HIV-1 specific IgA detected in vaginal secretions of HIV uninfected women participating in a microbicide trial in Southern Africa are primarily directed toward gp120 and gp140 specificities.

CAPRISA, 2014.Abstract available in pdf

Ex Vivo Comparison of Microbicide Efficacies for Preventing HIV-1 Genomic Integration in Intraepithelial Vaginal Cells ▿ †

Vaginally applied microbicides hold promise as a strategy to prevent sexual HIV transmission. Several nonspecific microbicides, including the polyanion cellulose sulfate, have been evaluated in large-scale clinical trials but have failed to show significant efficacy. These findings have prompted a renewed search for preclinical testing systems that can predict negative outcomes of microbicide trials. Moreover, the pipeline of potential topical microbicides has been expanded to include antiretroviral agents, such as reverse transcriptase, fusion, and integrase inhibitors. Using a novel ex vivo model of vaginal HIV-1 infection, we compared the prophylactic potentials of two forms of the fusion inhibitor T-20, the CCR5 antagonist TAK-778, the integrase inhibitor 118-D-24, and cellulose sulfate (Ushercell). The T-20 peptide with free N- and C-terminal amino acids was the most efficacious compound, causing significantly greater inhibition of viral genomic integration in intraepithelial vaginal leukocytes, measured by an optimized real-time PCR assay, than the more water-soluble N-acetylated T-20 peptide (Fuzeon) (50% inhibitory concentration [IC50], 0.153 μM versus 51.2 μM [0.687 ng/ml versus 230 ng/ml]; P < 0.0001). In contrast, no significant difference in IC50s was noted in peripheral blood cells (IC50, 13.58 μM versus 7.57 μM [61 ng/ml versus 34 ng/ml]; P = 0.0614). Cellulose sulfate was the least effective of all the compounds tested (IC50, 1.8 μg/ml). These results highlight the merit of our model for screening the mucosal efficacies of novel microbicides and their formulations and potentially rank ordering candidates for clinical evaluation

Initial Events in Establishing Vaginal Entry and Infection by Human Immunodeficiency Virus Type-1

Understanding the initial events in the establishment of vaginal human immunodeficiency virus type-1 (HIV-1) entry and infection has been hampered by the lack of appropriate experimental models. Here, we show in an ex vivo human organ culture system that upon contact in situ, HIV-1 rapidly penetrated both intraepithelial vaginal Langerhans and CD4+ T cells. HIV-1 entered CD4+ T cells almost exclusively by CD4 and CCR5 receptor-mediated direct fusion, without requiring passage from Langerhans cells, and overt productive infection ensued. By contrast, HIV-1 entered CD1a+ Langerhans cells primarily by endocytosis, by means of multiple receptors, and virions persisted intact within the cytoplasm for several days. Our findings shed light on the very earliest steps of mucosal HIV infection in vivo and may guide the design of effective strategies to block local transmission and prevent HIV-1 spread

Innate immune signatures to a partially-efficacious HIV vaccine predict correlates of HIV-1 infection risk.

The pox-protein regimen tested in the RV144 trial is the only vaccine strategy demonstrated to prevent HIV-1 infection. Subsequent analyses identified antibody and cellular immune responses as correlates of risk (CoRs) for HIV infection. Early predictors of these CoRs could provide insight into vaccine-induced protection and guide efforts to enhance vaccine efficacy. Using specimens from a phase 1b trial of the RV144 regimen in HIV-1-uninfected South Africans (HVTN 097), we profiled innate responses to the first ALVAC-HIV immunization. PBMC transcriptional responses peaked 1 day post-vaccination. Type I and II interferon signaling pathways were activated, as were innate pathways critical for adaptive immune priming. We then identified two innate immune transcriptional signatures strongly associated with adaptive immune CoR after completion of the 4-dose regimen. Day 1 signatures were positively associated with antibody-dependent cellular cytotoxicity and phagocytosis activity at Month 6.5. Conversely, a signature present on Days 3 and 7 was inversely associated with Env-specific CD4+ T cell responses at Months 6.5 and 12; rapid resolution of this signature was associated with higher Env-specific CD4+ T-cell responses. These are the first-reported early immune biomarkers of vaccine-induced responses associated with HIV-1 acquisition risk in humans and suggest hypotheses to improve HIV-1 vaccine regimens

Total and HIV-1-specific IgG and IgA in vaginal secretions do not differ by sampling device or timepoint in the same women.

<p>(A) Dacron swabs, flocked swabs, and Merocel sponges were collected from 5 HIV-1 infected (colored circles) and 5 HIV uninfected (grey triangles) women and the eluate was analyzed for total IgG (left) and total IgA (right). Symbols represent the average of two collection time points spaced one hour apart, for each woman and sampling device. For HIV-1 infected women, colors indicate specific individuals. (B) Samples from the first time point (filled circles) and one hour later (open circles) from the 5 HIV-1 infected women were analyzed for gp41-specific IgG (left) and IgA (right) activity, calculated as antigen-specific mean fluorescence intensity (MFI)/ng ml⁻¹ total IgG or IgA. Colors indicate specific individuals. The box-and-whisker plots represent median, 25^th and 75^th percentiles, and range.</p

HIV-1 exposure elicits anti-Env IgA but not IgG antibodies in the vaginal mucosa.

<p>Vaginal Dacron swabs were collected from 57 HIV seronegative women enrolled in the HPTN 035 microbicide trial and analyzed for IgG (C) and IgA (D–E) binding to the indicated HIV-1 Env antigens. (A) Positive IgG controls. Binding of purified pooled HIV-1⁺ immunoglobulin (HIVIG), 4E10 monoclonal IgG (50 µg/ml), 2F5 monoclonal IgG (16 µg/ml) and swabs from an HIV-1 infected HPTN 035 participant (HIV⁺) in mean fluorescent intensity (MFI). (B) Positive IgA controls. Binding of 7B2 monoclonal IgA (1 µg/ml), b12 monoclonal IgA (20 µg/ml) and 2F5 monoclonal IgA (1 µg/ml) in MFI. Lack of IgA binding from an HIV-1 infected HPTN 035 participant (HIV⁺) is also shown. (C) HIV-1 antigen-specific IgG activity, calculated as antigen-specific MFI/ng ml⁻¹ total IgG, in 57 women participating in HPTN 035. One additional HIV-1 infected HPTN 035 participant (HIV⁺) is also shown. (D) HIV-1 antigen-specific IgA activity, calculated as antigen-specific MFI/ng ml¹ total IgA. For the 57 HPTN 035 women (squares), black symbols signify negative responses and colored symbols signify positive responses, with colors indicating specific women. Samples that did not meet the positivity criteria are displayed at zero for specific activity. One additional HIV-1 infected HPTN 035 participant (HIV⁺) is also shown (open circles). (E) Percentage of the 57 HPTN 035 women with positive IgA binding.</p

HIV-1 infection induces a broader range of HIV-1 Env-specific IgG than IgA antibodies in vaginal secretions.

<p>Vaginal secretions were collected from 5 HIV-1 infected women and analyzed for IgG (A–B) and IgA (C–D) binding to the indicated HIV-1 Env antigens. Antigens not specified as Clade C or consensus (Con6 and ConS) are derived from Clade B viruses. (A) Average HIV-1 antigen-specific IgG activity from the combination of the three sampling devices and two time points, calculated as antigen-specific MFI/ng ml⁻¹ total IgG. Black symbols represent negative responses and colored symbols indicate positive responses, with the colors corresponding to specific individuals. Samples that did not meet the positivity criteria are displayed at zero for specific activity. (B) Percentage of women with positive IgG binding. (C) Average HIV-1 antigen-specific IgA activity, calculated as antigen-specific MFI/ng ml⁻¹ total IgA. (D) Percentage of women with positive IgA binding.</p

A first-in-human germline-targeting HIV nanoparticle vaccine induced broad and publicly targeted helper T cell responses

The engineered outer domain germline targeting version 8 (eOD-GT8) 60-mer nanoparticle was designed to prime VRC01-class HIV-specific B cells that would need to be matured, through additional heterologous immunizations, into B cells that are able to produce broadly neutralizing antibodies. CD4 T cell help will be critical for the development of such high-affinity neutralizing antibody responses. Thus, we assessed the induction and epitope specificities of the vaccine-specific T cells from the IAVI G001 phase 1 clinical trial that tested immunization with eOD-GT8 60-mer adjuvanted with AS01. Robust polyfunctional CD4 T cells specific for eOD-GT8 and the lumazine synthase (LumSyn) component of eOD-GT8 60-mer were induced after two vaccinations with either the 20- or 100-microgram dose. Antigen-specific CD4 T helper responses to eOD-GT8 and LumSyn were observed in 84 and 93% of vaccine recipients, respectively. CD4 helper T cell epitope hotspots preferentially targeted across participants were identified within both the eOD-GT8 and LumSyn proteins. CD4 T cell responses specific to one of these three LumSyn epitope hotspots were observed in 85% of vaccine recipients. Last, we found that induction of vaccine-specific peripheral CD4 T cells correlated with expansion of eOD-GT8-specific memory B cells. Our findings demonstrate strong human CD4 T cell responses to an HIV vaccine candidate priming immunogen and identify immunodominant CD4 T cell epitopes that might improve human immune responses either to heterologous boost immunogens after this prime vaccination or to other human vaccine immunogens

Vaccination induces HIV broadly neutralizing antibody precursors in humans

Broadly neutralizing antibodies (bnAbs) can protect against HIV infection but have not been induced by human vaccination. A key barrier to bnAb induction is vaccine priming of rare bnAb-precursor B cells. In a randomized, double-blind, placebo-controlled phase 1 clinical trial, the HIV vaccine-priming candidate eOD-GT8 60mer adjuvanted with AS01 had a favorable safety profile and induced VRC01-class bnAb precursors in 97% of vaccine recipients with median frequencies reaching 0.1% among immunoglobulin G B cells in blood. bnAb precursors shared properties with bnAbs and gained somatic hypermutation and affinity with the boost. The results establish clinical proof of concept for germline-targeting vaccine priming, support development of boosting regimens to induce bnAbs, and encourage application of the germline-targeting strategy to other targets in HIV and other pathogens