HIV-specific Cellular Immune Responses Research Articles

Generation of Anti-HIV CAR-T Cells for Preclinical Research.

The inability of people living with HIV (PLWH) to eradicate human immunodeficiency virus (HIV) infection is due in part to the inadequate HIV-specific cellular immune response. The antiviral function of cytotoxic CD8+ T cells, which are crucial for HIV control, is impaired during chronic viral infection because of viral escape mutations, immune exhaustion, HIV antigen downregulation, inflammation, and apoptosis. In addition, some HIV-infected cells either localize to tissue sanctuaries inaccessible to CD8+ T cells or are intrinsically resistant to CD8+ T cell killing. The novel design of synthetic chimeric antigen receptors (CARs) that enable T cells to target specific antigens has led to the development of potent and effective CAR-T cell therapies. While initial clinical trials using anti-HIV CAR-T cells performed over 20years ago showed limited anti-HIV effects, the improved CAR-T cell design, which enabled its success in treating cancer, has reinstated CAR-T cell therapy as a strategy for HIV cure with notable progress being made in the recent decade.Effective CAR-T cell therapy against HIV infection requires the generation of anti-HIV CAR-T cells with potent in vivo activity against HIV-infected cells. Preclinical evaluation of anti-HIV efficacy of CAR-T cells and their safety is fundamental for supporting the initiation of subsequent clinical trials in PLWH. For these preclinical studies, we developed a novel humanized mouse model supporting in vivo HIV infection, the development of viremia, and the evaluation of novel HIV therapeutics. Preclinical assessment of anti-HIV CAR-T cells using this mouse model involves a multistep process including peripheral blood mononuclear cells (PBMCs) harvested from human donors, T cell purification, ex vivo T cell activation, transduction with lentiviral vectors encoding ananti-HIV CAR, CAR-T cell expansion and infusion in mice intrasplenically injected with autologous PBMCs followed by the determination of CAR-T cell capacity for HIV suppression. Each of the steps described in the following protocol were optimized in the lab to maximize the quantity and quality of the final anti-HIV CAR-T cell products.

The Combination of an mRNA Immunogen, a TLR7 Agonist and a PD1 Blocking Agent Enhances In-Vitro HIV T-Cell Immune Responses.

The development of new strategies to achieve a functional cure for HIV remains a priority. We tested a novel HIV therapeutic vaccine using unmodified mRNA (TMEP-B) and mRNA modified by 1-methyl-3'-pseudouridylyl (TMEP-Bmod) expressing both a multiepitopic sequences from Gag, Pol, and Nef proteins, including different CD4 and CD8 T-cell epitopes functionally associated with HIV control in transfected monocyte-derived dendritic cells (MDDCs) obtained from HIV infected patients. In vitro assays were used to test the mRNAs alone and in combination with immunomodulator agents, such as the TLR-7 agonist Vesatolimod and the PD-1 antagonist Nivolumab to try to improve HIV-specific cellular immune responses. Combining the mRNAs with the immunomodulators enhanced HIV-specific T-cell responses, together with the secretion of IFNγ, IP10, MIP-1α, and MIP-1β, which are fundamental mediators of viral control. Our data suggest that the mRNA vaccine prototypes TMEP-B and TMEP-Bmod, when combined with Vesatolimod and/or Nivolumab, could achieve functional cure for patients with HIV.

Evaluation of chimeric antigen receptor T cell therapy in non-human primates infected with SHIV or SIV.

Achieving a functional cure is an important goal in the development of HIV therapy. Eliciting HIV-specific cellular immune responses has not been sufficient to achieve durable removal of HIV-infected cells due to the restriction on effective immune responses by mutation and establishment of latent reservoirs. Chimeric antigen receptor (CAR) T cells are an avenue to potentially develop more potent redirected cellular responses against infected T cells. We developed and tested a range of HIV- and SIV-specific chimeric antigen receptor (CAR) T cell reagents based on Env-binding proteins. In general, SHIV/SIV CAR T cells showed potent viral suppression in vitro, and adding additional CAR molecules in the same transduction resulted in more potent viral suppression than single CAR transduction. Importantly, the primary determinant of virus suppression potency by CAR was the accessibility to the Env epitope, and not the neutralization potency of the binding moiety. However, upon transduction of autologous T cells followed by infusion in vivo, none of these CAR T cells impacted either acquisition as a test of prevention, or viremia as a test of treatment. Our study illustrates limitations of the CAR T cells as possible antiviral therapeutics.

Loading dendritic cells with gold nanoparticles (GNPs) bearing HIV-peptides and mannosides enhance HIV-specific T cell responses

Gold nanoparticles (GNPs) decorated with glycans ameliorate dendritic cells (DC) uptake, antigen-presentation and T-cells cross-talk, which are important aspects in vaccine design. GNPs allow for high antigen loading, DC targeting, lack of toxicity and are straightforward prepared and easy to handle. The present study aimed to assess the capacity of DC to process and present HIV-1-peptides loaded onto GNPs bearing high-mannoside-type oligosaccharides (P1@HM) to autologous T-cells from HIV-1 patients. The results showed that P1@HM increased HIV-specific CD4+ and CD8+ T-cell proliferation and induced highly functional cytokine secretion compared with HIV-peptides alone. P1@HM elicits a highly efficient secretion of pro-TH1 cytokines and chemokines, a moderate production of pro-TH2 and significant higher secretion of pro-inflammatory cytokines such as TNF‐α and IL-1β. Thus, co-delivery of HIV-1 antigens and HM by GNPs is an excellent vaccine delivery system inducing HIV-specific cellular immune responses in HIV+ patients, being a promising approach to improve anti-HIV-1 vaccines.

Memory B Cells, the HLA-B*57 Allele and Natural Control of HIV Infection

Memory B Cells, the HLA-B*57 Allele and Natural Control of HIV Infection

Dendritic Cell Targeting Effectively Boosts T Cell Responses Elicited by an HIV Multiepitope DNA Vaccine.

Despite several efforts in the last decades, an efficacious HIV-1 vaccine is still not available. Different approaches have been evaluated, such as recombinant proteins, viral vectors, DNA vaccines, and, most recently, dendritic cell (DC) targeting. This strategy is based on DC features that place them as central for induction of immunity. Targeting is accomplished by the use of chimeric monoclonal antibodies directed to DC surface receptors fused to the antigen of interest. In this work, we targeted eight promiscuous HIV-derived CD4+ T cell epitopes (HIVBr8) to the DEC205+ DCs by fusing the multiepitope immunogen to the heavy chain of αDEC205 (αDECHIVBr8), in the presence of the TLR3 agonist poly (I:C). In addition, we tested a DNA vaccine encoding the same epitopes using homologous or heterologous prime-boost regimens. Our results showed that mice immunized with αDECHIVBr8 presented higher CD4+ and CD8+ T cell responses when compared to mice that received the DNA vaccine (pVAXHIVBr8). In addition, pVAXHIVBr8 priming followed by αDECHIVBr8 boosting induced higher polyfunctional proliferative and cytokine-producing T cell responses to HIV-1 peptides than homologous DNA immunization or heterologous αDEC prime/DNA boost. Based on these results, we conclude that homologous prime-boost and heterologous boosting immunization strategies targeting CD4+ epitopes to DCs are effective to improve HIV-specific cellular immune responses when compared to standalone DNA immunization. Moreover, our results indicate that antigen targeting to DC is an efficient strategy to boost immunity against a multiepitope immunogen, especially in the context of DNA vaccination.

Dendritic cells primed with a chimeric plasmid containing HIV-1-gag associated with lysosomal-associated protein-1 (LAMP/gag) is a potential therapeutic vaccine against HIV.

The decline in number and function of T cells is a hallmark of HIV infection, and preservation or restoration of HIV-specific cellular immune response is a major goal of AIDS treatment. Dendritic cells (DCs) play a key role in the initiation and maintenance of the immune response, and their use as a vaccine vehicle is a promising strategy for enhancing vaccine efficacy. We evaluated the potential of DC-mediated immunization with a DNA vaccine consisting of HIV-1-p55gag (gag, group-specific antigen) associated to lysosomal associated protein (LAMP) sequence (LAMP/gag vaccine). Immunization of mice with mouse DCs transfected with LAMP/gag (Lg-mDCs) stimulated more potent B- and T-cell responses than naked DNA or DCs pulsed with inactivated HIV. Anti-Gag antibody levels were sustained for at least 3 mo after immunization, and recall T-cell responses were also strongly detected at this time point. Human DCs transfected with LAMP/gag (Lg-hDCs) were also activated and able to stimulate greater T-cell response than native gag-transfected DCs. Coculture between Lg-hDCs and T lymphocytes obtained from patients with HIV resulted in upregulation of CD38, CD69, HLA-DR, and granzyme B by CD4(+) and CD8(+) T cells, and increased IFN-γ and TNF-α production. These results indicate that the use of LAMP/gag-DC may be an efficient strategy for enhancing immune function in patients with HIV.-Lucas, C. G. D. O., Matassoli, F. L., Peçanha, L. M. T., Santillo, B. T., Oliveira, L. M. D. S., Oshiro, T. M., Marques, E. T. D. A., Jr., Oxenius, A., de Arruda, L. B. Dendritic cells primed with a chimeric plasmid containing HIV-1-gag associated with lysosomal-associated protein-1 (LAMP/gag) is a potential therapeutic vaccine against HIV.

Results of phase I clinical trials of a combined vaccine against HIV-1 based on synthetic polyepitope immunogens

The CombiHIVvac candidate vaccine against HIV-1/AIDS containing two synthetic polyepitope immunogens such as TBI and TCI to stimulate the humoral and cellular response is described. The recombinant TBI protein is constructed as a polypeptide with predetermined tertiary structure and contains epitopes of Env and Gag proteins of HIV-1. TCI contains CD8+ CTL and CD4+ Th epitopes of the major viral proteins such as Env, Gag, Pol and Nef which are highly conserved among subtypes A, B and C of HIV-1. A gene encoding the polyepitope TCI immunogen is inserted into a pcDNA-3.1 plasmid vector. The CombiHIVvac vaccine was designed as virus-like particles containing the pcDNA-TCI plasmid in their cores (DNA vaccine) and the TBI protein conjugated with polyglucin on their surfaces. Immunogenicity and safety of CombiHIVvac has been shown in preclinical studies in several animal species. Phase I clinical trials of the vaccine have been completed and the results obtained in human volunteers confirmed that the CombiHIVvac candidate vaccine was safe and did not cause side effects, at the same time, inducing the HIV-specific humoral and cellular immune response. The phase II clinical trials have been approved by the Ministry of Health and Social Development of the Russian Federation.

Success and failure of the cellular immune response against HIV-1.

The cellular immune response to HIV-1 has now been studied in extraordinary detail. A very large body of data provides the most likely reasons that the HIV-specific cellular immune response succeeds in a small number of people but fails in most. Understanding the success and failure of the HIV-specific cellular immune response has implications that extend not only to immunotherapies and vaccines for HIV-1 but also to the cellular immune response in other disease states. This Review focuses on the mechanisms that are most likely responsible for durable and potent immunologic control of HIV-1. Although we now have a detailed picture of the cellular immune responses to HIV-1, important questions remain regarding the nature of these responses and how they arise.

Early Initiation of ART in Acute HIV Infection (Fiebig I to III) Does Not Preclude the Development of HIV-specific Cellular Immune Responses

AIDS Research and Human RetrovirusesVol. 30, No. S1 Vaccine, Viral Latency, and CureEarly Initiation of ART in Acute HIV Infection (Fiebig I to III) Does Not Preclude the Development of HIV-specific Cellular Immune ResponsesAlexandra Schuetz, Yuwadee Phuang-Ngern, Rapee Trichavaroj, Nittaya Phanuphak, Rungsun Rerknimitr, Suchada Sukhumvittaya, Surat Jongrakthaitae, Silvia Ratto-Kim, James Fletscher, Eugene Kroon, Nitaya Chomchey, Robert J. O'Connell, Viseth Ngauy, Praphan Phanuphak, Nelson L. Michael, Jerome H. Kim, Mark S. De Souza, Jintanat Ananworanich, and RV254/SEARCH 010 Study GroupAlexandra SchuetzArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandHenry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United StatesSearch for more papers by this author, Yuwadee Phuang-NgernArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandSearch for more papers by this author, Rapee TrichavarojArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandSearch for more papers by this author, Nittaya PhanuphakSEARCH, Bangkok, ThailandThe Thai Red Cross AIDS Research Centre, Bangkok, ThailandSearch for more papers by this author, Rungsun RerknimitrChulalongkorn University, Department of Medicine, Bangkok, ThailandSearch for more papers by this author, Suchada SukhumvittayaArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandSearch for more papers by this author, Surat JongrakthaitaeArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandSearch for more papers by this author, Silvia Ratto-KimHenry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United StatesUnited States Military HIV Research Program (MHRP), Walter Reed Army Institute of Research, Silver Spring, MD, United StatesSearch for more papers by this author, James FletscherSEARCH, Bangkok, ThailandSearch for more papers by this author, Eugene KroonArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandSEARCH, Bangkok, ThailandSearch for more papers by this author, Nitaya ChomcheySEARCH, Bangkok, ThailandThe Thai Red Cross AIDS Research Centre, Bangkok, ThailandSearch for more papers by this author, Robert J. O'ConnellArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandSearch for more papers by this author, Viseth NgauyArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandSearch for more papers by this author, Praphan PhanuphakSEARCH, Bangkok, ThailandThe Thai Red Cross AIDS Research Centre, Bangkok, ThailandChulalongkorn University, Department of Medicine, Bangkok, ThailandSearch for more papers by this author, Nelson L. MichaelUnited States Military HIV Research Program (MHRP), Walter Reed Army Institute of Research, Silver Spring, MD, United StatesSearch for more papers by this author, Jerome H. KimUnited States Military HIV Research Program (MHRP), Walter Reed Army Institute of Research, Silver Spring, MD, United StatesSearch for more papers by this author, Mark S. De SouzaArmed Forces Research Institute of Medical Sciences – United States Component, Retrovirology, Bangkok, ThailandSEARCH, Bangkok, ThailandThe Thai Red Cross AIDS Research Centre, Bangkok, ThailandSearch for more papers by this author, Jintanat AnanworanichHenry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United StatesSEARCH, Bangkok, ThailandUnited States Military HIV Research Program (MHRP), Walter Reed Army Institute of Research, Silver Spring, MD, United StatesSearch for more papers by this author, and RV254/SEARCH 010 Study GroupSearch for more papers by this authorPublished Online:30 Oct 2014https://doi.org/10.1089/aid.2014.5021.abstractAboutSectionsView articleView Full TextPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail View article"Early Initiation of ART in Acute HIV Infection (Fiebig I to III) Does Not Preclude the Development of HIV-specific Cellular Immune Responses." AIDS Research and Human Retroviruses, 30(S1), p. A18FiguresReferencesRelatedDetails Volume 30Issue S1Oct 2014 InformationCopyright 2014, Mary Ann Liebert, Inc.To cite this article:Alexandra Schuetz, Yuwadee Phuang-Ngern, Rapee Trichavaroj, Nittaya Phanuphak, Rungsun Rerknimitr, Suchada Sukhumvittaya, Surat Jongrakthaitae, Silvia Ratto-Kim, James Fletscher, Eugene Kroon, Nitaya Chomchey, Robert J. O'Connell, Viseth Ngauy, Praphan Phanuphak, Nelson L. Michael, Jerome H. Kim, Mark S. De Souza, Jintanat Ananworanich, and RV254/SEARCH 010 Study Group.Early Initiation of ART in Acute HIV Infection (Fiebig I to III) Does Not Preclude the Development of HIV-specific Cellular Immune Responses.AIDS Research and Human Retroviruses.Oct 2014.A18-A18.http://doi.org/10.1089/aid.2014.5021.abstractPublished in Volume: 30 Issue S1: October 30, 2014PDF download

Immunotherapy with an HIV-DNA Vaccine in Children and Adults.

Therapeutic HIV immunization is intended to induce new HIV-specific cellular immune responses and to reduce viral load, possibly permitting extended periods without antiretroviral drugs. A multigene, multi-subtype A, B, C HIV-DNA vaccine (HIVIS) has been used in clinical trials in both children and adults with the aim of improving and broadening the infected individuals’ immune responses. Despite the different country locations, different regimens and the necessary variations in assays performed, this is, to our knowledge, the first attempt to compare children’s and adults’ responses to a particular HIV vaccine. Ten vertically HIV-infected children aged 4–16 years were immunized during antiretroviral therapy (ART). Another ten children were blindly recruited as controls. Both groups continued their antiretroviral treatment during and after vaccinations. Twelve chronically HIV-infected adults were vaccinated, followed by repeated structured therapy interruptions (STI) of their antiretroviral treatment. The adult group included four controls, receiving placebo vaccinations. The HIV-DNA vaccine was generally well tolerated, and no serious adverse events were registered in any group. In the HIV-infected children, an increased specific immune response to Gag and RT proteins was detected by antigen-specific lymphoproliferation. Moreover, the frequency of HIV-specific CD8+ T-cell lymphocytes releasing perforin was significantly higher in the vaccinees than the controls. In the HIV-infected adults, increased CD8+ T-cell responses to Gag, RT and viral protease peptides were detected. No augmentation of HIV-specific lymphoproliferative responses were detected in adults after vaccination. In conclusion, the HIV-DNA vaccine can elicit new HIV-specific cellular immune responses, particularly to Gag antigens, in both HIV-infected children and adults. Vaccinated children mounted transient new HIV-specific immune responses, including both CD4+ T-cell lymphoproliferation and late CD8+ T-cell responses. In the adult cohort, primarily CD8+ T-cell responses related to MHC class I alleles were noted. However, no clinical benefits with respect to viral load reduction were ascribable to the vaccinations alone. No severe adverse effects related to the vaccine were found in either cohort, and no virological failures or drug resistances were detected.

Safety, Tolerability, and Immunogenicity of Repeated Doses of DermaVir, a Candidate Therapeutic HIV Vaccine, in HIV-Infected Patients Receiving Combination Antiretroviral Therapy

HIV-specific cellular immune responses are associated with control of viremia and delayed disease progression. An effective therapeutic vaccine could mimic these effects and reduce the need for continued antiretroviral therapy. DermaVir, a topically administered plasmid DNA-nanomedicine expressing HIV (CladeB) virus-like particles consisting of 15 antigens, induces predominantly central memory T-cell responses. Treated HIV-infected adults (HIV RNA <50 and CD4 >350) were randomized to placebo or escalating DermaVir doses (0.1 or 0.4 mg of plasmid DNA at weeks 1, 7, and 13 in the low- and intermediate-dose groups and 0.8 mg at weeks 0, 1, 6, 7, 12, and 13 in the high-dose group), n = 5-6 evaluable subjects per group. Immunogenicity was assessed by a 12-day cultured interferon-γ enzyme-linked immunosorbent spot assay at baseline and at weeks 9, 17, and 37 using 1 Tat/Rev and 3 overlapping Gag peptide pools (p17, p24, and p15). Groups were comparable at baseline. The study intervention was well tolerated, without dose-limiting toxicities. Most responses were highest at week 17 (4 weeks after last vaccination) when Gag p24 responses were significantly greater among intermediate-dose group compared with control subjects [median (IQR): 67,600 (5633-74,368) versus 1194 (9-1667)] net spot-forming units per million cells, P = 0.032. In the intermediate-dose group, there was also a marginal Gag p15 response increase from baseline to week 17 [2859 (1867-56,933), P = 0.06], and this change was significantly greater than in the placebo group [0 (-713 to 297), P = 0.016]. DermaVir administration was associated with a trend toward greater HIV-specific, predominantly central memory T-cell responses. The intermediate DermaVir dose tended to show the greatest immunogenicity, consistent with previous studies in different HIV-infected patient populations.

Therapeutic DNA Vaccination of Vertically HIV-Infected Children: Report of the First Pediatric Randomised Trial (PEDVAC)

SubjectsTwenty vertically HIV-infected children, 6–16 years of age, with stable viral load control and CD4+ values above 400 cells/mm3.InterventionTen subjects continued their ongoing antiretroviral treatment (ART, Group A) and 10 were immunized with a HIV-DNA vaccine in addition to their previous therapy (ART and vaccine, Group B). The genetic vaccine represented HIV-1 subtypes A, B and C, encoded Env, Rev, Gag and RT and had no additional adjuvant. Immunizations took place at weeks 0, 4 and 12, with a boosting dose at week 36. Monitoring was performed until week 60 and extended to week 96.ResultsSafety data showed good tolerance of the vaccine. Adherence to ART remained high and persistent during the study and did not differ significantly between controls and vaccinees. Neither group experienced either virological failure or a decline of CD4+ counts from baseline. Higher HIV-specific cellular immune responses were noted transiently to Gag but not to other components of the vaccine. Lymphoproliferative responses to a virion antigen HIV-1 MN were higher in the vaccinees than in the controls (p = 0.047), whereas differences in reactivity to clade-specific Gag p24, RT or Env did not reach significance. Compared to baseline, the percentage of HIV-specific CD8+ lymphocytes releasing perforin in the Group B was higher after the vaccination schedule had been completed (p = 0.031). No increased CD8+ perforin levels were observed in control Group A.ConclusionsThe present study demonstrates the feasibility, safety and moderate immunogenicity of genetic vaccination in vertically HIV-infected children, paving the way for amplified immunotherapeutic approaches in the pediatric population.Trial registration clinicaltrialsregister.eu _2007-002359-18 IT

Recent Advances in Humanized Mice: Accelerating the Development of an HIV Vaccine

Recent advances in the development of humanized mice hold great promise to advance our understanding of protective immunity to human immunodeficiency virus (HIV) infection and to aid in the design of an effective HIV vaccine. This supplement of the Journal of Infectious Diseases summarizes work in the humanized mouse model presented at an HIV Humanized Mouse workshop in Boston, Massachusetts, in November 2012, including recent advances in the development of humanized mice, the trafficking of human immune cells following mucosal HIV transmission, the role of immune activation and Toll-like receptor agonists in the control of HIV, the induction and efficacy of HIV-specific cellular and humoral immune responses, and the preclinical modeling of novel anti-HIV therapeutics. Many gaps remain in our understanding of how to design an effective HIV vaccine and novel therapeutics to eliminate the viral reservoir. Promising early results from studies in humanized mice suggest great potential and enthusiasm for this model to accelerate these critical areas of HIV research.

Successful vaccination of immune suppressed recipients using Listeria vector HIV-1 vaccines in helminth infected mice

Vaccines for HIV, malaria and TB remain high priorities, especially for sub-Saharan populations. The question is: will vaccines currently in development for these diseases function in populations that have a high prevalence of helminth infection? Infection with helminth parasites causes immune suppression and a CD4+ Th2 skewing of the immune system, thereby impairing Th1-type vaccine efficacy. In this study, we conduct HIV vaccine trials in mice with and without chronic helminth infection to mimic the human vaccine recipient populations in Sub-Saharan Africa and other helminth parasite endemic regions of the world, as there is large overlap in global prevalence for HIV and helminth infection. Here, we demonstrate that Listeria monocytogenes functions as a vaccine vector to drive robust and functional HIV-specific cellular immune responses, irrespective of chronic helminth infection. This observation represents a significant advance in the field of vaccine research and underscores the concept that vaccines in the developmental pipeline should be effective in the target populations.

Immunization with multiple vaccine modalities induce strong HIV-specific cellular and humoral immune responses.

Heterologous priming and boosting with antigens expressed by DNA, viral vectors, or as proteins, are experimental strategies to induce strong immune responses against infectious diseases and cancer. In a preclinical study we compared the ability of recombinant modified vaccinia Ankara encoding HIV antigens (MVA-CMDR), and/or recombinant gp140C (rgp140C), to boost responses induced by a multigene/multisubtype HIV DNA vaccine delivered by electroporation (EP). Homologous DNA immunizations augmented by EP stimulated strong cellular immune responses. Still stronger cellular immune responses were observed after DNA priming and MVA-CMDR boosting, which was superior to all other immunization schedules tested in terms of antigen-specific IFN-γ, IL-2, and bifunctional IFN-γ and IL-2 responses. For HIV Env-specific antibody responses, mice receiving repeated rgp140C immunizations, and mice boosted with rgp140C, elicited the highest binding titers and the highest numbers of antibody-secreting B cells. When considering both cellular and humoral immune responses, a combination of DNA, MVA-CMDR, and rgp140C immunizations induced the overall most potent immune responses and the highest avidity of HIV Env-specific antibodies. These data emphasize the importance of including multiple vaccine modalities that can stimulate both T and B cells, and thus elicit strong and balanced immune responses. The present HIV vaccine combination holds promise for further evaluation in clinical trials.

The High Frequency of HIV Type 1-Specific Cellular Immune Responses in Seronegative Individuals with Parenteral and/or Heterosexual HIV Type 1 Exposure

Some individuals remain HIV seronegative despite repeated unprotected exposure to the virus. Recent observations led to a concept that acquired immunity plays a role in protection or at least in altered susceptibility to HIV-1 infection in highly exposed seronegative (ESN) individuals. Our aim was to study HIV-specific cellular immune responses induced in parenterally and/or heterosexually ESN individuals. Nine seronegative injection drug users (IDUs), 10 seronegative individuals, and nine of their HIV-positive sexual and/or IDU partners from the cohort of IDUs were included in the study. The discordant couples had unprotected sex, and some of seronegative partners also had parenteral exposure. Cell-mediated responses were measured in peripheral blood mononuclear cells (PBMCs) by ex vivo interferon (IFN)-γ-ELISpot and ICS combining IFN-γ, tumor necrosis factor (TNF)-α, and interleukin (IL)-2 after stimulation with four consensus peptide pools (Nef, Gag, RT, Env, subtype A-EE). Thirteen out of 19 (68%) seronegative study subjects had strong Nef peptide pool-specific ELISpot responses, three (16%) subjects responded against the Gag peptide pool, and one subject had an RT peptide pool response. Nef peptide pool responses in ESN were as high as in seropositive subjects. The multiple HIV-specific cytokine production in both CD4(+) and CD8(+) T cells was shown for several ESN subjects. The functional profiles of the immune responses were different between seronegative and HIV-positive study groups. Whether the observed cellular responses have any protective role against HIV needs to be further investigated.

The Magnitude and Kinetics of the Mucosal HIV-Specific CD8+ T Lymphocyte Response and Virus RNA Load in Breast Milk

BackgroundThe risk of postnatal HIV transmission is associated with the magnitude of the milk virus load. While HIV-specific cellular immune responses control systemic virus load and are detectable in milk, the contribution of these responses to the control of virus load in milk is unknown.MethodsWe assessed the magnitude of the immunodominant GagRY11 and subdominant EnvKY9-specific CD8+ T lymphocyte response in blood and milk of 10 A*3002+, HIV-infected Malawian women throughout the period of lactation and correlated this response to milk virus RNA load and markers of breast inflammation.ResultsThe magnitude and kinetics of the HIV-specific CD8+ T lymphocyte responses were discordant in blood and milk of the right and left breast, indicating independent regulation of these responses in each breast. However, there was no correlation between the magnitude of the HIV-specific CD8+ T lymphocyte response and the milk virus RNA load. Further, there was no correlation between the magnitude of this response and markers of breast inflammation.ConclusionsThe magnitude of the HIV-specific CD8+ T lymphocyte response in milk does not appear to be solely determined by the milk virus RNA load and is likely only one of the factors contributing to maintenance of low virus load in milk.

Polymorphisms in innate immunity genes and patients response to dendritic cell-based HIV immuno-treatment

Dendritic cells (DCs)-based vaccine was demonstrated to increase HIV specific cellular immune response; however, in some HIV-infected patients, the response to the vaccine resulted to be not effective. In order to understand if the outcome of the vaccination may be influenced by the host's genome and natural immunity, we studied the innate immune genome of HIV-infected patients previously vaccinated with DCs. We identified 15 SNPs potentially associated with the response to the immuno-treatment and two SNPs significantly associated with the modulation of the response to the DC vaccine: MBL2 rs10824792 and NOS1 rs693534. These two SNPs were also studied in different ethnic groups (Brazilians, African and Caucasian) of HIV-infected, exposed uninfected and unexposed uninfected subjects. The HIV positive Caucasian patients were also characterized by different disease progressions.Our findings suggest that, independently and/or in addition to other variables, the host's genome could significantly contribute to the modulation of the response to the DC vaccine.

P02-04. Multimeric soluble CD40 ligand efficiently enhances HIV specific cellular immune responses during DNA prime and boost with attenuated poxvirus strains

1 page.-- Poster presentation.-- This article is part of the supplement: AIDS Vaccine 2009.