kali-080 1 0.300000 ## 4 IGHV1-8 Kali-080 2 4.400000 ## 5 IGHV1-8 Kali-110 1 7.800000 ## 6 IGHV1-8 Kali-121 1 0.700000 ## 7 IGHV3-11 Kali-121 1 1.000000 ## 8 IGHV3-15 Kali-110 5 10.540000 ## 9 IGHV3-15 Kali-121 2 6.350000 ## 10 IGHV3-23 Kali-121 1 3.400000 ## 11 IGHV3-23D Kali-080 1 7.500000 ## 12 IGHV3-30 Kali-121 2 11.900000 ## 13 IGHV3-30-3 Kali-080 1 0.000000 ## 14 IGHV3-30-5 Kali-147 1 8.800000 ## 15 IGHV3-33 Kali-080 1 9.800000 ## 16 IGHV3-48 Kali-110 1 8.200000 ## 17 IGHV3-48 Kali-125 1 0.700000 ## 18 IGHV3-7 Kali-077 1 4.500000 ## 19 IGHV3-74 Kali-121 1 7.100000 ## 20 IGHV3-9 Kali-080 3 6.033333 ## 21 IGHV3-9 Kali-138 3 14.266667 ## 22 IGHV4-30-4 Kali-121 1 9.100000 ## 23 IGHV4-30-4 Kali-147 1 9.600000 ## 24 IGHV4-31 Kali-121 1 1.700000 ## 25 IGHV4-34 Kali-102 4 3.000000 ## 26 IGHV4-34 Kali-110 3 8.233333 ## 27 IGHV4-34 Kali-121 1 1.000000 ## 28 IGHV4-34 Kali-138 1 18.400000 ## 29 IGHV4-34 Kali-147 2 4.950000 ## 30 IGHV4-38-2 Kali-080 1 0.000000 ## 31 IGHV4-38-2 Kali-110 1 1.000000 ## 32 IGHV4-38-2 Kali-121 1 1.000000 ## 33 IGHV4-38-2 Kali-138 2 19.250000 ## 34 IGHV4- 39 Kali-077 2 1.800000 ## 35 IGHV4-39 Kali-080 1 0.000000 ## 36 IGHV4-39 Kali-102 1 1.300000 ## 37 IGHV4-39 Kali-110 1 3.100000 ## 38 IGHV4-39 Kali-121 2 9.750000 ## 39 IGHV4-4 Kali-077 1 5.900000 ## 40 IGHV4-59 Kali-102 2 16.200000 ## 41 IGHV4-59 Kali-125 1 3.200000 ## 42 IGHV4-61 Kali-080 5 6.900000 ## 43 IGHV4-61 Kali-125 1 4.400000 ## 44 IGHV5-51 Kali-077 1 11.100000 ## 45 IGHV5-51 Kali-147 1 4.400000

Table 21: Mutation Rates (%) by VH Segment and Cell Subset

## V. Segment Cell. Subset Count Mean .V. Mutation . Rate

## 1 IGHV1-2 IgG FIBC 2 7.300000 ## 2 IGHV1-46 IgN FIBC 1 9.500000 ## 3 IGHV1-69 IgN FIBC 1 0.300000 ## 4 IGHV1-8 IgG FIBC 1 8.800000 ## 5 IGHV1-8 IgN NBC 3 2.833333 ## 6 IGHV3-11 IgN NBC 1 1.000000 ## 7 IGHV3-15 IgG MBC 6 10.116667 ## 8 IGHV3-15 IgM MBC 1 4.700000 ## 9 IGHV3-23 IgM MBC 1 3.400000 ## 10 IGHV3-23D IgG MBC 1 7.500000 ## 11 IGHV3-30 IgG MBC 2 11.900000 ## 12 IGHV3-30-3 IgM MBC 1 0.000000 ## 13 IGHV3-30-5 IgG MBC 1 8.800000 ## 14 IGHV3-33 IgG MBC 1 9.800000 ## 15 IGHV3-48 IgG MBC 1 8.200000 ## 16 IGHV3-48 IgM MBC 1 0.700000 ## 17 IGHV3-7 IgM MBC 1 4.500000 ## 18 IGHV3-74 IgM MBC 1 7.100000 ## 19 IGHV3-9 IgG MBC 6 10.150000 ## 20 IGHV4-30-4 IgG MBC 2 9.350000 ## 21 IGHV4-31 IgM MBC 1 1.700000 ## 22 IGHV4-34 IgG MBC 4 10.775000 ## 23 IGHV4-34 IgM MBC 7 3.271429 ## 24 IGHV4-38-2 IgG MBC 3 13.166667 ## 25 IGHV4-38-2 IgM MBC 2 0.500000 ## 26 IGHV4-39 IgG MBC 3 7.700000 ## 27 IGHV4-39 IgM MBC 4 1.100000 ## 28 IGHV4-4 IgG MBC 1 5.900000 ## 29 IGHV4-59 IgG MBC 2 16.200000 ## 30 IGHV4-59 IgM MBC 1 3.200000 ## 31 IGHV4-61 IgG MBC 3 11.500000 ## 32 IGHV4-61 IgM MBC 3 1.466667 ## 33 IGHV5-51 IgG MBC 1 11.100000 ## 34 IGHV5-51 IgM MBC 1 4.400000

Table 22: Mutation Rates (%) by VK Segment and Cell Subset

## # A tibble: 17 x 4

## # Groups: V. Segment [?]

## V. Segment Cell. Subset Count Mean. V. Mutation. Rate ## <fctr> <fctr> <int> <dbl> ## 1 IGKV1-12 IgG MBC 1 7.800000 ## 2 IGKV1-39 IgM MBC 3 3.233333 ## 3 IGKV1-5 IgG MBC 7 7.257143 ## 4 IGKV1-5 IgM MBC 4 2.375000 ## 5 IGKV1-8 IgG MBC 1 8.300000 ## 6 IGKV1D-33 IgG MBC 1 9.400000 ## 7 IGKV2-28 IgM MBC 1 3.400000 ## 8 IGKV2-30 IgG MBC 5 5.400000 ## 9 IGKV2D-29 IgG MBC 1 5.200000 ## 10 IGKV3-11 IgM MBC 1 0.000000 ## 11 IGKV3-15 IgG MBC 3 6.833333 ## 12 IGKV3-15 IgM MBC 1 2.000000 ## 13 IGKV3-20 IgG MBC 4 3.800000 ## 14 IGKV3-20 IgM MBC 5 2.760000 ## 15 IGKV3D-20 IgM MBC 1 3.900000 ## 16 IGKV4-1 IgG MBC 4 6.650000 ## 17 IGKV4-1 IgM MBC 4 2.650000 Table 23: Mutation Rates (%) by VL Segment and Cell Subset

## # A tibble: 14 x 4

## # Groups: V. Segment [?]

## V. Segment Cell. Subset Count Mean .V. Mutation . Rate

## <fctn> <fctn> <int> <dbl>

## 1 IGLV1-44 IgM MBC 2 3.900000

## 2 IGLV1-47 IgG MBC 1 3.400000

## 3 IGLV1-47 IgM MBC 1 5.500000

## 4 IGLV1-51 IgM MBC 2 1.350000

## 5 IGLV2-11 IgM MBC 1 0.700000

## 6 IGLV2-14 IgG MBC 1 6.700000

## 7 IGLV2-23 IgM MBC 1 1.400000

## 8 IGLV2-8 IgM MBC 1 10.800000

## 9 IGLV3-21 IgM MBC 1 0.000000

## 10 IGLV3-9 IgG MBC 2 4.100000

## 11 IGLV4-69 IgG MBC 1 5.400000

## 12 IGLV4-69 IgM MBC 1 2.100000

## 13 IGLV6-57 IgM MBC 3 8.366667

## 14 IGLV8-61 IgM MBC 1 0.000000

Table 24: IgM MBC VH Segments Paired by Light Chain Type; NA represents paired sequence not found.

## Chain . Light

## V. Segment . Heavy Kappa Lambda <NA>

## IGHV1-46 1 0 0

## IGHV1-69 1 0 0

## IGHV1-8 3 0 0

## IGHV3-11 0 1 0

## IGHV3-15 0 0 1

## IGHV3-23 0 0 1

## IGHV3-30-3 0 0 1

## IGHV3-48 0 0 1

## IGHV3-7 0 0 1

## IGHV3-74 0 0 1

## IGHV4-31 0 1 0

## IGHV4-34 3 3 1

## IGHV4-38-2 1 1 0

## IGHV4-39 1 1 2

## IGHV4-59 1 0 0

## IGHV4-61 1 2 0

## IGHV5-51 0 1 0

## <NA> 0 0 0

Table 25: IgG MBC VH Segments Paired by Light Chain Type; NA represents paired sequence not found.

## Chain. Light

## V. Segment . Heavy Kappa Lambda <NA>

## IGHV1-2 0 0 2

## IGHV1-8 0 0 1 ## IGHV3-15 2 2 2

## IGHV3-23D 1 0 0

## IGHV3-30 0 0 2

## IGHV3-30-5 1 0 0

## IGHV3-33 1 0 0

## IGHV3-48 0 0 1

## IGHV3-9 0 1 5

## IGHV4-30-4 1 0 1

## IGHV4-34 4 0 0

## IGHV4-38-2 2 0 1

## IGHV4-39 0 0 3

## IGHV4-4 1 0 0

## IGHV4-59 2 0 0

## IGHV4-61 3 0 0

## IGHV5-51 1 0 0

## <NA> 0 0 0

Table 26: IgM MBC VH Segments Paired by Light Chain V Segment

## V. Segment Light

## V Segment . Heavy IGKV1-39 IGKV1- 5 IGKV2-28 IGKV3-11 IGKV3-15 IGKV4-1 ## IGHV1-46 0 0 0 0 1 0

## IGHV1-69 0 0 0 1 0 0

## IGHV1-8 1 2 0 0 0 0

## IGHV3-11 0 0 0 0 0 0

## IGHV4-31 0 0 0 0 0 0

## IGHV4-34 0 0 0 0 0 3

## IGHV4-38- 0 0 0 0 0 1

## IGHV4-39 0 0 1 0 0 0

## IGHV4-59 0 1 0 0 0 0

## IGHV4-61 0 1 0 0 0 0

## IGHV5-51 0 0 0 0 0 0

## V. Segment Light

## V Segment . Heavy IGLV1-44 IGLV1- 47 IGLV1-51 IGLV2-11 IGLV2-23 IGLV3-21 ## IGHV1-46 0 0 0 0 0 0

## IGHV1-69 0 0 0 0 0 0

## IGHV1-8 0 0 0 0 0 0

## IGHV3-11 0 0 0 0 0 0

## IGHV4-31 0 0 0 0 1 0

## IGHV4-34 0 1 1 0 0 0

## IGHV4-38- 0 0 0 1 0 0

## IGHV4-39 1 0 0 0 0 0

## IGHV4-59 0 0 0 0 0 0

## IGHV4-61 0 0 0 0 0 1

## IGHV5-51 1 0 0 0 0 0

## V. Segment Light

## V Segment . Heavy IGLV4-69 IGLV6- 57 IGLV8-61

## IGHV1-46 0 0 0

## IGHV1-69 0 0 0

## IGHV1-8 0 0 0

## IGHV3-11 1 0 0

## IGHV4-31 0 0 0 ## IGHV4-34 0 1 0

## IGHV4-38-2 0 0 0

## IGHV4-39 0 0 0

## IGHV4-59 0 0 0

## IGHV4-61 0 0 1

## IGHV5-51 0 0 0

Table 27: IgG MBC VH Segments Paired by Light Chain V Segment

## V. Segment . Light

## V Segment. Heavy IGKV1-12 IGKV1- IGKV1-8 IGKV2-30 IGKV2D-29 IGKV3- 15

Table 28: Average Difference in Heavy and Light Chain V Segment Mutation Rates by Person, Chain, and Cell Subset

## cDNA. plate. Heavy Cell . Subset . Heavy Chain. Light Avg . Mut . Rate . Diff

## 1 Kali-077 IgG MBC Kappa 3.6500000

## 2 Kali-080 IgG MBC Kappa 3.4600000

## 3 Kali-080 IgG MBC Lambda 2.0000000

## 4 Kali-080 IgM MBC Kappa 0.1500000

## 5 Kali-080 IgM MBC Lambda -0.2333333

## 6 Kali-102 IgG MBC Kappa 7.5000000

## 7 Kali-102 IgM MBC Kappa 0.5000000

## 8 Kali-102 IgM MBC Lambda -0.0500000

## 9 Kali-110 IgG MBC Kappa 3.3600000

## 10 Kali-110 IgM MBC Kappa 2.1500000 Attorney Docket No. 067505-092610WOPT

## 11 Kali-121 IgG MBC Lambda 2.2500000

## 12 Kali-121 IgM MBC Kappa 0.3000000 ## 13 Kali-121 IgM MBC Lambda -0.4000000 ## 14 Kali-125 IgM MBC Kappa 2.9333333 ## 15 Kali-138 IgG MBC Kappa 10.7333333 ## 16 Kali-147 IgG MBC Kappa 5.0500000 ## 17 Kali-147 IgM MBC Lambda -0.2333333 ## StdDev . Mut . Rate . Diff

## 1 0.4949747

## 2 1.8063776

## 3 NA

## 4 0.2121320

## 5 0.4041452

## 6 0.0000000

## 7 2.7513633

## 8 0.4949747

## 9 2.6548070

## 10 3.4648232

## 11 0.4949747

## 12 0.5656854

## 13 0.9899495

## 14 4.3247351

## 15 1.4047538

## 16 2.0506097

## 17 1.8823744

Table #29. Sequences of recombinant MSPi ₉ -specific monoclonal antibodies and their corresponding multimer IgGls (m-IgG).