Silvia Ratto-Kim

Adoptive transfer of costimulated CD4 + T cells induces expansion of peripheral T cells and decreased CCR5 expression in HIV infection

To study the safety and feasibility of T-cell reconstitution in HIV-infected individuals, we adoptively transferred activated autologous CD4+ T cells. Polyclonal peripheral blood CD4+ cells were costimulated ex vivo and subjects were given infusions of up to 3 × 1010 activated CD4+ cells. Dose-dependent increases in CD4+ cell counts and in the CD4:CD8 ratio were observed. Sustained increases in the fraction of cytokine-secreting T cells and decreases in the percentage of CD4+CCR5+ cells were noted in vivo, suggesting enhanced function and resistance to HIV infection. The frequency of CD4+Ki-67+ cells increased whereas CD4+ T cells containing T cell–receptor rearrangement excision circles (TRECs) decreased. These findings indicate that expansion of the peripheral T-cell pool mediated the increase in CD4 counts and suggest that approaches to reconstitute CD4 helper cell activity and decrease CCR5 expression may augment natural immunity to HIV infection.

Safety and immunogenicity of an HIV subtype B and E prime-boost vaccine combination in HIV-negative Thai adults

ALVAC-HIV (vCP1521) and AIDSVAX B/E were evaluated in a phase 1/2 trial of human immunodeficiency virus (HIV)-negative Thai adults. Of 133 volunteers enrolled, 122 completed the trial. There were no serious vaccine-related adverse events, nor were there intercurrent HIV infections. Lymphoproliferative responses to glycoprotein 120 E were induced in 63% of the volunteers, and HIV-specific CD8 cytotoxic T lymphocyte responses were induced in 24%. Antibody responses increased in frequency and magnitude in association with the dose level of AIDSVAX B/E. Binding and neutralizing antibodies to the MN strain were induced in 100% and 98%, respectively, of the volunteers receiving 600 microg of AIDSVAX B/E, and such antibodies to E strains were induced in 96% and 71%, respectively, of these volunteers. This vaccine combination was well tolerated and was immunogenic, meeting milestones for advancement to phase 3 evaluation.

The Thai Phase III Trial (RV144) Vaccine Regimen Induces T Cell Responses That Preferentially Target Epitopes within the V2 Region of HIV-1 Envelope

The Thai HIV phase III prime/boost vaccine trial (RV144) using ALVAC-HIV (vCP1521) and AIDSVAX B/E was, to our knowledge, the first to demonstrate acquisition efficacy. Vaccine-induced, cell-mediated immune responses were assessed. T cell epitope mapping studies using IFN-γ ELISPOT was performed on PBMCs from HIV-1–uninfected vaccine (n = 61) and placebo (n = 10) recipients using HIV-1 Env peptides. Positive responses were measured in 25 (41%) vaccinees and were predominantly CD4+ T cell-mediated. Responses were targeted within the HIV Env region, with 15 of 25 (60%) of vaccinees recognizing peptides derived from the V2 region of HIV-1 Env, which includes the α4β7 integrin binding site. Intracellular cytokine staining confirmed that Env responses predominated (19 of 30; 63% of vaccine recipients) and were mediated by polyfunctional effector memory CD4+ T cells, with the majority of responders producing both IL-2 and IFN-γ (12 of 19; 63%). HIV Env Ab titers were higher in subjects with IL-2 compared with those without IL-2–secreting HIV Env-specific effector memory T cells. Proliferation assays revealed that HIV Ag-specific T cells were CD4+, with the majority (80%) expressing CD107a. HIV-specific T cell lines obtained from vaccine recipients confirmed V2 specificity, polyfunctionality, and functional cytolytic capacity. Although the RV144 T cell responses were modest in frequency compared with humoral immune responses, the CD4+ T cell response was directed to HIV-1 Env and more particularly the V2 region.

Circulating proviral HIV DNA and HIV-associated dementia

Objective:Individuals continue to develop HIV-1-associated dementia (HAD) despite treatment with highly active antiretroviral therapy (HAART). Monocytes/macrophages (M/MΦ) can harbor proviral DNA that is not eradicated by HAART. To determine if HAD is associated with the level of HIV-1 infection within circulating leukocytes, we quantified HIV-1 DNA copy number in peripheral blood mononuclear cells (PBMC), and in PBMC subsets. Design:Cross-sectional analysis within the Hawaii Aging with HIV Cohort comparing participants with HAD to those with normal cognition (NC). Methods:Real-time PCR assays assessing HIV DNA copy number/1 × 106 cells were performed on PBMC and subsets. Results.Individuals with HAD (n = 27) had a median (interquartile range) of 9.11 (37.20) HIV DNA per 1 × 106 PBMC compared to 0.49 (0.89) HIV DNA per 1 × 106 PBMC in individuals with NC (n = 22). Using a univariate analysis in the subset of individuals with undetectable viral load (HAD, n = 11; NC, n = 13), the odds of HAD attributable to HIV DNA copy number was 2.76 (1.28–5.94), P < 0.01. Preliminary analysis of a small subset of patients (n = 5) suggested that the primary source of HIV DNA may be the activated M/MΦ (CD14/CD16) subset. Conclusions.These findings suggest a potentially important association between circulating provirus and HAD.

Phase I Safety and Immunogenicity Evaluation of MVA-CMDR, a Multigenic, Recombinant Modified Vaccinia Ankara-HIV-1 Vaccine Candidate

Background We conducted a Phase I randomized, dose-escalation, route-comparison trial of MVA-CMDR, a candidate HIV-1 vaccine based on a recombinant modified vaccinia Ankara viral vector expressing HIV-1 genes env/gag/pol. The HIV sequences were derived from circulating recombinant form CRF01_AE, which predominates in Thailand. The objective was to evaluate safety and immunogenicity of MVA-CMDR in human volunteers in the US and Thailand. Methodology/Principal Findings MVA-CMDR or placebo was administered intra-muscularly (IM; 107 or 108 pfu) or intradermally (ID; 106 or 107 pfu) at months 0, 1 and 3, to 48 healthy volunteers at low risk for HIV-1 infection. Twelve volunteers in each dosage group were randomized to receive MVA-CMDR or placebo (10∶2). Volunteers were actively monitored for local and systemic reactogenicity and adverse events post vaccination. Cellular immunogenicity was assessed by a validated IFNγ Elispot assay, an intracellular cytokine staining assay, lymphocyte proliferation and a 51Cr-release assay. Humoral immunogenicity was assessed by ADCC for gp120 and binding antibody ELISAs for gp120 and p24. MVA-CMDR was safe and well tolerated with no vaccine related serious adverse events. Cell-mediated immune responses were: (i) moderate in magnitude (median IFNγ Elispot of 78 SFC/106 PBMC at 108 pfu IM), but high in response rate (70% 51Cr-release positive; 90% Elispot positive; 100% ICS positive, at 108 pfu IM); (ii) predominantly HIV Env-specific CD4+ T cells, with a high proliferative capacity and durable for at least 6 months (100% LPA response rate by the IM route); (iv) dose- and route-dependent with 108 pfu IM being the most immunogenic treatment. Binding antibodies against gp120 and p24 were detectable in all vaccination groups with ADCC capacity detectable at the highest dose (40% positive at 108 pfu IM). Conclusions/Significance MVA-CMDR delivered both intramuscularly and intradermally was safe, well-tolerated and elicited durable cell-mediated and humoral immune responses. Trial Registration ClinicalTrials.gov NCT00376090

A phase 1/2 comparative vaccine trial of the safety and immunogenicity of a CRF01_AE (subtype E) candidate vaccine: ALVAC-HIV (vCP1521) prime with oligomeric gp160 (92TH023/LAI-DID) or bivalent gp120 (CM235/SF2) boost.

Background:The development of an effective HIV-1 vaccine is critical to control the pandemic. A prime-boost HIV-1 vaccine trial assessing safety and immunogenicity was conducted in Thailand as part of an evaluation of candidate regimens for a phase 3 efficacy trial. Methods:ALVAC-HIV (vCP1521), expressing circulating recombinant form 01_AE (CRF01_AE) gp120/subtype B LAI and subtype B Gag/Protease boosted with recombinant envelope oligomeric CRF01_AE gp160 (ogp160) or bivalent CRF01_AE/subtype B gp120 CM235/SF2, was evaluated in a phase 1/II trial of 130 HIV-negative Thai adults. Results:One hundred forty volunteers were enrolled, and 130 completed all safety and immunogenicity visits. Reactogenicity was common but generally mild, and there was no significant difference in the adverse event rate between vaccine and placebo recipients (P = 0.26). There were 7 serious adverse events during the follow-up period, none of which were vaccine related. Cumulative HIV-specific, CD8-mediated, cytotoxic T-lymphocyte responses were observed in 11 (25%) of 44 subjects who received ALVAC boosted by bivalent gp120 and in 5 (11%) of 45 subjects who received ALVAC boosted by ogp160, but these differences were not statistically significant compared with those in placebo recipients (P = 0.62 and P = 0.37, respectively). HIV-specific lymphoproliferative responses were detected in 84% of subunit-boosted vaccine recipients and in 10% of placebo recipients. Neutralizing antibody responses to CRF01_AE and subtype B laboratory strains were seen in 95% of ogp160-boosted and 100% of gp120 B/E-boosted vaccinees, respectively. Conclusions:These 2 different prime-boost regimens seem to be safe and displayed cell-mediated immune responses consistent with those in other trials of canarypox vectors.

Change in Brain Magnetic Resonance Spectroscopy after Treatment during Acute HIV Infection

Objective Single voxel proton magnetic resonance spectroscopy (MRS) can be used to monitor changes in brain inflammation and neuronal integrity associated with HIV infection and its treatments. We used MRS to measure brain changes during the first weeks following HIV infection and in response to antiretroviral therapy (ART). Methods Brain metabolite levels of N-acetyl aspartate (NAA), choline (tCHO), creatine (CR), myoinositol (MI), and glutamate and glutamine (GLX) were measured in acute HIV subjects (n = 31) and compared to chronic HIV+individuals (n = 26) and HIV negative control subjects (n = 10) from Bangkok, Thailand. Metabolites were measured in frontal gray matter (FGM), frontal white matter (FWM), occipital gray matter (OGM), and basal ganglia (BG). Repeat measures were obtained in 17 acute subjects 1, 3 and 6 months following initiation of ART. Results After adjustment for age we identified elevated BG tCHO/CR in acute HIV cases at baseline (median 14 days after HIV infection) compared to control (p = 0.0014), as well as chronic subjects (p = 0.0023). A similar tCHO/CR elevation was noted in OGM; no other metabolite abnormalities were seen between acute and control subjects. Mixed longitudinal models revealed resolution of BG tCHO/CR elevation after ART (p = 0.022) with tCHO/CR similar to control subjects at 6 months. Interpretation We detected cellular inflammation in the absence of measurable neuronal injury within the first month of HIV infection, and normalization of this inflammation following acutely administered ART. Our findings suggest that early ART may be neuroprotective in HIV infection by mitigating processes leading to CNS injury.

Adjuvant-dependent innate and adaptive immune signatures of risk of SIVmac251 acquisition.

A recombinant vaccine containing Aventis Pasteurs canarypox vector (ALVAC)–HIV and gp120 alum decreased the risk of HIV acquisition in the RV144 vaccine trial. The substitution of alum with the more immunogenic MF59 adjuvant is under consideration for the next efficacy human trial. We found here that an ALVAC–simian immunodeficiency virus (SIV) and gp120 alum (ALVAC–SIV + gp120) equivalent vaccine, but not an ALVAC–SIV + gp120 MF59 vaccine, was efficacious in delaying the onset of SIVmac251 in rhesus macaques, despite the higher immunogenicity of the latter adjuvant. Vaccine efficacy was associated with alum-induced, but not with MF59-induced, envelope (Env)-dependent mucosal innate lymphoid cells (ILCs) that produce interleukin (IL)-17, as well as with mucosal IgG to the gp120 variable region 2 (V2) and the expression of 12 genes, ten of which are part of the RAS pathway. The association between RAS activation and vaccine efficacy was also observed in an independent efficacious SIV-vaccine approach. Whether RAS activation, mucosal ILCs and antibodies to V2 are also important hallmarks of HIV-vaccine efficacy in humans will require further studies.

A phase I/II trial of HIV SF2 gp120/MF59 vaccine in seronegative Thais.

Abstract Fifty-two human immunodeficiency virus type 1, seronegative Thai adults from the community were enrolled in a double-blind, placebo controlled, phase I/II trial of HIV SF2 gp120/MF59 vaccine to determine the safety and immunogenicity of this recombinant, B clade, HIV envelope protein vaccine. Twenty-six subjects were enrolled at each of two sites in Thailand, Bangkok and Chiang Mai. Twelve subjects received placebo and 40 subjects received vaccine (50 μg). Subjects were immunized according to one of two schedules, 0, 1 and 4 or 0, 1 and 6 months. The frequency of adverse reactions was not different between placebo and vaccine subjects, nor between immunization schedules. Of vaccinees, all developed high-titer binding antibody to the immunogen (rgp120), 39 developed neutralizing antibody (NA) responses against homologous virus (HIV-1SF2), and 22 developed NA against heterologous virus (HIV-1MN). No subject demonstrated intercurrent HIV infection, however screening EIA reactivity occurred in 27% of recipients. Thus, this candidate HIV vaccine was found to be safe and immunogenic in Thai adults, laying the foundation for development of a subtype E construct in this population.

Safety and Immunogenicity of Combinations of Recombinant Subtype E and B Human Immunodeficiency Virus Type 1 Envelope Glycoprotein 120 Vaccines in Healthy Thai Adults

Safety and immunogenicity of 2 recombinant human immunodeficiency virus (HIV) type 1 envelope glycoprotein (gp) 120 vaccines derived from SF2 (subtype B) and CM235 (CRF01_AE, Thai E) were evaluated in 370 Thai adults at low risk of HIV infection. Various doses of CM235 (25, 50, or 100 microg) and SF2 (0, 25, or 50 microg) gp120 were used. Eighty volunteers received placebo. There were no serious adverse events related to vaccination. Binding antibody developed in all vaccine recipients. There was no dose response to CM235 gp120, but a dose response to gp120 SF2 was present. Neutralizing antibodies to subtype E HIV-1 NPO3 and subtype B HIV-1 SF2 developed in 84% and 82% of vaccine recipients, respectively. Lymphoproliferative responses were detected in >95% of vaccine recipients. There was no evidence of antigenic interference in HIV-specific humoral or cellular responses. The gp120 Thai E and SF2 vaccines were safe and immunogenic in combination and could be advanced into phase 3 testing.