NON-REPLICATIVE VIRIONS OF HUMAN IMMUNODEFICIENCY VIRUS AND THERAPEUTIC APPLICATIONS THEREOF

Technical Field of the Invention

The invention is encompassed in the field of treating viral diseases, more specifically in preventing and/or treating infection caused by the human immunodeficiency virus (HIV) by means of using non-replicative virions .

Background of the Invention

UNAIDS (Joint United Nation Programme on HIV/AIDS) estimates that human immunodeficiency virus (HIV) infection has caused more than 20 million deaths since its appearance in 1981 and the worldwide figure of infected persons at the end of 2008 was about 40 million, mainly (95%) in developing countries. It is one of the infectious diseases which causes the most deaths worldwide and it is calculated that 14,000 new infections (5 million/year ) take place everyday. In the United States and Western Europe, the morbidity and mortality due to HIV infection have reduced spectacularly after the introduction of Highly Active Antiretroviral Therapy (HAART).

Besides its high efficiency for controlling viral replication and for restoring immunity against opportunistic infections, HAART is incapable of eradicating the virus and recovering the specific responses against HIV in HIV-infected persons. In fact, after withdrawing HAART a rapid increase of viral load occurs in all cases (Carcelain et al. , 2001. J Virol 75 (1) : 234-41) . This implies that once HAART is started it must be continued throughout life, which is problematic due to the different types of serious side effects which it may involve, such as metabolic alterations and the cardiovascular risk that it entails .

Currently, the therapeutic arsenal against HIV infection is very complete and there are perspectives that it will continue to increase in a significant manner in the upcoming years. This situation is in contrast with the limited advances obtained in the development of a preventive or therapeutic vaccine. This is due to, among other reasons, the genetic diversity, the fast replication rate and the high mutation frequency inherent to HIV (Autran et al . , 2003. Nat Rev Immunol 3(6) : 503-8), the difficulty for inducing neutralizing antibodies, the lack of a suitable animal model, the limited knowledge of the immune response capable of generating protection against HIV infection and the different transmission routes of the virus (Kaufmann et al., 2005. Nat Med. 11(4 Suppl ) : S33-4 ) .

A future objective for vaccine design consists of increasing their efficiency by enabling their accessibility to the greatest number of antigen presenting cells (APCs) possible and achieving high local concentrations required to induce strong immunological responses. By facilitating the proper penetration of vaccine compounds into the APC-rich immunization sites as well as the specific migration and activation of APCs, the efficiency of the new vaccines in inducting protective immune responses would be increased. The vaccines could be efficient for inducing strong and protective immune responses against pathogens if they penetrate properly and activate the dendritic cells (DCs) which play a unique role as inducers of antigen specific responses. In the case of HIV infection, the clearance of the virus depends on the generation of antibodies but also on the induction of effector and memory T cells, CD4+ and CD8+. Different in depth studies on memory immune responses have been focused on the importance of forming a functional pool of memory CD8+ T cells for controlling the viral infection and requiring a suitable function of the APCs and of CD4+ T cell responses .

Currently, there is no preventive or therapeutic vaccine approved for use in HIV. None of the therapeutic vaccines used have shown long term efficacy with respect to the control of viral replication, the increase of CD4 lymphocytes or the progression to AIDS in randomized studies. Vaccines from attenuated live viruses have traditionally been used to prevent viral infections, such as, for example, measles, mumps or rubella. These vaccines are highly immunogenic because they imitate the natural infection both in the cell and humoral response (McMichael and Hanke, 2003. Nat Med. 9:874-80), and they induce life-long immunity after one or two doses. In contrast, vaccines using dead organisms or subunits do not imitate the infection and the administration of these vaccines only induces a humoral response, periodic boosters are required to maintain the antibodies at suitable concentrations, and furthermore adjuvants such as aluminium salts are used to increase these responses which are at times very poor. Noninfectious HIV-1 retrovirus-like particles have been produced in VERO cells that have been transfected with an expression construct encoding HIV-1 structural proteins wherein the sequences encoding the reverse transcriptase and integrase have been removed (Persson et al., Biologicals (1988) 26:255-265).

Some of these traditional vaccine strategies cannot be used to prevent HIV infection or therapeutically due to safety problems (Mwau, McMichael. 2003. J Gene Med. 5:3-10) or because they have had nil efficacy when used (Moss et al., 2000. Vaccine. 18:1081-87) . For example, attenuated live vaccines are prohibited in humans since in experiments with animals the highly attenuated simian immunodeficiency virus (SIV) protecting adult macaques from HIV infection caused AIDS in infant macaques, furthermore some adult macaques subsequently developed AIDS (Wyand et al . , 1997. Nat Med.; 3:32-36) . Moreover, the degree of attenuation was inversely correlated with immunogenicity (Wyand et al. 1991. Nat. Med.; 3:32-36) . In addition, the vaccines of dead viruses have given null results in clinical trials (Moss et al . 2000. Vaccine. 18:1081-87).

Therefore, the development of new effective and safe HIV vaccines is necessary.

Summary of the Invention

The authors of the present invention have developed viral vectors comprising an HIV virus genome as well as non- replicative virions capable of generating an immune response. In a first aspect, the invention relates to a viral vector comprising a human immunodeficiency virus (HIV) genome containing a mutation in the pol gene in which said mutation causes the virus produced solely from said viral vector to be a non-replicative virus; wherein said genome further comprises a second mutation in a gene different from the pol gene or in the sequence encoding the protease protein in the pol gene, wherein said second mutation comprises the deletion of a region comprising all or part of said gene different from the pol gene or the deletion of a region comprising all or part of the sequence encoding the protease protein in the pol gene; wherein said gene different from the pol gene is selected from the group consisting of the env, gag, nef, tat, rev, vif, vpu and vpr genes; and further comprising a sequence homologous to that of the region deleted by means of said second mutation, originating from a second HIV genome, wherein the genome of said second HIV is different from the HIV genome containing the deleted region and originates from an HIV-infected subject, with the proviso that when the mutation in the pol gene is a deletion of the sequence encoding the reverse transcriptase (RT) and the integrase proteins, then the second mutation is not in the env gene .

In another additional aspect, the invention relates to a non-replicative virion comprising a viral vector of the invention .

In another additional aspect, the invention relates to a method for obtaining an activated immune cell which comprises the steps of:

a) contacting an immune cell with a non-replicative virion of the invention,

b) maintaining the mixture obtained in step a) in conditions suitable for infecting said immune cells with the virion and for processing the antigens originating from the non-replicative virion, and c) optionally, recovering the activated immune cells.

In another additional aspect, the invention relates to an in vitro method for obtaining a customized HIV vaccine for an HIV-infected subject, wherein said vaccine comprises activated immune cells, which comprises:

a) contacting immune cells in vitro with a non- replicative virion of the invention comprising a viral vector of the invention in which the genome of said second HIV originates from an HIV of said HIV- infected subject;

b) maintaining the mixture obtained in step a) in conditions suitable for infecting said cells with the virion and for processing the antigens originating from the non-replicative virion;

c) detecting and quantifying the activation of the immune cells activated according to steps a) and b) ; d) comparing the activation of said immune cells activated according to steps a) and b) with the activation of control immune cells,

e) selecting the virions which cause a greater activation of the immune cells activated according to steps a) and b) than the activation of the control immune cells,

f) infecting immune cells of said HIV-infected subject with the non-replicative virions selected in step e), and

g) recovering the immune cells activated according to step f ) .

In another additional aspect, the invention relates to an in vitro method for obtaining a customized HIV vaccine for an HIV-infected subject, wherein said vaccine comprises activated immune cells, which comprises:

a) contacting immune cells originating from said HIV-infected subject in vitro with a non-replicative virion comprising a viral vector of the invention in which the genome of said second HIV originates from an HIV of said HIV- infected subject;

b) maintaining the mixture obtained in step a) in conditions suitable for infecting said immune cells with the virion and for processing the antigens originating from the non- replicative virion; and

c) recovering the immune cells activated according to step b) .

In another aspect, the invention relates to a cell obtainable according to any of the methods of the invention.

In another additional aspect, the invention relates to the use of the non-replicative virion of the invention or of the activated immune cell of the invention in medicine, or, alternatively expressed, to a non-replicative virion of the invention or to an activated immune cell of the invention for use in medicine. A pharmaceutical composition comprising said non-replicative virion of the invention or said activated immune cell of the invention together with, optionally, a pharmaceutically acceptable carrier constitutes an additional aspect of this invention.

In another additional aspect, the invention relates to the use of the non-replicative virion of the invention or of the activated immune cell of the invention in the manufacture of an HIV vaccine, or, alternatively expressed, to a non-replicative virion of the invention or to an activated immune cell of the invention for use as an HIV vaccine.

In another additional aspect, the invention relates to the use of the non-replicative virion of the invention or of the activated immune cell of the invention in the manufacture of a pharmaceutical composition for treating AIDS, or, alternatively expressed, to a non-replicative virion of the invention or to an activated immune cell of the invention for use in the treatment of AIDS.

In another aspect, the invention relates to a method for the treatment and/or prevention of the infection caused by HIV and/or AIDS in a subject in need thereof which comprises the administration to said subject of an effective amount of a non- replicative virion of the invention or an activated immune cell of the invention. Deposit of microorganisms

The plasmids pNL4-3/ART, pNL 4-3/ART/AGag [ LacZ ] , pNL4-3/ ART/ΔΕη [LacZ ] , pNL4-3/ART/ΔΕην-Nef [LacZ ] , pNL4-3/ART/ANef [LacZ ] and pNL4-3/ART/AGag-Pro [LacZ ] were deposited on March 27 ^th , 2012 in DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH), I n h o f f e n s t r a β e 7 B, D-38124 Braunschweig, Federal Republic of Germany. The depositor was Laboratories del Dr. Esteve S.A., Barcelona, Spain. The access numbers assigned to said deposits are the following:

pNL4-3/ART:

pNL4-3/ART/AGag [LacZ] :

pNL4-3/ART/AEnv[LacZ] :

pNL4-3/ART/AEnv-Nef [LacZ] : ;

pNL4-3/ART/ANef [LacZ] : ; and

pNL4-3/ART/AGag-Pro [LacZ] :

Brief Description of the Drawings

Figure 1 A shows the schematic depiction of the HIV genome pNL4-3. B. Schematic depiction of pNL4-3 ART. C. Schematic depiction of viral vectors pNL4-3 ART/Agag- [LacZ] , pNL4-3 ART/Aenv- [LacZ] , pNL4-3 AR /Aenv-nef- [LacZ] , pNL4-3 AR /Anef- [LacZ] and pNL4-3 ART/Agag-pro- [ LacZ] , wherein the LacZ (beta- galactosidase ) gene is substituting the gene fragments corresponding to the gag, env, env-nef, nef or gag-pro genes, respectively

Figure 2 shows the measurement of luciferase activity to analyze the infection/replication capacity of the NL4-3 Ren WT, heat-inactivated NL4-3 Ren WT virions or NL4-3 ART Ren (NL4-3 DRT Ren) virions after 24 or 96 hours post-infection of MT-2 cells. Ren: renilla gene, WT : wild-type strain.

Figure 3 shows the measurement of luciferase activity to analyze the replicative capacity of the NL4-3 ART (deltaRT) and NL4-3 (WT) virions after 72 hours post-infection of TZM-bl cells. Figure 4 A shows 293T cells co-transfected with pGAG-GFP (5 μς) , pNL4-3 ART (3 μς) + pGAG-GFP (2 μς) and pNL4-3WT (3 μς) + pGAG-GFP (2 μg) . Upper panel, image overlay showing the cell nucleus, the cortical actin of the cell and the signal visualization of the expression of GAG-GFP. Lower panel, visualization of the expression of GAG-GFP by means of confocal microscopy. B. Infection of PBMC cells (peripheral mononuclear cells) with the virions obtained after co-transfecting 293T with pGAG-GFP (5 μς) , pNL4-3WT (3 μς) + pGAG-GFP (2 μς) and pNL4-3 ART (3 pg ) + pGAG-GFP (2 μg) . Upper panel, image overlay showing the cell nucleus, the cortical actin of the cell and the expression of GAG-GFP. Lower panel, visualization of the location of the GAG-GFP signal by means of confocal microscopy.

Figure 5 shows the visualization by means of transmission electron microscopy of the NL4-3 (A) and NL4-3 ART (B) virion- producing 293T cells. Virions purified from NL4-3 (C) and NL4-3 ART (D) .

Figure 6 shows the Western blot of protein extracts NL4-3 and NL4-3 ART virions and of the 293T cells transfected with pNL4-3 (NL4-3) and pNL4-3 ART (ART) .

Figure 7 shows the sequential scheme of the ex vivo model of the MD-DC assay.

Figure 8 shows the assessment of the cellular response of the MD-DC cells against different immunogens : BaL30 (heat- inactivated R5 strain of HIV-1), heat-inactivated recombinant p24, NL4-3 WT or NL4-3 ART in an HIV patient. The proliferation index (S.I.) (A), and the production of IL-2 (B) and interferon γ ( I FN γ) (C) are quantified.

Figure 9 shows the results of the cellular response obtained in the ex vivo model of MD-DC pulsed with the following immunogens: NL4-3 WT (heat-inactivated) or NL4-3 ART. Test performed with 8 responding patients and against one and the same stock of immunogens with a degree of significance 0.01 **.

Figure 10 shows the comparison of the results obtained using the MD-DC co-culture model and the ex vivo model established with PBMC.

Figure 11 shows the visualization by means of electron microscopy of purified NL4-3 virions obtained by transfecting 293T cells in the absence (A) or in the presence (B) of Amprenavir (protease inhibitor) .

Detailed Description of the Invention

The authors of the present invention have developed viral vectors comprising a human immunodeficiency virus (HIV) genome, as well as non-replicative virions comprising said viral vectors for the purpose of obtaining autologous and heterologous vaccines, both preventive and therapeutic, against HIV/AIDS infection. Thus, as shown in Example 3, the virions of the invention are capable of generating an immune response.

In a first aspect, the invention relates to a viral vector, hereinafter viral vector of the invention, comprising a human immunodeficiency virus (HIV) genome containing a mutation in the pol gene, wherein said mutation causes the virus produced solely from said viral vector to be a non-replicative virus; wherein said genome further comprises a second mutation in a gene different from the pol gene or in the sequence encoding the protease protein in the pol gene, wherein said second mutation comprises the deletion of a region comprising all or part of said gene different from the pol gene or the deletion of a region comprising all or part of the sequence encoding the protease protein in the pol gene; wherein said gene different from the pol gene is selected from the group consisting of the env, gag, nef, tat, rev, vif, vpu and vpr genes; and further comprising a sequence homologous to that of the region deleted by means of said second mutation, originating from a second HIV genome, wherein the genome of said second HIV is different from the HIV genome containing the deleted region and originates from an HIV-infected subject, with the proviso that when the mutation in the pol gene is a deletion of the sequence encoding the reverse transcriptase (RT) and the integrase proteins, then the second mutation is not in the env gene. As it is used herein, "viral vector" refers to a nucleic acid sequence comprising the necessary sequences so that after transcribing and translating said sequences in a cell a viral particle with capacity for infecting a new cell is generated.

The vectors of the invention can be obtained by means of techniques widely known in the state of the art [Sambrook et al . , "Molecular cloning, a Laboratory Manual", 2 ^nd ed., Cold Spring Harbor Laboratory Press, N.Y., 1989 Vol 1-3].

As it is used herein, "HIV" is intended to include HIV-1 and HIV-2. "HIV-1" means the type 1 human immunodeficiency virus. HIV-1 includes but is not limited to extracellular virus particles and the forms of HIV-1 associated with HIV-l-infected cells. "HIV-2" means the type 2 human immunodeficiency virus. HIV-2 includes but is not limited to extracellular virus particles and the forms of HIV-2 associated with HIV-2-infected cells .

In a particular embodiment, the WT (wild-type) HIV genome that has been used for obtaining the viral vectors of the invention corresponds to the HIV-1 genome pNL4-3, NIH AIDS Research & Reference Reagent Program, no. 114, GenBank database accession number M19921.1 (SEQ ID NO: 1) as of 1st December 2010.

As it is used herein, the term "mutation" refers to a change in a nucleic acid sequence. Said mutation can include, among others, substitution, i.e., exchanging one or more nucleotides for others; inversion, i.e., a DNA segment inside a gene is inverted, to that end two 180° rotations are necessary, one for inverting the sequence and the other for maintaining the polarity of the DNA; translocation, i.e., a segment of a gene changes position to be in another different site of the same gene or in another site of the genome; nucleotide insertions or deletions, i.e., this refers to the addition of one or more nucleotides (insertions or additions) or the loss of one or more nucleotides (deletions) having as a consequence changes in the reading frame, a reading error occurring during the translation ranging from the formation of non-functional proteins to the absence of said protein.

As it is used herein, "pol" is understood as the gene encoding the viral enzymes necessary for the viral replication process: protease (PRO), reverse transcriptase (RT) and integrase (INT) . These enzymes are produced as a Gag-Pol precursor polyprotein which is processed by the viral protease. In a particular embodiment, the sequence of the RT protein is that shown in SEQ ID NO: 2.

In a particular embodiment, the mutation in the pol gene comprises the complete or partial deletion of said gene.

As it is used herein, "complete deletion" of the sequence of a gene refers to the loss of 100% of the nucleotides forming the nucleotide sequence of said gene.

As it is used herein, "partial deletion" of the sequence of a gene refers to the loss of at least 0.5%, 1%, 5%, 10%, 20%, 40%, 50%, 60%, 70%, 80%, 90% or 99% of the nucleotides forming the nucleotide sequence of said gene.

In another particular embodiment, the mutation in the pol gene gives rise to a non-functional RT protein.

As it is used herein, "non-functional RT protein" refers to fact that the RT protein does not have reverse transcriptase function, i.e., it is not capable of synthesizing double- stranded DNA using single-stranded RNA as a template. Different methods of the state of the art can be used to analyze the function of a protein; said methods will depend on the function of said protein. Thus, for example, to determine whether the RT protein is functional, different assays can be performed, among others, reverse transcription reactions of an RNA sequence or analyzing the absence of replication of a virus as a consequence of having a non-functional RT protein by colorimetrically or fluorimetrically determining the presence of a marker gene of the viral genome in cells infected with a virion comprising the sequence encoding the RT protein to be analyzed.

In another particular embodiment, the mutation in the pol gene is a complete or partial deletion of the sequence encoding the RT protein and said mutation does not comprise any deletion of the sequence encoding the integrase protein.

In another particular embodiment, the mutation in the pol gene is a complete or partial deletion of the sequence encoding the RT protein, i.e., said mutation does not comprise any deletion of the sequence encoding the protease protein or any deletion of the sequence encoding the integrase protein.

As mentioned, above, the viral vector of the invention comprises a genome in which said genome further comprises a second mutation in a gene different from the pol gene or in the sequence encoding the protease protein in the pol gene, wherein said second mutation comprises the deletion of a region comprising all or part of said gene different from the pol gene or the deletion of a region comprising all or part of the sequence encoding the protease protein in the pol gene. In an embodiment, the second mutation is in the sequence encoding the protease protein in the pol gene. In another embodiment, the second mutation is in a gene different from the pol gene selected from the group consisting of the env, gag, nef, tat, rev, vif, vpu and vpr genes; preferably selected from the env, gag and nef genes; more preferably is the gag gene.

As it is used herein, the "protease" protein is a retroviral aspartyl protease that is essential for the life- cycle of HIV. The protease cleaves newly synthesized polyproteins at the appropriate places to create the mature protein components of an infectious HIV virion. Without effective protease, HIV virions remain uninfectious . Thus, mutation of HIV protease' s active site or inhibition of its activity disrupts HIV's ability to replicate and infect additional cells .

As it is used herein, "env" gene is understood as the gene encoding the gpl60 protein of the viral envelope. In a particular embodiment, the sequence of the gpl60 protein is that shown in SEQ ID NO: 3.

As it is used herein, "gag" gene is understood as the gene encoding the p55 protein of the capsid formed by 3 protein subunits (MA, CA and NC) . In a particular embodiment, the sequence of the p55 protein is that shown in SEQ ID NO: 4.

As it is used herein, "nef" gene is understood as the gene encoding the Nef protein which negatively controls CD4 and HLA molecules of the infected cell and plays a role in the pathogenicity of the virus. In a particular embodiment, the sequence of the Nef protein is that shown in SEQ ID NO: 5.

As it is used herein, "tat" gene is understood as the gene encoding the Tat protein, a viral messenger RNA transactivator and elongator. In a particular embodiment, the sequence of the Tat protein is that shown in SEQ ID NO: 6.

As it is used herein, "rev" gene is understood as the gene encoding the Rev protein responsible for processing messenger RNA and transporting it to the cytoplasm. In a particular embodiment, the sequence of the Rev protein is that shown in SEQ ID NO: 7.

As it is used herein, "vif" gene is understood as the gene encoding the Vif protein (SEQ ID NO: 8) associated with the infectivity of the extracellular virions . In a particular embodiment, the sequence of the Vif protein is that shown in SEQ ID NO: 8.

As it is used herein, "vpu" gene is understood as the gene encoding the Vpu protein involved in the release of the virions . In a particular embodiment, the sequence of the Vpu protein is that shown in SEQ ID NO: 9.

As it is used herein, "vpr" gene is understood as the gene encoding the Vpr protein which acts as an accelerator for the replication cycle at different levels . In a particular embodiment, the sequence of the Vpr protein is that shown in SEQ ID NO: 10.

According to the first aspect of the present invention, when the mutation in the pol gene is a deletion of the sequence encoding both the RT and the integrase proteins, then the second mutation is not in the env gene.

The viral vector of the invention may further comprise a marker gene, wherein said marker gene is located at the site occupied by the region deleted by means of said second mutation. As it is used herein, "marker gene" or "reporter gene" is understood as a gene the product of which gives rise to a signal that can be readily measured or detected. Non-limiting illustrative examples of marker genes suitable for carrying out the present invention include, among others, GFP (green fluorescent protein) gene, LacZ gene encoding the β- galactosidase protein, the Renilla or firefly luciferase gene encoding the luciferase protein, etc.

According to the first aspect of the present invention, the viral vector of the invention further comprises a sequence, originating from a second HIV genome, homologous to that of the region deleted by means of said second mutation, wherein the genome of said second HIV is different from the HIV genome containing the region deleted.

As it is used herein, "homologous sequence" refers to the sequence of a gene of a genome A equivalent to a sequence of that same gene in a genome B; i.e., by way of illustration, for the sequence of the env gene in a genome A (e.g., an HIV genome), its homologous sequence will be the sequence of the env gene of a genome B (e.g., a different HIV genome) .

According to the first aspect of the present invention the genome of the second HIV originates from an HIV-infected subject. In a particular embodiment, the HIV-infected subject is a subject for which a customized HIV vaccine is to be obtained.

The homologous sequences originating from the HIV genome of a subject can be obtained by means of different methods known in the state of the art, among others, from blood cells of the HIV- infected patient by means of the QIAmp DNA blood kit (Qiagen) , and the viral RNA can be obtained from the plasma of an HIV- infected patient by means of the QIAmp kit (Qiagen) . Said extracted HIV RNA is used as a template for obtaining cDNA, using techniques known by a person skilled in the art.

In another aspect the invention relates to a non- replicative virion, hereinafter non-replicative virion of the invention, comprising a viral vector of the invention.

As it is used herein, "virion" is understood as a replication-deficient infectious viral particle comprising the viral genome packed in a capsid and, optionally, in a lipid envelope surrounding the capsid. As it is used herein, "non- replicative virion" refers to a virion lacking capacity for multiplying its genetic material and therefore new copies of said virion cannot be formed.

For the production of the virions of the invention, it is necessary to first incorporate the viral vector of the invention in a cell by using any of the transfection methods known by the person skilled in the art (see sections 9.1 to 9.5 in Ausubel, F.M. et al. , Current Protocols in Molecular Biology, John Wiley & Sons Inc; ringbou edition, 2003). Non-limiting illustrative examples of transfection methods include co-precipitation with calcium phosphate, DEAE-dextran, polybrene, electroporation, microinjection, liposome-me d i a t e d fusion, lipofection, retrovirus infection and biolistic transfection. In a particular embodiment, the transfection is carried out by means of co- precipitation with calcium phosphate. As a person skilled in the art will understand, the cell in which the vector of the invention is incorporated must be capable of expressing the information encoded in said viral vector of the invention and packing the proteins of the virus and the genetic material thereof to form the viral particles. Cells suitable for carrying out the present invention include, among others, cells from the 293T cell line, a cell line derived from the highly transfectable 293 cell line (derived from human embryonic kidney cells), to which cell the SV40 T antigen of SV40 has been inserted, available in the American Type Culture Collection (ATCC) . The virions produced are released into the culture medium of the cells transfected with the vectors of the invention, therefore to obtain the virions of the invention it is necessary to collect the supernatants after several hours post-transfection, preferably 24 and 48 hours post-transfection . The non-replicative virions of the invention can be stored at - 80°C.

In an additional embodiment, the invention relates to a method for obtaining an activated immune cell comprising the steps of:

a) contacting an immune cell with a non-replicative virion of the invention,

b) maintaining the mixture obtained in step a) in conditions suitable for infecting said immune cells with the virion and for processing the antigens originating from the non-replicative virion, and c) optionally, recovering the activated immune cells.

As it is used herein, "activated immune cell" hereinafter activated immune cell of the invention, is understood as an immune cell which, after being treated with immunogenic factors, is capable of generating an immune response against said immunogens . Said immune cells can be, among others, lymphocytes or dendritic cells (DC) .

The suitable conditions for infecting the immune cells with the virion of the invention and the processing of antigens are known by a person skilled in the art. By way of illustration, it can be carried out, for example, by maintaining 5xl0 ⁶ immature monocyte-derived dendritic cells (MD-DC) in contact with lxlO ⁹ virions for 3 hours at 37°C.

The recovery of the activated immune cells of the invention can be carried out by means of different methods known by a person skilled in the art. By way of non-limiting illustration, the recovery of said cells can be performed by means of detaching the cells adhered on the culture plate, for example, by means of using trypsin-EDTA (0.25% and 0.02%, respectively) and subsequent centrifugation at 650 g for 4 minutes at room temperature .

In another aspect, the invention relates to an in vitro method for obtaining a customized HIV vaccine for an HIV- infected subject, wherein said vaccine comprises activated immune cells, which comprises:

a) contacting immune cells in vitro with a non-replicative virion comprising a viral vector of the invention wherein said sequence homologous to that of the region deleted by means of said second mutation, comprised in said viral vector of the invention, is a sequence from said second HIV genome wherein the genome of said second HIV originates from an HIV from said HIV-infected subj ect;

b) maintaining the mixture obtained in step a) in conditions suitable for infecting said cells with the virion and for processing the antigens originating from the non-replicative virion;

c) detecting and quantifying the activation of the immune cells activated according to steps a) and b) ;

d) comparing the activation of said immune cells activated according to steps a) and b) with the activation of control immune cells,,

e) selecting the virions which cause a greater activation of the immune cells activated according to steps a) and b) than the activation of the control immune cells, f) infecting immune cells of said HIV-infected subject with the non-replicative virions selected in step e) , and g) recovering the immune cells activated according to step f ) ·

A person skilled in the art knows how to perform the different steps comprised in the in vitro method for obtaining a customized HIV vaccine for an HIV-infected subject. Said method first comprises contacting immune cells in vitro with a non- replicative virion of the invention. In a particular embodiment, said immune cells are lymphocytes, peripheral blood mononuclear cells or monocyte-derived dendritic cells. The immune cells and the non-replicative virion of the invention must be maintained in suitable conditions so that said cells are infected by the virion and so that the antigens originating from the non- replicative virion of the invention are processed. In a particular embodiment, said conditions are 37°C for 7 days.

It is then necessary to compare the activation of said immune cells with the activation of control immune cells. Different techniques are known in the state of the art for analyzing the activation of immune cells. Non-limiting, illustrative examples are, among others, the detection of cytokine production, the detection of the number of IFNy and IL- 2 producing cells, or the frequency analysis of dividing antigen-specific CD4 and CD8 cells by means of flow cytometry analysis. The virions causing an activation of the activated immune cells greater than the activation of the control immune cells are then selected and said non-replicative virions are used for infecting immune cells of said HIV-infected subject. Finally, the method comprises recovering said activated immune cells .

As used herein, "control immune cells" are understood as immune cells activated with other viral preparations, such as viruses inactivated by means of heat or chemical treatment, or heterologous gene-carrying defective viral particles, immature virions obtained by different mechanisms such as treatment with protease inhibitors or by mutations, recombinant proteins or peptide combinations .

In another aspect, the invention relates to an in vitro method for obtaining a customized HIV vaccine for an HIV- infected subject, wherein said vaccine comprises activated immune cells, which comprises:

a) contacting immune cells originating from said HIV- infected subject in vitro with a non-replicative virion comprising a viral vector of the invention wherein wherein said sequence homologous to that of the region deleted by means of said second mutation, comprised in said viral vector of the invention, is a sequence from said second HIV genome wherein the genome of said second HIV originates from an HIV from said HIV-infected subj ect;

b) maintaining the mixture obtained in step a) in conditions suitable for infecting said immune cells with the virion and for processing the antigens originating from the non-replicative virion; and

c) recovering the immune cells activated according to step b) .

In a particular embodiment, the immune cell is selected from a lymphocyte, a peripheral blood mononuclear cell and a monocyte-derived dendritic cell.

In another particular embodiment, the method for obtaining a customized HIV vaccine further comprises the step of subjecting the activated immune cells to a treatment to ensure the safety of said activated immune cells .

"Treatment to ensure the safety" refers to those treatments which prevent the virions of the invention used in generating a customized HIV vaccine, despite being non-replicative, from being able to induce the development of AIDS in the vaccinated subject. To that end, different methods known in the state of the art can be used, including treatment with HIV RT protein and/or protease and/or integrase inhibitors and/or the inactivation of the virions with AT-2 or heat.

RT protein inhibitors suitable for use in the present invention are, among others, zidovudine (AZT) , Retrovir®, didanosine (ddl), Videx®, zalcitabine (ddC), Hivid®, stavudine (d4T) , Zerit®, lamivudine (3TC) , Epivir®, abacavir (ABC) , Ziagen®, emtricitabine (FTC), Emtriva®, tenofovir DF (TDF) , Viread®, nevirapine (NVP) , Viramune®, delavirdine (DLV) , Rescriptor®, efavirenz (EFV) , Sustiva®, etravirine (ETV) , Intelence® and suitable HIV integrase inhibitors like Raltegravir (RTG) Isentress®. The inactivation of the virions of the invention by heat can be carried out at 56°C for 60 minutes. The inactivation with AT-2 ( aldrithiol-2 ) can be carried out by means of incubating the virions with AT-2 at a concentration of 1 mM overnight at 4°C. The inactivation with protease inhibitors is performed by treating the virus-producing 293T cells while changing medium after transfection with drugs like saquinavir (SQV), Invirase®, indinavir (IDV), Crixivan®, ritonavir (RTV), Norvir®, nelfinavir (NFV) , Viracept®, fosamprenavir (FOSAPV), Telzir®, lopinavir / rtv ( LPV/r ) -Kaletra®, atazanavir (ATV) , Reyataz®, tipranavir (TPV) , Aptivus®, darunavir (DRV) , Prezista® at concentrations capable of inhibiting 90% of the viral maturation .

In another aspect, the invention relates to the activated immune cells obtained according to the methods of the invention.

The non-replicative virion of the invention or the activated immune cell of the invention are potentially useful for the prevention and/or treatment of the infection caused by HIV and/or AIDS.

Thus, in another aspect, the invention relates to the use of a non-replicative virion of the invention or of the activated immune cell of the invention in medicine, or, alternatively expressed, to a non-replicative virion of the invention or to an activated immune cell of the invention for use as a medicament. In other words, according to this aspect, the invention relates to a pharmaceutical composition comprising a non-replicative virion of the invention or an activated immune cell of the invention optionally together with a pharmaceutically acceptable carrier .

The amount of non-replicative virions of the invention or of activated immune cells of the invention in the pharmaceutical composition provided by this invention, as well as the administration time, will be within the capacity of the person skilled in the art having the benefit of the present teaching. Typically, the non-replicative virions of the invention or activated immune cells of the invention will be present in the pharmaceutical composition of the invention in a therapeutically effective amount which may vary within a broad range. By illustrative, the pharmaceutical composition of the invention can contain, for example, from about 1% to about 99%, preferably from about 10% to about 80%, most preferably from about 20% to about 60%, of the active ingredients (i.e., non-replicative virions of the invention or activated immune cells of the invention) . In fact, the administration of therapeutically effective amounts of non-replicative virions of the invention or of activated immune cells of the invention can be achieved by means of a single administration, such as, for example, a single injection of a sufficient number of said virions or cells to provide a therapeutic benefit to the patient who is subjected to such treatment. Alternatively, in some circumstances, it may be desirable to provide multiple or consecutive administrations, either for a relatively short or a relatively prolonged time period, which may be determined by the specialist supervising the administration of such compositions. In fact, in certain embodiments, it may be desirable to administer two or more compositions of different non-replicative virions or activated immune cells of the invention either alone or in combination with one or more drugs to achieve the desired effects of the particular therapeutic regimen. The pharmaceutical composition provided by the invention is preferably useful for administration and/or application to the human body.

The dosage indicated to prevent and/or treat an infection caused by HIV or AIDS using the non-replicative virions and/or activated immune cells of the invention will depend on numerous factors - including patient age, condition, the severity of the infection and sydrome, the route and frequency of administration of the non-replicative virions or activated immune cells of the invention involved. Thus, the pharmaceutical compositions according to the invention may be delivered in a therapeutically effective amount. The precise therapeutically effective amount is that amount of the composition that will yield the most effective results in terms of efficacy of treatment in a given subject. This amount will vary depending upon a variety of factors, including but not limited to the characteristics of the therapeutic substance, i.e., non-replicative virion or activated immune cell of the invention (including activity, pharmacokinetics, pharmacodynamics, and bioavailability), the physiological condition of the subject (including age, sex, disease type and stage, general physical condition, responsiveness to a given dosage, and type of medication) , the nature of the pharmaceutically acceptable excipient or excipients in the composition, etc. One skilled in the clinical and pharmacological arts will be able to determine a therapeutically effective amount through routine experimentation, for instance, by monitoring a subject's response to administration of an amount of non-replicative virions or activated immune cells of theinvention and adjusting the dosage accordingly. For additional guidance, see Remington: The Science and Practice of Pharmacy - Gennaro ed. 20th edition, Williams & Wilkins PA, USA (2000) .

The pharmaceutical compositions containing the non- replicative virions or activated immune cells of the invention can be formulated in any suitable form of administration and can be administered via any appropriate route of administration. In a particular embodiment, the pharmaceutical composition of the invention is parenterally administered. "Parenteral" refers to a route of administration that is generally associated with injection. Via the parenteral route, the pharmaceutical compositions of the invention may be in the form of suspensions for infusion or for injection, or as lyophilized powders. To this effect, pharmaceutically acceptable carriers needed for the formulation of the desired administration form should be included. "Pharmaceutically acceptable carrier" includes a vehicle or excipient that is involved in carrying or transporting a product of interest from a tissue, organ, or portion of the body to another tissue, organ, or portion of the body, and that is useful in preparing a pharmaceutical composition that is generally safe and non-toxic; the term includes excipients that are acceptable for human pharmaceutical use. The pharmaceutical compositions of the invention may be made following the conventional techniques of pharmacy. Information concerning this matter can be found in Remington: The Science and Practice of Pharmacy - Gennaro ed. 20th edition, Williams & Wilkins PA, USA (2000), as well as in the handbook "Tratado de Farmacia Galenica", C. Fauli i Trillo, 1993, Luzan 5, S.A. Ediciones, Madrid.

The use of the non-replicative virions of the invention or the activated immune cells of the invention for the prevention and/or treatment of the infection caused by HIV and/or AIDS constitutes an additional aspect of this invention.

Thus, in another aspect, the invention relates to the use of a non-replicative virion of the invention or of the activated immune cell of the invention in the manufacture of an HIV vaccine, or, alternatively expressed to a non-replicative virion according to the invention or to an activated immune cell according to the invention for use as an HIV vaccine, i.e, for use in the prevention and/or treatment of an infection caused by HIV.

The vaccines of the invention will be administered in a pharmacologically effective amount producing an improvement of one or more symptoms of a viral disorder or preventing the progression of a viral disease or causing a regression of the disease or reducing the viral transmission. For example, a therapeutically effective amount preferably relates to the amount of a therapeutic agent which reduces the transmission index, reduces the HIV viral load or reduces the number of infected cells by at least 5%, preferably at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or even more. A therapeutically effective amount referring to an HIV also relates to the amount of a therapeutic agent which increases the CD4+ cell count, increases the time to progression to AIDS or increases the survival time by at least 5%, preferably at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95% or even more .

The administration of the non-replicative virions of the invention or of the activated immune cells of the invention can be performed together with a pharmaceutically acceptable carrier or support. Occasionally, said pharmaceutically acceptable carrier or support is an adjuvant; an aluminium salt or an oil in water emulsion; an emulsifying agent and a metabolizable oil; or an immunostimulating agent, and the composition is administered to the subject by means of injection.

Said vaccines may further comprise at least one adjuvant which increases and/or mediates an immune response chosen from an innate immune response and/or an adaptive immune response. The adjuvants which can be used can increase the immune response by activating the antigen presenting cells (APC) , macrophages and/or by stimulating specific groups of lymphocytes.

An adjuvant that may be suitable for the present invention can be any ligand suitable for the activation of a pathogen recognition receptor (PRR) expressed in and on dendritic cells

(DC), T cells, B cells or other antigen presenting cells. The ligands activating the nucleotide binding oligomerization domain

(NOD) receptor pathway may be suitable for the purposes of the invention. The adjuvants suitable for these ligands may be derived from muramyl dipeptide . The ligands activating the tolllike receptors (TLR) may also be suitable for the purposes of the invention. These receptors are members of the PRR family and are widely expressed in a variety of innate immune cells including DC, macrophages, mast cells and neutrophils.

The following can be mentioned as examples of ligands which activate TLR: for TLR4, monophosphoryl lipid A, 3-O-deacetylated monophosphoryl lipid A, E. coli LPS, taxol, RSV fusion protein and host heat shock proteins 60 and 70; for TLR2 , lipopeptides such as N-palmitoyl-S-2 , 3 (bispalmitoyloxy) -propyl-cysteinyl- seryl- (lysyl) 3-lysine, S. aureus peptidoglycan, M. tuberculosis lipoproteins, S. cerevisiae zymosan and highly purified P. gingivalis LPS; for TLR3, dsRNA, flagellin TLR5 and TLR7 of synthetic compounds such as imidazoquinoline; or for TLR9, certain types of CpG-rich DNA. Other adjuvants useful for the invention may be T helper epitopes .

A T helper epitope is a peptide normally derived from exogenous proteins which have undergone protein degradation and processing in the endocytic pathway of antigen presenting cells (APC) . In those cells, the class II major histocompatibility complex (MHC II) is associated with those peptides in the endosomes. This complex transported to the surface of the APCs can interact with a specific T cell receptor of CD4 T lymphocytes which causes the activation thereof. As is known in the art, the response of the T cell can be Thl and/or Th2 type, depending on the helper epitope.

An example of a Th-oriented response epitope is the pan DR helper T cell epitope (PADRE) . This epitope is manipulated so that it binds to the more common high affinity HLA-DRA molecules and so that it acts as a strong immunogen. It has been shown that the PADRE HTL epitope increases the strength of vaccines designed for stimulating a cellular immune response. See Alexander J, et al . , Immunol. Res. 1998; 18:79-92.

The formulation of vaccines according to the invention uses an effective amount of the antigen of interest. In other words, it will include an amount of antigen which, in combination with the adjuvant, causes the subject to produce a specific and sufficient immune response such that it confers protection to the subject against subsequent exposure to HIV. When it is used as an immunogenic composition, the formulation will contain an amount of antigen which, in combination with the adjuvant, causes the subject to produce specific antibodies that can be used for diagnostic or therapeutic purposes .

The vaccine compositions of the invention may be useful for preventing HIV-1 infection or for HIV-1 infection therapy. While all animals that may be affected with HIV-1 or its equivalents can be treated in this manner, the vaccines of the invention are particularly aimed at their preventive and therapeutic uses in human beings . More than one administration may often be required to produce the desired prophylactic or therapeutic effect; the exact protocol (dose and frequency) can be established by means of standard clinical procedures.

The vaccine formulations will contain an effective amount of the selected antigen/antigens which, when combined with the adjuvant, causes the vaccinated subject to produce a sufficient and specific immune response to the antigen. The vaccine compositions can also be used therapeutically for treating subjects already infected with HIV.

In some embodiments, it may be desirable to administer combination vaccines having a component which causes an immune response mainly against HIV strains with tropism for CCR5 receptor and a second component which causes an immune response mainly against HIV strains with tropism for CXCR4 receptor. It may also be desirable for one or both components to be formed by a mixture of antigens, such as for example, a mixture of antigens each of which causes an immune response against a particular HIV strain or group of HIV strains .

In another additional embodiment, the invention relates to the use of a non-replicative virion of the invention or to an activated immune cell of the invention in the manufacture of a pharmaceutical composition for treating AIDS, or, alternatively expressed, to a non-replicative virion of the invention or to an activated immune cell of the invention for use in treating AIDS. The particulars of said pharmaceutical composition have been previously mentioned and are incorporated herein by reference.

In another aspect, the invention relates to a method for the treatment or prevention of the infection caused by HIV ad/or AIDS in a subject in need thereof comprising the administration to said subject of an effective amount of a non-replicative virion of the invention or of an activated immune cell according to the invention.

As it is used herein, the term "treatment" relates to the act of reverting, improving or inhibiting the evolution of the disorder or condition for which such term is applied, or one or more symptoms of such disorder or condition, as well as to prevent it from occurring, having it, or alternatively delaying the onset or recurrence of a disease, disorder or condition for which such term is applied, or one or more of the symptoms associated with a disease, disorder or condition.

The invention is illustrated below based on the following examples which are provided by way of non-limiting illustration the scope of the invention.

EXAMPLE 1

Production of virions

1.1 Generation of viral vectors

To generate the pNL4-3ART vector, HIV genome-1 pNL4-3 (NIH AIDS Research & Reference Reagent Program, no. 114, accession number M19921.1 as of 1 December 2010 in the GenBank database) (SEQ ID NO: 1) (Figure 1A) was used. To that end, restriction sites which allowed readily "extracting" particular DNA fragments from the provirus matrix (such as, for example, the gene encoding RT, the pol, gag, nef or env genes, etc.) were initially inserted by means of directed mutagenesis in order to substitute them with the same genes originating from the isolates of patients to be assessed. This system of "cloning" and generating a "chimera virus" allows studying the characteristics of the different viral proteins of the patients. Therefore, the following main modifications were performed:

first, the deletion of HIV-1 fragments, for example, the deletion of a fragment comprising the gene encoding reverse transcriptase (RT), specifically the fragment comprised between position 2592 and 3485 of the pNL4-3 proviral vector; and

then, the LacZ gene (encoding the beta-galactosidase enzyme) was inserted substituting different sequences of the viral genome, on one hand, to find out the generation frequency of recombinant viruses, and, on the other hand, to avoid the carry-over of sequences of wild-type viruses .

The HIV-based recombinant viral clones of the present invention are characterized in that they have the general structure depicted in Figure 1, comprising in direction 5' to 3' the following elements :

LTR (long terminal repeats) or terminally redundant sequences containing various consensus sequences for transcription factors regulating viral expression; gag, the gene encoding the p55 protein of the capsid formed by 3 protein subunits (MA, CA and NC) ;

pol, the gene encoding the viral enzymes necessary for the viral replication process: protease (PRO), reverse transcriptase (RT) and integrase (INT) , and it overlaps at its 5' end with the gag element;

vif, the gene encoding the Vif protein associated with the infectivity of the extracellular virions, and it overlaps at its 5' end with the pol gene and at its 3' end with vpr;

vpr, the gene encoding the Vpr protein acting as an accelerator of the replication cycle at different levels, and it overlaps at its 5' end with the vif gene;

tat, the gene encoding the Tat protein which is a transactivator , and its second exon is contained in the env sequence;

vpu, the gene encoding the Vpu protein involved in the release of the virions;

env, the gene encoding the gpl60 protein of the viral envelope ;

rev, the gene encoding the Rev protein, responsible for processing and transporting messenger RNA to the cytoplasm, and its second exon is contained in the env sequence; and

nef _f the gene encoding the Nef protein which negatively regulates CD4 and HLA molecules of the infected cell and plays a role in the pathogenicity of the virus .

The pNL4-3ART [lacZJRen viral vector described in EP1752541 as IP HIV NL LacZ/RT Ren is characterized by having the substitution of the 896 bp fragment of the pol gene encoding the RT between Ncol/Agel with the LacZ gene. pNL4-3ART [lacZ] was generated from this construct by means of removing the marker gene encoding the Renilla (Ren) luciferase protein (SEQ ID NO: 13) and restoring the sequence of the nef gene (90 bp) which had been previously removed, located between the Notl/Xhol restriction sites (in positions 8797 and 8887, respectively). For this purpose, the area with the oligonucleotides specific for pNL4-3, 52EU: (SEQ ID NO: 11) and 104ED: (SEQ ID NO: 12), the Notl and Xhol restriction sites being included in these oligonucleotides, was previously amplified. Once the 90 bp region of the nef gene was amplified from pNL4-3, it was cloned into the Notl (8797) /Xhol (8887) position, where the Ren gene had been removed, the plasmid pNL4-3 ART [lacZ] having a size of 14,483 bp being generated.

The following step was the removal of an Narl restriction site located in the plasmid pNL4-3 outside the coding sequence of the virus, i.e., in pUC18. The previously generated plasmid (pNL4-3 ART [lacZ] ) was used and digested with the Aatll and Apal restriction enzymes, a 3613 bp fragment (insert) being obtained, where the Narl site had already been removed. This fragment was cloned with the same corresponding restriction enzymes into pNL4-3ART [lacZ] , converting it into plasmid pNL4-3 ART [LacZ] , Narl ^" . The size of the generated plasmid is about 14,483 bp.

The LacZ gene encoding the β-galactosidase protein (SEQ ID NO: 14) cloned into Ncol/Agel by means of digestion with the corresponding restriction enzymes and the subsequent filling of the sticky ends with the DNA polymerase I Klenow fragment (GE Healthcare) was then removed and re-ligated, giving rise to plasmid pNL4-3 ART, Narl- hereinafter called pNL4-3 ART. The size of this plasmid generated is about 13,983 bp (Figure IB) .

Different constructs of the invention were generated from pNL4-3 ART; to that end the LacZ gene was cloned into the pNL4- 3ART vector in the position of gag gene (pNL4-3ART/Agag- [LacZ] ) , env gene (pNL4-3ART/Aenv- [LacZ] ) , env-nef gene (pNL4-3ART/Aenv- ne_- [LacZ ] ) , nef gene (pNL4-3ART/Anei- [LacZ] ) and in gag-pro gene (pNL4-3ART/Agag-pro- [LacZ] ) (Figure 1C, Table 1) for the purpose of increasing the cloning efficacy and avoiding the carry-over of minority populations of the reference virus. Thus, the ligated clones without the insert from the patient gave blue colonies, whereas the plasmid which incorporated the gag gene, env gene, env-nef gene, nef gene, and/or gag-pro gene originating from the patient gave white colonies.

The following viral vectors were generated from pNL4-3 ART (Figure 1C, Table 1) :

1. pNL4-3 ART/Agag [LacZ] : It is characterized by the removal of part of the gag gene, 1368 bp, between the Narl (in position 637) and Apal (in position 2006) restriction sites of pNL4-3ART; the 500 bp amino-terminal end of the LacZ gene was cloned in its place with the same enzyme. The LacZ gene was amplified by means of PCR of plasmid pUC19 (Invitrogen) with the Narl-LacZ-UP (SEQ ID NO: 15) and Apal-IacZ-D (SEQ ID NO: 16) oligonucleotides. The plasmid generated is referred to as pNL4-3 ART/Agag [LacZ] with a total size of 13,115 bp.

2. pNL4-3 ART Kspl ⁺ : A new Kspl (SacII) restriction site was introduced in position 9433 of pNL4-3 by directed mutagenesis. In order to generate this plasmid, the BamHI-

Nael fragment of pNL4-3-NotI was first subcloned into pBluescript II SK(-) vector (Stratagene) at the same sites, the pBluescript SK/NL BamHI-Nael vector being generated, and on the latter directed mutagenesis was performed to generate the Kspl site with the following oligonucleotides: M-KspI-UP (SEQ ID NO: 17) and M-Kspl- Down (SEQ ID NO: 18), the plasmid pBluescript SK/NL BamHI- Nael, Kspl+, being generated; the BamHI-Nael fragment was then extracted from the latter plasmid with Kspl mutation and was cloned into pNL4-3 ART at the same restriction sites, giving rise to pNL4-3 ART Kspl ⁺ . The presence of the new target Kspl restriction was confirmed by means of sequencing in the corresponding position of pNL4-3. The size of the vector generated was 13,983 bp.

3. pNL4-3 ΑΚΐ/Anef [LacZ] : The 640 bp nef gene between Notl (nt 8797 of pNL4-3) and Kspl (SacII) (nt 9437) was removed from pNL4-3 ART Kspl ⁺ and the 500 bp amino-terminal end of the LacZ gene was cloned in its place with the same enzymes. The LacZ gene was amplified by means of PCR of plasmid pUC19 (Invitrogen) with the Notl-LacZ-UP (SEQ ID

NO: 19) and KspI-LacZ-D (SEQ ID NO: 20) oligonucleotides. 13,843 bp plasmid pNL4-3 ΑΚΊ/Anef [LacZ] was generated. 4. pNL4-3 ART Kspl ⁺ , NcoI ⁺ : A new Ncol restriction site was introduced in position 6113 in pNL4-3 by mutagenesis. The oligonucleotides used were: Mut-NcoI-Env-UP (SEQ ID

NO: 21) and Mut-NcoI-Env-down (SEQ ID NO: 22) . The presence of the new target Ncol restriction was confirmed by means of sequencing in the corresponding position of pNL4-3. The size is 13,838 bp.

5. pNL4-3 ART/Aenv [LacZ] : The 2683 bp env gene between

Ncol (nt 6113) and Notl (nt 8797) was removed from pNL4-3 ART Kspl ⁺ , NcoI ⁺ ; the 500 bp amino-terminal end of the LacZ gene was cloned in its place with the same enzymes. The LacZ gene was amplified by means of PCR of the plasmid pUC19 (Invitrogen) with the 127 (SEQ ID NO: 23) and Not-

LacZ-down (SEQ ID NO: 24) oligonucleotides. 11 , 800 bp plasmid pNL4-3 ART/Aenv [LacZ] was generated.

6. pNL4-3 ART/Aenv-nef [LacZ] : The 3320 bp env and nef genes between the Ncol and Kspl (SacII) restriction sites in pNL4-3 ART, Kspl ⁺ , NcoI ⁺ were removed at the same time, the 500 bp amino-terminal end of the LacZ. gene was cloned in their place with the same enzymes . The LacZ gene was amplified by means of PCR of the plasmid pUCl 9 (Invitrogen) with the 127 (SEQ ID NO: 23), and KspI-LacZ-D (SEQ ID NO: 20) oligonucleotides. 11,160 bp plasmid pNL4-3

ART/Aenv-Afe- [LacZ] was generated.

7. pNL4-3 ART, Kspl ⁺ , NcoI ⁺ , Agel ⁺ : A new Agel restriction site was introduced in position 2572 according to the sequence of pNL4-3 by mutagenesis. The primers used were: Mut-Agel-UP (SEQ ID NO: 25) and Mut-Agel-Down (SEQ ID NO: 26) . The presence of the new target Agel restriction was confirmed by means of sequencing in the corresponding position of pNL4-3. The size is 13,838 bp. 8. pNL4-3 ΑΚΊ/Agag-pro[LacZ] : The 1935 bp fragment comprising the gag and pro genes comprised between the Nar I (in position 637) and Agel (in position 2572) sites of the pNL4-3 ART, Kspl ⁺ , NcoI ⁺ , Agel ⁺ was removed; the 500 bp amino-terminal end of the LacZ gene was cloned in its place with the same enzymes. The LacZ gene was amplified by means of PCR of the plasmid pUC19 (Invitrogen) with the primers Narl-LacZ-UP (SEQ ID NO: 15) and Agel-lacZ-D (SEQ ID NO: 27) . 12,403 bp plasmid pNL4-3 ART/Agag-pro [LacZ] was generated.

9.

Table 1

List of plasmids generated in the invention

PLASMIDS INTERMEDIATE bp New Sites Enzymes

PLASMIDS restriction removed for

sites cloning (position

pNL4.3) pNL4-3 14879 pNL4-3 ART 13983 Narl

(pUC18) pNL4-3 ART 13983 pNL4-3 13115 Narl +

ART/Agragr[ LacZ] Apal pNL4-3 ART Kspl + 13983 KspI/SacII

(9433) pNL4-3 13843 Notl +

ART/ nef [LacZ] Kspl pNL4-3 ART Kspl+ 13838 Ncol (6113)

NcoI + pNL4-3 11800 Ncol +

ART/Aenv[LacZ] Notl pNL4-3 11160 Ncol + ART/Aenv- Kspl nef[ LacZ]

pNL4-3 ART Kspl+ Agel +

NcoI+ Agel+ 13838 (2572) pNL4-3 12403 Narl + ART/Agag- Agel pro [ LacZ]

Vectors/chimeras were then constructed by means of cloning the env, gag, gag-pro, env- nef and/or nef gene fragments of HIV-l-infected patients in the previously described corresponding vectors (Figure 1C, Table 1) in order to subsequently generate virions and to analyze the induced immune response .

The total blood viral DNA of HIV-1 positive patients under study were obtained from the cell pellet by means of the QIAmp DNA blood kit (Qiagen) .

For the extraction of viral RNA, 1 ml of plasma from the patients under study was used; the viral RNA was extracted by means of the QIAmp kit (Qiagen) . The extracted HIV-1 RNA was used as a template to obtain cDNA. The RNA was initially transcribed and subsequently amplified using the specific primers for each of the areas to be characterized.

The amplified fragments were:

1. gag fragment: 1793 bp were amplified by means of specific primers [(107 (SEQ ID NO: 28) / 122 (SEQ ID NO: 29) ) and (163 (SEQ ID NO: 30) / 123 (SEQ ID NO: 31) ) ] which include Narl and Apal restriction sites in primers 163 and 123, respectively, necessary for the subsequent cloning thereof into the pNL4-3 ART / Agag[ LacZ] proviral vector substituting the corresponding LacZ gene.

2. gag-pro fragment: 1935 bp were amplified by means of specific primers [(107 (SEQ ID NO: 28) / 125 (SEQ ID NO: 40)) and (163 (SEQ ID NO: 30) / 159(SEQ ID NO: 41))] which include Narl and Agel restriction sites in primers 163 (SEQ ID NO: 30) and 159 (SEQ ID NO: 4), respectively, necessary for the subsequent cloning thereof into the pNL4-3 ART /Agag-pro [LacZ] proviral vector, the LacZ gene being removed first.

3. nef fragment: 637 bp were amplified by means of specific primers [(117 (SEQ ID NO: 35) / 118 (SEQ ID NO: 34) and (119 (SEQ ID NO: 32) / 121 (SEQ ID NO: 33))] which include Notl and Kspl sites in primers 119 (SEQ ID NO: 32) and 121 (SEQ ID NO: 33), respectively, necessary for the subsequent cloning thereof into the pNL4-3 ART /Anef[LacZ] proviral vector after removing the LacZ gene located in the position of the nef gene.

4. env fragment: 2683 bp were amplified by means of specific primers [(101 (SEQ ID NO: 37) / 102 (SEQ ID NO: 36) ) and (126 (SEQ ID NO: 39) / 161 (SEQ ID NO: 38) ) ] which include Ncol and Notl restriction sites in primers 126 (SEQ ID NO: 39) and 161 (SEQ ID NO: 38), respectively, necessary for the subsequent cloning thereof into the pNL4-3 ΑΚΊ/Aenv[LacZ] proviral vector, the LacZ gene being removed first.

5. env-nef fragment: 3320 bp were amplified by means of specific primers [(101 (SEQ ID NO: 37) / 118 (SEQ ID NO: 34)) and (126 (SEQ ID NO: 3) / 121(SEQ ID NO: 33))] which include Ncol and Kspl restriction sites in primers 126 (SEQ ID NO: 3) and 121(SEQ ID NO: 33) , respectively, necessary for the subsequent cloning thereof into the pNL4-3 ART /Aenv-nef [LacZ] proviral vector, the LacZ gene being removed first.

In any case, after amplification, an enzymatic digestion of the amplified product and of the vector was performed with the corresponding enzymes in each case (Table 1), according to the manufacturer's instructions, and an in vitro ligation process was then performed using T4 ligase according to the manufacturer's instructions. All the plasmids were amplified in bacterial strain stbl2 ^tm (Invitrogen) and they were subsequently purified by means of maxi-preparations with the Qiagen-tip 500 kit (QiagenTM) and were stored at -20°C. All the plasmids were verified by means of restriction analysis and subsequent sequencing.

Several pNL4-3 ART/Agag chimeras were obtained by cloning the gag fragment of different infected HIV patients into the pNL4-3 ART/Agag[LacZ] proviral vector substituting the LacZ gene. Table 2 lists the DNA or RNA sequence corresponding to a fragment of each chimera obtained:

Table 2

List of pNL4-3 ART/Agag chimeras generated in the invention

1.2 Production and concentration of virions

Virions were generated by means of transfecting 293T cells (ATCC) with the different viral vectors under study through the calcium phosphate method (Profection Kit; Promega) . 5 g of plasmid DNA from different viral vectors (Qiagen, Valencia, CA) were used. The day before transfection, 1.5xl0 ⁶ cells were seeded in 10 ml of DMEM-10 (DMEM supplemented with 10% (v/v) fetal bovine serum) in 75 cm ² culture bottles. At 24 hours post- transfection, the medium was changed and at 48 hours the supernatants were collected, clarified and subsequently concentrated. Once the virions were obtained, they were stored at -80°C. In any case, a supernatant was obtained in cells treated in the same manner but transfected with the "empty vector" which was used as negative control. The supernatant collected after transfection was centrifuged in 30 ml threaded tubes for 32 minutes at 28,000 rpm in a Thermo scientific Sorvall® WX Ultra Centrifuge Series 80 centrifuge (Thermo Scientific Corporation) . The supernatant was discarded. The pellet obtained after centrifugation was resuspended in 500 μΐ of phosphate buffered saline (PBS) which was transferred to an Eppendorf tube. They were again centrifuged for 10 minutes at 40,000 rpm. The supernatant was discarded and the pellet was resuspended in 500 μΐ of PBS.

The detection of the p24 antigen by means of the ELISA/Ag HIV technique was used to quantify the viral immunogen ( Innogenetics , Belgium) . The quantification was always performed before and after its concentration.

EXAMPLE 2

Characterization of the virions

2.1 Assessment of the viral replication in MT-2 cells

The assessment of the viral replication was performed by means of using marker gene-carrying virions, specifically the Ren (renilla) gene. The assessment of the viral replication was analyzed by means of an assay in MT-2 cells obtained from NIH AIDS Research and Reference Reagent Program, Catalog number: 237. The virions were obtained by transfection with the corresponding pNL4-3 Ren WT or pNL4-3 ART Ren viral vectors, described in EP1752541, in 293T cells. At 48 hours the supernatant was collected and the p24 antigen was quantified by capture ELISA [Innogenetics, Belgium] . Part of the NL4-3 Ren WT virions was heat-inactivated [56°C for 60 minutes)] .

In order to assess the replication capacity, 5 x 10 ⁴ MT-2 cells were seeded per well in 96-well round bottom plates at a final volume of 200 μΐ. They were subsequently infected with different dilutions of the viral stocks (NL4-3 Ren WT, heat- inactivated NL4-3 Ren WT or NL4-3 ART Ren) which had previously been quantified by means of p24 antigen quantification. The assay was performed in triplicate. The infections were maintained at 37 °C in 5% C0 ₂ atmosphere. At 24 and 96 hours of the infection, the luciferase activity was determined with the Renilla Luciferase Assay System (Promega) system following the manufacturer's recommendations for Renilla. The cells were lysed in 100 μΐ of the lysis buffer for 5 minutes at 4°C. The luciferase activity of these cell extracts was evaluated by introducing 50 μΐ of the cell lysate in a plate illuminator (Orion, Berthold) programmed for injecting 50 ml of substrate. This value provides the relative light units (RLUs) per ml of viral stock viral at 24 or 96 hours of infection in MT-2 cells (Table 3), Figure 2.

As can be seen in Table 3, both the heat-inactivated NL4-3 Ren WT virions and the NL4-3 ART Ren virions lack replicative capacity . Table 3

Quantification of luciferase activity to analyze viral infection/replication in MT-2 cells, 24 and 96 hours post- transfection

RLUs : Relative light units

2.2 Assessment of the replication of NL4-3 ART virions in TZM- bl cells

The replication of the NL3.4 ART (DRT) and NL4-3 (WT) virions was assessed by means of quantifying luciferase activity in TZM-bl cells.

The TZM-bl indicator cells express the CD4 receptor and the CCR5/CXCR4 co-receptors with an integrated LTR-Luc reporter system. After assessing the p24 antigen, 1:4 dilutions of the transfection supernatant where the virions are placed in 96-well plates were prepared in triplicate. 10,000 TZM-bl cells were added and the plate was maintained in an incubator at 37 °C in 5% C0 ₂ atmosphere. After 72 hours, the luciferase activity present in the cell extracts was analyzed in a luminometer (Turner Biosystems, Sunnyvale, CA) using the Biotherma assay kit (Sweden) following the manufacturer's instructions. As can be seen in Figure 3, the NL4-3 ART (DRT) virions lacked replicative capacity .

2.3 Confocal microscopy assay

A) Transfections in 293T cells

293T cells were co-transfected with the plasmids: pGAG-GFP (5 μς) , pNL4-3 WT (3μς) + pGAG-GFP (2 μς) and pNL4-3 ART (3μς) + pGAG-GFP (2 μg) . At 48 hours post-transfection, the supernatant was collected and used to subsequently infect new susceptible cells. The cells were fixed with FACS lysis solution for 20 minutes at room temperature. After washing with PBT (PBS, 0.1% Tween® 20) the cells were stained with 4' , 6-diamidino-2- phenylindole (DAPI) (1/10000) and phalloidin (1/1000) for 30 minutes at room temperature. Subsequently, the cells were mounted with mounting medium ( Vectashield) (Figure 4 A) .

B) Infection

The virion was quantified by means of assessing the p24 antigen by ELISA ( Innogenetics , Belgium) . The PBMC cells

(peripheral blood mononuclear cells) (25xl0 ⁶ ) were infected with the amount of virions corresponding to 2 μg of p24 antigen of the following virions obtained by co-transfection in 293T cells: pNL4-3 + pGAG-GFP, pNL4-3 ART + pGAG-GFP and 1 ml of GAG-GFP.

It was incubated between 3-4 hours at 37°C. The cells were subsequently collected, fixed, stained and prepared for visualization by means of confocal microscopy following the same process as that for the transfected cells. The images were taken with a LEICA SP2 confocal microscope and processed with ImageJ

(Figure 4B) .

Both the virions originating from the pNL4-3WT + pGAG-GFP co-transfection and pNL4-3 ART + pGAG-GFP were capable of infecting PBMCs .

2.4 Visualization of the virion by means of electron microscopy 293T cells were transfected using the mammal transfection kit (Promega) with two different pNL4-3 (5 g) and pNL4-3 ART (5 ^g) constructs. 48 hours after transfection, the supernatant was removed and the cells were cleaned with IX PBS. The PBS was removed and the cell monolayer was maintained in 10 ml of 2.5% glutaraldehyde in PB (phosphate solution) for 20 minutes at 4°C. After these 20 minutes, the cells were passed to a 15 ml falcon and were centrifuged for 5 minutes at 1500 rpm (C. Lopez- Iglesias et al., Ultrastruct Mol Struct Res. 1988; 101 (1): 75- 91). The supernatants were clarified and subsequently concentrated by centrifugation for 32 minutes at 28,000 rpm in a Thermo scientific Sorvall® WX Ultra Centrifuge Series 80 centrifuge (Thermo Scientific Corporation) . Sorvall Ultra Series. The supernatant was discarded and the sediment obtained after centrifugation was resuspended in 500 μΐ of PBS. It was again centrifuged for 10 minutes at 40,000 rpm. The sediment was resuspended in 500 μΐ of 2.5% glutaraldehyde in PB . Once the sediment was properly resuspended, it was left for 30 minutes at 4°C with the glutaraldehyde and after that time the glutaraldehyde was changed for another 500 μΐ of new glutaraldehyde. It was left for 1 hour at 4°C, the glutaraldehyde was removed and washed two or three times with 1% PB and it was left in PB until it was used in electron microscopy .

The protocol described by Lopez-Iglesias et al. (C. Lopez- Iglesias et al., Ultrastruct Mol Struct Res. 1988; 101 (1) : 75- 91) was used for staining the samples and for the inclusion in paraffin .

As can be seen in Figure 5A, the NL4-3 viral particles were perfectly formed (arrows) and their core well defined, and gemmating viral particles were also observed. In contrast, the NL4-3 ART virions were immature and neither the formed core (arrows) nor the typical compaction of a WT viral particle could be observed in Figure 5B.

It can be observed in Figure 5C that the NL4-3 viral particles were perfectly formed in 90% of the cases although 10% defective, immature particles are observed. The purified viral particles obtained from transfecting the 293T cells transfected with the pNL4-3 ART constructs can be observed in Figure 5D. It can be observed that 93% of the population has immature viral particle morphology, no mature particles being observed. 2.5 Analysis of the expression of the HIV-1 gag protein by means of western-blot (wb)

In order to analyze the expression of the HIV-1 gag protein, extracts from 293T cells and from purified virions obtained 48 hours post-transfection in 293T cells with the indicated plasmids (pNL4-3 and pNL4-3 ART) were used. Approximately 2 x 10 ⁶ 293T cells per experimental point collected at 48 hours of transfection were used for preparing the cell extracts. The cells were washed in PBS and in buffer A (10 mM Hepes pH 8, 10 mM KC1, 15 mM MgCl ₂ and 1 mM DTT) , resuspended in 20 μΐ of buffer C (20 mM Hepes pH 8, 0.1% NP-40, 25% glycerol, 420 mM NaCl, 10 mM KC1, 1.5 mM MgCl ₂ , 0.2 mM EDTA ( ethylenediaminetetraacetic acid), 0.5 g/ml leupeptin, 0.5 g/ml pepstatin, 0.5 g/ml aprotinin, 1 mM PMSF (phenylmethylsulfonyl fluoride) and 1 mM DTT ( dithiothreitol ) ) , left to lyse for 15 minutes at 4°C and centrifuged at 4, 062 g for 10 minutes at 4°C. The supernatant obtained was diluted in buffer D (20 mM Hepes pH 8, 20% glycerol, 50 mM KC1, 0.2 mM EDTA, 0.5 g/ml leupeptin, 0.5 g/ml pepstatin, 0.5 g/ml aprotinin, 1 mM PMSF and 1 mM DTT) depending on the desired final protein concentration.

The assessment of protein concentration was determined by means of the Bradford reaction (Biorad) (Bradford MM, Anal Biochem 1976; 72:248-54) .

10 g of the different extracts were migrated in 10% polyacrylamide-SDS (sodium dodecyl sulfate) gel to perform the Western-blot (WB) . The transfer of the gels to polyvinylidene fluoride (PVDF) membranes ( Sigma-Aldrich) previously incubated for 5 minutes in methanol was performed in transfer buffer (20 mM glycine, 150 mM Tris-base and 20% methanol) using an electrotransfer apparatus (Pharmacia). The membranes were blocked by incubation at 37°C for 1 hour with 5% milk powder in 0.1% PBS/Tween-20. After blocking, the membranes were incubated with a monoclonal antibody directed against the p24 protein

(clone 491, Santa Cruz Laboratories) at a 1:1000 dilution. After three 5-minute washings with 0.1% PBS/Tween-20, they were incubated with peroxidase-bound mouse anti-immunoglobulin antibodies for one hour at 37°C. Three 5 minute-washings were subsequently performed with 0.1% PBS/Tween-20. The detection of the antigen-antibody interactions was performed by means of the SuperSignal WestPico Chemi lumi ne s ce nt Substrate (Pierce) chemiluminescence system and exposure to photographic film

(Hyperfilm ECL, GE HEALTHCARE) .

As seen in Figure 6, both the NL4-3 and NL4-3 ART (ART) virions produced the gag protein.

EXAMPLE 3

Assessment of the cellular immune response

Once the NL4-3 ART virions have been obtained and characterized, the cellular immune response was assessed in two ways. It was first assessed by means of an ex vivo model with monocyte-derived dendritic cells (MD-DC) , the capacity for producing the specific anti-HIV cellular response in CD4+ and CD8+ cells was assessed. Assays were also performed with PBMC to detect the specific anti-HIV cellular response, among others, intracellular cytokine detection (ICS) and the assessment of the number of IFN-γ producing cells and by means of ELISPOT.

3.1 Ex vivo generation of monocyte-derived dendritic cells (MD- DC) pulsed with immunogen

The autologous MD-DCs were obtained from the monocytes present in the PBMC obtained from an anticoagulated sample. The PBMCs were washed three times in serum-free culture medium, X- VIV015, and resuspended (5xl0 ⁶ /ml) in said culture medium supplemented with 1% inactivated autologous serum and they were deposited in culture vials at 37°C and 1% C0 ₂ for 2 hours, during which time the monocytes adhered to the surface of the vial. The non-adhered cells (lymphocytes) were removed by suction. The adhered monocytes were cultured for 5 days in X- VIVO 15 supplemented with 5% inactivated autologous serum in the presence of human recombinant IL-4 and GM-CSF at the dose of 1000 IU/ml for each cytokine and with or without 1 mM of AZT to test whether or not it was better to suppress the possible viral replication in relation to patients without antiretroviral treatment. After 5 days in culture, the monocytes turned into immature dendritic cells (DC) and they were ready to be pulsed with the different immunogens . At least 5xl0 ⁶ immature MD-DC were used for pulsing, they were washed two times in medium and resuspended in 1 ml of medium containing the inactivated HIV-1 or immunogen aliquot (lxlO ⁹ virions) as well as GM-CSF+ IL4

(1000 IU/ml of each), they were maintained at 37°C for 5 hours. A cocktail of human recombinant cytokines (TNF-alpha+IL-6+IL-lp) inducing the maturation of MD-DCs was then added into the culture and it was prolonged for about 40 additional hours

(Figure 7) . All the MD-DCs in culture (at least 5xl0 ⁶ ) were collected and centrifuged, and the supernatant was aliquoted to perform the latest possible cytokine and remaining HIV-1 measurements. The MD-DCs were washed two times with X-VIVO10 culture medium.

As controls in all the experiments, the MD-DCs were also pulsed with HIV recombinant proteins (p24), as positive control, HIV 1 recombinant p24 (Protein Sciences Corp. Meridien, CT, USA) . They were also pulsed with the SEA superantigen as positive control. The same steps were repeated for the negative controls with the exception that the MD-DCs were not pulsed with the immunogen.

3.2 Measurement and analysis of the immune response

3.2.1 Labeling with CFSE and flow cytometry analysis

The PBMCs were labeled for 20 minutes at 37 °C with a 1.5 mM CFSE ( 5-6-carboxyfluorescein diacetate succinimidyl ester) solution. After 2 washings, the labeled PBMCs were stimulated with HIV-1 recombinant proteins and the relevant controls for 6 days in culture medium supplemented with 10% fetal calf serum (FCS) in an incubator at 37°C and 5% C0 ₂ . Subsequently and after the corresponding surface labeling, the frequency of CD4 and CD8 antigen specific cells that had been divided for each stimulus was evaluated by means of flow cytometry analysis (Figure 7) .

The dilution of the CSFE label was also evaluated after co- culturing for 2 days MD-DCs pulsed with the different types of immunogens and fresh autologous T cells in a DC:T cell ratio of 1:10. In vitro studies were performed by pulsing MD-DC cells with NL4-3 ART virions and analyzing the response induced in the autologous T cells of HIV-1 patients. The data obtained indicated that after co-culturing MD-DCs pulsed with NL4-3 ART and autologous T lymphocytes, an increase of cell proliferation and cytokine production (IL-2 and IFN- a) with respect to that obtained with recombinant proteins or with the heat-inactivated autologous virus itself (Figure 8) was generated in particular patients .

3.2.2 Detection of the intracellular cytokine production of specific anti-HIV-1 CD4/CD8 lymphocytes

After culturing the PBMCs of the patients for 6 or 18 hours with groups of HIV-1 peptides, recombinant virions and co- stimulating antibodies (CD28 and CD49d) in the presence of Brefeldin A (10 g/ml), the cells were fixed and permeated. The phenotypic markers of the CD4/CD8 lymphocytes were subsequently added and the HIV-1 specific T lymphocytes were identified and quantified by means of staining with anti-IFN-γ, anti-TNF-α and anti-IL-2, and activation labels (CD38, CD69) after the subsequent flow cytometry analysis.

Similarly, the measurement of CD69 expressing and IFN-γ producing CD4 and CD8 T cells was performed by means of intracellular staining and cytofluorometric analysis after re- stimulating the autologous T lymphocytes with CDDM for 1-2 days . 3.2.3 Analysis of the specific response of CD8+ T cells by means of ELISPOT

The analysis of the specific response of CD8+ T cells was performed by means of using a specific ELISPOT based on the determination of the production of IFN-γ by the CD8+ T cells against dominant epitopes of the HIV-1 proteins restricted for HLA-class I antigens. The cells were stimulated with pools of 15-mer overlapping synthetic peptides of the HIV-1 gag, pol, env and nef proteins, chimeric recombinant virions.

Assays with depletion of cell subpopulations (CD4, B, NK) were also performed by means of immunomagnetic selection to analyze the degree of participation thereof in the response obtained .

3.3 High-resolution HLA typing

High-resolution HLA typing was evaluated by means of PCR- SBT of the genomic DNA of peripheral blood mononuclear or polynuclear cells and/or cells from B cell lines. The polymorphic exons of the genes encoding MHC (mainly exon 2 of the DRB1 gene) were amplified using generic primers. The PCR products were sequenced by using the automatic fluorescent sequencing method and the sequences obtained were analyzed by means of suitable software ( Perkin-Elmer ) .

3.4 Optimization of the ex vivo assay for the detection and characterization of the immune responses against HIV-1 using defective recombinant and non-replicative virions

Samples of approximately 20-30 asymptomatic chronic HIV+ patients with a high CD4 number (>500/mm ³ ) were used. An assay for intracellular cytokine detection (ICS) used with different pre-stimulations of the PBMC has fundamentally been used. The pre-stimulations tested were: low doses of recombinant IL-2 (20 U/ml) or a cocktail with CD28 and CD49d (1 g/ml) . No differences have been found between these 2 types of pre- stimulations although the use of the cocktail of antibodies produced greater reproducibility of IFNy and IL-2 secretion by the CD4 and CD8 cells. The immunogenic antigens assayed were heat-inactivated NL4-3 WT, NL4-3 ART, and BAL and MN (reference strains from laboratory isolates, occasionally known as HIV-BaL and HIV-MN, respectively) inactivated by heat or by means of treatment with 1 mM AT2 (aldrithiol-2 ) at 4°C overnight (dose corresponding to 20 g of p24/ml) . After stimulating the cells for 18 to 24 hours with the mentioned stimuli, the results obtained were heterogeneous, a marked response being observed in 20-30% of the patients (n≥6), the response induced by the NL4-3 ART being very similar to that obtained by the entirely heat- inactivated virions (Figure 9) .

3.5 Comparison of the results obtained using the ex vivo model established with PBMC with the MD-DC co-culture model

Majority of the ex vivo assays with PBMC (ICS) were performed in parallel using both MD-DC and T lymphocytes of the same HIV-infected patients. The preliminary results showed a practically complete parallelism between both assays, the patients responding to the NL4-3 ART virions and other heat- inactivated reference virions can be perfectly discriminated from the non-responding patients. The production of cytokines (IFNy, IL-2) and the induction of proliferation in CD4 and CD8 cells (Figure 10) were assessed. As observed in Figure 10, there is a parallel grouping of patients depending on their response to the different immunogens between both assays. These data suggest that the ex vivo assay with PBMC optimized for the detection of the anti-HIV immune response could allow a rapid in vitro assessment of the immunogenic activity of possible future candidates responding to therapeutic vaccines based on MD-DC since the results can be analyzed at 48-72 hours, whereas the results after co-culturing with MD-DC required the prior generation of MD-DC for 7 days and the patient has to be subjected to two blood donations.

3.6 Assays with PBMC to detect specific anti-HIV cellular response measured by the number of IFN-γ producing cells (ELISPOT)

Different assays were performed to detect specific anti-HIV cellular response, such as evaluating the immunogenicity of ART against the WT-AT2 (pNL4-3) virion, evaluating the effect of the inactivation by AT2 ( aldrithiol-2 ) (WT-AT2 vs. ART-AT2) and evaluating the efficiency of the tropism of the envelope X4 (ART) vs. R5 (BaL and AC10) .

After evaluating the immunogenicity of the ART against WT- AT2 (NL4-3) virion, it was observed that the ART produced response, measured by the number of IFN-γ producing cells (ELISPOT), in a larger number of patients from the analyzed cohort of asymptomatic HIV-1 positive patients. After evaluating the effect of inactivation by AT2 (aldrithiol) (WT-AT2 vs ART- AT2 ) , it was observed that this inactivation process did not influence the immunogenicity of the viral particle. After evaluating the efficacy with respect to the tropism of envelopes X4 (NL4-3) vs. R5 (BaL and AC10) within the ART: the envelopes R5 appeared to be slightly less immunogenic (Table 4) .

Table 4

Immune response screening of HIV-l-positive patients. Assessment of the immune response after stimulation with different virions by means of the IFN-γ production (ELISPOT)

PATIENTS /Virions Mean SFC

13 of 59 correspond to WT -AT2 22% 186

24 of 47 correspond to ART 49% 324

(X4)

31 of 47 correspond to ART- 63% 596

AT2

21 of 41 correspond to 51% 286

ART/AC10 (R5 )

22 of 41 correspond to 54% 315

ART/BaL ( R5) Finally, the immunogenicity of ART was evaluated compared to the WT-AT2 (NL4-3) virion which had been treated previously in their production with a protease inhibitor (Amprenavir, 50 μΜ APV) , WT/APV-AT2. Consequently, treatment with the inhibitor caused the production of immature virions. Said immature particles are shown in Figure 11 by means of electron microscopy. After evaluating the immunogenicity of ART compared to the WT/APV-AT2 virion, it was observed that WT/APV-AT2 produced a response, measured by the number of IFN-γ producing cells (ELISPOT) , higher than its untreated homolog, 75% responding patients being obtained in a population of 12 patients .

The autologous chimeras were evaluated as a way of enhancing the response. After evaluating the immunogenicity of ART/Agag ("patient") virions in patients in whom there was material for amplifying, either DNA or RNA, compared to the different non-chimeric virions described previously, it was observed that the response intensified up to 49%. The heterologous responses observed in other individuals were very heterogeneous. In the responding patients, the use of autologous Gag (for example, patient 596) involved an increase of 33% in the number of SFC with respect to its ART analog. In patients categorized as non-responding patients who have not responded to any of the viral constructs, they only responded to the autologous Gag at its maximum concentration, concentrations greater than 600 ng of p24 antigen (Table 5) .

Table 5

Evaluation of autologous chimeras in two patients

Patient WT-AT2 ART Gag 70 Gag 596

70. ICS 5 15 20 *

596.8 55 255 * 380 EXAMPLE 4

Immunization model of a patient

In each of the patients who are going to receive vaccinations, i.e., monocyte-derived dendritic cells (MD-DC) pulsed with the infectious HIV-1 immunogen (non-replicative infectious virion) , the first step is the isolation and large scale production of HIV-1 by means of transfecting the vector into cells under GMP conditions . Said non-replicative infectious virion comprises a viral genome containing a mutation in the pol gene such that the RT protein is non-functional and, in addition, the sequence of another gene different from pol gene substituted with the sequence of the same gene originating from the HIV of the patient. The virus obtained is concentrated and kept at -80°C until it is needed to pulse the MD-DCs of the same patient .

The MD-DCs are freshly prepared from the PBMC monocytes of a 150 ml venous blood sample which is drawn one week prior to each immunization and is immediately processed. After 5 days of culturing the monocytes to generate immature MD-DCs, they are pulsed with the non-replicative infective immunogen for 2 additional culture days, adding thereto a cocktail of MD-DC maturation-inducing cytokines. These will then be washed and administered immediately to the patient through sub-dermal injection close to the axillae (F. Garcia, et al. _r JIC 2011, 203: 473-478) .

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