COMPOSITIONS AND METHODS RELATED TO HUMAN NEUTRALIZING ANTIBODIES TO ZIKA AND DENGUE 1 VIRUS CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent application no. 62/483,001, filed April 7, 2017, the disclosure of which is incorporated herein by reference. GOVERNMENT FUNDING

This invention was made with government support under grant no. UM1AI100663 awarded by the National Institutes of Health. The government has certain rights in the invention. SEQUENCE LISTING

The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on April 6, 2018, is named 076091_00046_SL.txt and is 507,614 bytes in size. BACKGROUND

Zika virus (ZIKV) infection typically produces mild symptoms consisting of fever, rash and arthralgia that resolve rapidly, and the infection is also occasionally associated with Guillain- Barré Syndrome (Lessler et al., 2016; Miner and Diamond, 2017). However, when infection occurs during pregnancy, vertical transmission can lead to a spectrum of devastating neurodevelopmental aberrations, collectively referred to as Congenital Zika Syndrome. Although the data are still incomplete, infants born to mothers infected with ZIKV during pregnancy carry an up to 42% risk of developing overt clinical or neuroimaging abnormalities (Brasil et al., 2016; Costa et al., 2016; Franca et al., 2016). ZIKV belongs to the Flavivirus genus, which includes yellow fever (YFV), West Nile (WNV), and the 4 serotypes of dengue virus (DENV1-4). These positive-stranded RNA viruses are responsible for considerable morbidity and mortality in the equatorial and subequatorial regions populated by their mosquito vectors (Kramer et al., 2007; Murray et al., 2013; Weaver and Reisen, 2010). Unlike most other flaviviruses, ZIKV can also be transmitted sexually, and on occasion persists for months (Barzon et al., 2016; Foy et al., 2011; Murray et al., 2017; Suy et al., 2016). All flaviviruses display a single envelope protein, E, that is highly conserved between different members of this virus family. The E protein ectodomain consists of three structural domains. Domain I (EDI) contains the N-terminus, domain II (EDII) is an extended finger-like structure that includes the dimerization domain and also a pH- sensitive fusion loop that mediates viral fusion in the lysosomes. Finally, domain III (EDIII) is an immunoglobulin-like domain that mediates attachment to target cells (Barba-Spaeth et al., 2016; Dai et al., 2016; Kostyuchenko et al., 2016; Modis et al., 2003; Mukhopadhyay et al., 2005; Rey et al., 1995; Sirohi et al., 2016; Zhang et al., 2004). Several human neutralizing antibodies targeting different E protein epitopes have been described. Antibodies against the EDIII of flaviviruses are among the most potent neutralizers in this group (Beasley and Barrett, 2002; Crill and Roehrig, 2001; Screaton et al., 2015). Due to the conserved structural features of the E protein, antibodies that develop in response to infection by one flavivirus may also recognize others (Heinz and Stiasny, 2017). Cross- reactivity can lead to cross-protection as first documented by Sabin who showed experimentally in humans that exposure to DENV1 could provide short-term protection from subsequent challenge with DENV2. In contrast, immunity to the autologous strain was long lasting (Sabin, 1950). More recently, human monoclonal antibodies to DENV have been shown to cross-neutralize ZIKV, and vice versa (Barba-Spaeth et al., 2016; Stettler et al., 2016; Swanstrom et al., 2016). However, there is concern that cross-reacting antibodies that fail to neutralize the virus may enhance rather than curb subsequent flavivirus infections (Harrison, 2016; Wahala and Silva, 2011). In vitro and in vivo experiments in mice suggest that this phenomenon, commonly referred to as Antibody Dependent Enhancement (ADE), extends to ZIKV (Bardina et al., 2017; Dejnirattisai et al., 2016; Harrison, 2016; Priyamvada et al., 2016). While several human antibodies to ZIKV have been cloned from convalescent individuals by methods utilizing B cell transformation with Epstein-Barr virus (Sapparapu et al., 2016; Stettler et al., 2016), individual donors were not selected for high neutralization titers; whether their antibodies are representative of optimal immune responses, and how these antibodies might relate to previous flavivirus exposure remains unknown. Since no approved prophylaxis or treatment exists, there is an ongoing need for compositions and methods that provide robust protection against ZIKV and other flaviviruses (such as DENV1). Because of the risk of ADE, it is preferable that such compositions and methods avoid the generation of antibodies that bind to the virus but are non-neutralizing and potentially enhancing. Passive administration of monoclonal antibodies represents an alternative approach to vaccines, and has the advantage that antibodies can be modified to prevent interaction with cellular receptors that mediate ADE. The present disclosure is pertinent to this need. BRIEF SUMMARY

Antibodies to Zika virus (ZIKV) can be protective. To examine the antibody response in individuals that develop high titers of anti-ZIKV antibodies we screened cohorts in Brazil and Mexico for ZIKV envelope domain III (ZEDIII) binding and neutralization. Sequencing of nearly 300 antibodies showed that donors with high ZIKV neutralizing antibody titers had expanded clones of memory B cells that carried the same immunoglobulin VH3-23/VK1-5 genes. These recurring antibodies cross-reacted with DENV1, but not other flaviviruses. In particular, a VH3-23/VK1-5 antibody described in detail below as Z004 neutralized both DENV1 and ZIKV, and protected mice against ZIKV challenge. Structural analyses revealed the mechanism of recognition of the ZEDIII lateral ridge by VH3-23/VK1-5 antibodies. Serologic testing showed that antibodies to this region correlate with serum neutralizing activity to ZIKV, and that reactivity to dengue 1 virus (DENV1) EDIII before ZIKV exposure was associated with increased ZIKV neutralizing titers after exposure. Thus, high neutralizing responses to ZIKV are associated with pre-existing reactivity to DENV1. Accordingly, mice immunization experiments showed that immunization with the EDIII of DENV1 followed by boosting with ZEDIII resulted in higher neutralizing titers against ZIKV than immunization with either component alone. The disclosure takes advantage of these discoveries to provide novel compositions and methods for approaching ZIKV and DENV1 prophylaxis and/or therapy. Furthermore, the present disclosure demonstrates that a combination of two different antibodies that recognize distinct but overlapping epitopes on the EDIII lateral ridge of ZIKV and DENV1 has unique properties. In particular, the antibody described below as Z021 potently neutralized ZIKV and DENV1 in vitro and prevented disease in mice. In macaques, prophylactic co-administration of Z004 with Z021 was protective and suppressed emergence of ZIKV resistant variants. Thus, the present disclosure demonstrates that a combination of two human monoclonal antibodies that recognize distinct but overlapping epitopes on ZIKV EDIII is sufficient to suppress infection and thwart viral escape in macaques, a natural host for ZIKV. It is considered based on these data that similar effects can be elicited in humans. In embodiments the disclosure thus provides an isolated or recombinant antibody, or polynucleotides encoding the antibody, comprising a complementarity determining region (CDR) 3 (CDR3) amino acid sequence selected from heavy chain and light chain CDR3 sequences in Table 1 and Table 2. Table 1 also provides variable sequences for numerous antibody heavy and light chain from which CDR1, CDR2 and CDR3 sequences can be determined. In certain embodiments the disclosure provides a Z004 antibody comprising a heavy chain comprising: a CDR1 comprising GFTFRDYA (SEQ ID NO:1), a CDR2 comprising

YSGIDDST (SEQ ID NO:2), and a CDR3 comprising AKDRGPRGVGELFDS (SEQ ID NO:3) (a Z004 heavy chain); and a light chain comprising: a CDR1 comprising QSISKW (SEQ ID NO:4), a CDR2 comprising TTS, and a CDR3 comprising QHFYSVPWT (SEQ ID NO:5) (a Z004 light chain). In an embodiment the disclosure provides a Z021 antibody comprising a heavy chain comprising: a CDR1 comprising GGSIDTYY (SEQ ID NO:6), a CDR2 comprising FYYSVDN (SEQ ID NO:7), and a CDR3 comprising ARNQPGGRAFDY (SEQ ID NO:8) (a Z021 heavy chain); and a light chain comprising: a CDR1 comprising QSVSNY (SEQ ID NO:9), a CDR2 comprising DTS, and a CDR3 comprising

QERNNWPLTWT (SEQ ID NO:10) (a Z021 light chain), or iii) a bispecific antibody comprising the Z004 heavy chain CDR1, CDR2, CDR3, and the Z004 light chain CDR1, CDR2, CDR3, and the Z021 heavy chain CDR1, CDR2, CDR3, and the Z021 light chain CDR1, CDR2, CDR3. In embodiments, the Z004 antibody (also referred to herein as MEX18_89) comprises a heavy chain having the sequence:

In this Z004 sequence and Z021 sequence below, the CDR1 is italicized, the CDR2 is bolded and the CDR3 is italicized and bolded. In embodiments, the Z021 antibody (also referred to herein as MEX84_p4-23) has a heavy chain having the sequence:

Any antibody described herein can comprise at least one modification of its constant region. The modification is of any one or more amino acids. The modification can have any of a number of desirable effects. In certain approaches, the modification increases in vivo half-life of the antibody, or alters the ability of the antibody to bind to Fc receptors, or alters the ability of the antibody to cross placenta or to cross a blood-brain barrier or to cross a blood- testes barrier, or inhibits aggregation of the antibodies, or a combination of said

modifications, or wherein the antibody is attached to a label or a substrate. In embodiments, the modification improves the manufacturability of the antibody. In embodiments, any antibody or combination thereof described herein can be present in an immunological assay, such as an enzyme-linked immunosorbent assay (ELISA) assay, or an ELISA assay control. The ELISA assay can be any of a direct ELISA assay, an indirect ELISA assay, a sandwich ELISA assay, or a competition ELISA assay. In another aspect the disclosure provides a method for prophylaxis or therapy of a viral infection comprising administering to an individual in need thereof an effective amount of at least one antibody or antigen binding fragment thereof. The antibody may comprise at least one modification of the constant region. In embodiments, the composition is administered to an individual who is infected with or is at risk of being infected with a virus selected from the group consisting of Zika virus (ZIKV), dengue 1,2,3 or 4 viruses (DENV1-4), yellow fever virus (YFV), West Nile virus (WNV), and combinations thereof. In one approach, at least two antibodies are administered. In an embodiment, administering at least two distinct antibodies suppressed formation of viruses that are resistant to the antibodies. In one embodiment, the Z004 antibody and the Z021 antibody are administered. In another aspect the disclosure provides vaccine formulations. In an embodiment a vaccine formulation comprises: i) an isolated or recombinant polypeptide or a polynucleotide encoding the polypeptide, wherein the polypeptide is derived from the ZIKV EDIII protein, wherein the polypeptide comprises a segment of the lateral ridge of ZIKV EDIII (ZEDIII); or ii) an isolated or recombinant polypeptide or a polynucleotide encoding the polypeptide, wherein the polypeptide is derived from the DENV1 EDIII protein, wherein the polypeptide comprises a segment of the lateral ridge of the DENV1 EDIII protein, or a combination of i) and ii). In certain implementations, a vaccine formulation comprises a ZEDIII polypeptide which comprises at least one contiguous segment of ZEDIII comprising amino acids 305-311, 333- 336, or 350-352, and/or wherein the segment comprises one or more of ZEDIII amino acids L307, S306, T309, K394, A311, E393, T335, G334, A310, and D336, and/or wherein the polypeptide comprises one or more of DENV1 EDIII amino acids M301, V300, T303, E384, T329, K385, S305, E327, G328, and D330. In certain approaches, a ZIKV EDIII epitope and/or a DENV1 EDIII epitope is duplicated in the polypeptide, and/or the polypeptide comprises both ZIKV EDIII and DENV1 EDIII epitopes. In certain approaches,

the polypeptide in the vaccine is modified such that it comprises one or more glycans, and/or by addition of amino acids that comprise Th epitope(s), and/or the polypeptide is stapled, and/or is cyclicized, and/or is multimerized. In another approach the disclosure provides a method for prophylaxis or therapy of a viral infection comprising administering to an individual in need thereof an effective amount of at least one vaccine formulation described herein. In certain embodiments, a first vaccination is performed with a polypeptide or a polynucleotide encoding the polypeptide, wherein the polypeptide is derived from the DENV1 EDIII protein, and wherein the polypeptide comprises a segment of the lateral ridge of the DENV1 EDIII. This can be followed by performing a second vaccination with a polypeptide or polynucleotide encoding the polypeptide, wherein the polypeptide is derived from the ZIKV EDIII protein, and wherein the polypeptide comprises a segment of the lateral ridge of ZIKV EDIII (ZEDIII). Such vaccination approaches can stimulate production of neutralizing antibodies in the individual that inhibit infectivity of a virus selected from the group of viruses consisting of Zika virus, dengue 1,2,3 or 4 viruses (DENV1-4), yellow fever virus (YFV), West Nile virus (WNV), and combinations thereof. In another aspect, a method for detecting antibodies to Zika virus (ZIKV) and/or dengue 1 virus (DENV1) is provided, and comprises: contacting a biological sample with an isolated or recombinant polypeptide derived from ZIKV EDIII protein, wherein the polypeptide comprises a contiguous segment of the ZIKV EDIII protein that includes an epitope that comprises amino acids E393-K394 of the EDIII protein, and/or with an isolated or recombinant polypeptide derived from DENV1 EDIII protein that comprises a contiguous segment of the DENV1 EDIII protein that includes an epitope that comprises amino acids E384-K385 of the DENV1 EDIII protein, and directly or indirectly detecting a complex comprising the polypeptide and the antibodies if the antibodies are present in the biological sample. In embodiments, the method is performed using an ELISA assay, such as a competition ELISA assay. A suitable assays may further comprise contacting the biological sample with the isolated or recombinant polypeptide with added antibodies, wherein the added antibodies are detectably labeled, and wherein the added antibodies compete with antibodies in the biological sample (if present prior to the adding) for binding to the isolated or recombinant polypeptide, and wherein less binding of the added antibodies relative to a control indicates serologic activity against ZIKV and/or DENV1 in the biological sample. In another embodiment, a suitable assay further comprises performing a control reaction. The control reaction substitutes a recombinant polypeptide derived from ZIKV EDIII protein with a recombinant polypeptide derived from ZIKV EDIII protein that comprises a mutation of E393 and/or K394, wherein the mutation is optionally a substitution of E and/or K with an alanine, and comparing an antibody binding value from the control reaction with an antibody binding value to characterize serologic activity against ZIKV in the biological sample. In another aspect the disclosure provides one or more recombinant expression vectors, and kits comprising the expression vectors. The expression vectors encode the heavy chain and the light chain of any of the antibodies of described herein. Cells comprising the recombinant expression vectors are included, as are methods of making antibodies by culturing cells that comprise expression vectors that express the antibodies, and separating antibodies from the cells. Cell culture media containing such cells and/or antibodies is also included. BRIEF DESCRIPTION OF THE FIGURES

Figure 1– Identification of individuals with high ZEDIII binding and neutralization capacity

A- Sera from the Brazilian and Mexican cohorts were screened by ELISA for IgG antibodies binding to ZEDIII. Each dot represents an individual donor. Optical densities are normalized to control serum from a flavivirus naïve individual vaccinated for YFV. In black are sera selected for neutralization analysis. B- The neutralization capacity of selected sera from Mexico (dark grey) and Brazil (light grey) was determined by a ZIKV luciferase reporter viral particle (RVP) neutralization assay. The reciprocal of the serum dilution that resulted in 50% inhibition compared to RVP alone is reported as the 50% neutralization titer (NT50). The dotted line indicates the lower limit of dilutions that were examined. The five samples below the dotted line have NT ₅₀ values lower than 10 ³ . Individuals from whom antibodies were sequenced and cloned are indicated. Figure 2– Discovery of ZEDIII-specific antibodies

A- Frequency of ZEDIII-specific, IgG ⁺ memory B cells in peripheral blood of 6 donors. Flow cytometry plots display the percentage of all IgG ⁺ memory B cells that bind to a fluorescently tagged ZEDIII bait. Flavivirus naïve peripheral blood samples are shown alongside as negative controls. B- Pie charts show the distribution of antibody clones that share the same IGHV and IGLV; the width of each colored or shaded slice is proportional to the number of clones sharing a distinct combination of IGHV and IGLV sequences. The total number of antibody clones sequenced from each donor is indicated in the center of the pie chart. VH3-23/VK1-5 clones are in red, while other VH3-23 clones are indicated with different shades of blue. Non VH3- 23 clones are shown in shades of grey, and singlets are in white. None of the grey clones are recurrent across individuals. C- V(D)J assignments for the VH3-23/VK1-5 clones. IgBLAST was used to assign the germline (GL) reference sequence for IGHV and IGLV. Red highlights differences in D and J usage in the VH3-23 clones between individuals.

See also Figure 8, and Tables 1 and 2. Figure 3– Binding of cloned antibodies to EDIII from ZIKV and other flaviviruses A- Binding of human monoclonal antibodies to ZEDIII. Human anti-HIV antibody 10-1074 was used as a negative control (Mouquet et al., 2012). The average half effective concentration (EC50) from at least two independent experiments is shown. B- Somatic mutations are required for ZEDIII binding. Binding of Z004 (arrow), its predicted germline (GL), and control antibodies to ZEDIII as assessed by ELISA is shown. C- Human monoclonal antibody cross- reactivity by ELISA. Reactivity to the EDIII of the indicated flaviviruses is shown in grey. The list of antibodies is reported on the left of panel A. D- Z004 binds to the EDIII of DENV1. Binding of Z004 (arrow), its predicted germline (GL), and control antibodies to DENV1 EDIII as assessed by ELISA is shown.

See also Figure 9. Figure 4– VH3-23/VK1-5 antibodies neutralize ZIKV and DENV1

A- Neutralization potency of human monoclonal antibodies by ZIKV luciferase RVP assay. The human anti-HIV antibody 10-1074 serves as a negative control. Average values of the half maximal inhibitory concentration (IC50) from at least two independent experiments are shown. B and C- Z004 neutralizes ZIKV (B) and DENV1 (C) RVPs. Luciferase activity relative to the no antibody control was determined in the presence of increasing concentrations of Z004 (arrow) or of its predicted germline antibody as indicated. Control antibody was tested at a single concentration. Data are represented as mean ± SD. D, E, and F- Z004 protects IFNAR1- ^/- mice from ZIKV disease. Mice were infected by footpad (f.p.) injection with the Puerto Rican PRVABC59 ZIKV strain and treated intraperitoneally (i.p.) with Z004 (or 10-1074 control) either before (E) or 1 day after (F) infection. Mice were monitored for symptoms and survival. Survival: p<0.0001 (pre-exposure) and p=0.0027 (post-exposure). Symptoms: p<0.0001 (both pre- and post-exposure, Mantel-Cox test). Three independent experiments, of 4 to 7 mice per group, were combined and displayed. G- Amino acid alignment of a portion of the EDIII lateral ridge region for a panel of flaviviruses (SEQ ID NOS 1061-1069, respectively, in order of appearance). The corresponding accession numbers are indicated in parenthesis. H- The K394 residue in the ZEDIII lateral ridge is required for ZIKV neutralization by Z004. Luciferase activity relative to no antibody control was determined for ZIKV wild type or mutant E393A and K394A RVPs. I- Z004 neutralizes both Asian/American and African strains. RVPs bearing Asian/American ZIKV wild type (E393), mutant (Asian/American with E393D) and African strain (D393) E proteins were neutralized by Z004. In H and I data are represented as mean ± SD.

See also Fig.10. Figure 5– Structures of Fab complexes with ZIKV and DENV1 EDIII domains

A- Superimposition of Z006 Fab-ZEDIII and Z004 Fab-DENV1 EDIII crystal structures after alignment of the EDIII domains. The VH domain positions differ by a 14° rotation about an axis passing through the center of the interface. Inset: close-up of interactions between the E393 _ZIKV –K394 _ZIKV /E384 _DENV1 –K385 _DENV1 motif (shown as sticks) within the EDIII lateral ridge and the two Fabs. Fab CDRs are highlighted. B- Overlay of the Z006-ZEDIII complex structure (EDIII in black) with previously solved structures of antibodies in complex with ZIKV and DENV1 EDIII domains. The E393 _ZIKV –K394 _ZIKV side chains in ZEDIII are shown as spheres. Structures were aligned on the EDIII domains; only ZEDIII is shown for clarity. C- ZEDIII epitope: EDIII residues contacted by Z006 Fab are highlighted on a surface representation of the EDIII structure. Residues making interactions with both VH and VL are dark grey. The E393 _ZIKV –K394 _ZIKV motif is outlined. Contacts between the Z004 Fab and DENV1 EDIII were less extensive than Z006–ZEDIII contacts, in part because of disorder of the CC’ loop in DENV1 EDIII (residues 343-349). D to F- Comparison of key antibody- antigen interactions for Z006 Fab-ZEDIII and Z004 Fab-DENV1 EDIII structures. Hydrogen bonds are shown as dotted lines. D- Fab interactions with K394 _ZIKV /K385 _DENV1 . E- Fab interactions with E393ZIKV/E384DENV1. F- Y58HC (germline-encoded in VH3-23) interactions with antigen.

See also Tables 5 and 6. Figure 6– EDIII reactivity over time

A- A set (n=63) of paired sera from the Brazilian cohort participants were collected in April and November 2015 and assayed for binding to flavivirus EDIII. Optical densities are normalized as described in Fig.1A. Paired sera from the same individual are connected by a line. Each value represents the average of two independent measurements. P values were determined with the two-tailed paired t test (n.s., not significant). B- Correlation between DENV1 EDIII reactivity in April and ZEDIII reactivity in November 2015. Circles and plus signs distinguish data from two independent experiments. Pseudo- ^=0.48, p<0.001 by univariate analysis. Figure 7– EDIII antibodies contribute to the serologic response and ZIKV neutralization capacity

A- Competition ELISA shows the increase within individuals of serum antibodies that block biotin-Z004 ZEDIII binding after ZIKV exposure. Each dot represents a serum sample (n=62 at each of the indicated time points). A line connects sera from the same individual obtained at different time points. The p value was determined with the two-tailed paired t test. B and C- The estimated quantity ( ^g/ml) of Z004 blocking antibodies in the serum obtained after ZIKV introduction (X axes) was plotted with the overall serum binding activity to ZEDIII (Y axis, B), and the change in that individual’s serum ZEDIII binding from before to after ZIKV (Y axis, C). Binding activity change was determined by subtracting the pre- from the post-ZIKV ELISA relative optical density value (average of two independent measurements). Each dot represents an individual (n=62, two-tailed Spearman r test). D and E- Serum neutralization potency expressed as NT ₅₀ versus the overall serum binding activity to ZEDIII (D), or Z004 blocking antibody concentrations in sera (E) obtained after ZIKV introduction are plotted. Each dot represents a serum sample from a single donor (n=27, two-tailed Spearman r test). Representative of two independent experiments is shown. Figure 8– Maximum likelihood tree of VH3-23/VK1-5 antibodies. Related to Figure 2 and Table 1.

Antibody amino acid sequences (heavy and light chain combined) are clustered and labeled according to the donor ID (MEX18, MEX105, MEX84, BRA112, BRA12) followed by the clone’s unique sequence ID. Figure 9– Features of anti-ZIKV antibodies. Related to Figure 3 and Table 1.

A- Dose-dependent binding of recombinant human monoclonal antibodies to ZEDIII as measured by ELISA. Representative non-linear regression curves are shown. B and C- VH3- 23/VK1-5 antibodies have low levels of somatic mutation. The number of V gene nucleotide (B) or amino acid (C) mutations at Heavy (H) and Light (L) chain genes are shown for each donor. Each dot represents one individual antibody V gene (n=69). The average number of nucleotide mutations overall is 27.7 within VH3-23 and 17.5 within VK1-5. The average number of amino acid mutations overall is 14.3 at VH3-23 and 10.6 at VK1-5. Figure 10– Neutralization and polyreactivity of anti-ZIKV antibodies. Related to Figure 4.

A- Dose-dependent neutralization of ZIKV RVPs by recombinant human monoclonal antibodies. Luciferase activity relative to no antibody control is determined in the presence of increasing antibody concentrations. Data are represented as mean ± SD. B- ZIKV neutralization by Z004 antibody assessed by PRNT assay. C- DENV1 neutralization by Z004 antibody measured by a flow cytometry-based assay. The number of infected cells was determined using the pan-flavivirus monoclonal antibody 4G2. Data are represented as mean ± SD. D- Z004 protects IFNAR1 ^-/- mice from ZIKV infection. Three independent experiments were performed as described in Fig.4D-F; results were pooled and presented in Fig.4. E- Low auto- and polyreactivity profile of Z004. ELISA measures Z004 binding over a range of concentrations against the following antigens: single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), lipopolysaccharides (LPS), insulin, and keyhole limpet hemocyanin (KLH). Figure 11– Treatment with Z004 antibody alone leads to the emergence of resistant ZIKV in rhesus macaques (Macaca mulatta).

(a) Macaques were administered Z004 (arrows) or remained untreated (black) one day before intravenous inoculation with 10 ⁵ PFU of ZIKV. Graph shows plasma viral RNA levels of ZIKV over time as determined by RT-qPCR. (b) Mutations emerging in macaques treated with Z004 alone. An alignment in the region of residues E393/K394 (in bold) is shown at the top (SEQ ID NOS 1061, 1070, 1062, and 1070, respectively, in order of appearance) and chromatograms of the PCR amplicons showing the mutations (indicated by arrows) are shown at the bottom. In macaque 6414, E393D and K394R are on separate viruses, as determined by sequencing of the cloned amplicon. (c) Footprint of the Z004–related antibody Z006 onto the EDIII of ZIKV. The E393/K394 residues are highlighted. (d) Impaired binding of Z004 to the EDIII escape mutants. ELISA demonstrates impaired binding of Z004 Fab to EDIIIE393D and EDIIIK394R. The positive control antibody Z015 recognizes an epitope that is independent of Z004. Data are represented as mean ± SD of triplicates and a representative of two experiments is shown.

See also Figure 5. Figure 12– Antibody Z021 neutralizes ZIKV in vitro and in mice.

(a) Z021 is effective against ZIKV. ZIKV neutralization was determined by measuring the ability of increasing concentrations of Z021 to reduce the number of plaques in a PRNT assay. Data are represented as mean ± SD of two independent experiments. (b) Z021 is effective against DENV1. DENV1 neutralization was assessed by measuring the number of 4G2 positive infected cells by flow cytometry. Data are represented as mean ± SD of triplicates and a representative of two experiments is shown. In (a) and (b) values are relative to control antibody 10-1074 and antibody Z004 is shown alongside for comparison ⁵ . (c-e) Z021 protects mice from ZIKV disease. (c) Ifnar1 ^-/- mice were treated with Z021 or control 10-1074 antibody 1 day before (d) or 1 day after (e) challenge with ZIKV in the footpad (f.p.). Mice were monitored for symptoms and survival. The graph indicates death or symptoms. Survival: p<0.0001 (pre-exposure) and p=0.0002 (post-exposure). Symptoms: p=0.0002 (pre- exposure) and p=0.0006 (post-exposure; Mantel-Cox test). Data represent two combined experiments. Figure 13– Antibodies Z021 and Z004 recognize distinct epitopes.

(a) Residues E393/K394 of ZIKV EDIII are dispensable for Z021 binding. Graphs show ELISA binding to ZIKV EDIII by increasing concentrations of antibody Z004 (left) or Z021 (right) after blocking with wild type EDIII or EDIII _E393A/K394A . (b) Residues E393/K394 are dispensable for ZIKV neutralization by Z021. Graphs show neutralization of ZIKV luciferase RVPs by Z021 and Z004 using wild type RVPs (left) or RVPs mutated at the Z004 binding site (E393A/K394A; right). Data are represented as mean ± SD of triplicates and a representative of two experiments is plotted. Values are relative to no antibody control. (c) The epitopes of Z004 and Z021 are overlapping. ZIKV EDIII antigen was immobilized with either Z021 IgG (left) or Z004 IgG (right) before detection by ELISA with Fragments antigen binding (Fab) of Z021 and Z004. The positive control Z015 Fab recognizes an epitope that is independent of both Z021 and Z004 ⁵ . Data are represented as mean ± SD from one experiment done in quadruplicate. Figure 14 - Comparison of Z021 and Z004 Fab binding to the ZIKV and DENV1 EDIII domain.

(a) Superimposition of Z021 Fab-ZIKV and Z021 Fab-DENV1. The E394 and K395 residues of ZIKV are highlighted. (b) Superimposition of Z021 Fab-DENV1 EDIII with Z004 Fab- DENV1 (PDB ID: 5VIC). The VHVL of Z021 Fab is rotated ~48º around an axis near CDRH2 compared to the Z004 V _H V _L bound to the same antigen. (c) DENV1 EDIII residues within 4Å of Z021 Fab, Z004 Fab, or both are highlighted on surface representations of the DENV1 EDIII structure. The E384/K385DENV1 motif is outlined. The two panels are related by a 90º rotation. Figure 15 - The combination of Z004 and Z021 protects ZIKV challenged macaques from viral escape.

Macaques were administered the combination of Z004 and Z021 or their Fc mutant version (Z004-GRLR and Z021-GRLR) one day before intravenous inoculation with high-dose (10 ⁵ PFU) of ZIKV. Graph shows plasma viral RNA levels of ZIKV over time as determined by RT-qPCR. No mutations were detected in the EDIII region of the emerging virus in the combination treated macaques. Figure 16 - The combination of Z004-GRLR and Z021-GRLR antibodies fully protects from subcutaneous challenge with 10 ³ PFU of ZIKV.

Macaques were co-administered Z004-GRLR and Z021-GRLR one day before infection. Graph shows plasma viral RNA levels of ZIKV over time, as determined by RT-qPCR. Figure 17 - ZIKV mutations in Ifnar1 ^-/- mice. Related to Figure 11.

Summary of the analysis of ZIKV EDIII sequences from infected mouse blood at the indicated time points. Empty cell is sequence not determined, grey cell is symptomatic mouse, wt is wild type EDIII sequence. The only identified mutation (K394R) was in a mouse treated with Z004. Figure 18 - Z021 neutralizes ZIKV RVPs corresponding to both the Asian/American and the African strain. Related to Figure 12,

Neutralization by Z004 is shown alongside for comparison. Data are represented as mean ± SD of triplicates. Figure 19 - Human IgG levels in macaque plasma over time. Related to Figure 15.

The levels of human IgG antibodies were determined by ELISA. The top panel displays human IgGs in individual macaques, the bottom panel shows the mean for each group.

Macaques were administered 15mg/kg of each of the antibodies on day -1. The mean peak antibody levels on the day of infection (day 0) were 334 ^g/ml in the Z004 + Z021 group and 326 ^g/ml in the Z004-GRLR + Z021-GRLR group. The antibody levels on day 15 were 32 ^g/ml in the Z004 + Z021 group and 34 ^g/ml in the Z004-GRLR + Z021-GRLR group, resulting in plasma half-lives of 4.4 days and 4.6 days, respectively. Figure 20 - Z004 with engineered modifications at the antibody Fc portion that prevent Fc-gamma receptor binding (GRLR mutation; ^25,26 ) and extend the half-life (LS mutation; ^27,28 ) prevents ADE and remains effective against ZIKV. Related to Figure 15. (a) ADE of Fc-gamma receptor bearing K562 cells is abrogated with Z004 antibodies bearing GRLR and GRLR/LS substitutions. Data are represented as mean ± SD of triplicates. Positive control (+) is wild type Z004 antibody (10 ng/ml). (b) Surface plasmon resonance (SPR) binding profile of Z004 bearing the LS and GRLR mutations alone or in combination. (c-d) Z004 antibodies bearing the LS and GRLR substitutions alone or in combination remain effective against ZIKV RVPs in vitro (c) or ZIKV in vivo (d). Figure 21 - Z021 with substitutions that prevent Fc-gamma receptor binding (GRLR) and extend the half-life (LS) prevents ADE and remains effective against ZIKV. Related to Figure 15.

(a) ADE is abrogated with Z021 antibodies bearing GRLR and GRLR/LS substitutions. Data are represented as mean ± SD of triplicates. Positive control (+) is wild type Z004 antibody (10 ng/ml). (b-c) Z021 antibodies bearing the LS and GRLR substitutions remain effective against ZIKV RVPs in vitro (b) or ZIKV in vivo (c). Figure 22 - Immunizing wild type mice with DENV1 EDIII before ZIKV EDIII enhances the mice neutralizing antibody response against ZIKV.

A- Sequential immunization with DENV1 followed by ZIKV EDIII proteins improves antibody titers to the ZEDIII lateral ridge. Competition ELISA with the biotinylated antibody Z004 was used to estimate the concentration of antibodies to the lateral ridge of ZIKV. * is p<0.05. B- Sequential immunization with DENV1 followed by ZIKV EDIII proteins induces higher neutralization in more mice. IgG was purified from mouse serum and assayed for neutralization using ZIKV RVPs. IC50 is in ^g/ml. DESCRIPTION OF INVENTION

Unless defined otherwise, 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 invention belongs. Every numerical range given throughout this specification includes its upper and lower values, as well as every narrower numerical range that falls within it, as if such narrower numerical ranges were all expressly written herein. This disclosure includes every nucleotide sequence described herein, and in the tables and figures, and all sequences that are complementary to them, RNA equivalents of DNA sequences, all amino acid sequences described herein, and all polynucleotide sequences encoding the amino acid sequences. Every antibody sequence and functional fragments of them are included. Polynucleotide and amino acid sequences having from 80-99% similarity, inclusive, and including ranges of numbers there between, with the sequences provided here are included in the invention. All of the amino acid sequences described herein can include amino acid substitutions, such as conservative substitutions, that do not adversely affect the function of the protein or polypeptide that comprises the amino acid sequences. It will be recognized that when reference herein is made to an“antibody” it does not necessarily mean a single antibody molecule. For example,“administering an antibody” includes administering a plurality of the same antibodies. Likewise, a composition comprising an“antibody” can comprise a plurality of the same antibodies. Those skilled in the art will recognize that representative sequences from specific ZIKV and DENV1 viruses are presented for use in vaccine formulations and diagnostic approaches, but other sequences from different strains of these viruses are encompassed by this disclosure. The disclosure includes polynucleotides encoding antigens and antibodies from which introns present in the genomic DNA have been removed, i.e., cDNA sequences and DNA sequences complementary thereto. For amino acid and polynucleotide sequences of this disclosure contiguous segments of the sequences are included, and can range from 2 amino acids, up to full-length viral protein sequences. Polynucleotide sequences encoding such segments are also included. The disclosure includes DNA and RNA sequences encoding the antibodies and virus peptides described herein for use in prophylactic and therapeutic approaches as protein or DNA and/or RNA vaccines, which may be formulated and/or delivered according to known approaches, given the benefit of this disclosure. From DNA sequences and amino acid sequences presented in the tables of this disclosure antibody complementarity determining region (CDR) sequences can be identified by using publicly available databases, such as IGBLAST (www.ncbi.nlm.nih.gov/igblast) using the germline database. The disclosure includes antibodies described herein, which are present in an in vitro complex with a ZIKV or a DENV1 protein. In certain approaches compositions and methods of this disclosure may be adapted for use in non-human animals that may be determined to be an actual or potential reservoir or vector for the Zika and/or dengue viruses. Thus, veterinary compositions and methods of administering them are included. From the examples and descriptions of this disclosure it will be apparent to those skilled in the art that the instant disclosure can be distinguished from studies that have examined anti- ZIKV antibodies developing in a small number of available individuals (Sapparapu et al., 2016; Stettler et al., 2016; Wang et al., 2016). In contrast, we screened sera from more than 400 donors from ZIKV epidemic areas of Mexico and Brazil to select high responders.

Serologic reactivity to ZIKV varied greatly among individuals, with neutralization potencies spanning over more than 2 logs. To better understand this activity we isolated 290 memory B cell antibodies from 6 individuals with high serum neutralizing activity. The sequencing experiments revealed the existence of expanded clones of memory B cells expressing E protein lateral ridge-specific ZIKV and DENV1 neutralizing VH3-23/VK1-5 antibodies in 4 of the 6 individuals. Three separate groups have cloned human anti-ZIKV E protein reactive antibodies before the present disclosure (Sapparapu et al., 2016; Stettler et al., 2016; Wang et al., 2016). In all they studied 8 individuals and documented 92 antibodies to the E protein. The great majority of these antibodies (79) were obtained by screening supernatants of Epstein-Barr virus transformed B lymphocytes for binding to ZIKV, and only a minority (15) were directed to the ZEDIII. Among all of these antibodies there was only a single expanded clone containing 3 related VH1-46/VK1-39 antibodies specific for a yet to be determined E epitope. These 3 antibodies were relatively poor neutralizers (3-257 ^g/ml)(Wang et al., 2016). There was also a single VH3-23/VK1-5 antibody that targeted the ZEDIII and neutralized ZIKV (ZIKV- 116), but this antibody is believed to be different than those of this disclosure because it failed to neutralize the African ZIKV strain (Sapparapu et al., 2016). Thus, there was no prior indication of a potent recurrent neutralizing response to ZIKV. We found a total of 69 individual VH3-23/VK1-5 memory B cells antibodies in 5 out of 6 individuals. In addition to recurring V gene segments, VH3-23/VK1-5 antibodies bear the same IGL J gene, and a limited set of IGH D and J genes. These antibodies are closely related and they are potent neutralizers with IC ₅₀ values ranging from 0.7-4.6 ng/ml. This variation in activity is likely due to somatic mutations, since predicted germline versions of the VH3- 23/VK1-5 antibodies bind to ZEDIII and neutralize the virus only weakly. Thus, and without intending to be constrained by any particular theory, it is considered that somatic mutations are required for optimal VH3-23/VK1-5 antibody neutralizing activity. Recurring antibodies that share the same IGV genes and the same molecular interactions with antigen have not been reported for ZIKV or other flaviviruses before the present disclosure, but they have been described in other viral infections including HIV-1 and influenza. Broadly neutralizing antibodies targeting the CD4 binding site of HIV-1 frequently utilize VH1-2 or VH1-46 genes (Scheid et al., 2011; West et al., 2012), and broadly neutralizing antibodies to Influenza utilize VH1-69 (Laursen and Wilson, 2013; Pappas et al., 2014; Sui et al., 2009; Throsby et al., 2008; Wrammert et al., 2011). However, in both HIV-1 and influenza, the VH genes can be paired with a collection of different VL genes, a finding that was explained by structural analysis showing that many of the essential contacts made by influenza and HIV-1 antibodies involve variable portions of the IGHV (Ekiert et al., 2009; Pappas et al., 2014; Scheid et al., 2011; Wrammert et al., 2011; Zhou et al., 2010). Although the Z004 and the related Z006 antibodies have CDRH3s and CDRL3s of different lengths they share a common mode of EDIII binding. Several shared sequence features may be important for this binding mode. The most suggestive of these is R96 _HC . This CDRH3 residue appears to derive from N region addition, thus the different VH3-23/VK1-5 clones do not share this residue due to shared germline genes. Examination of a large collection (n=44,270) of VH3-23-derived antibody sequences indicates that only 13% have R at position 100 (Rubelt et al., 2012). However, 68 of 69 of the sequenced VH3-23/VK1-5 clones contain R96. The clones also tend to conserve the germline residues forming the

Z004/Z006/EDIII common interactions: Y58HC, W32LC, Y91LC, and S93LC. Without intending to be bound by any particular interpretation, the requirement for conserved IGHV and IGLV genes in VH3-23/VK1-5 antibodies appears to be explained in part by interactions using germline residues. For the light chain, CDRL1 germline residue W32 _LC interacts with K394ZIKV. Few IGLV genes contain W32; the most common of these is VK1-5 (followed by VK1-12, but this gene is several-fold less common than VK1-5). For the heavy chain, residue Y58HC (present in the VH3-23 germline) makes a contact with EDIII residue 307 _ZIKV . Y58 _HC is present in ~50% of VH germlines, potentially explaining a portion of the restriction. Finally, VH3-23 is among the most frequently used VH genes as is VK1-5 (Arnaout et al., 2011; DeKosky et al., 2015). Therefore it is likely that naïve B cell precursors carrying DENV1 and ZIKV reactive VH3-23/VK1-5 antibodies would also be common in the pre-immune repertoire making this epitope a particularly attractive vaccine candidate. VH3-23/VK1-5 antibodies recognize and neutralize both DENV1 and ZIKV, suggesting that clones of VH3-23/VK1-5 producing B cells originally elicited in response to DENV1 were further expanded in response to ZIKV. This prime-boost, or original antigenic sin hypothesis, is supported by two observations. First, pre-existing antibodies to DENV1 EDIII are associated with a higher antibody response to ZEDIII. Second, at the population level, the introduction of ZIKV correlates with an increase in DENV1 EDIII-reactive antibodies at a time when DENV1 was not circulating. Although DENV1 and ZIKV only share 50% amino acid identity in EDIII, they are structurally very similar, particularly in the lateral ridge region that is recognized by VH3-23/VK1-5 (Fig.5). Thus, DENV1 EDIII reactive memory B cells have a significant probability of being cross-reactive to ZEDIII. A primary response to DENV1 would increase the frequency of these ZIKV cross-reactive memory B cells and thereby increase their likelihood of undergoing clonal expansion in response to ZIKV.

Consistent with this, memory B cells with VH3-23/VK1-5 antibodies represent close to half of all ZEDIII-specific B cell clones in 3 of the 6 individuals examined. Infection by DENV1 confers transient protection to infection by DENV2 (Sabin, 1950, 1952). Whether prior DENV1 infection also protects from ZIKV by cross-priming or in other cases enhances infection is unclear (Castanha et al., 2016; Dejnirattisai et al., 2016;

Priyamvada et al., 2016; Swanstrom et al., 2016; Wahala and Silva, 2011). However, the existence of human antibodies to DENV that cross-neutralize or enhance ZIKV in vitro indicates that protection by cross-priming is possible (Barba-Spaeth et al., 2016; Dejnirattisai et al., 2016; Harrison, 2016; Pierson and Graham, 2016; Priyamvada et al., 2016; Stettler et al., 2016; Swanstrom et al., 2016). ZIKV infection is asymptomatic in most people. Only 20% of ZIKV infected individuals develop symptoms, and in those cases the severity of the disease varies broadly (Miner and Diamond, 2017). Similarly, the spectrum and incidence of developmental sequelae in infants born to women infected with ZIKV during pregnancy differs within and across geographic areas with risk estimates that range from 6-42% (Brasil et al., 2016; Honein et al., 2017). Examples of this disclosure indicate a cellular and molecular explanation for how a history of DENV1 exposure could alter host responses and susceptibility to ZIKV. In embodiments, the disclosure provides an isolated or recombinant antibody that binds with specificity to a neutralizing epitope in the lateral ridge of Zika virus (ZIKV) envelope domain III (ZEDIII) protein, wherein the epitope comprises E393-K394 of the ZEDIII protein, and wherein the antibody optionally comprises a modification of the amino acid sequence, including but not limited to a modification of its constant region. Such antibodies can also bind with specificity to a neutralizing epitope of dengue 1 virus (DENV1) EDIII protein. Specific and non-limiting examples of antibodies are provided herein, along with amino acid sequences of pertinent parts of the antibodies, including heavy (H) and light (L) chain sequences. All combinations of H and L chains are included. In embodiments, a single antibody of this disclosure may comprise an H+L chain from one antibody, and an H+L chain from another antibody that is described below. In embodiments, the modifications are not coded for in any B cells obtained from an individual, and/or the antibodies are not produced by immune cells in an individual from which a biological sample from the individual is used at least in part to identify and/or generate and/or characterize the antibodies of this disclosure. In embodiments, antibodies provided by this disclosure can be made recombinantly, and can be expressed with a constant region of choice, which may be different from a constant region that was coded for in any sample from which the amino acid sequences of the antibodies were deduced. In certain approaches the disclosure provides one or more isolated or recombinant antibodies comprising a complementarity determining region 3 (CDR3) amino acid sequence selected from heavy chain and light chain CDR3 sequences in Table 1 and Table 2, and combinations of said heavy and light chain CDR3 amino acid sequences. In non-limiting embodiments the disclosure includes amino acid sequences encoded by VH3-23/VK1-5 human

immunoglobulin genes, but all of the H and L gene segments described herein and the proteins they encode are included in the invention. In certain embodiments, the antibodies contain one or more modifications, such as non- naturally occurring mutations, non-limiting examples of which are further described herein. In non-limiting examples, antibodies described herein can be modified according to various approaches that will be apparent to those skilled in the art, given the benefit of this disclosure. In certain approaches the Fc region of the antibodies can be changed, and may be of any isotype, including but not limited to any IgG type, or an IgA type, etc. Antibodies of this disclosure can be modified to improve certain biological properties of the antibody, e.g., to improve stability, to modify effector functions, to improve or prevent interaction with cell- mediated immunity and transfer across tissues (placenta, blood-brain barrier, blood-testes barrier), and for improved recycling, half-life and other effects, such as manufacturability and delivery. In embodiments, an antibody of this disclosure can be modified by using techniques known in the art, such as those described in Buchanan, et al., Engineering a therapeutic IgG molecule to address cysteinylation, aggregation and enhance thermal stability and expression mAbs 5:2, 255–262; March/April 2013, and in Zalevsky J. et al., (2010) Nature

Biotechnology, Vol.28, No.2, p157-159, and Ko, S-Y, et al., (2014) Nature, Vol.514, p642- 647, and Horton, H. et al., Cancer Res 2008; 68: (19), October 1, 2008, from which the descriptions are incorporated herein by reference. In certain embodiments an antibody modification increases in vivo half-life of the antibody (e.g. LS mutations), or alters the ability of the antibody to bind to Fc receptors (e.g. GRLR mutations), or alters the ability to cross the placenta or to cross the blood-brain barrier or to cross the blood-testes barrier. In embodiments bi-specific antibodies are provided by modifying and combining segments of antibodies as described herein, such as by combining heavy and light chain pairs from distinct antibodies into a single antibody. Suitable methods of making bispecific antibodies are known in the art, such as in Kontermann, E. et al., Bispecific antibodies, Drug Discovery Today, Volume 20, Issue 7, July 2015, Pages 838-847, the description of which is

incorporated herein by reference. In embodiments, any antibody described herein comprises a modified heavy chain, a modified light chain, a modified constant region, or a combination thereof, thus rendering them distinct from antibodies produced by humans. In embodiments, the modification is made in a hypervariable region, and/or in a framework region (FR). In certain embodiments an antibody modification increases in vivo half-life of the antibody and/or alters the ability of the antibody to bind to Fc receptors. In embodiments, the mutations comprise LS or GRLR mutations. In certain embodiments an antibody modification increases in vivo half-life of the antibody by way of LS mutations, or alters the ability of the antibody to bind to Fc receptors by way of GRLR mutations. In embodiments, the mutation(s) can thus comprise a change of G to R, L to R, M to L, or N to S, or any combination thereof. In embodiments, mutations to an antibody described herein, including but not limited to the antibodies described below as Z004 and Z021, comprise modifications relative to the antibodies originally produced in humans. Such modifications include but are not necessarily limited to the heavy chain of Z004, which can comprise G241R and/or L333R mutations to prevent binding to Fc gamma receptors, and/or M433L/N439S mutations to increase the antibody half-life. In an embodiment, a Z004 IgG1 heavy chain comprises or consists of a contiguous segment or the entire sequence:

PG (SEQ ID NO: 15). In this SEQ ID NO: 15 the variable sequence is bolded, and the remaining sequence comprises Fc sequence which is shown with the G241R and/or L333R mutations to prevent binding to Fc gamma receptors and M433L/N439S mutations to increase the antibody half-life in bold and italics. A C-terminal lysine was removed to reduce micro-heterogeneity (removed lysine not shown). In an embodiment, a Z004 light chain comprises or consists of a contiguous segment or the entire sequence: . . In an embodiment, a Z021 heavy chain includes an IgG1, with modifications that can include G237R/L329R mutations to prevent binding to Fc gamma receptors, M429L/N435S mutations to increase the antibody half-life, and a C-terminal lysine removed to reduce micro-heterogeneity. In an embodiment, a Z021 heavy chain comprises or consists of a contiguous segment or the entire sequence:

: . n s : , e var a e sequence s o e , an e rema n ng sequence comprises Fc sequence which is shown with the G237R/L329R mutations to prevent binding to Fc gamma receptors and M429L/N435S mutations to increase the antibody half-life in bold and italics. A C-terminal lysine was removed to reduce micro- heterogeneity (removed lysine not shown). In an embodiment, the Z021 heavy chain sequence comprises a C50 modification, which may reduce unwanted disulfide bond formation. Thus, in one embodiment, the disclosure comprises a Z021 heavy chain of SEQ ID NO: 17, wherein the C50 is changed, such as to a V, but other amino acid substitutions can also be made provided they do not adversely affect affinity of the antibody for its epitope and/or the antibody’s ability to neutralize ZIKV and/or DENV1. In an embodiment, a Z021 light chain comprises or consists of a contiguous segment or the entire sequence:

Similar mutations can be made in any antibody of this disclosure. In embodiments, antibodies of this disclosure have variable regions that are described herein, and may comprise or consist of any of these sequences, and may include sequences that have from 80-99% similarity, inclusive, and including ranges of numbers there between, with the sequences expressly disclosed herein, provided antibodies that have differing sequences retain the same or similar binding affinity as an antibody with an unmodified sequence. In embodiments, the sequences are at least 95%, 96%, 97%, 98% or 99% similar to an expressly disclosed sequence herein. Those skilled in the art will recognize that antibodies of this disclosure are from time to time described using nomenclature that includes a“Z” and a number, and that these are correlated with nomenclature in the tables of this disclosure, such as“MEX” or“BRA” followed by an alphanumeric designation. Those skilled in the art will be able to readily attribute the particular Z number with the MEX and BRA numbers in view of the description and tables presented herein. For example, Z004 is also referred to herein as MEX18_89 and Z021 is referred to as MEX84_p4-23. In non-limiting embodiments the disclosure provides antibodies with a CDR3 heavy chain sequence and a CDR3 light chain sequence selected from amino acid sequences in Table 1 or Table 2 having one of the following designations:

Z001 (MEX18_21), Z006 (MEX105_42), Z010 (MEX105_88), Z012 (MEX105_57), Z014 (MEX18_91),Z015 (MEX84_p2-44), Z018 (MEX84_p2-45) , Z024 (MEX84_p4-12) , Z028 (MEX84_p4-53), Z031 (BRA112_46), Z035 (BRA112_71), Z037 (BRA112_57), Z038 (BRA12_2), Z039 (BRA12_21), Z041 (BRA138_57), Z042 (BRA138_17), Z043 (BRA138_15), Z002 (MEX18_27), Z003 (MEX18_58), Z005 (MEX18_13), Z007 (MEX105_50), Z008 (MEX105_60), Z009 (MEX105_64), Z011 (MEX105_15), Z013 (MEX18_84), Z016 (MEX84_p2-55), Z017 (MEX84_p2-58), Z019 (MEX84_p4-16), Z020 (MEX84_p4-30), Z032 (BRA112_24), Z034 (BRA112_09), Z036 (BRA112_91), Z040 (BRA12_81), Z044 (BRA138_46), Z045 (BRA12_08), Z048 (BRA112_23), Z050

(BRA138_28), Z051 (BRA138_59), Z052 (BRA138_62), Z053 (BRA138_65), Z054 (BRA138_94), Z055 (MEX84_p4-61), Z056 (MEX84_p2-94), Z057 (MEX84_p4-54), Z058 (MEX84_p2-53), Z059 (MEX84_p4-34), Z060 (BRA12_58), Z061 (BRA112_36), and Z062 (BRA112_70). In embodiments an antibody of this disclosure comprises a CDR1 and/or a CDR2 amino acid sequence comprised by IgH and/or IgL amino acid sequences of Table 1. Antibodies comprising the following list of variable sequences have been expressed and characterized for at least binding affinity, and as otherwise described herein. Bispecific antibodies comprising distinct heavy and light chain pairs from distinct antibodies listed below are included in the disclosure. In the following sequences, the CDR1 is italicized, the CDR2 is bolded and the CDR3 is italicized and bolded. All of these CDR1, CDR2 and CDR3 sequences are included in this disclosure as separate sequences, apart from the remainder of the disclosed variable/framework sequences that are also disclosed in this list:

The following Table A table provides a summary of neutralizing and binding properties that 20 pertain to the immediately forgoing 32 antibodies.

n.d. = not determined

n.n. = non-neutralizing In embodiments the disclosure provides neutralizing antibodies. The term“neutralizing antibody” refers to an antibody or a plurality of antibodies that inhibits, reduces or completely prevents viral infection. Whether any particular antibody is a neutralizing antibody can be determined by in vitro assays described in the examples below, and as is otherwise known in the art. Antibodies of this disclosure can be provided as intact immunoglobulins, or as fragments of immunoglobulins, including but not necessarily limited to antigen-binding (Fab) fragments, Fab' fragments, (Fab') ₂ fragments, Fd (N-terminal part of the heavy chain) fragments, Fv fragments (the two variable domains), dAb fragments, single domain fragments or single monomeric variable antibody domains, isolated CDR regions, single-chain variable fragment (scFv), and other antibody fragments that retain virus-binding capability and preferably virus neutralizing activity as further described below. Antibodies and peptides or mRNA or DNA vaccines of this disclosure can be provided in pharmaceutical formulations. It is considered that administering a DNA or RNA vaccine encoding any protein (including peptides and polypeptides) antigen described herein is also a method of delivering such peptide antigens to an individual, provided the DNA and RNA are expressed in the individual. Methods of delivering DNA and RNAs encoding proteins are known in the art and can be adapted to deliver the protein antigens, given the benefit of the present disclosure. Similarly, the antibodies of this disclosure can be administered as DNA molecules encoding for such antibodies using any suitable expression vector(s), or as RNA molecules encoding the antibodies. Pharmaceutical formulations containing antibodies or viral antigens can be prepared by mixing them with pharmaceutically acceptable carriers. Pharmaceutically acceptable carriers include solvents, dispersion media, isotonic agents and the like. The carrier can be liquid, semi-solid, e.g. pastes, or solid carriers. Examples of carriers include water, saline solutions or other buffers (such as phosphate, citrate buffers), oil, alcohol, proteins (such as serum albumin, gelatin), carbohydrates (such as monosaccharides, disaccharides, and other carbohydrates including glucose, sucrose, trehalose, mannose, mannitol, sorbitol or dextrins), gel, lipids, liposomes, resins, porous matrices, binders, fillers, coatings, stabilizers, preservatives, liposomes, antioxidants, chelating agents such as EDTA; salt forming counter- ions such as sodium; non-ionic surfactants such as TWEEN, PLURONICS or polyethylene glycol (PEG), or combinations thereof. In embodiments, a pharmaceutical/vaccine formulation exhibits an improved activity relative to a control, such as antibodies that are delivered without adding additional agents, or a particular added agent improves the activity of the antibodies. The formulation can contain more than one antibody type or antigen, and thus mixtures of antibodies, and mixtures of antigens, and combinations thereof as described herein can be included. These components can be combined with a carrier in any suitable manner, e.g., by admixture, solution, suspension, emulsification, encapsulation, absorption and the like, and can be made in formulations such as tablets, capsules, powder (including lyophilized powder), syrup, suspensions that are suitable for injections, ingestions, infusion, or the like. Sustained-release preparations can also be prepared. The antibodies and vaccine components of this disclosure are employed for the treatment and/or prevention of ZIKV and/or DENV1 infection in a subject, as well as for inhibition and/or prevention of their transmission from one individual to another, and in particular in the case of transmission of Zika virus from a mother to a fetus, or from one partner to another during sexual intercourse wherein transmission between the individuals can take place.

Accordingly, while embodiments of the disclosure are appropriate for use with any individual who is at risk of, is suspected of having, or has been diagnosed with a Zika virus infection, or a dengue 1 virus infection (or other related viruses), in particular embodiments of the disclosure comprise administering a composition of this invention to a female who is known to be pregnant, intending to become pregnant, suspected of being pregnant, or is engaging in sexual activity which raises a likelihood of pregnancy. Administration soon after delivery is also included, and direct administration to a fetus or to a newborn is also included. The term "treatment" of viral infection refers to effective inhibition of the viral infection so as to delay the onset, slow down the progression, reduce viral load, and/or ameliorate the symptoms caused by the infection. The term "prevention" of viral infection means the onset of the infection is delayed, and/or the incidence or likelihood of contracting the infection is reduced or eliminated. The term "prevention" of viral transmission means the incidence or likelihood of a viral infection being transmitted from one individual to another (e.g., from a ZIKV-positive woman to her child during pregnancy, labor or delivery, or breastfeeding; or between sexual partners) is reduced or eliminated. In embodiments, to treat and/or prevent viral infection, a therapeutic amount of an antibody or antigen vaccine disclosed herein is administered to a subject in need. The term

"therapeutically effective amount" means the dose required to effect an inhibition of infection so as to treat and/or prevent the infection. In embodiments, the disclosure comprises co-administration of a combination of antibodies. In an embodiment, administration of a combination of distinct antibodies suppresses formation of viruses that are resistant to the effects of either one of the antibodies alone. In embodiments, a combination of at least two antibodies includes at least two antibodies that each recognize distinct epitopes on Zika Envelope Domain III (EDIII), non-limiting examples of which are described below. In one non-limiting example, a combination of antibodies described herein as Z004 and Z021 is protective and suppresses emergence of resistant variants and/or fully suppresses virus emergence altogether. Thus, in embodiments, such a co-administration of a combination of at least two distinct antibodies described herein suppresses formation of variant Zika viruses that are resistant to treatment and/or prevents infection. In embodiments, the Z004 and Z021 antibodies can be administered concurrently or sequentially. The dosage of an antibody or antigen vaccine depends on the disease state and other clinical factors, such as weight and condition of the subject, the subject's response to the therapy, the type of formulations and the route of administration. The precise dosage to be therapeutically effective and non-detrimental can be determined by those skilled in the art. As a general rule, a suitable dose of an antibody for the administration to adult humans parenterally is in the range of about 0.1 to 20 mg/kg of patient body weight per day, once a week, or even once a month, with the typical initial range used being in the range of about 2 to 10 mg/kg. Since the antibodies will eventually be cleared from the bloodstream, re-administration may be required. Alternatively, implantation or injection of the antibodies provided in a controlled release matrix can be employed. The antibodies and/or antigen vaccines (as proteins or polynucleotides encoding the proteins) can be administered to the subject by standard routes, including oral, transdermal, and parenteral (e.g., intravenous, intraperitoneal, intradermal, subcutaneous or intramuscular). In addition, the antibodies and/or the antigen vaccines can be introduced into the body, by injection or by surgical implantation or attachment such that a significant amount of an antibody or the vaccine is able to enter blood stream in a controlled release fashion. In certain embodiments antibodies described herein are incorporated into one or more prophylactic compositions or devices to, for instance, neutralize a virus before it enters cells of the recipient’s body. For example, in certain embodiments a composition and/or device comprises a polymeric matrix that may be formed as a gel, and comprises at least one of hydrophilic polymers, hydrophobic polymers, poly(acrylic acids) (PAA), poly(lactic acids) (PLA), carageenans, polystyrene sulfonate, polyamides, polyethylene oxides, cellulose, poly(vinylpyrrolidone) (PVP), poly(vinyl alcohol) (PVA), chitosan, poly(ethylacrylate), methylmethacrylate, chlorotrimethyl ammonium methylmethacrylate, hydroxyapatite, pectin, porcine gastric mucin, poly(sebacic acid) (PSA), hydroxypropyl methylcellulose (HPMC), cellulose acetate phthalate (CAP), magnesium stearate (MS), polyethylene glycol, gum-based polymers and variants thereof, poly (D,L)-lactide (PDLL), polyvinyl acetate and povidone, carboxypolymethylene, and derivatives thereof. In certain aspects the disclosure comprises including antibodies in micro- or nano-particles formed from any suitable biocompatible material, including but not necessarily limited to poly(lactic-co-glycolic acid) (PLGA).

Liposomal and microsomal compositions are also included. In certain aspects a gel of this disclosure comprises a carbomer, methylparaben, propylparaben, propylene glycol, sodium carboxymethylcellulose, sorbic acid, dimethicone, a sorbitol solution, or a combination thereof. In embodiments a gel of this disclosure comprises one or a combination of benzoic acid, BHA, mineral oil, peglicol 5 oleate, pegoxol 7 stearate, and purified water, and can include any combination of these compositions. The disclosure includes devices and kits that relate to inserting into vagina an intravaginal medicated device comprising antibodies of the disclosure. In certain embodiments the disclosure provides a vaginal tampon, vaginal ring, vaginal cup, vaginal tablet, vaginal sponge, a vaginal bioadhesive tablet, a vaginal lubricant, a condom, or a modified female hygiene or other vaginal health care product, such as prescription and over-the-counter antifungal products that treat and/or cure vaginal yeast infections, or bacterial vaginosis, but that have been adapted to include antibodies of this disclosure. Applicators that are provided with female hygiene or vaginal health care products can be adapted for intravaginal administration of the antibodies. In certain aspects a method of the invention comprises intravaginal insertion of a medicated device antibodies of this disclosure. The delivery composition can be formulated to adhere to and act directly on the vaginal epithelium and/or mucosa. In certain aspects a composition and/or device of this may comprise one or more additional agents known to be suitable for treatment of viral, or other bacterial or parasitic infections. Such compositions include but are not limited to antibiotics and previously known anti-viral agents, and chemical compounds that act as biocides or antiseptic agents, such as benzalkonium chloride. Additional agents include but are not limited to soothing

compositions that contain, for example anti-irritant and/or anti-inflammatory agents, such as hydrocortisone or related compounds, or emollients, or anti-hemorrhagic or hemostatic or anti-allergic agents. In embodiments a composition and/or device of this disclosure comprises a contraceptive agent, such as a spermicide or a hormonal or non-hormonal contraceptive drug that is combined with one or more antibodies of this disclosure. Antibodies of this disclosure can be produced by utilizing techniques available to those skilled in the art. For example, one or distinct DNA molecules encoding one or both of the H and L chains of the antibodies can be constructed based on the coding sequence using standard molecular cloning techniques. The resulting DNAs can be placed into a variety of suitable expression vectors known in the art, which are then transfected into host cells, which are preferably human cells cultured in vitro, but may include E. coli or yeast cells, simian COS cells, Chinese Hamster Ovary (CHO) cells, and human embryonic kidney 293 cells, etc. In certain approaches the invention includes neutralizing antibodies as discussed above, and methods of stimulating the production of such antibodies. Antibodies can be produced from a single, or separate expression vectors, including but not limited to separate vectors for heavy and light chains, and may include separate vectors for kappa and lambda light chains as apporpriate. The antibodies may be neutralizing with respect to infectivity by ZIKV, DENV1, and combinations thereof. Neutralization may extend beyond ZIKV and DENV1 to include other viruses of the same genus (such as but not limited to DENV2, DENV3, DENV4, YFV, WNV), given that the EDIII of these viruses shares structural similarities. In this regard, the present disclosure demonstrates that at least some of the antibodies described herein bind to DENV2-4, yellow fever virus (YFV) and West Nile virus (WNV) (see e.g. Fig.3C). In embodiments antibodies are neutralizing with respect to Asian/American strains of ZIKV, and also to African ZIKV, wherein the African ZIKV comprises an amino acid difference in its EDIII protein relative to the ZIKV Asian/American EDIII protein, and wherein the difference is optionally at position 393 in the African ZIKV EDIII protein, and wherein the difference at position 393 is optionally D393 instead of E393. In certain approaches the disclosure includes methods for prophylaxis and/or therapy for a viral infection(s) comprising administering to an individual a vaccine formulation comprising antibodies and/or viral antigens described herein. The compositions can be administered to any individual in need thereof, wherein the individual is infected with or is at risk of being infected with Zika virus and/or dengue 1 virus. In one approach, administration of a vaccine comprising and/or encoding Zika polypeptides described herein is preceded by administering to the individual a composition comprising a DENV1 antigen, which without intending to be bound by any particular theory is believed to be able at least in some instances to enhance protection against Zika virus. In certain embodiments the disclosure provides for consecutive or concurrent administration of ZIKV and DENV1 antigens, as well as other EDIII-derived antigens from other structurally similar viruses, including but not limited to DENV2-4, YFV, and WNV. In connection with this, it is contemplated that administering an antigen described herein, or a structurally similar antigen, may provide for stimulating production and/or proliferation of B lymphocytes that express a VH3-23/VK1-5 gene combination, which without intending to be bound by any particular theory, may provide for enhanced neutralizing antibodies against ZIKV, DENV1 and other related viruses. An aspect of the disclosure is illustrated in Figure 22. Data summarized in Figure 22 show results of immunizing mice using the EDIII of flaviviruses as the immunogen. The antibody response to the EDIII lateral ridge region, which as discussed above is the neutralizing epitope recognized by antibody Z004, is enhanced if the immunization with the ZIKV EDIII is preceded by priming with the EDIII of DENV1 (Panel A). Moreover, this regimen results in antibodies with higher neutralization capacity (Panel B). This result is consistent with the observation that the lateral ridge represents a shared neutralizing epitope for both ZIKV and DENV1, and that individuals exposed to DENV1 are more likely to become high responders to ZIKV. In certain implementations the invention includes antigens and segments thereof for use in vaccine formulations and diagnostic approaches. In non-limiting examples the ZEDIII polypeptide for use as antigen in vaccination comprises or consists of all or a contiguous or non-contiguous segment of the ZIKV EDIII sequence: i)

VSYSLCTAAFTFTKIPAETLHGTVTVEVQYAGTDGPCKVPAQMAVDMQTLTPVGRLI TANPVITESTENSKMMLELDPPFGDSYIVIGVGEKKITHHWHRS (SEQ ID NO: 117) (ZIKV E protein residues 303-403); and/or comprises or consists of all or a contiguous or non-contiguous segments of the DENV1 EDIII sequence: ii)

MSYVMCTGSFKLEKEVAETQHGTVLVQVKYEGTDAPCKIPFSSQDEKGVTQNGRLI TANPIVTDKEKPVNIEAEPPFGESYIVVGAGEKALKLSWFKK (SEQ ID NO: 118) (DENV1 E protein residues 297-394), or sequences having from 80-99% identity with the sequence of i) and/or ii). In embodiments a ZEDIII polypeptide of this disclosure optionally comprises at least one contiguous segment of ZEDIII comprising amino acids 305-311, 333-336, or 350-352 (and combinations thereof), and/or the segment optionally comprises one or more of ZEDIII amino acids L307, S306, T309, K394, A311, E393, T335, G334, A310, and D336, and/or the polypeptide comprises a segment of the DENV1 EDIII that includes an epitope that comprises amino acids M301, V300, T303, E384, T329, K385, S305, E327, G328, D330 DENV1 EDIII protein. In certain approaches the disclosure includes vaccinating an individual using a composition described herein, and determining the presence, absence, and/or an amount of neutralizing antibodies produced in response to the vaccination. Thus, methods of determining and monitoring efficacy of a vaccination at least in terms of neutralizing antibody production are included. Determination of the neutralizing antibodies can be performed using any suitable approach, one of which includes a competitive ELISA assay as described herein. In an embodiment, subsequent to determining an absence of neutralizing antibodies, and/or an amount of neutralizing antibodies below a suitable reference value, the invention includes administering a composition disclosed herein to the individual. Subsequent administrations and measurements can be made to track the treatment efficacy and make further adjustments to treatment accordingly. In one embodiment the presence, absence and/or amount of ZIKV and/or DENV1 neutralizing antibodies is determined using a biological sample from a pregnant human female, and the determination of the antibodies is used in estimating risk of fetal complications, including but not necessarily a risk of the fetus developing microcephaly. In one approach, determining an absence of neutralizing antibodies, and/or an amount of neutralizing antibodies below a suitable reference value for a pregnant female is followed by administering a composition described herein for the purpose of inhibiting development of the fetal complications. Antibodies and proteins of this disclosure can be detectably labeled and/or attached to a substrate. Any substrate and detectable label conventionally used in immunological assays and/or devices is included. In embodiments the substrate comprises biotin, or a similar agent that binds specifically with another binding partner to facilitate immobilization and/or detection and/or quantification of antibodies and/or viral proteins. In embodiments the disclosure comprises immunological assays to, for example, characterize serologic activity against ZIKV or DENV1. In embodiments any type of enzyme-linked immunosorbent (ELISA) assay can be used, and can be performed using polypeptides and/or antibodies of this disclosure for diagnostic purposes, and can include direct, indirect, and competitive ELISA assays, and adaptations thereof that will be apparent to those skilled in the art given the benefit of this disclosure. In embodiments the disclosure provides for a competition ELISA using, for example, assay plates coated with any ZEDII protein described herein. Upon exposure of a patient sample, such as a blood or serum sample, patient antibodies to the lateral ridge (LR) epitope present on the ZEDII protein (if such patient antibodies are present) will bind to the ZEDII protein. Taking a labeled Z004 antibody as a non-limiting example of a detecting antibody, the presence in serum of antibodies to the LR-epitope will block binding of labeled Z004, whereas absence of (or less) patient antibodies to the LR-epitope will allow binding of labeled Z004, enabling detection. The concentration of Z004 blocking antibodies can then extrapolated from a standard curve. In another embodiment an ELISA is conducted after serum blocking is performed. To perform such an assay, patient serum dilutions are incubated (‘blocked’) with saturating amounts of either wild type ZEDIII protein or with ZEDIII protein mutated as described herein, such as by alanine at the E393 and K394 residues. (Alternatively, DENV1 proteins can be adapted for similar use, and can include, for example, using DENV1 EDIII protein mutated at the E384 and/or K385 residues). Next, the remaining IgG binding to wild type ZEDIII is measured by ELISA and the BT ₅₀ values (= 50% of maximal binding titer, binding titer 50) for the samples blocked with ZEDIII wild type or with ZEDIII mutant proteins are determined. The shift in binding activity between the two blocking can be represented graphically as the ^BT ₅₀ and is a measure of the amount of LR-epitope specific antibodies in the patient sample. Any diagnostic result described herein can be compared to any suitable control. Further, any diagnostic result can be fixed in a tangible medium of expression and communicated to a health care provider, or any other recipient. In one aspect the disclosure comprises diagnosing an individual as infected with ZIKV and/or DENV1 and administering a composition of this invention to the individual. In certain embodiments the disclosure includes one or more recombinant expression vectors encoding H and L chains of an antibody of this disclosure, cells and cell cultures comprising the expression vectors, methods comprising culturing such cells and separating antibodies from the cell culture, the cell culture media that comprises the antibodies, antibodies that are separated from the cell culture, and kits comprising the expression vectors encoding an antibody and/or a polypeptide of this disclosure. Products containing the antibodies and/or the polypeptides are provided, wherein the antibodies and/or the polypeptides are provided as a pharmaceutical formulation contained in one or more sealed containers, which may be sterile and arranged in any manner by which such agents would be suitable for administration to a human or non-human subject. The products / kits may further comprise one or more articles for use in administering the compositions. The following Examples are intended to illustrate but not limit the invention. Example 1

Serologic Responses to ZIKV in Brazil and Mexico

Individuals infected with pathogens display a spectrum of antibody responses ranging from low levels of non-neutralizing antibodies to high titers of neutralizing antibodies. To determine whether a population infected with ZIKV also displays a range of antibody responses we screened 405 individuals living in ZIKV epidemic areas for serum IgG capable of binding to ZIKV E Domain III (ZEDIII, Fig.1A). Nearly three hundred sera were obtained in November 2015, shortly after ZIKV was introduced in Salvador, Brazil, from participants who were enrolled in a prospective study in 2013 from Pau da Lima, an urban slum community within the city (Cardoso et al., 2015; Felzemburgh et al., 2014; Hagan et al., 2016). An additional 108 sera were from Santa Maria Mixtequilla, a rural town in Oaxaca, Mexico. ZIKV infections were documented by PCR in Santa Maria Mixtequilla at the time of sample collection in April of 2016. Dengue virus (DENV) is endemic at both sites. Sera obtained from the Pau da Lima cohort in 2010 following a DENV outbreak, but before the introduction of ZIKV into Brazil, served as non- ZIKV flavivirus-exposed control for background reactivity against ZIKV (Silva et al., 2016). ZIKV introduction was associated with a broad distribution of serologic reactivity against ZEDIII in both Brazilian and Mexican samples by ELISA (Fig.1A). To determine whether serologic reactivity to ZEDIII is associated with ZIKV neutralizing activity, we assessed the top 31 sera (black symbols in Fig.1A) for neutralization of luciferase-expressing reporter viral particles (RVP) bearing ZIKV structural proteins (see Methods; Fig.1B). Neutralizing titers, expressed as the reciprocal of the dilution resulting in a 50% reduction of the luciferase signal achieved in the absence of serum (NT50), varied by over 2 logs indicating a broad range of humoral immune responses to ZIKV (Fig.1B). Human Monoclonal Antibodies to ZIKV

To further characterize the antibody response in 6 individuals with high neutralizing titers, 3 from each cohort, we used fluorescently-labeled ZEDIII to identify and purify single memory B cells in the peripheral blood (Fig.2A). ZEDIII-specific memory B cells were found at frequencies ranging from 0.13– 1.98% of all circulating IgG ⁺ memory B cells (Fig.2A, see Methods). Although the sample size is limited, the frequency of ZEDIII-specific memory B cells did not appear to correlate with either ZEDIII binding or neutralizing activity (Fig.1). We conclude that there is significant variability in the frequency of ZEDIII-specific memory B cells in individuals that show serum ZIKV neutralizing activity. Antibody heavy (IGH) and light (IGL) chain genes were amplified from single purified ZEDIII binding B cells by RT-PCR and sequenced (Scheid et al., 2009; von Boehmer et al., 2016). Overall, 290 antibodies were identified from the 6 individuals. Nearly one half of all of the antibodies (133) were found in expanded clones that shared the same IGH and IGL variable (IGVH and IGVL) gene segments, and the remaining half were unique (Fig.2B and Tables 1 and 2). Memory B cells expressing antibodies composed of VH3-23 paired with VK1-5 were found in 5 out of the 6 individuals assayed (Fig.2B, and Fig.8). Moreover, VH3-23/VK1-5 was present as an expanded clone in 4 individuals, and was the largest expanded clone in 3 out of the 6 individuals. The sequence of the VH3-23/VK1-5 antibodies in the expanded clones was further limited in that the VK1-5 gene segment was always recombined with JK1 (Fig.2C). In addition to VH3-23/VK1-5 clones we also found expanded clones of memory B cells expressing antibodies composed of VH3-23 paired with other IGL genes (VH3-23/VK1-27, VH3-23/VK3-11 and VH3-23/VK3-20; Fig.2B). Of the 6 individuals examined, only BRA 138, who exhibited the lowest level of neutralizing activity, did not have any detectable memory B cells expressing VH3-23/VK1-5 antibodies. We conclude that individuals with high serologic neutralizing titers to ZIKV in geographically distinct outbreak areas frequently show clonally expanded ZEDIII-specific memory B cells that express VH3-23/VK1-5 antibodies. Cross-reactivity with Other Flaviviruses

Nineteen representative antibodies obtained from expanded memory B cell clones from the 6 individuals were expressed for further testing. This antibody panel included 8 different VH3- 23/VK1-5 antibodies from 5 separate volunteers. Antibody binding activity to ZEDIII was measured by ELISA, and found to vary broadly even among the closely related VH3- 23/VK1-5 antibodies, with EC ₅₀ values ranging from 20 to >4000 ng/ml (Figs.3A, 3B, and 9A). Like other human antibodies derived from memory B cells, anti-ZEDIII antibodies showed somatic mutations. For example, the number of IGH V gene mutations in the VH3- 23/VK1-5 clones ranged from 12-40 nucleotides (average = 27.7, Figure 9B), which is far lower than that seen in antibodies during chronic HIV-1 infection (Escolano et al., 2017). Nevertheless, the mutations in anti-ZEDIII antibodies are essential to the binding activity of the antibodies since reversion of the mutations to the predicted germline sequence impaired binding to the antigen (Fig.3B). To determine whether the antibodies cloned from our cohorts cross-react to the EDIII proteins of other flaviviruses, we screened for binding to the four DENV serotypes (DENV1- 4), YFV (Asibi and 17D strains), and WNV. We observed 5 different patterns of cross- reactivity with other flaviviruses (Fig.3C). All 8 of the VH3-23/VK1-5 antibodies tested cross-reacted with DENV1, but not with the other flaviviruses in our panel (Figs.3C and 3D). Other antibodies showed singular cross-reactivity to WNV, or broader reactivity to DENV1- 4, or YF and WNV, and some antibodies were uniquely specific for ZIKV (Fig.3C). Similar to ZIKV, mutations in the VH3-23/VK1-5 antibodies were required for optimal binding to DENV1 EDIII since reversion to the predicted germline sequence impaired binding to the DENV1 antigen (Fig.3D). We conclude that anti-ZEDIII VH3-23/VK1-5 antibodies cross- react with DENV1 but not with other flaviviruses. Neutralizing Activity in vitro and in vivo

To determine whether the anti-ZEDIII antibodies neutralize ZIKV in vitro we measured their neutralizing activity in the ZIKV luciferase RVP assay described above. Neutralizing activity varied among the different antibodies ranging from sub-nanogram 50% inhibitory

concentrations (IC ₅₀ ) to non-neutralizing (Figs.4A, 4B and 10A). The most potent antibody, Z004, a member of one of the VH3-23/VK1-5 clones, displayed an IC50 of 0.7 ng/ml (Figs. 4A, 4B). Similar results were obtained by plaque reduction neutralization test (PRNT) using a Puerto Rican strain of ZIKV (IC ₅₀ of 2.2 ng/ml, Fig.10B). All of the other VH3-23/VK1-5 antibodies tested were also potent neutralizers of ZIKV with IC50 values ranging from 0.7-4.6 ng/ml (Fig.4A). Z004 is a member of the VH3-23/VK1-5 family that cross-reacts with DENV1. To determine whether Z004 also neutralizes DENV1, we measured its neutralizing activity against DENV1 luciferase RVPs and by flow cytometry using authentic DENV1. We found that Z004 is a potent neutralizer of DENV1 in both assays (IC ₅₀ =1.6 ng/ml by luciferase assay, and

IC50=16.4 ng/ml by flow cytometry; Fig.4C and 10C). Thus, the VH3-23/VK1-5 antibody Z004 binds and neutralizes both ZIKV and DENV1. To determine whether VH3-23/VK1-5 antibodies also neutralize ZIKV in vivo, we passively transferred Z004 to IFNAR1 ^-/- mice one day before or one day after ZIKV infection (Fig. 4D). In 3 independent pre-exposure experiments, with a total of 14 mice infected with ZIKV in the presence of control antibody, we found that 93% developed clinical symptoms and 79% succumbed to infection. In contrast, pre-exposure prophylaxis with Z004 resulted in a significant reduction in disease symptoms and mortality. Only 12.5% of the Z004 group developed clinical symptoms and none died (p<0.0001 for both disease and survival; Figs.4E and 10D). Similar results were also obtained when the antibody was administered one day after infection (p<0.0001 for symptoms, p=0.0027 for survival; Figs.4F and 10D). We conclude that Z004 was protective and significantly reduced both symptoms and mortality when administered either before or after infection. Z004 also displayed a suitable profile of low poly- and auto-reactivity (Fig.10E). Thus, VH3-23/VK1-5 antibodies have the potential for further pre-clinical evaluation. VH3-23/VK1-5 Antibodies Recognize the Lateral Ridge of ZEDIII

There are only 2 contiguous amino acids that are uniquely shared between the EDIIIs of ZIKV and DENV1, and not by DENV2, DENV3, DENV4, WNV or YFV (E393 and K394 in ZIKV, E384 and K385 in DENV1; Fig.4G). These 2 amino acids are found in the lateral ridge region of the ZEDIII, which is a region that is associated with virus interaction with cellular receptors (Mukhopadhyay et al., 2005). To determine whether these 2 amino acids are essential for interaction between VH3-23/VK1-5 antibodies and ZIKV, we made alanine substitutions in the context of the ZIKV RVPs and tested the recombinant RVPs for sensitivity to Z004-mediated neutralization. Although ZIKV RVPs bearing the E393A substitution remained sensitive to Z004, K394A mutant RVPs were resistant to the antibody (Fig.4H). African ZIKV strains differ from others at position 393 carrying aspartic acid at this position. Similar to wild type Asian/American ZIKV RVPs, African ZIKV RVPs carrying D393 instead of E393 were sensitive to Z004, and Asian/American ZIKV RVPs with an E393D substitution were also efficiently neutralized (Figs.4G and I). Thus a shared epitope in the lateral ridge region could account for the finding that Z004 neutralizes ZIKV and DENV1, but not other flaviviruses. Structures of ZIKV Antibodies/EDIII Complexes Reveal a Shared Binding Mode

To gain additional insights into the molecular basis of ZEDIII recognition by VH3-23/VK1-5 antibodies, we solved crystal structures of complexes of the antigen-binding fragment (Fab) of two antibodies isolated from different donors, Z006 and Z004, with ZIKV and DENV1 EDIII domains, respectively (Figure 5). The Z006 Fab-ZEDIII and Z004 Fab-DENV1 EDIII structures showed a common mode of antigen recognition, as revealed by similar orientations of Fab VH and VL domains when the EDIII domains were superimposed (Fig.5A). The Z006/Z004 Fab orientation is distinct from orientations in other crystallographically- characterized Fab/ZIKV and Fab/DENV1 EDIII complexes (Fig.5B). The Z006 epitope extends over much of the EDIII lateral ridge (Fig.5C): beyond the E393-K394 _ZIKV region, the next largest parts of the interface consist of the N-terminal region of EDIII (residues 305- 311ZIKV), CC’ loop residues 350-352ZIKV, and BC loop residues 333-336ZIKV. The E393- K394 _ZIKV (E384-K385 _DENV1 ) motif is central to the interface (Fig.5C) and contacts residues within the Fab CDRH3, CDRL3, and CDRL1 loops in both structures (Fig.5A, D-F). Despite the antibodies originating from different donors and binding to two different flavivirus EDIIIs, a number of contact interactions occur in both complexes (Table 6). Specifically, the side chain of residue K394 _ZIKV (K385 _DENV1 ) occupies a hydrophobic pocket formed by W32LC and Y91LC(Z006)/F91LC(Z004) and forms an H-bond with the latter residue’s backbone oxygen atom (Fig.5D). The side chain of residue E393ZIKV (E384DENV1) interacts with R96 _HC , although this interaction differs somewhat in the two structures: in the Z006 structure, E393 _ZIKV forms an H-bond with the Y91 _LC hydroxyl and an electrostatic interaction with R96HC, while for Z004, the side chain of residue F91LC lacks a hydroxyl group to form an H-bond, and instead the side chain of E384 _DENV1 forms a salt bridge with R96 _HC (Fig.5E). Other common interactions include the side chain of Y58 _HC forming an H-bond to the backbone oxygen of L307ZIKV (M301DENV1) (Fig.5F), and the side chain of T93LC

(Z006)/S93LC (Z004) forming an H-bond to the backbone N of T335ZIKV (T329DENV1). Hence the common mode of recognition involves using equivalent pairwise interactions as well as binding with a similar orientation. Pre-existing DENV1 Reactivity is Associated with Enhanced ZEDIII Antibody

Responses

The existence of VH3-23/VK1-5 antibodies that neutralize both DENV1 and ZIKV and are recurrently found in expanded clones suggests that prior exposure to DENV1 primes the development of protective ZIKV immunity. To examine this possibility, we tested sera obtained at time points before and after introduction of ZIKV in the Pau da Lima community in Salvador, Brazil. Anti-ZEDIII serum IgG reactivity increased significantly between April and November of 2015 (Fig.6A). Interestingly, a similar increase was seen for DENV1, although there was no documented DENV1 outbreak in this area at this time, with only 5 DENV1 cases reported between September 2014 and July 2016 (Fig.6A). In contrast, no significant increase in reactivity was observed for DENV2, DENV3, DENV4, YFV, or WNV EDIIIs (Fig.6A). Consistent with the hypothesis that DENV1 primes the subsequent response to ZIKV, we observed a significant positive correlation between DENV1 EDIII-reactive IgG levels pre-ZIKV, and ZEDIII-reactive IgG levels post-ZIKV (Pseudo- ^=0.48, p<0.001, Fig. 6B). Together, these data indicate that the exposure to ZIKV boosted the pre-existing DENV1 antibody response, and that individuals with pre-existing antibodies targeting the DENV1 EDIII are more likely to develop high levels of EDIII antibodies upon ZIKV infection. Lateral Ridge Antibodies Are Associated with ZIKV Neutralization

To determine whether antibodies to the lateral ridge region recognized by Z004 contribute to serologic activity against ZIKV in the Pau da Lima cohort, we developed a competition ELISA assay. In this assay we measure inhibition of biotin-Z004 binding to ZEDIII in order to quantify lateral ridge-binding antibodies present in serum (see Methods). Paired samples from April 2015 (before ZIKV) and November 2015 (after ZIKV) showed an increase in lateral ridge reactivity after ZIKV introduction (p=0.0007, Fig.7A). Levels of antibodies present in the post-ZIKV serum that are capable of blocking Z004 binding to ZEDIII were directly correlated with the overall reactivity of antibodies to ZEDIII (Spearman coefficient, ^=0.7319, p<0.0001 Fig.7B), as well as with the increase in reactivity to ZEDIII from prior to after ZIKV ( ^=0.8190, p<0.0001, Fig.7C). Finally, there was also a significant correlation between ZIKV neutralizing activity and total ZEDIII reactivity ( ^=0.5885, p=0.0012, Fig. 7D), as well as Z004 blocking activity ( ^=0.6585, p=0.0002, Fig.7E). We conclude that antibodies that block Z004 binding to the lateral ridge make a measurable contribution to the overall serum neutralizing activity to ZIKV in exposed individuals. Example 2

This Example provides a description of materials and methods used to obtain the results discussed above. EXPERIMENTAL MODEL AND SUBJECTS DETAILS Human subjects

Samples of peripheral blood were obtained upon consent from community participants of cohort studies in Pau da Lima (Brazil) and Santa Maria Mixtequilla (Mexico) under protocols approved by the ethical committees of the Rockefeller University (IRB DRO-0898), Yale University (IRB HIC 1603017508), FIOCRUZ (CAAE 63343516.1.0000.5028), Hospital Geral Roberto Santos (1.998.103), and National Institute of Respiratory Diseases (C16-16). Information regarding sex and age of study participants can be obtained upon request. Details on the size of the cohorts and time when samples were obtained is listed in the Results section of the manuscript. Mice

IFNAR1 ^-/- mice were obtained from The Jackson Laboratory and bred and maintained in the AAALAC-certified facility of the Rockefeller University. Mice were specific pathogen free and maintained under a 12 hr light/dark cycle with standard chow diet. Both male and female mice (3-4 week old) were used for all experiments and were equally distributed within experimental and control groups. Animal protocols were in agreement with NIH guidelines and approved by the Rockefeller University Institutional Animal Care and Use Committee (16855-H). Cell lines

Human embryonic kidney HEK-293-6E suspension cells were cultured at 37˚C in 8% CO ₂ , shaking at 120 rpm. All other cell lines described below were cultured at 37˚C in 5% CO2, without shaking. Green monkey VERO cells and human hepatocytes Huh-7.5 cells (Blight et al., 2002) were cultured in Dulbecco’s Modified Eagle Medium (DMEM) supplemented with 1% nonessential amino acids (NEAA) and 5% FBS. Human Lenti-X 293T cells (Clontech) and STAT1 ^-/- , an SV40 large T antigen immortalized skin fibroblast line (Chapgier et al., 2006), were grown in DMEM 10% FBS. Bacteria

E. coli BL21(DE3) were cultured at 37˚C, shaking at 250 rpm. MC1061 cells were cultured in LB medium, with 250 rpm shaking, at 30-37˚C depending on the plasmid. Viruses

Zika virus (ZIKV), 2015 Puerto Rican PRVABC59 strain (Lanciotti et al., 2016), was obtained from the CDC and passaged once in STAT1 ^-/- fibroblasts (STAT1 ^-/- -ZIKV stock, used in mouse experiments) or twice in Huh-7.5 cells (Huh-7.5-ZIKV stock, used in all other experiments). The Thai human isolate of DENV1 PUO-359 (TVP-1140) was obtained from Robert Tesh and amplified by three passages in C6/36 insect cells. METHOD DETAILS Collection of human samples

Samples of peripheral blood for serum or mononuclear cells (PBMCs) isolation were obtained from community participants and donors and frozen at the cohorts’ sites. PBMCs were purified using the gradient centrifugation method with Ficoll and cryopreserved in 90% heat-inactivated fetal bovine serum (FBS) supplemented with 10% dimethylsulfoxide (DMSO), prior to shipment to Rockefeller University in liquid nitrogen. Serum aliquots were heat-inactivated at 56˚C for 1h and stored at 4˚C thereafter. Production and biotinylation of flavivirus protein

The coding sequences for the EDIII portion of flaviviruses were preceded by sequences encoding the human CD5 signal peptide (MPMGSLQPLATLYLLGMLVASCLG (SEQ ID NO: 119)) and followed by a polyhistidine-AviTag (HHHHHH-GLNDIFEAQKIEWHE (SEQ ID NO: 120)). The followin flavivirus sequences were used.

Gene synthesis was by Genscript. The proteins were produced by transient transfection into HEK-293-6E cells using PEI (polyethylenimine, branched). After 7 days of incubation, cell supernatants were cleared by centrifugation and histidine-tagged proteins were purified with Ni Sepharose 6 Fast Flow. Purified ZEDIII was biotinylated using the Biotin-Protein Ligase- BIRA kit according to manufacturer’s instructions. ELISA assays Serum and recombinant antibody

The binding of serum IgG or recombinant IgG antibodies to the EDIII proteins was measured by standard ELISA. ELISA plates were coated with 250 ng of EDIII protein in PBS per well and stored overnight at room temperature. Plates were then blocked with 1% BSA, 0.1mM EDTA in PBS-T (PBS with 0.05% Tween20) for 1h at 37˚C. Plates were washed with PBS-T in between each step above. Serum samples were diluted 1:500 with PBS-T and added for 1h at 37˚C. Secondary HRP-conjugated goat anti-human IgG (0.16 ^g/ml) was added for 1h at 37˚C. Plates were then developed using ABTS substrate and read at 405 nm. The relative binding affinity of recombinant monoclonal antibodies was determined similarly, using serially diluted samples. The half effective concentration (EC50) needed for maximal binding was determined by non-linear regression analysis. Cross-reactivity ELISA

The binding of monoclonal antibodies to the panel of flavivirus EDIII proteins was determined using the standard ELISA setup described above. Antibodies were tested at 10 ^g/ml alongside a control serum weakly cross-reactive to all flaviviruses. Samples with a relative optical density ratio of >1 compared to control were deemed reactive. Auto- and poly-reactivity ELISA

To determine the auto- and poly-reactivity of recombinant antibodies, ELISA plates were coated with 50 ^l PBS containing dsDNA (10 ^g/ml), ssDNA (10 ^g/ml, obtained by denaturing dsDNA at 95˚C for 30 minutes), LPS (10 ^g/ml), Insulin (5 ^g/ml), or keyhole limpet hemocyanin (KLH; 10 ^g/ml). After washing with PBS-T, plates were blocked with 1% BSA and 0.5mM EDTA in 0.05% PBS-T for 2h at room temperature. Serial dilutions of antibody samples were then incubated for 2h, also at room temperature. Incubation with secondary antibody and ELISA development were performed as described above. Previously reported antibodies ED38 (Wardemann et al., 2003) and mG053 (Yurasov et al., 2005) were used as positive and negative control, respectively. Competition ELISA

Competition ELISA was performed as described above for serum EDIII binding, with the following modifications. After 1h of incubation with serum (diluted 1:10 in PBS-T) at room temperature, biotinylated antibody Z004 (biotin-Z004) was added at a final concentration of 0.16 ^g/ml to compete for an additional 15 min at room temperature. After washing, streptavidin-HRP was used for detection of bound biotin-Z004. The optimal concentration of biotin-Z004 (0.16 ^g/ml) was determined by measuring its binding to ZEDIII over a range of concentrations, and corresponds to 50% of the observed maximal binding. The concentration of Z004 blocking antibodies in serum was estimated by interpolation with a standard curve generated by competing biotin-Z004 (0.16 with a range of non-biotinylated Z004 concentrations, and using the stats package nls() function in R 3.3.2. Antibody discovery and production Isolation of ZEDIII ⁺ memory B cells

B cell purification, labeling and antibody discovery were performed as previously described in detail (Tiller et al., 2008; von Boehmer et al., 2016), with the following modifications. PBMCs were resuscitated and washed in 37˚C RPMI. To enrich for B cells, PBMCs were incubated with CD19 microbeads according to the manufacturer’s instructions. Upon washing, B cells were positively selected using LS magnetic columns, washed with PBS 3%FBS, and incubated with anti-CD20-PECy7, anti IgG-APC, and fluorescently-labeled ZEDIII bait at 4˚C for 20 min. The fluorescently-labeled ZEDIII bait was previously prepared by incubating 2-3 ^g of biotin-ZEDIII with streptavidin-PE for at least 1h at 4˚C in the dark. After wash, single CD20 ⁺ ZEDIII ⁺ gG ⁺ memory B cells were sorted into 96-well plates using a FACSAriaII (Becton Dickinson). Antibody sequencing and production

RNA from single cells was reverse-transcribed using random primers (von Boehmer et al., 2016), followed by nested PCR amplifications and sequencing using the primers listed in (Tiller et al., 2008). V(D)J gene segment assignment and determination of the CDR3 sequences were with IgBlast (Ye et al., 2013). Sequences that were non-productive, out of frame, or with premature stop codons were excluded. Similarly, sequences for which a matching light or heavy chain sequence was not identifiable were omitted. Cloning for recombinant antibody production was by the Sequence and Ligation-Independent Cloning (SLIC; (Li and Elledge, 2007)) method as detailed in (von Boehmer et al., 2016). Amplicons from the first sequencing PCR reaction were used as template for amplification with the SLIC-adapted primers listed in Table 3, and cloned into IGγ1-, IG ^ or IGλ-expression vectors as detailed in (von Boehmer et al., 2016). The recombinantly expressed antibodies correspond to the folIowing antibody sequence IDs (see Tables 1 and 2): Z028 (MEX84_p4- 53), Z001 (MEX18_21), Z004 (MEX18_89), Z006 (MEX105_42), Z010 (MEX105_88), Z031 (BRA112_46), Z035 (BRA112_71), Z038 (BRA12_2), Z014 (MEX18_91), Z039 (BRA12_21), Z015 (MEX84_p2-44), Z018 (MEX84_p2-45), Z021 (MEX84_p4-23), Z024 (MEX84_p4-12), Z012 (MEX105_57), Z037 (BRA112_57), Z041 (BRA138_57), Z042 (BRA138_17), Z043 (BRA138_15). The variable portion of the predicted germline antibody Z004-GL was codon-optimized, synthesized by Genscript, and cloned as described above (IGH

NO: 130)). Recombinant antibodies were produced as previously described (Klein et al., 2014). Briefly, HEK-293-6E cells were transiently transfected with equal amounts of immunoglobulin heavy and light chain expression vectors. After 7 days, the supernatant was harvested and antibodies were purified with Protein G Sepharose 4 Fast Flow. For antibody biotinylation, 1.5 mg/ml of Z004 were used with FluoReporter Mini-biotin-XX Protein Labeling Kit as instructed by the manufacturer. Mouse experiments

All experiments involving mice were performed under protocols approved by the Rockefeller University Institutional Animal Care and Use Committee.123 ^g of monoclonal antibodies in 200 ^l of PBS were administered intraperitoneally to 3-4 week old IFNAR1 ^-/- mice one day prior or after infection with 1.25 x 10 ⁵ PFU ZIKV Puerto Rican strain in 50 ^l into the footpad. Mice were monitored for symptoms and survival over time. Virus titration

Viral titers were measured on VERO cells by plaque assay (PA) for ZIKV virus and focus forming assay (FFA) for DENV-1 strains. For PA, 200 ^l of serial 10-fold virus dilutions in OPTI-MEM were used to infect 400,000 cells seeded the day prior in a 6-well format. After 90 minutes adsorption, the cells were overlayed with DMEM containing 2% FBS with 1.2% Avicel and Pen/Strep. Four days later the cells were fixed with 3.5% formaldehyde and stained with crystal violet for plaque enumeration. For FFA, 100 ^l of serial 10-fold virus dilutions in OPTI-MEM were used to infect 250,000 cells seeded the day prior in a 12-well format. After 90 minutes, the cells were overlayed as described above for PA. Six to 7 days later the cells were fixed and incubated with 2 ^g/ml of antibody Z004 in PBS/5%

FBS/0.25% Triton X-100 for 1 h at room temperature. Foci were enumerated after reaction with goat anti-human IgG HRP-conjugated antibodies and TrueBlue HRP substrate, followed by addition of a few drops of DAB buffer solution (DAKO). Experiments with infectious ZIKV and DENV strains were performed in a biosafety level 2 laboratory. Plaque reduction neutralization test

Antibody neutralization activity was measured using a standard plaque reduction

neutralization test (PRNT) on VERO cells. Diluent medium consisted of medium 199 (Lonza) supplemented with 1% BSA and Pen/Strep (BA-1 diluent). Briefly, 3- to 10-fold serial human antibody dilutions were added to a constant amount of Huh-7.5-ZIKV stock diluted in BA-1 diluent and incubated for 1 h at 37˚C prior to application to VERO cells seeded at 400,000 cells per 6-well the day prior. After 90 min adsorption at 37˚C the cells were overlayed as per PA protocol above. After 4 days at 37˚C, the wells were fixed and stained to enumerate plaques. PRNT ₅₀ values were determined as the antibody concentration that resulted in 50% of the number of plaques obtained with the no antibody control. RVP plasmid construction

West Nile virus (WNV) subgenomic replicon-expressing plasmid pWNVII-Rep-REN-IB (Pierson et al., 2006) and a ZIKV C-prM-E expression plasmid (pZIKV/HPF/CprME) were obtained from Ted Pierson (NIH). Plasmid pWNVII-Rep-REN-IB encodes a Renilla luciferase-expressing WNV replicon RNA while pZIKV/HPF/CprME encodes the structural proteins (C-prM-E) of the ZIKV French Polynesian strain H/PF/2013, both under the control of a CMV promoter. Co-transfection of the two plasmids into permissive cells allows the WNV replicon RNA to replicate, express luciferase and be packaged by the ZIKV H/PF/2013 structural proteins to generate RVPs that can be used for single round infection studies (Mukherjee et al., 2014; Pierson et al., 2006). To facilitate expression of the envelopes of a wide range of ZIKV strains, plasmid pZIKV/HPF/CprME was engineered to have a unique BspHI restriction enzyme site immediately upstream of the envelope region by PCR-based site-directed mutagenesis of two other BspHI restriction sites located in the plasmid backbone. The resulting plasmid, pZIKV/HPF/CprM*E*, has unique BspHI and SacII restriction sites flanking the envelope region, allowing facile manipulation. PCR-based site- directed mutagenesis was used to introduce E393A or K394A mutations into the envelope of H/PF/2013 in pZIKV/HPF/CprM*E*, resulting in plasmids pZIKV/HPF/CprME(E393A) and pZIKV/HPF/CprME(K394A). We generated pZIKV/HPF-CprM/MR766-E by replacing the H/PF/2013 envelope in pZIKV/HPF/CprM*E* with that of the ZIKV African strain, MR766. Because the African strains contain a BspHI site within the E protein coding region, this site was mutated using assembly PCR prior to swapping in the MR766-based BspHI and SacII fragment. To generate pDENV1/PUO-359/CprME, DENV1 (strain PUO-359) virion RNA was isolated by TRIzol extraction (Thermo Fisher Scientific), cDNA generated using Superscript II reverse transcriptase (Thermo Fisher Scientific), and the C-prM-E region amplified by PCR. After PCR assembly with the upstream promoter and vector sequences, the corresponding region of pZIKV/HPF/CprME was replaced using SnaBI/SacII enzymes. PCR reactions utilized either PfuUltra Hotstart DNA Polymerase (Agilent technologies), Phusion High Fidelity DNA polymerase (NEB) or KOD DNA polymerase (Toyobo). All PCR-derived plasmid regions were verified by sequencing. Primer sequences used for assembly PCR and mutagenesis are listed in Table 4. RVP production

Reporter viral particles (RVPs) were produced in Lenti-X 293T cells, seeded the day before DNA transfection at 1x10 ⁶ cells/well in collagen coated 6-well plates. One ^g of pWNVII- Rep-REN-IB (WNV replicon expression construct) and 3 ^g of the appropriate flavivirus CprME expression construct were co-transfected using Lipofectamine 2000 (Invitrogen) according to the manufacturer’s instructions. Lipid–DNA complexes were removed after 4–5 h incubation at 37˚C and replaced with DMEM containing 20 mM HEPES and 10% FBS. After incubation for 48-72 h at 34˚C, RVP-containing supernatants were harvested, filtered through a 0.45 micron filter and frozen at -80˚C. RVPs were titrated on Huh-7.5 cells to determine the dilution to use in the RVP-based neutralization assay to achieve ~2-5x10 ⁶ RLU in the absence of serum/antibody. RVP neutralization assay

The day before infection, 96-well plates were seeded with 15,000 Huh-7.5 cells/well in a volume of 100 ^l. RVPs were diluted in BA-diluent (ranging from 1:4 to 1:32 depending on the RVP stock) and 100 ^l were added to 100 ^l of triplicate samples of 3- or 10-fold serially diluted human serum/antibody. After incubation for 1 h at 37°C, 100 ^l of the RVP/antibody mixture was added to the cells. After 24 h incubation at 37˚C, the medium was removed and cells were lysed in 75 ^l lysis buffer and 20 ^l used for Renilla luciferase measurement using the Renilla Luciferase Assay System (Promega) according to the manufacturer’s instructions using a FLUOstar Omega luminometer (BMG LabTech). Neutralization capacity of the serum/antibody was determined by the percentage of luciferase activity obtained relative to activity from RVPs incubated with BA-diluent alone (no serum/antibody). NT50 values represented the reciprocal of the serum dilution or the antibody concentration that resulted in 50% inhibition compared to RVP alone. Flow cytometry-based neutralization assay

The day prior to infection 5,000 VERO cells/well were seeded in 96-well plates. Serial dilutions of antibody were mixed with ZIKV or DENV-1 virus for 1 h at 37˚C and then applied to infect cells, using an MOI of 0.02 for ZIKV and DENV-1. After 3 days, cells were fixed with 2% formaldehyde and permeabilized in PBS containing 1% FBS and 0.5% saponin. Cells were stained with 2 ^g/ml of the pan flavivirus anti-E protein 4G2 monoclonal antibody (Henchal et al., 1982). After incubation with Alexa Fluor 488- conjugated anti-mouse IgG antibody (Invitrogen) at 1:1,000 dilution, the number of infected cells was determined by flow cytometry. The percentage of infected cells relative to cells infected with virus in the absence of antibody was calculated for each antibody dilution to estimate the 50% reduction. Protein production and crystallization

His-tagged Fabs were transiently expressed in HEK-293-6E cells by co-transfecting with appropriate heavy and light chain plasmids. Fabs were purified from the supernatant using Ni-NTA affinity chromatography (GE Healthcare) and size exclusion chromatography (Superdex 200; GE Healthcare) in 20mM Tris pH 8.0, 150mM NaCl, 0.02% NaN ₃ . The Fabs were concentrated to 10-20 mg/mL for crystallography. Untagged constructs of ZEDIII and DENV1 EDIII were expressed in E. coli and refolded from inclusion bodies as previously described (Sapparapu et al., 2016). Briefly, BL21(DE3) E. coli were transformed with an appropriate expression vector encoding ZIKV E protein residues 299-407 (ZIKV EDIII, strain H/PF/2013) or DENV1 E protein residues 297-396 (DENV1 EDIII, strain clone 45AZ5). Cells were grown to mid-log phase and induced with isopropyl β-D-1- thiogalactopyranoside (IPTG) for 4 hours. The cells were lysed and the insoluble fraction containing inclusion bodies was solubilized in buffer containing 6M guanidine hydrochloride and 20mM ^-mercaptoethanol, and then clarified by centrifugation. The solubilized inclusion bodies were refolded using rapid dilution into 400 mM L-arginine, 100 mM Tris-base (pH 8.0), 2 mM EDTA, 0.2 mM phenyl-methylsulfonyl fluoride, and 5 and 0.5 mM reduced and oxidized glutathione at 4º C. The refolded protein was filtered and concentrated, and then purified by size exclusion chromatography (Superdex 75; GE Healthcare) in 20mM Tris pH 8.0, 150mM NaCl, 0.02% NaN3. Antigens were concentrated to 2-15 mg/mL for

crystallography. Complexes for crystallization were produced by mixing Fab and antigen at a 1:1 molar ratio and incubating at room temperature for 1-2 hours. Crystals of Z006 Fab– ZEDIII complex (space group H32; a = 385.08 Å, b = 385.08 Å, c = 56.64 Å, ^ = 90º, ^ = 90º, ^ = 120º; two molecules per asymmetric unit) were obtained by combining 0.2 μL of crystallization sample with 0.2 μL of 10% isopropanol, 0.1M sodium citrate tribasic dihydrate pH 5.0, 26% PEG 400 in sitting drops at 22ºC. Crystals of Z004 Fab–DENV1 EDIII complex (space group P4 ₃ 2 ₁ 2; a = 74.23 Å, b = 74.23 Å, c = 190.76 Å; one molecule per asymmetric unit) were obtained by combining 0.2 μL of crystallization sample with 0.2 μL of 0.1M sodium acetate trihydrate pH 4.5, 30% w/v PEG 1500 in sitting drops at 22ºC. Structure Determination and Refinement

X-ray diffraction data were collected at Stanford Synchrotron Radiation Lightsource (SSRL) beamline 12-2 using a Dectris Pilatus 6M detector. The data were integrated using Mosflm (Battye et al., 2011) and scaled using CCP4 (Winn et al., 2011)(Table 5). The Z006–ZEDIII complex structure (PDB ID 5VIG) was solved by molecular replacement with a Z006 unbound Fab structure (data not shown) and Zika EDIII (PDB ID 5KVG) as the search models using Phaser and Molrep (CCP4) and refined to 3.0 Å using an iterative approach involving (i) refinement in CNS and Phenix applying NCS constraints and (ii) manual rebuilding into electron density maps using O and AntibodyDatabase (Jones, 2004; West et al., 2013). The final model (R _work = 21.2%; R _free = 25.7%) contains 7,892 protein atoms and one citrate ion (12 atoms).90.8, 7.6, and 1.6% of the residues were in the favored, allowed, and disallowed regions, respectively, of the Ramachandran plot (Table 5). Residues 1, 128- 133, 214-219, and the 6x-His tag of the Z006 heavy chain; residue 214 of the LC; and residues 299-304 and 405-407 were disordered and are not included in the model. The Z004- DENV1 EDIII complex structure (PDB ID 5VIC) was solved by molecular replacement using the V _H V _L (CDR residues removed) and C _H C _L domains from PDB 3SKJ and DENV1 EDIII from PDB 4L5F as search models in Phenix (Adams et al., 2010). The model was refined to 3.0 Å resolution using an iterative approach involving (i) refinement in Phenix and (ii) manual rebuilding into a simulated annealing composite omit map using Coot (Emsley and Cowtan, 2004). The final model (R _work = 23.6%; R _free = 28.1%) contains 3,904 protein atoms.93.0%, 6.8%, and 0.2% of the residues were in the favored, allowed, and disallowed regions, respectively, of the Ramachandran plot (Table 5). Residues that were disordered and not included in the model were Fab HC residues 129-132, 215-219, and the 6x-His tag; LC residues 212-214; and DENV1 EDIII domain residues 315-317, 341-347, 373-374, and 393- 396. Structures were superimposed, rmsd calculations done, and figures were generated using PyMOL. Hydrogen bonds were assigned using the following criteria: a distance of < 3.5 Å, and an A-D-H angle of > 90˚. STATISTICAL ANALYSIS DETAILS Unless otherwise noted, statistical analysis was with Prism software. The half effective concentration (EC50) needed for maximal binding by ELISA was determined by non-linear regression analysis (Fig.3A). Data are the average of at least two independent experiments. Similarly, luciferase- and flow cytometry-based neutralization assays were performed in triplicate wells, and the serum dilution (NT50) or antibody concentration (IC50) that neutralized 50% of the virus or RVP inoculum was calculated by nonlinear, dose-response regression analysis (Fig.4A). The Mantel-Cox test was applied to analyze disease and survival in mice infection experiments (Fig.4D-F). The Paired t test was used to analyze changes in sero-reactivity over time (Fig.6A and 7A). Univariate associations were assessed between log-relative optical densities of anti-ZEDIII antibodies at t=2 (November 2015) with log-relative optical densities of anti-DENV1 EDIII antibodies at t=1 (April 2015) using proc mixed in SAS v 9.4 (Fig.6B). An individual-level random intercept was included to account for non-independence of the two replicated measurements. The two-tailed Spearman r test was used for the correlations in Fig.7B-E.

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References cited for the foregoing description and Figures 1-10. This reference listing is not an indication that any of the references are material to patentability of any invention encompassed by this disclosure

Adams, P.D., Afonine, P.V., Bunkoczi, G., Chen, V.B., Davis, I.W., Echols, N., Headd, J.J., Hung, L.W., Kapral, G.J., Grosse-Kunstleve, R.W., et al. (2010). PHENIX: a comprehensive Python-based system for macromolecular structure solution. Acta crystallographica Section D, Biological crystallography 66, 213-221.

Arnaout, R., Lee, W., Cahill, P., Honan, T., Sparrow, T., Weiand, M., Nusbaum, C., Rajewsky, K., and Koralov, S.B. (2011). High-resolution description of antibody heavy-chain repertoires in humans. PloS one 6, e22365.

Barba-Spaeth, G., Dejnirattisai, W., Rouvinski, A., Vaney, M.C., Medits, I., Sharma, A., Simon- Loriere, E., Sakuntabhai, A., Cao-Lormeau, V.M., Haouz, A., et al. (2016). Structural basis of potent Zika-dengue virus antibody cross-neutralization. Nature 536, 48-53.

Bardina, S.V., Bunduc, P., Tripathi, S., Duehr, J., Frere, J.J., Brown, J.A., Nachbagauer, R., Foster, G.A., Krysztof, D., Tortorella, D., et al. (2017). Enhancement of Zika virus pathogenesis by preexisting antiflavivirus immunity. Science.

Barzon, L., Pacenti, M., Franchin, E., Lavezzo, E., Trevisan, M., Sgarabotto, D., and Palu, G. (2016). Infection dynamics in a traveller with persistent shedding of Zika virus RNA in semen for six months after returning from Haiti to Italy, January 2016. Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin 21.

Battye, T.G., Kontogiannis, L., Johnson, O., Powell, H.R., and Leslie, A.G. (2011). iMOSFLM: a new graphical interface for diffraction-image processing with MOSFLM. Acta crystallographica Section D, Biological crystallography 67, 271-281.

Beasley, D.W., and Barrett, A.D. (2002). Identification of neutralizing epitopes within structural domain III of the West Nile virus envelope protein. Journal of virology 76, 13097-13100.

Blight, K.J., McKeating, J.A., and Rice, C.M. (2002). Highly permissive cell lines for subgenomic and genomic hepatitis C virus RNA replication. Journal of virology 76, 13001-13014.

Brasil, P., Pereira, J.P., Jr., Moreira, M.E., Ribeiro Nogueira, R.M., Damasceno, L., Wakimoto, M., Rabello, R.S., Valderramos, S.G., Halai, U.A., Salles, T.S., et al. (2016). Zika Virus Infection in Pregnant Women in Rio de Janeiro. The New England journal of medicine 375, 2321-2334.

Cardoso, C.W., Paploski, I.A., Kikuti, M., Rodrigues, M.S., Silva, M.M., Campos, G.S., Sardi, S.I., Kitron, U., Reis, M.G., and Ribeiro, G.S. (2015). Outbreak of Exanthematous Illness Associated with Zika, Chikungunya, and Dengue Viruses, Salvador, Brazil. Emerging infectious diseases 21, 2274- 2276.

Castanha, P.M., Nascimento, E.J., Cynthia, B., Cordeiro, M.T., de Carvalho, O.V., de Mendonca, L.R., Azevedo, E.A., Franca, R.F., Rafael, D., and Marques, E.T., Jr. (2016). Dengue virus (DENV)- specific antibodies enhance Brazilian Zika virus (ZIKV) infection. The Journal of infectious diseases.

Chapgier, A., Boisson-Dupuis, S., Jouanguy, E., Vogt, G., Feinberg, J., Prochnicka-Chalufour, A., Casrouge, A., Yang, K., Soudais, C., Fieschi, C., et al. (2006). Novel STAT1 alleles in otherwise healthy patients with mycobacterial disease. PLoS genetics 2, e131.

Costa, F., Sarno, M., Khouri, R., de Paula Freitas, B., Siqueira, I., Ribeiro, G.S., Ribeiro, H.C., Campos, G.S., Alcantara, L.C., Reis, M.G., et al. (2016). Emergence of Congenital Zika Syndrome: Viewpoint From the Front Lines. Annals of internal medicine 164, 689-691.

Crill, W.D., and Roehrig, J.T. (2001). Monoclonal antibodies that bind to domain III of dengue virus E glycoprotein are the most efficient blockers of virus adsorption to Vero cells. Journal of virology 75, 7769-7773.

Dai, L., Song, J., Lu, X., Deng, Y.Q., Musyoki, A.M., Cheng, H., Zhang, Y., Yuan, Y., Song, H., Haywood, J., et al. (2016). Structures of the Zika Virus Envelope Protein and Its Complex with a Flavivirus Broadly Protective Antibody. Cell host & microbe 19, 696-704.

Dejnirattisai, W., Supasa, P., Wongwiwat, W., Rouvinski, A., Barba-Spaeth, G., Duangchinda, T., Sakuntabhai, A., Cao-Lormeau, V.M., Malasit, P., Rey, F.A., et al. (2016). Dengue virus sero-cross- reactivity drives antibody-dependent enhancement of infection with zika virus. Nature immunology 17, 1102-1108. DeKosky, B.J., Kojima, T., Rodin, A., Charab, W., Ippolito, G.C., Ellington, A.D., and Georgiou, G. (2015). In-depth determination and analysis of the human paired heavy- and light-chain antibody repertoire. Nature medicine 21, 86-91.

Ekiert, D.C., Bhabha, G., Elsliger, M.A., Friesen, R.H., Jongeneelen, M., Throsby, M., Goudsmit, J., and Wilson, I.A. (2009). Antibody recognition of a highly conserved influenza virus epitope. Science 324, 246-251.

Emsley, P., and Cowtan, K. (2004). Coot: model-building tools for molecular graphics. Acta crystallographica Section D, Biological crystallography 60, 2126-2132.

Escolano, A., Dosenovic, P., and Nussenzweig, M.C. (2017). Progress toward active or passive HIV- 1 vaccination. The Journal of experimental medicine 214, 3-16.

Felzemburgh, R.D., Ribeiro, G.S., Costa, F., Reis, R.B., Hagan, J.E., Melendez, A.X., Fraga, D., Santana, F.S., Mohr, S., dos Santos, B.L., et al. (2014). Prospective study of leptospirosis transmission in an urban slum community: role of poor environment in repeated exposures to the Leptospira agent. PLoS neglected tropical diseases 8, e2927.

Foy, B.D., Kobylinski, K.C., Chilson Foy, J.L., Blitvich, B.J., Travassos da Rosa, A., Haddow, A.D., Lanciotti, R.S., and Tesh, R.B. (2011). Probable non-vector-borne transmission of Zika virus, Colorado, USA. Emerging infectious diseases 17, 880-882.

Franca, G.V., Schuler-Faccini, L., Oliveira, W.K., Henriques, C.M., Carmo, E.H., Pedi, V.D., Nunes, M.L., Castro, M.C., Serruya, S., Silveira, M.F., et al. (2016). Congenital Zika virus syndrome in Brazil: a case series of the first 1501 livebirths with complete investigation. Lancet 388, 891-897. Hagan, J.E., Moraga, P., Costa, F., Capian, N., Ribeiro, G.S., Wunder, E.A., Jr., Felzemburgh, R.D., Reis, R.B., Nery, N., Santana, F.S., et al. (2016). Spatiotemporal Determinants of Urban

Leptospirosis Transmission: Four-Year Prospective Cohort Study of Slum Residents in Brazil. PLoS neglected tropical diseases 10, e0004275.

Harrison, S.C. (2016). Immunogenic cross-talk between dengue and Zika viruses. Nature immunology 17, 1010-1012.

Heinz, F.X., and Stiasny, K. (2017). The Antigenic Structure of Zika Virus and Its Relation to Other Flaviviruses: Implications for Infection and Immunoprophylaxis. Microbiology and molecular biology reviews : MMBR 81.

Henchal, E.A., Gentry, M.K., McCown, J.M., and Brandt, W.E. (1982). Dengue virus-specific and flavivirus group determinants identified with monoclonal antibodies by indirect

immunofluorescence. The American journal of tropical medicine and hygiene 31, 830-836.

Honein, M.A., Dawson, A.L., Petersen, E.E., Jones, A.M., Lee, E.H., Yazdy, M.M., Ahmad, N., Macdonald, J., Evert, N., Bingham, A., et al. (2017). Birth Defects Among Fetuses and Infants of US Women With Evidence of Possible Zika Virus Infection During Pregnancy. Jama 317, 59-68.

Jones, T.A. (2004). Interactive electron-density map interpretation: from INTER to O. Acta crystallographica Section D, Biological crystallography 60, 2115-2125. Klein, F., Nogueira, L., Nishimura, Y., Phad, G., West, A.P., Jr., Halper-Stromberg, A., Horwitz, J.A., Gazumyan, A., Liu, C., Eisenreich, T.R., et al. (2014). Enhanced HIV-1 immunotherapy by commonly arising antibodies that target virus escape variants. The Journal of experimental medicine 211, 2361-2372.

Kostyuchenko, V.A., Lim, E.X., Zhang, S., Fibriansah, G., Ng, T.S., Ooi, J.S., Shi, J., and Lok, S.M. (2016). Structure of the thermally stable Zika virus. Nature 533, 425-428.

Kramer, L.D., Li, J., and Shi, P.Y. (2007). West Nile virus. The Lancet Neurology 6, 171-181. Lanciotti, R.S., Lambert, A.J., Holodniy, M., Saavedra, S., and Signor Ldel, C. (2016). Phylogeny of Zika Virus in Western Hemisphere, 2015. Emerging infectious diseases 22, 933-935.

Laursen, N.S., and Wilson, I.A. (2013). Broadly neutralizing antibodies against influenza viruses. Antiviral research 98, 476-483.

Lessler, J., Chaisson, L.H., Kucirka, L.M., Bi, Q., Grantz, K., Salje, H., Carcelen, A.C., Ott, C.T., Sheffield, J.S., Ferguson, N.M., et al. (2016). Assessing the global threat from Zika virus. Science 353, aaf8160.

Li, M.Z., and Elledge, S.J. (2007). Harnessing homologous recombination in vitro to generate recombinant DNA via SLIC. Nature methods 4, 251-256.

Miner, J.J., and Diamond, M.S. (2017). Zika Virus Pathogenesis and Tissue Tropism. Cell host & microbe 21, 134-142.

Modis, Y., Ogata, S., Clements, D., and Harrison, S.C. (2003). A ligand-binding pocket in the dengue virus envelope glycoprotein. Proceedings of the National Academy of Sciences of the United States of America 100, 6986-6991.

Mouquet, H., Scharf, L., Euler, Z., Liu, Y., Eden, C., Scheid, J.F., Halper-Stromberg, A.,

Gnanapragasam, P.N., Spencer, D.I., Seaman, M.S., et al. (2012). Complex-type N-glycan recognition by potent broadly neutralizing HIV antibodies. Proceedings of the National Academy of Sciences of the United States of America 109, E3268-3277.

Mukherjee, S., Pierson, T.C., and Dowd, K.A. (2014). Pseudo-infectious reporter virus particles for measuring antibody-mediated neutralization and enhancement of dengue virus infection. Methods in molecular biology 1138, 75-97.

Mukhopadhyay, S., Kuhn, R.J., and Rossmann, M.G. (2005). A structural perspective of the flavivirus life cycle. Nature reviews Microbiology 3, 13-22.

Murray, K.O., Gorchakov, R., Carlson, A.R., Berry, R., Lai, L., Natrajan, M., Garcia, M.N., Correa, A., Patel, S.M., Aagaard, K., et al. (2017). Prolonged Detection of Zika Virus in Vaginal Secretions and Whole Blood. Emerging infectious diseases 23, 99-101.

Murray, N.E., Quam, M.B., and Wilder-Smith, A. (2013). Epidemiology of dengue: past, present and future prospects. Clinical epidemiology 5, 299-309. Pappas, L., Foglierini, M., Piccoli, L., Kallewaard, N.L., Turrini, F., Silacci, C., Fernandez- Rodriguez, B., Agatic, G., Giacchetto-Sasselli, I., Pellicciotta, G., et al. (2014). Rapid development of broadly influenza neutralizing antibodies through redundant mutations. Nature 516, 418-422. Pierson, T.C., and Graham, B.S. (2016). Zika Virus: Immunity and Vaccine Development. Cell 167, 625-631.

Pierson, T.C., Sanchez, M.D., Puffer, B.A., Ahmed, A.A., Geiss, B.J., Valentine, L.E., Altamura, L.A., Diamond, M.S., and Doms, R.W. (2006). A rapid and quantitative assay for measuring antibody-mediated neutralization of West Nile virus infection. Virology 346, 53-65.

Priyamvada, L., Quicke, K.M., Hudson, W.H., Onlamoon, N., Sewatanon, J., Edupuganti, S., Pattanapanyasat, K., Chokephaibulkit, K., Mulligan, M.J., Wilson, P.C., et al. (2016). Human antibody responses after dengue virus infection are highly cross-reactive to Zika virus. Proceedings of the National Academy of Sciences of the United States of America 113, 7852-7857.

Rey, F.A., Heinz, F.X., Mandl, C., Kunz, C., and Harrison, S.C. (1995). The envelope glycoprotein from tick-borne encephalitis virus at 2 A resolution. Nature 375, 291-298.

Rubelt, F., Sievert, V., Knaust, F., Diener, C., Lim, T.S., Skriner, K., Klipp, E., Reinhardt, R., Lehrach, H., and Konthur, Z. (2012). Onset of immune senescence defined by unbiased

pyrosequencing of human immunoglobulin mRNA repertoires. PloS one 7, e49774.

Sabin, A.B. (1950). The dengue group of viruses and its family relationships. Bacteriological reviews 14, 225-232.

Sabin, A.B. (1952). Research on dengue during World War II. The American journal of tropical medicine and hygiene 1, 30-50.

Sapparapu, G., Fernandez, E., Kose, N., Bin, C., Fox, J.M., Bombardi, R.G., Zhao, H., Nelson, C.A., Bryan, A.L., Barnes, T., et al. (2016). Neutralizing human antibodies prevent Zika virus replication and fetal disease in mice. Nature 540, 443-447.

Scheid, J.F., Mouquet, H., Feldhahn, N., Walker, B.D., Pereyra, F., Cutrell, E., Seaman, M.S., Mascola, J.R., Wyatt, R.T., Wardemann, H., et al. (2009). A method for identification of HIV gp140 binding memory B cells in human blood. Journal of immunological methods 343, 65-67.

Scheid, J.F., Mouquet, H., Ueberheide, B., Diskin, R., Klein, F., Oliveira, T.Y., Pietzsch, J., Fenyo, D., Abadir, A., Velinzon, K., et al. (2011). Sequence and structural convergence of broad and potent HIV antibodies that mimic CD4 binding. Science 333, 1633-1637.

Screaton, G., Mongkolsapaya, J., Yacoub, S., and Roberts, C. (2015). New insights into the immunopathology and control of dengue virus infection. Nature reviews Immunology 15, 745-759. Silva, M.M., Rodrigues, M.S., Paploski, I.A., Kikuti, M., Kasper, A.M., Cruz, J.S., Queiroz, T.L., Tavares, A.S., Santana, P.M., Araujo, J.M., et al. (2016). Accuracy of Dengue Reporting by National Surveillance System, Brazil. Emerging infectious diseases 22, 336-339.

Sirohi, D., Chen, Z., Sun, L., Klose, T., Pierson, T.C., Rossmann, M.G., and Kuhn, R.J. (2016). The 3.8 A resolution cryo-EM structure of Zika virus. Science 352, 467-470. Stettler, K., Beltramello, M., Espinosa, D.A., Graham, V., Cassotta, A., Bianchi, S., Vanzetta, F., Minola, A., Jaconi, S., Mele, F., et al. (2016). Specificity, cross-reactivity, and function of antibodies elicited by Zika virus infection. Science 353, 823-826.

Sui, J., Hwang, W.C., Perez, S., Wei, G., Aird, D., Chen, L.M., Santelli, E., Stec, B., Cadwell, G., Ali, M., et al. (2009). Structural and functional bases for broad-spectrum neutralization of avian and human influenza A viruses. Nature structural & molecular biology 16, 265-273.

Suy, A., Sulleiro, E., Rodo, C., Vazquez, E., Bocanegra, C., Molina, I., Esperalba, J., Sanchez-Seco, M.P., Boix, H., Pumarola, T., et al. (2016). Prolonged Zika Virus Viremia during Pregnancy. The New England journal of medicine 375, 2611-2613.

Swanstrom, J.A., Plante, J.A., Plante, K.S., Young, E.F., McGowan, E., Gallichotte, E.N., Widman, D.G., Heise, M.T., de Silva, A.M., and Baric, R.S. (2016). Dengue Virus Envelope Dimer Epitope Monoclonal Antibodies Isolated from Dengue Patients Are Protective against Zika Virus. mBio 7. Throsby, M., van den Brink, E., Jongeneelen, M., Poon, L.L., Alard, P., Cornelissen, L., Bakker, A., Cox, F., van Deventer, E., Guan, Y., et al. (2008). Heterosubtypic neutralizing monoclonal antibodies cross-protective against H5N1 and H1N1 recovered from human IgM+ memory B cells. PloS one 3, e3942.

Tiller, T., Meffre, E., Yurasov, S., Tsuiji, M., Nussenzweig, M.C., and Wardemann, H. (2008). Efficient generation of monoclonal antibodies from single human B cells by single cell RT-PCR and expression vector cloning. Journal of immunological methods 329, 112-124.

von Boehmer, L., Liu, C., Ackerman, S., Gitlin, A.D., Wang, Q., Gazumyan, A., and Nussenzweig, M.C. (2016). Sequencing and cloning of antigen-specific antibodies from mouse memory B cells. Nature protocols 11, 1908-1923.

Wahala, W.M., and Silva, A.M. (2011). The human antibody response to dengue virus infection. Viruses 3, 2374-2395.

Wang, Q., Yang, H., Liu, X., Dai, L., Ma, T., Qi, J., Wong, G., Peng, R., Liu, S., Li, J., et al. (2016). Molecular determinants of human neutralizing antibodies isolated from a patient infected with Zika virus. Science translational medicine 8, 369ra179.

Wardemann, H., Yurasov, S., Schaefer, A., Young, J.W., Meffre, E., and Nussenzweig, M.C. (2003). Predominant autoantibody production by early human B cell precursors. Science 301, 1374-1377. Weaver, S.C., Costa, F., Garcia-Blanco, M.A., Ko, A.I., Ribeiro, G.S., Saade, G., Shi, P.Y., and Vasilakis, N. (2016). Zika virus: History, emergence, biology, and prospects for control. Antiviral research 130, 69-80.

Weaver, S.C., and Reisen, W.K. (2010). Present and future arboviral threats. Antiviral research 85, 328-345.

West, A.P., Jr., Diskin, R., Nussenzweig, M.C., and Bjorkman, P.J. (2012). Structural basis for germ- line gene usage of a potent class of antibodies targeting the CD4-binding site of HIV-1 gp120.

Proceedings of the National Academy of Sciences of the United States of America 109, E2083-2090. West, A.P., Jr., Scharf, L., Horwitz, J., Klein, F., Nussenzweig, M.C., and Bjorkman, P.J. (2013). Computational analysis of anti-HIV-1 antibody neutralization panel data to identify potential functional epitope residues. Proceedings of the National Academy of Sciences of the United States of America 110, 10598-10603.

Winn, M.D., Ballard, C.C., Cowtan, K.D., Dodson, E.J., Emsley, P., Evans, P.R., Keegan, R.M., Krissinel, E.B., Leslie, A.G., McCoy, A., et al. (2011). Overview of the CCP4 suite and current developments. Acta crystallographica Section D, Biological crystallography 67, 235-242.

Wrammert, J., Koutsonanos, D., Li, G.M., Edupuganti, S., Sui, J., Morrissey, M., McCausland, M., Skountzou, I., Hornig, M., Lipkin, W.I., et al. (2011). Broadly cross-reactive antibodies dominate the human B cell response against 2009 pandemic H1N1 influenza virus infection. The Journal of experimental medicine 208, 181-193.

Ye, J., Ma, N., Madden, T.L., and Ostell, J.M. (2013). IgBLAST: an immunoglobulin variable domain sequence analysis tool. Nucleic acids research 41, W34-40.

Yurasov, S., Wardemann, H., Hammersen, J., Tsuiji, M., Meffre, E., Pascual, V., and Nussenzweig, M.C. (2005). Defective B cell tolerance checkpoints in systemic lupus erythematosus. The Journal of experimental medicine 201, 703-711.

Zhang, Y., Zhang, W., Ogata, S., Clements, D., Strauss, J.H., Baker, T.S., Kuhn, R.J., and

Rossmann, M.G. (2004). Conformational changes of the flavivirus E glycoprotein. Structure 12, 1607-1618.

Zhou, T., Georgiev, I., Wu, X., Yang, Z.Y., Dai, K., Finzi, A., Kwon, Y.D., Scheid, J.F., Shi, W., Xu, L., et al. (2010). Structural basis for broad and potent neutralization of HIV-1 by antibody VRC01. Science 329, 811-81.

       

     

   

   

                                                                       

 

                                         

                               

 

 

 

                                     

       

   

                                                                       

                   

                                                         

                                           

   

                                                                                 

   

 

                                 

                   

                     

                               

 

                                                                                     

   

   

                                                   

     

     

             

                   

     

 

                               

                                   

                                   

                       

 

                                                                                                                                                                                       

  Contacts are defined as residues in which any atom is within 4 Å of an atom from a residue on the interacting partner using AntibodyDatabase (West et al., 2013). Table 6 is organized by antibody residue, listing all antigen residues contacted by each antibody residue (ordered by contact distance). Antibody residues are highlighted when corresponding interactions occur in both complexes. For the highlighted interactions additional information is listed including the antibody residue’s origin in V(D)J recombination and the residue distribution at that antibody position in the sequenced antibody clones. Example 3

This Example extends the disclosure of Examples 1 and 2 above. Zika virus (ZIKV) infection causes severe neurologic complications and fetal aberrations ¹ . As discussed in Examples 1 and 2, human monoclonal antibody Z004 is a VH3-23/VK1-5 antibody that recognizes the lateral ridge of the Envelope Domain III (EDIII) of ZIKV, is a potent neutralizer in vitro, and prevents disease in mice. In this Example we demonstrate that when Z004 is administered to macaques for prophylaxis, it leads to emergence of resistant ZIKV variants bearing mutations in the antibody target site. As discussed above, Z021 has a structure in complex with the antigen that reveals a distinct although overlapping epitope on EDIII. Z021 potently neutralizes ZIKV in vitro and prevents disease in mice. This Example shows that in a clinically relevant macaque model, prophylactic co-administration of Z004 with Z021 is protective and suppresses emergence of resistant variants. Thus, a combination of two potent human monoclonal antibodies to EDIII is sufficient to suppress infection and thwart viral escape in macaques, a natural host for ZIKV. In more detail, to determine whether human monoclonal antibodies are efficacious against ZIKV in primates, who are natural hosts for infection, we administered Z004 to rhesus macaques 24 hours before intravenous challenge with high dose (10 ⁵ PFU) of a Brazilian strain of ZIKV. Infection was monitored by PCR to detect viral RNA in the plasma (Fig. 11a). All four control animals developed viremia, which peaked on day 3 with plasma viral loads ranging between 10 ⁵ -10 ⁷ RNA copies/ml (Fig.11a, in black). Similar to previous reports, viremia cleared spontaneously beginning on day 7 (Fig.11a, and ¹⁹ ). In contrast, viremia was either undetectable or below 10 ⁴ RNA copies/ml in the Z004-treated macaques on day 3. However, the Z004-treated macaques showed delayed viremia peaking on day 7-10 at 3x10 ² -5x10 ⁵ RNA copies/ml (Fig.11a, in grey). Thus, Z004 alone alters the course of ZIKV infection and leads to prolonged but lower levels of viremia. To determine whether the viremia in Z004-treated animals was associated with viral escape mutations, we sequenced the EDIII from the virus found in the plasma of the treated macaques on day 7 and 10. In both animals the circulating viruses carried mutations in the Z004 target site; K394R in one animal and E393D or K394R in the other (Fig.11b and 11c). We were unable to find these mutant viruses at earlier time points in the same animals, in untreated controls, or in the inoculum (data not shown). While D393 is present in ZIKV strains of African origin, no ZIKV sequences with R394 were found out of 704 ZIKV sequences that were analyzed (ViPR database, October 9, 2017). ELISA assays using ZIKV EDIIIE393D and EDIIIK394R mutant proteins confirmed that these mutations interfere with Z004 binding (Fig.11d). In contrast to the macaque, antibody resistance mutations were rare in Ifnar1 ^-/- mice treated with Z004; nevertheless, the only mouse that developed mutations had the same K394R as observed in macaque (n=8; Fig.17). Therefore, when administered prophylactically to macaques prior to a high-dose intravenous ZIKV inoculation, Z004 selects for resistant viral mutants. We tested whether a second antibody could help prevent the development of resistance. Z021 is a human monoclonal antibody that, like Z004, was isolated from an individual with exceptional serum neutralizing activity against ZIKV ⁵ . Z021 binds to the EDIII of both ZIKV and DENV1, it neutralizes ZIKV reporter viral particles (RVPs) bearing Asian/American or African lineage E proteins with an IC50 of 1 ng/ml and 0.7 ng/ml, respectively (Fig.12 and Fig.18), and has strong activity in plaque reduction neutralization assays using an infectious Puerto Rican strain of ZIKV (PRNT; IC50 of 4 ng/ml, Fig.12a). Z021 is also a potent neutralizer of DENV1 (IC50 of 10.1 ng/ml; Fig.12b). To determine whether Z021 neutralizes ZIKV in vivo, we administered Z021 to Ifnar1 ^-/- mice either 24 hours before or 24 hours after ZIKV challenge (Fig.12c). Whereas 100% of control mice developed symptoms and died (n=11, Fig.12d), only 15% did so when Z021 was administered before infection (n=13; p=0.0002 for disease and p<0.0001 for survival; Fig. 12d). Moreover, only 42% developed symptoms and 33% succumbed to disease when the antibody was administered 1 day after infection (n=12; p=0.0006 for disease and p=0.0002 for survival; Fig.12e). Thus, Z021 is efficacious against ZIKV in vitro and in Ifnar1 ^-/- mice. Z004 binding and neutralization of ZIKV and DENV1 is dependent on ZIKV EDIII residue K394 and also partially dependent on E393 (DENV1 residues K385 and E384, respectively; Fig.11d and ⁵ ). To determine whether Z004 and Z021 recognize distinct neutralizing epitopes on EDIII, we performed ELISA assays (Fig.13a and see Methods of this Example). Each monoclonal antibody was incubated with saturating amounts of either wild type ZIKV EDIII, or an EDIII bearing mutations in the Z004 target site that interfere with its binding and neutralizing activity (EDIIIE393A/K394A). Residual binding to wild type EDIII was measured by ELISA. Whereas, Z004 binding to ZIKV EDIII was only blocked by wild type ZIKV EDIII, binding of Z021 was blocked by both wild type and ZIKV EDIII _E393A/K394A , indicating that residues E393 and K394 are critical for Z004 but dispensable for Z021 binding (Fig.13a). In agreement with this finding, Z004 failed to neutralize ZIKV RVPs that were altered to bear the E393A/K394A mutations but Z021 remained active against the mutant RVPs in vitro (Fig.13b). To determine whether the Z004 and Z021 epitopes overlap, we performed competition ELISA assays, which showed that Z004 prevented binding by Z021, and vice- versa (Fig.13c and see Methods of this Example). Thus, Z021 binds to a neutralizing epitope on the EDIII that does not require E393/K394 but is close to or overlapping with the epitope recognized by Z004. Structural analysis of Z004 and of the related VH3-23/VK1-5 antibody Z006 with the EDIII of DENV1 and ZIKV, respectively, revealed that VH3-23/VK1-5 antibodies bind to these two different flaviviruses in a very similar manner, with E393/K394ZIKV and E384/K385DENV1 being central to the epitope ⁵ . To gain structural insights into how Z021 recognizes its epitope, we crystallized Z021 in complex with the EDIII of ZIKV and of DENV1 (Fig.14). Z021 recognizes the EDIII of both flaviviruses in a similar fashion, and makes no contacts with the E393/K394 _ZIKV and E384/K385 _DENV1 residues (Fig.14a). Similar to Z004, Z021 recognizes the lateral ridge region of DENV1 EDIII, but its epitope is distinct. Compared to the Z004 Fab, the Z021 Fab is rotated ~48º around an axis near the complementarity determining region 2 (CDRH2), positioning the heavy chains in similar regions, while the light chains exhibit divergent footprints (Fig.14b). Z021 uses both its heavy and light chains to contact the N-terminal region and the BC loop of DENV EDIII, makes light chain contacts to the DE loop, and heavy chain contacts to the FG loop. Notably, when compared to Z004 Fab, Z021 Fab makes unique contacts to the N-terminal region of DENV1 EDIII and shows no ordered contacts with K385DENV1 (Fig.14c). Thus, consistent with the ELISA and neutralization results (Fig.13), Z021 recognizes a distinct but overlapping epitope on EDIII from that of Z004. Since Z021 binding and neutralizing activity is resistant to mutations in EDIII E393 and K394, and its epitope is distinct from Z004 (Figs.13 and 14), we co-administered the two antibodies to macaques 24 hours before challenge with ZIKV. Two out of three macaques developed low viremia, with approximately 10 ² or lower RNA copies/ml at around day 5 or 13 after infection. The third macaque developed viremia below 10 ³ RNA copies/ml starting on day 13 (Fig.15). Viremia was not a consequence of rapid clearance of Z004 and Z021, as high levels of human antibodies were detectable in the macaque plasma (Fig.19). In contrast to macaques treated with Z004 alone (Fig.11), no mutations in the EDIII region of the circulating virus were detected in animals treated with the combination of Z004 with Z021 (data not shown). We conclude that treatment of non-human primates with the combination of Z004 and Z021, two antibodies that target distinct but overlapping epitopes, suppresses and delays viremia and prevents the emergence of ZIKV escape mutants upon high-dose intravenous ZIKV challenge. Viremia in the absence of viral escape could result from antibody Z004 and Z021 promoting ZIKV infection through antibody-dependent enhancement (ADE). ADE depends on the ability of antibodies to engage Fc-gamma receptors. We modified the fragment crystallizable (Fc) region of both antibodies to preclude Fc-gamma receptor binding (GRLR or GRLR/LS mutations. These modifications prevented Fc binding and ADE in vitro, while maintaining neutralization potentcy against ZIKV in vitro and in mice (Figs.20 and 21). To determine whether the late-onset low-level plasma viremia of macaques treated with the combination of Z004 and Z021 was dependent on Fc-gamma receptors, we administered to macaques Z004- GRLR and Z021-GRLR antibodies and challenged them with ZIKV. Human antibody levels were comparable in macaques treated with the wild type or GRLR version of Z004 and Z021 (Fig.19). Low plasma viremia was detected in all three animals (Fig.15): one macaque had a single viral blip less than 10 ² RNA copies/ml on day 3, one had viremia below 10 ³ RNA copies/ml between days 2-4, and one was viremic between days 6-13 (peak viremia of 10 ⁴ RNA copies/ml). No mutations were identified in the EDIII region of the emerging viruses. We conclude that the low-level viremia that develops in the presence of Z004 and Z021 is not dependent on Fc-gamma receptor engagement. The most common mean of ZIKV transmission is through the bite of an infected mosquito. To determine whether the combination of Z004-GRLR and Z021-GRLR was protective against subcutaneous challenge, we infected macaques with 10 ³ PFU of a Puerto Rican strain of ZIKV by this route. As the size of the inoculum during mosquito feeding is uncertain, we chose this dose of virus because it is similar to recent vaccination experiments in non-human primates ^18,20,21 . None of the challenged macaques developed viremia during the observation period (Figure 16). Without intending to be bound by any particular viewpoint, we conclude that combining Z004-GRLR with Z021-GRLR prevents viremia altogether after

subcutaneous infection with ZIKV. Those skilled in the art will recognize that although the error rate of the ZIKV polymerase has not been determined, flaviviruses are RNA viruses that are generally assumed to undergo high rates of error prone replication thereby producing mutant forms that can be selected for antibody resistance ^29‐31 . Antibody evasion by flaviviruses such as DENV ^32-34 , WNV ^35,36 , YFV ³⁷ , Japanese encephalitis virus ³⁸ , tick-borne encephalitis virus ³⁹ , and recently ZIKV ⁴⁰ , has been amply documented using cell culture experiments. Resistant virus also emerged upon administration of a single monoclonal antibody to mice challenged with WNV ⁴¹ or to Rhesus monkeys challenged with DENV ^42,43 . In macaques, a combination of 3 antibodies (including 2 VH3-23/VK1-5 antibodies) is effective against subcutaneous challenge with 10 ³ PFU of ZIKV ¹⁸ , but whether escape occurs with single antibodies, or whether fewer than 3 antibodies might be sufficient to protect was not determined. The present disclosure demonstrates that in contrast to in Ifnar1 ^-/- mice escape is a significant problem upon challenge with 10 ⁵ PFU of ZIKV in single-antibody treated primates, which are a natural host for the virus. Moreover, it is demonstrated herein that prophylaxis with 2 antibodies to the EDIII is sufficient to prevent escape. The Z004 and Z021 antibodies share a number of important features including potent neutralizing activity against both ZIKV and DENV1 but no binding to any of the other flaviviruses tested ⁵ . The overlapping activity can be attributed to distinct but overlapping target sites. Although the epitopes are similar, Z021 makes unique contacts to the N-terminal region of DENV1 EDIII with both its heavy and light chains, while Z004 makes more extensive contacts to the FG loop, including the E384/K385DENV1 motif. Because the

E384/K385 _DENV1 motif is peripheral to the Z021 epitope, viruses with mutations at these positions will likely remain sensitive to Z021. These differences account for the efficacy of the combination of the two antibodies despite the similarities in their target sites. Method for this Example.

Reagents.

Antibodies. Z021, Z004, Z015 and 10-1074 were prepared by transient transfection of mammalian HEK-293-6E cells and purified as previously described ⁵ . LPS was removed with TritonX-114 and the antibodies concentrated to 4.6 to 19 mg/ml in PBS. The GRLR, LS and combined (GRLR/LS) modifications in the Fc portion of Z004 and Z021 human IgG1 expression plasmids were generated with Q5 site-directed mutagenesis kit (New England Biolabs) according to the company’s instructions and primers: DFRp1455

Virus. For in vitro experiments, ZIKV 2015 Puerto Rican PRVABC59 ⁴⁴ was obtained from the CDC and passaged twice in human Huh-7.5 cells, and the Thai isolate of DENV1 PUO- 359 (TVP-1140) was obtained from Robert Tesh and amplified by three passages in C6/36 insect cells. For mouse experiments, ZIKV 2015 Puerto Rican PRVABC59 was passaged once in STAT1 ^-/- human fibroblasts. For macaque experiments, a 2015 isolate of ZIKV from Brazil (strain Zika virus/H.sapiens-tc/BRA/2015/Brazil_SPH2015; genbank accession number KU321639.1) was used. The strain was isolated from the plasma of a transfusion recipient and was passaged twice in mycoplasma free Vero cells. The Puerto Rican ZIKV strain (PRVABC59; KU501215) was used for subcutansous challenge. Virus titration was as previously described ^5,19 .

Reporter viral particles (RVPs). Wild type ZIKV RVPs with E proteins corresponding to Asian/American or African lineage were previously reported ⁵ . A plasmid for expression of ZIKV CprME with E393A/K394A mutations was generated from plasmid

pZIKV/HPF/CprM*E* ⁵ , a derivative of pZIKV/HPF/CprME, a ZIKV C-prM-E expression construct provided by Ted Pierson (NIH), engineered to contain unique BspHI and SacII restriction sites flanking the envelope region, allowing facile manipulation. Assembly PCR- based site-directed mutagenesis was used to introduce the E393A/K394A double mutation into the envelope of ZIKV H/PF/2013 in pZIKV/HPF/CprM*E*, resulting in plasmid pZIKV/HPF/CprME(E393A/K394A). All PCR-derived plasmid regions were verified by sequencing. Primers used for assembly PCR and mutagenesis were: Forward outer (RU-O- 24379)

1048). RVPs bearing the ZIKV E protein with E393A/K394A mutations were generated by cotransfection of Lenti-X-293T cells with plasmids pZIKV/HPF/CprME(E393A/K394A) and pWNVII-Rep-REN-IB ⁴⁵ as previously described ⁵ .

EDIII proteins. Expression plasmids encoding the ZIKV mutant proteins EDIII _E393A/K394A , EDIIIE393D and EDIIIK394R were generated by QuikChange site-directed mutagenesis (Agilent Technologies) and confirmed by DNA sequencing. Primers used for mutagenesis are the following: E393A/K394A 5’

Mutant ZIKV EDIII proteins were expressed in E. coli, refolded from inclusion bodies, and purified as described previously ^5,13 . Animal care and experiments.

Mice. Interferon- ^ ^ receptor knock-out mice were obtained from The Jackson Laboratory (Ifnar1 ^-/- ; B6.129S2-Ifnar1 ^tm1Agt /Mmjax) and were bred and maintained in the animal facility at the Rockefeller University. Mice were specific pathogen free and on a standard chow diet. Both male and female mice (3-4 week old) were used for experiments and were equally distributed within experimental and control groups.125 ^g of monoclonal antibodies in 200 ^l of PBS were administered intraperitoneally to Ifnar1 ^-/- mice one day before or one day after footpad infection with 1.25x10 ⁵ plaque forming units (PFU) of ZIKV Puerto Rican strain in 50 ^l. Mice were monitored for symptoms and survival over time. Animal protocols were in agreement with NIH guidelines and approved by the Rockefeller University

Institutional Animal Care and Use Committee.

Macaques. Macaques were from the conventional colony at the California National Primate Research Center (CNPRC), and were type D retrovirus-free, SIV-free and simian lymphocyte tropic virus type 1 antibody negative. Animals were housed in accordance with Association for Assessment and Accreditation of Laboratory Animal Care Standards. We strictly adhered to Guide for the Care and Use of Laboratory Animals prepared by the Institute for

Laboratory Animal Research. The study was approved by the Institutional Animal Care and Use Committee of the University of California Davis. Z004 and Z021 antibodies were administered to macaques at doses of 15 mg/kg body weight each by slow intravenous (i.v.) infusion (2ml/minute) 24 hours before saphenous vein i.v. inoculation with ZIKV Brazilian strain (10 ⁵ PFU in 1 ml of RPMI-1640 medium). Macaques were evaluated twice daily for clinical signs of disease including poor appetence, stool quality, dehydration, diarrhea, and inactivity. When necessary, macaques were immobilized with 10 mg/kg ketamine

hydrochloride (Parke-Davis) injected intramuscularly after overnight fasting. Animals were sedated at time zero (time of virus inoculation), daily for 7 to 8 days, and then every few days for sample collection. EDTA-anti-coagulated blood samples were collected using

venipuncture. Complete blood counts and separation of plasma for cryopreservation of aliquots were performed as described earlier ¹⁹ . Neutralization and ADE assays in vitro.

Plaque reduction neutralization test with ZIKV PRVABC59, and flow cytometry-based neutralization assay with DENV1 PUO-359 were used to measure antibody neutralization activity in Vero cells, as described ⁵ . Neutralization of luciferase-encoding RVPs by antibodies using the ZIKV wild type, E393A/K394A, and African mutant RVPs was performed as previously described ⁵ . Antibody dependent enhancement (ADE) assays using antibodies or macaque plasma were similar to neutralization assays with RVPs, except that Fc-receptor bearing K562 cells were used, and that the cells were in 96-well plates coated with 0.01% poly-L-lysine (Sigma). ELISA assays.

ELISA after antibody blocking. Serial dilutions of Z004 or Z021 antibody were incubated overnight with nutation at 4ºC in V-bottom 96-well plates in the presence of saturating concentrations of either wild type EDIII, EDIIIE393A/K394A, or no protein control. In

preliminary experiments, the saturating concentration of EDIII protein was determined as being approximately 1 ^g/ml, and was increased to 10 ^g/ml for the actual experiment. After overnight incubation the samples were added to ELISA plates that had been pre-coated with wild type EDIII and the residual antibody binding to EDIII was detected as previously described ⁵ , with the exception that the signal was enhanced by two amplification steps. First, after incubating with goat anti-human IgG-HRP (Jackson ImmunoResearch Cat# 109-035- 098; 1 hour, room temperature) and washing with PBS containing Tween-200.05%, anti-goat IgG-biotin was added (Jackson ImmunoResearch Cat# 705-065-147; 1 hour, room

temperature). Second, after washing, streptavidin-HRP was added (Jackson ImmunoResearch Cat# 016-030-084; 1 hour, room temperature). After the final washes, the reaction was developed with ABTS substrate (Life Technologies).

Competition ELISA. Z004 or Z021 IgG (5 ^g/mL) was adsorbed overnight at 4ºC in a Nunc MaxiSorp 384-well ELISA plate. The ELISA plate was blocked with 3% bovine serum albumin (BSA) in TRIS buffered saline with 0.05% Tween-20 (TBS–T), and then 5 ^g/mL EDIII (ZIKV EDIII or DENV1 EDIII) was added and incubated for 3 hours at room temperature. The plate was washed with TBS-T to remove excess antigen, and serial dilutions of Fab were then added and incubated for 3 hours at room temperature. Bound His-tagged Fab was detected using THE His Tag Antibody (Genscript Cat # A00186; 1 hour, room temperature), followed by goat-anti mouse IgG-HRP (Jackson ImmunoResearch Cat# 115- 035-003; 1 hour, room temperature), and developed with SuperSignal ELISA Femto

Substrate (Thermo Fisher). Relative light units (RLU) were plotted as a function of Fab concentration for each IgG-antigen pair.

Fab ELISA.5 ^g/mL EDIII antigen (WT ZIKV EDIII, E393A/K394A ZIKV EDIII, E393D ZIKV EDIII, or K394R ZIKV EDIII) was adsorbed to a Nunc MaxiSorp 384-well ELISA plate overnight at 4ºC. The ELISA plate was blocked with 3% BSA in TBS-T, washed with TBS-T, and then serial dilutions of Fab were added and incubated for 3 hours at room temperature. After washing the plate with TBS-T, bound Fab was detected using goat-anti- human IgG-HRP (GenScript Cat# A00166; 1 hour, room temperature) and developed with SuperSignal ELISA Femto Substrate (Thermo Fisher). ELISA for human IgG detection in macaque plasma. Neutravidin (ThermoScientific 31000; 2 ^g/ml in PBS) was absorbed to high binding 96-well plates for overnight at 4ºC. After washing the plate using PBS with 0.05% Tween-20 (PBS-T), the biotinylated anti-human IgG capture antibody was added (ThermoScientific 7103322100; 2 ^g/ml in PBS-T, 1 hour at room temperature). Upon washes, the plates were blocked with 2% BSA in PBS-T (2 hours at room temperature), blotted, and then serial dilutions of the macaque plasma were added to the wells (5 steps of 1:4 dilutions in PBS-T, starting with 1:10). Each plate included two dilution series of the standard (Z004 IgG, 11 steps of 1:3 dilutions in PBS-T, starting with 10 ^g/ml). Plates were incubated for 1 hour at room temperature and washed prior to adding the detection reagent anti-human IgG-HRP (Jackson Immunoresearch 109-036-088; 1 hour at room temperature). After the final washes, the reaction was developed with ABTS substrate (Life Technologies). Surface Plasmon Resonance.

FcγR and FcRn binding affinity of the Z004 Fc domain variants was determined by surface plasmon resonance (SPR), using previously described protocols ^46,47 . All experiments were performed on a Biacore T200 SPR system (GE Healthcare) at 25 ^o C in HBS-EP ⁺ buffer (GE Healthcare; pH 7.4 for FcγRs, pH 6.0 for FcRn). Recombinant protein G (Thermo Fisher) was immobilized to the surface of a CM5 sensor chip (GE Healthcare) using amine coupling chemistry at a density of 500 resonance units (RU). Fc variants of the Z004 antibody were captured on the Protein G-coupled surface (250 nM injected for 60s at 20 μl/min) and recombinant human FcγR ectodomains (7.8125– 2000 nM; Sinobiological) or FcRn/β2 microglobulin (1.95– 500 nM; Sinobiological) were injected through flow cells at a flow rate of 20 μl/min. Association time was 60 s followed by a 600-s dissociation step. At the end of each cycle, the sensor surface was regenerated with 10 mM glycine, pH 2.0 (50 μl/min; 40 s). Background binding to blank immobilized flow cells was subtracted and affinity constants were calculated using BIAcore T200 evaluation software (GE Healthcare) using the 1:1 Langmuir binding model. Crystallization and structure determination.

Crystallization and structure determination. The complex for crystallization was produced by mixing Z021 Fab and DENV1 EDIII at a 1:1 molar ratio, incubating at room temperature for 1-2 hours, and concentrating to 12.25 mg/mL. Crystals of Z021 Fab–DENV1 EDIII complex (space group C2221; a = 60.54 Å, b = 91.60 Å, c = 187.14 Å; one molecule per asymmetric unit) were obtained by combining 0.2 μL of crystallization sample with 0.2 μL of 0.1M sodium citrate pH 4.8, 28% Jeffamine® ED-2001 pH 7.0 in sitting drops at 22ºC. Crystals were cryoprotected with Fomblin Y oil.

X-ray diffraction data were collected at Stanford Synchrotron Radiation Lightsource (SSRL) beamline 12-2 using a Dectris Pilatus 6M detector. The data were integrated using Mosflm ⁴⁸ and scaled using CCP4 ⁴⁹ . The Z021-DENV1 DIII complex structure was solved by molecular replacement using the VHVL and CHCL domains from PDB 4YK4 and DENV1 DIII from PDB 4L5F as search models in Phenix ⁵⁰ . The model was refined to 2.07 Å resolution using an iterative approach involving refinement in Phenix and manual rebuilding into a simulated annealing composite omit map using Coot ⁵¹ . The final model (Rwork = 18.8%; R _free = 23.0%) contains 532 protein residues and 120 water molecules.95%, 4%, and 1% of the protein residues were in the favored, allowed, and disallowed regions, respectively, of the Ramachandran plot. Residues that were disordered and not included in the model were: HC residues 215-219 and the 6X His tag; LC residues 1 and 213-214. Isolation and quantitation of viral RNA.

Zika virus RNA was isolated from plasma and measured by qRT-PCR according to methods described previously ⁵² and modified to increase the initial volume of sample tested from 140 to 300 ^l (when available) to increase sensitivity. The limit of detection for plasma viral RNA copies was typically 1.1 log10. Virus sequencing

For detection of virus escape mutations in macaques, ZIKV RNA was extracted from plasma using the Qiaamp viral RNA mini kit following the manufacturer’s recommendations with elution of RNA in water. Qiagen One-Step RT-PCR was performed using either of 2 primer sets targeting sequences surrounding the ZIKV EDIII region: 1618p

Next, 40 cycles of each of the 3 steps were performed: 94°C for 1 m, 58°C for 1 m, 72°C for 1m15°s, followed by final extension of 72°C for 10 m. RT-PCR amplicons were visualized on 1% agarose gels stained with ethidium bromide and sequenced after purification using the Qiaquick PCR purification kit. Sequences were called based on clean chromatograms sequenced with the primers used for amplification. Viral sequences in mice were from blood. RNA was extracted from TRIzol-LS (Life Technologies) and reverse transcribed with Superscript III RT (Thermo Fisher Scientific) and random primers according to the company’s protocol prior to PCR amplification of the ZIKV EDIII region with primers DFRp12845’GGATGATCGTTAATGACACAG (SEQ ID NO: 1056) and DFRp1469 5’ACCATCTTCCCAGGCTTG (SEQ ID NO: 1057) followed by PCR clean-up with Nucleospin (Macherey-Nagel) and direct sequencing with primer DFRp1283

5’GGATCCTGATTTGAAAGCTGC (SEQ ID NO: 1058). Where necessary, a second round of nested PCR was performed with primers DFRp14725’TTCCACGACATTCCATTACC (SEQ ID NO: 1059) and DFRp14705’ATCTACGGGGGGAGTCAGGATG (SEQ ID NO: 1060). References cited for this Example. This reference listing is not an indication that any of the references are material to patentability of any invention encompassed by this disclosure 1 Miner, J. J. & Diamond, M. S. Zika Virus Pathogenesis and Tissue Tropism. Cell host & microbe 21, 134-142, doi:10.1016/j.chom.2017.01.004 (2017).

2 Harrison, S. C. Immunogenic cross-talk between dengue and Zika viruses. Nature immunology 17, 1010-1012, doi:10.1038/ni.3539 (2016).

3 Screaton, G. & Mongkolsapaya, J. Which Dengue Vaccine Approach Is the Most Promising, and Should We Be Concerned about Enhanced Disease after Vaccination? The Challenges of a Dengue Vaccine. Cold Spring Harbor perspectives in biology, doi:10.1101/cshperspect.a029520 (2017).

4 Heinz, F. X. & Stiasny, K. The Antigenic Structure of Zika Virus and Its Relation to Other Flaviviruses: Implications for Infection and Immunoprophylaxis. Microbiology and molecular biology reviews : MMBR 81, doi:10.1128/MMBR.00055-16 (2017). 5 Examples 1 and 2 of this disclosure.

6 Weaver, S. C. & Reisen, W. K. Present and future arboviral threats. Antiviral research 85, 328-345, doi:10.1016/j.antiviral.2009.10.008 (2010).

7 Munoz, L. S., Barreras, P. & Pardo, C. A. Zika Virus-Associated Neurological

Disease in the Adult: Guillain-Barre Syndrome, Encephalitis, and Myelitis. Seminars in reproductive medicine 34, 273-279, doi:10.1055/s-0036-1592066 (2016). 8 Brasil, P. et al. Zika Virus Infection in Pregnant Women in Rio de Janeiro. The New England journal of medicine 375, 2321-2334, doi:10.1056/NEJMoa1602412 (2016). 9 Del Campo, M. et al. The phenotypic spectrum of congenital Zika syndrome.

American journal of medical genetics. Part A 173, 841-857,

doi:10.1002/ajmg.a.38170 (2017).

10 George, J. et al. Prior Exposure to Zika Virus Significantly Enhances Peak Dengue-2 Viremia in Rhesus Macaques. Scientific reports 7, 10498, doi:10.1038/s41598-017- 10901-1 (2017).

11 Katzelnick, L. C. et al. Antibody-dependent enhancement of severe dengue disease in humans. Science 358, 929-932, doi:10.1126/science.aan6836 (2017).

12 Stettler, K. et al. Specificity, cross-reactivity, and function of antibodies elicited by Zika virus infection. Science 353, 823-826, doi:10.1126/science.aaf8505 (2016). 13 Sapparapu, G. et al. Neutralizing human antibodies prevent Zika virus replication and fetal disease in mice. Nature 540, 443-447, doi:10.1038/nature20564 (2016).

14 Fernandez, E. et al. Human antibodies to the dengue virus E-dimer epitope have therapeutic activity against Zika virus infection. Nature immunology,

doi:10.1038/ni.3849 (2017).

15 Swanstrom, J. A. et al. Dengue Virus Envelope Dimer Epitope Monoclonal

Antibodies Isolated from Dengue Patients Are Protective against Zika Virus. mBio 7, doi:10.1128/mBio.01123-16 (2016).

16 Yu, L. et al. Delineating antibody recognition against Zika virus during natural

infection. JCI insight 2, doi:10.1172/jci.insight.93042 (2017).

17 Beltramello, M. et al. The human immune response to Dengue virus is dominated by highly cross-reactive antibodies endowed with neutralizing and enhancing activity. Cell host & microbe 8, 271-283, doi:10.1016/j.chom.2010.08.007 (2010).

18 Magnani, D. M. et al. Neutralizing human monoclonal antibodies prevent Zika virus infection in macaques. Science translational medicine 9,

doi:10.1126/scitranslmed.aan8184 (2017).

19 Coffey, L. L. et al. Zika Virus Tissue and Blood Compartmentalization in Acute Infection of Rhesus Macaques. PloS one 12, e0171148,

doi:10.1371/journal.pone.0171148 (2017).

20 Larocca, R. A. et al. Vaccine protection against Zika virus from Brazil. Nature 536, 474-478, doi:10.1038/nature18952 (2016). 21 Dowd, K. A. et al. Rapid development of a DNA vaccine for Zika virus. Science 354, 237-240, doi:10.1126/science.aai9137 (2016).

22 Whitehead, S. S. & Subbarao, K. Which Dengue Vaccine Approach Is the Most

Promising, and Should We Be Concerned about Enhanced Disease after Vaccination? The Risks of Incomplete Immunity to Dengue Virus Revealed by Vaccination. Cold Spring Harbor perspectives in biology, doi:10.1101/cshperspect.a028811 (2017). 23 Halstead, S. B. Which Dengue Vaccine Approach Is the Most Promising, and Should We Be Concerned about Enhanced Disease after Vaccination? There Is Only One True Winner. Cold Spring Harbor perspectives in biology,

doi:10.1101/cshperspect.a030700 (2017).

24 de Silva, A. M. & Harris, E. Which Dengue Vaccine Approach Is the Most Promising, and Should We Be Concerned about Enhanced Disease after Vaccination? The Path to a Dengue Vaccine: Learning from Human Natural Dengue Infection Studies and Vaccine Trials. Cold Spring Harbor perspectives in biology,

doi:10.1101/cshperspect.a029371 (2017).

25 Horton, H. M. et al. Potent in vitro and in vivo activity of an Fc-engineered anti- CD19 monoclonal antibody against lymphoma and leukemia. Cancer research 68, 8049-8057, doi:10.1158/0008-5472.CAN-08-2268 (2008).

26 Lu, C. L. et al. Enhanced clearance of HIV-1-infected cells by broadly neutralizing antibodies against HIV-1 in vivo. Science 352, 1001-1004,

doi:10.1126/science.aaf1279 (2016).

27 Zalevsky, J. et al. Enhanced antibody half-life improves in vivo activity. Nature

biotechnology 28, 157-159, doi:10.1038/nbt.1601 (2010).

28 Ko, S. Y. et al. Enhanced neonatal Fc receptor function improves protection against primate SHIV infection. Nature 514, 642-645, doi:10.1038/nature13612 (2014).

29 Elena, S. F., Miralles, R., Cuevas, J. M., Turner, P. E. & Moya, A. The two faces of mutation: extinction and adaptation in RNA viruses. IUBMB life 49, 5-9,

doi:10.1080/713803585 (2000).

30 Drake, J. W., Charlesworth, B., Charlesworth, D. & Crow, J. F. Rates of spontaneous mutation. Genetics 148, 1667-1686 (1998).

31 Diamond, M. S. Evasion of innate and adaptive immunity by flaviviruses.

Immunology and cell biology 81, 196-206, doi:10.1046/j.1440-1711.2003.01157.x (2003). 32 Lin, B., Parrish, C. R., Murray, J. M. & Wright, P. J. Localization of a neutralizing epitope on the envelope protein of dengue virus type 2. Virology 202, 885-890, doi:10.1006/viro.1994.1410 (1994).

33 Lok, S. M., Ng, M. L. & Aaskov, J. Amino acid and phenotypic changes in dengue 2 virus associated with escape from neutralisation by IgM antibody. Journal of medical virology 65, 315-323 (2001).

34 Zou, G. et al. Resistance analysis of an antibody that selectively inhibits dengue virus serotype-1. Antiviral research 95, 216-223, doi:10.1016/j.antiviral.2012.06.010 (2012).

35 Beasley, D. W. & Barrett, A. D. Identification of neutralizing epitopes within

structural domain III of the West Nile virus envelope protein. Journal of virology 76, 13097-13100 (2002).

36 Chambers, T. J., Halevy, M., Nestorowicz, A., Rice, C. M. & Lustig, S. West Nile virus envelope proteins: nucleotide sequence analysis of strains differing in mouse neuroinvasiveness. The Journal of general virology 79 ( Pt 10), 2375-2380, doi:10.1099/0022-1317-79-10-2375 (1998).

37 Daffis, S. et al. Antibody responses against wild-type yellow fever virus and the 17D vaccine strain: characterization with human monoclonal antibody fragments and neutralization escape variants. Virology 337, 262-272,

doi:10.1016/j.virol.2005.04.031 (2005).

38 Shimoda, H. et al. Production and characterization of monoclonal antibodies to

Japanese encephalitis virus. The Journal of veterinary medical science 75, 1077-1080 (2013).

39 Holzmann, H., Mandl, C. W., Guirakhoo, F., Heinz, F. X. & Kunz, C.

Characterization of antigenic variants of tick-borne encephalitis virus selected with neutralizing monoclonal antibodies. The Journal of general virology 70 ( Pt 1), 219- 222, doi:10.1099/0022-1317-70-1-219 (1989).

40 Wang, J. et al. A Human Bi-specific Antibody against Zika Virus with High

Therapeutic Potential. Cell 171, 229-241 e215, doi:10.1016/j.cell.2017.09.002 (2017). 41 Sapkal, G. N. et al. Neutralization escape variant of West Nile virus associated with altered peripheral pathogenicity and differential cytokine profile. Virus research 158, 130-139, doi:10.1016/j.virusres.2011.03.023 (2011).

42 Lai, C. J. et al. Epitope determinants of a chimpanzee dengue virus type 4 (DENV-4)- neutralizing antibody and protection against DENV-4 challenge in mice and rhesus monkeys by passively transferred humanized antibody. Journal of virology 81, 12766- 12774, doi:10.1128/JVI.01420-07 (2007).

43 Magnani, D. M. et al. Dengue Virus Evades AAV-Mediated Neutralizing Antibody Prophylaxis in Rhesus Monkeys. Molecular therapy : the journal of the American Society of Gene Therapy 25, 2323-2331, doi:10.1016/j.ymthe.2017.06.020 (2017). 44 Lanciotti, R. S., Lambert, A. J., Holodniy, M., Saavedra, S. & Signor Ldel, C.

Phylogeny of Zika Virus in Western Hemisphere, 2015. Emerging infectious diseases 22, 933-935, doi:10.3201/eid2205.160065 (2016).

45 Pierson, T. C. et al. A rapid and quantitative assay for measuring antibody-mediated neutralization of West Nile virus infection. Virology 346, 53-65,

doi:10.1016/j.virol.2005.10.030 (2006).

46 Li, T. et al. Modulating IgG effector function by Fc glycan engineering. Proceedings of the National Academy of Sciences of the United States of America 114, 3485-3490, doi:10.1073/pnas.1702173114 (2017).

47 Wang, T. T. et al. IgG antibodies to dengue enhanced for FcgammaRIIIA binding determine disease severity. Science 355, 395-398, doi:10.1126/science.aai8128 (2017).

48 Battye, T. G., Kontogiannis, L., Johnson, O., Powell, H. R. & Leslie, A. G.

iMOSFLM: a new graphical interface for diffraction-image processing with

MOSFLM. Acta crystallographica. Section D, Biological crystallography 67, 271- 281, doi:10.1107/S0907444910048675 (2011).

49 Winn, M. D. et al. Overview of the CCP4 suite and current developments. Acta

crystallographica. Section D, Biological crystallography 67, 235-242,

doi:10.1107/S0907444910045749 (2011).

50 Adams, P. D. et al. PHENIX: a comprehensive Python-based system for

macromolecular structure solution. Acta crystallographica. Section D, Biological crystallography 66, 213-221, doi:10.1107/S0907444909052925 (2010).

51 Emsley, P. & Cowtan, K. Coot: model-building tools for molecular graphics. Acta crystallographica. Section D, Biological crystallography 60, 2126-2132,

doi:10.1107/S0907444904019158 (2004).

52 Lanciotti, R. S. et al. Genetic and serologic properties of Zika virus associated with an epidemic, Yap State, Micronesia, 2007. Emerging infectious diseases 14, 1232-1239, doi:10.3201/eid1408.080287 (2008). While the invention has been described through specific embodiments, routine modifications will be apparent to those skilled in the art and such modifications are intended to be within the scope of the present invention.