Shelly Karuna

Efficacy Trial of a DNA/rAd5 HIV-1 Preventive Vaccine

BACKGROUND A safe and effective vaccine for the prevention of human immunodeficiency virus type 1 (HIV-1) infection is a global priority. We tested the efficacy of a DNA prime-recombinant adenovirus type 5 boost (DNA/rAd5) vaccine regimen in persons at increased risk for HIV-1 infection in the United States. METHODS At 21 sites, we randomly assigned 2504 men or transgender women who have sex with men to receive the DNA/rAd5 vaccine (1253 participants) or placebo (1251 participants). We assessed HIV-1 acquisition from week 28 through month 24 (termed week 28+ infection), viral-load set point (mean plasma HIV-1 RNA level 10 to 20 weeks after diagnosis), and safety. The 6-plasmid DNA vaccine (expressing clade B Gag, Pol, and Nef and Env proteins from clades A, B, and C) was administered at weeks 0, 4, and 8. The rAd5 vector boost (expressing clade B Gag-Pol fusion protein and Env glycoproteins from clades A, B, and C) was administered at week 24. RESULTS In April 2013, the data and safety monitoring board recommended halting vaccinations for lack of efficacy. The primary analysis showed that week 28+ infection had been diagnosed in 27 participants in the vaccine group and 21 in the placebo group (vaccine efficacy, -25.0%; 95% confidence interval, -121.2 to 29.3; P=0.44), with mean viral-load set points of 4.46 and 4.47 HIV-1 RNA log10 copies per milliliter, respectively. Analysis of all infections during the study period (41 in the vaccine group and 31 in the placebo group) also showed lack of vaccine efficacy (P=0.28). The vaccine regimen had an acceptable side-effect profile. CONCLUSIONS The DNA/rAd5 vaccine regimen did not reduce either the rate of HIV-1 acquisition or the viral-load set point in the population studied. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT00865566.).

Diversion of HIV-1 vaccine–induced immunity by gp41-microbiota cross-reactive antibodies

Microbiota can mislead antibodies Unlike the response to many viral infections, most people do not produce antibodies capable of clearing HIV-1. Non-neutralizing antibodies that target HIV-1s envelope glycoprotein (Env) typically dominate the response, which is generated by B cells that cross-react with Env and the intestinal microbiota. Williams et al. analyzed samples from individuals who had received a vaccine containing the Env protein, including the gp41 subunit. Most of the antibodies were non-neutralizing and targeted gp41. The antibodies also reacted to intestinal microbiota, suggesting that preexisting immunity to microbial communities skews vaccineinduced immune responses toward an unproductive target. Science, this issue 10.1126/science.aab1253. The antibody response to an HIV-1 vaccine is dominated by preexisting immunity to microbiota. INTRODUCTION Inducing protective antibodies is a key goal in HIV-1 vaccine development. In acute HIV-1 infection, the dominant initial plasma antibody response is to the gp41 subunit of the envelope (Env) glycoprotein of the virus. These antibodies derive from polyreactive B cells that cross-react with Env and intestinal microbiota (IM) and are unable to neutralize HIV-1. However, whether a similar gp41-IM cross-reactive antibody response would occur in the setting of HIV-1 Env vaccination is unknown. RATIONALE We studied antibody responses in individuals who received a DNA prime vaccine, with a recombinant adenovirus serotype 5 (rAd5) boost (DNA prime–rAd5 boost), a vaccine that included HIV-1 gag, pol, and nef genes, as well as a trivalent mixture of clade A, B, and C env gp140 genes containing both gp120 and gp41 components. This vaccine showed no efficacy. Thus, study of these vaccinees provided an opportunity to determine whether the Env-reactive antibody response in the setting of Env vaccination was dominated by gp41-reactive antibodies derived from Env-IM cross-reactive B cells. RESULTS We found that vaccine-induced antibodies to HIV-1 Env dominantly focused on gp41 compared with gp120 by both serologic analysis and by vaccine-Env memory B cells sorted by flow cytometry (see the figure). Remarkably, the majority of HIV-1 Env-reactive memory B cells induced by the vaccine produced gp41-reactive antibodies, and the majority of gp41-targeted antibodies used restricted immunoglobulin heavy chain variable genes. Functionally, none of the gp41-reactive antibodies could neutralize HIV, and the majority could not mediate antibody-dependent cellular cytotoxicity. Most of the vaccine-induced gp41-reactive antibodies cross-reacted with host and IM antigens. Two of the candidate gp41-intestinal cross-reactive antigens were bacterial RNA polymerase and pyruvate-flavodoxin oxidoreductase, which shared sequence similarities with the heptad repeat 1 region of HIV gp41. Next-generation sequencing of vaccinee B cells demonstrated a prevaccination antibody that was reactive to both IM and the vaccine–Env gp140, which demonstrated the presence of a preexisting pool of gp41-IM cross-reactive B cells from which the vaccine gp41-reactive antibody response was derived. CONCLUSION In this study, we found that the DNA prime–rAd5 boost HIV-1 vaccine induced a gp41-reactive antibody response that was mainly non-neutralizing and derived from an IM-gp41 cross-reactive B cell pool. These findings have important implications for HIV-1 vaccine design. Because IM antigens shape the B cell repertoire from birth, our data raise the hypothesis that neonatal immunization with HIV-1 envelope may be able to imprint the B cell repertoire to respond to envelope antigenic sites that may otherwise be subdominant or disfavored, such as Env broadly neutralizing antibody epitopes. Our data also suggest that deleting or modifying amino acids in the gp41 heptad repeat 1 region of Env-containing vaccine immunogens may avoid IM-gp41 cross-reactivity. Thus, an obstacle that may need to be overcome for development of a successful HIV vaccine is diversion of potentially protective HIV-1 antibody responses by preexisting envelope-IM cross-reactive pools of B cells. Diversion of HIV-1 vaccine–induced immunity by Env gp41–microbiota cross-reactive antibodies. Immunization of humans with a vaccine containing HIV-1 Env gp120 and gp41 components, including the membrane-proximal external region (MPER) of Env, induced a dominant B cell response primarily from a preexisting pool of gp41-IM cross-reactive B cells. This response diverted the vaccine-stimulated antibody response away from smaller subdominant B cell pools capable of reacting with potentially protective epitopes on HIV-1 Env. An HIV-1 DNA prime vaccine, with a recombinant adenovirus type 5 (rAd5) boost, failed to protect from HIV-1 acquisition. We studied the nature of the vaccine-induced antibody (Ab) response to HIV-1 envelope (Env). HIV-1–reactive plasma Ab titers were higher to Env gp41 than to gp120, and repertoire analysis demonstrated that 93% of HIV-1–reactive Abs from memory B cells responded to Env gp41. Vaccine-induced gp41-reactive monoclonal antibodies were non-neutralizing and frequently polyreactive with host and environmental antigens, including intestinal microbiota (IM). Next-generation sequencing of an immunoglobulin heavy chain variable region repertoire before vaccination revealed an Env-IM cross-reactive Ab that was clonally related to a subsequent vaccine-induced gp41-reactive Ab. Thus, HIV-1 Env DNA-rAd5 vaccine induced a dominant IM-polyreactive, non-neutralizing gp41-reactive Ab repertoire response that was associated with no vaccine efficacy.

HIV-specific humoral responses benefit from stronger prime in phase Ib clinical trial

BACKGROUND. Vector prime-boost immunization strategies induce strong cellular and humoral immune responses. We examined the priming dose and administration order of heterologous vectors in HIV Vaccine Trials Network 078 (HVTN 078), a randomized, double-blind phase Ib clinical trial to evaluate the safety and immunogenicity of heterologous prime-boost regimens, with a New York vaccinia HIV clade B (NYVAC-B) vaccine and a recombinant adenovirus 5-vectored (rAd5-vectored) vaccine. METHODS. NYVAC-B included HIV-1 clade B Gag-Pol-Nef and gp120, while rAd5 included HIV-1 clade B Gag-Pol and clades A, B, and C gp140. Eighty Ad5-seronegative subjects were randomized to receive 2 × NYVAC-B followed by 1 × 1010 PFU rAd5 (NYVAC/Ad5hi); 1 × 108 PFU rAd5 followed by 2 × NYVAC-B (Ad5lo/NYVAC); 1 × 109 PFU rAd5 followed by 2 × NYVAC-B (Ad5med/NYVAC); 1 × 1010 PFU rAd5 followed by 2 × NYVAC-B (Ad5hi/NYVAC); or placebo. Immune responses were assessed 2 weeks after the final vaccination. Intracellular cytokine staining measured T cells producing IFN-γ and/or IL-2; cross-clade and epitope-specific binding antibodies were determined; and neutralizing antibodies (nAbs) were assessed with 6 tier 1 viruses. RESULTS. CD4+ T cell response rates ranged from 42.9% to 93.3%. NYVAC/Ad5hi response rates (P ≤ 0.01) and magnitudes (P ≤ 0.03) were significantly lower than those of other groups. CD8+ T cell response rates ranged from 65.5% to 85.7%. NYVAC/Ad5hi magnitudes were significantly lower than those of other groups (P ≤ 0.04). IgG response rates to the group M consensus gp140 were 89.7% for NYVAC/Ad5hi and 21.4%, 84.6%, and 100% for Ad5lo/NYVAC, Ad5med/NYVAC, and Ad5hi/NYVAC, respectively, and were similar for other vaccine proteins. Overall nAb responses were low, but aggregate responses appeared stronger for Ad5med/NYVAC and Ad5hi/NYVAC than for NYVAC/Ad5hi. CONCLUSIONS. rAd5 prime followed by NYVAC boost is superior to the reverse regimen for both vaccine-induced cellular and humoral immune responses. Higher Ad5 priming doses significantly increased binding and nAbs. These data provide a basis for optimizing the design of future clinical trials testing vector-based heterologous prime-boost strategies. TRIAL REGISTRATION. ClinicalTrials.gov NCT00961883. FUNDING. NIAID, NIH UM1AI068618, AI068635, AI068614, and AI069443.

Intentions to use preexposure prophylaxis among current phase 2B preventive HIV-1 vaccine efficacy trial participants.

Abstract:In November 2010, the iPrEx study reported that preexposure prophylaxis (PrEP) with daily tenofovir disoproxil fumarate/emtricitabine reduced HIV infections by 44% among men who have sex with men and subsequent trials corroborated efficacy among heterosexual men and women. During regularly scheduled follow-up visits from January to March 2011, participants in an ongoing phase 2b vaccine efficacy trial completed an anonymous Web survey about PrEP. Among 376 respondents, 17% reported they were very likely to use PrEP in the next year. Nonwhite participants were more likely to use PrEP. Among those with some level of interest, intent to use PrEP was greatest if the drug were available through the clinical trial or health insurance. Most (91%) believed taking PrEP would not change their willingness to stay in the vaccine trial and few thought it would affect recruitment. As key stakeholders, currently enrolled trial participants can offer vital input about emerging prevention technologies that may affect the design of future HIV vaccine and nonvaccine prevention trials.

The Inner Foreskin of Healthy Males at Risk of HIV Infection Harbors Epithelial CD4+ CCR5+ Cells and Has Features of an Inflamed Epidermal Barrier

Male circumcision provides partial protection against multiple sexually transmitted infections (STIs), including HIV, but the mechanisms are not fully understood. To examine potential vulnerabilities in foreskin epithelial structure, we used Wilcoxon paired tests adjusted using the false discovery rate method to compare inner and outer foreskin samples from 20 healthy, sexually active Peruvian males who have sex with males or transgender females, ages 21–29, at elevated risk of HIV infection. No evidence of epithelial microtrauma was identified, as assessed by keratinocyte activation, fibronectin deposition, or parakeratosis. However, multiple suprabasal tight junction differences were identified: 1) inner foreskin stratum corneum was thinner than outer (p = 0.035); 2) claudin 1 had extended membrane-bound localization throughout inner epidermis stratum spinosum (p = 0.035); 3) membrane-bound claudin 4 was absent from inner foreskin stratum granulosum (p = 0.035); and 4) occludin had increased membrane deposition in inner foreskin stratum granulosum (p = 0.042) versus outer. Together, this suggests subclinical inflammation and paracellular transport modifications to the inner foreskin. A setting of inflammation was further supported by inner foreskin epithelial explant cultures secreting higher levels of GM-CSF (p = 0.029), IP-10 (p = 0.035) and RANTES (p = 0.022) than outer foreskin, and also containing an increased density of CCR5+ and CD4+ CCR5+ cells (p = 0.022). Inner foreskin dermis also secreted more RANTES than outer (p = 0.036), and had increased density of CCR5+ cells (p = 0.022). In conclusion, subclinical changes to the inner foreskin of sexually active males may support an inflammatory state, with availability of target cells for HIV infection and modifications to epidermal barriers, potentially explaining the benefits of circumcision for STI prevention.

Basis and Statistical Design of the Passive HIV-1 Antibody Mediated Prevention (AMP) Test-of-Concept Efficacy Trials

Abstract Background Anti-HIV-1 broadly neutralizing antibodies (bnAbs) have been developed as potential agents for prevention of HIV-1 infection. The HIV Vaccine Trials Network and the HIV Prevention Trials Network are conducting the Antibody Mediated Prevention (AMP) trials to assess whether, and how, intravenous infusion of the anti-CD4 binding site bnAb, VRC01, prevents HIV-1 infection. These are the first test-of-concept studies to assess HIV-1 bnAb prevention efficacy in humans. Methods The AMP trials are two parallel phase 2b HIV-1 prevention efficacy trials conducted in two cohorts: 2700 HIV-uninfected men and transgender persons who have sex with men in the United States, Peru, Brazil, and Switzerland; and 1500 HIV-uninfected sexually active women in seven countries in sub-Saharan Africa. Participants are randomized 1:1:1 to receive an intravenous infusion of 10 mg/kg VRC01, 30 mg/kg VRC01, or a control preparation every 8 weeks for a total of 10 infusions. Each trial is designed (1) to assess overall prevention efficacy (PE) pooled over the two VRC01 dose groups vs. control and (2) to assess VRC01 dose and laboratory markers as correlates of protection (CoPs) against overall and genotype- and phenotype-specific infection. Results Each AMP trial is designed to have 90 % power to detect PE > 0 % if PE is ≥ 60 %. The AMP trials are also designed to identify VRC01 properties (i. e., concentration and effector functions) that correlate with protection and to provide insight into mechanistic CoPs. CoPs are assessed using data from breakthrough HIV-1 infections, including genetic sequences and sensitivities to VRC01-mediated neutralization and Fc effector functions. Conclusions The AMP trials test whether VRC01 can prevent HIV-1 infection in two study populations. If affirmative, they will provide information for estimating the optimal dosage of VRC01 (or subsequent derivatives) and identify threshold levels of neutralization and Fc effector functions associated with high-level protection, setting a benchmark for future vaccine evaluation and constituting a bridge to other bnAb approaches for HIV-1 prevention.

Sieve analysis of breakthrough HIV-1 sequences in HVTN 505 identifies vaccine pressure targeting the CD4 binding site of Env-gp120

Although the HVTN 505 DNA/recombinant adenovirus type 5 vector HIV-1 vaccine trial showed no overall efficacy, analysis of breakthrough HIV-1 sequences in participants can help determine whether vaccine-induced immune responses impacted viruses that caused infection. We analyzed 480 HIV-1 genomes sampled from 27 vaccine and 20 placebo recipients and found that intra-host HIV-1 diversity was significantly lower in vaccine recipients (P ≤ 0.04, Q-values ≤ 0.09) in Gag, Pol, Vif and envelope glycoprotein gp120 (Env-gp120). Furthermore, Env-gp120 sequences from vaccine recipients were significantly more distant from the subtype B vaccine insert than sequences from placebo recipients (P = 0.01, Q-value = 0.12). These vaccine effects were associated with signatures mapping to CD4 binding site and CD4-induced monoclonal antibody footprints. These results suggest either (i) no vaccine efficacy to block acquisition of any viral genotype but vaccine-accelerated Env evolution post-acquisition; or (ii) vaccine efficacy against HIV-1s with Env sequences closest to the vaccine insert combined with increased acquisition due to other factors, potentially including the vaccine vector.

Higher T-Cell Responses Induced by DNA/rAd5 HIV-1 Preventive Vaccine Are Associated With Lower HIV-1 Infection Risk in an Efficacy Trial

Background It is important to identify vaccine-induced immune responses that predict the preventative efficacy of a human immunodeficiency virus (HIV)-1 vaccine. We assessed T-cell response markers as correlates of risk in the HIV Vaccine Trials Network (HVTN) 505 HIV-1 vaccine efficacy trial. Methods 2504 participants were randomized to DNA/rAd5 vaccine or placebo, administered at weeks 0, 4, 8, and 24. Peripheral blood mononuclear cells were obtained at week 26 from all 25 primary endpoint vaccine cases and 125 matched vaccine controls, and stimulated with vaccine-insert-matched peptides. Primary variables were total HIV-1-specific CD4+ T-cell magnitude and Env-specific CD4+ polyfunctionality. Four secondary variables were also assessed. Immune responses were evaluated as predictors of HIV-1 infection among vaccinees using Cox proportional hazards models. Machine learning analyses identified immune response combinations best predicting HIV-1 infection. Results We observed an unexpectedly strong inverse correlation between Env-specific CD8+ immune response magnitude and HIV-1 infection risk (hazard ratio [HR] = 0.18 per SD increment; P = .04) and between Env-specific CD8+ polyfunctionality and infection risk (HR = 0.34 per SD increment; P < .01). Conclusions Further research is needed to determine if these immune responses are predictors of vaccine efficacy or markers of natural resistance to HIV-1 infection.

Engaging Transgender People in NIH-Funded HIV/AIDS Clinical Trials Research

Abstract:In 2009, the National Institutes of Health recognized the need to expand knowledge of lesbian, gay, bisexual, and transgender (LGBT) health and commissioned the Institute of Medicine to report on the health of these populations in the United States. The resulting Institute of Medicine publication called for more knowledge of the health of LGBT populations, as well as improved methodologies to reach them, more LGBT-focused research, and enhanced training programs and cultural competency of physicians and researchers. Several of the National Institutes of Health–funded HIV/AIDS clinical trials networks, including the Adolescent Medicine Trials Network for HIV/AIDS Interventions, HIV Prevention Trials Network, HIV Vaccine Trials Network, and Microbicide Trials Network, have focused attention on engaging transgender (TG) individuals in research. They have identified issues that transcend the nature of research (ie, treatment or prevention, adult or adolescent) and have adopted various approaches to effectively engage the TG community. Each network has recognized the importance of developing partnerships to build trust with and seek input from TG individuals on research plans and policies. They have established standing advisory groups and convened consultations for this purpose. To ensure that trial data are reflective of the participants they are seeking to enroll, they have reviewed and revised data collection forms to incorporate the 2-step method of collecting sex at birth and gender identity as 2 independent variables, and some have also revised research protocol templates and policies for concept development to ensure that they are appropriate for the inclusion of TG participants. The networks have also initiated trainings to enhance cultural sensitivity and developed a range of materials and resources for network and clinical research site staff. They continue to identify TG-specific research needs in an effort to be more responsive to and improve the health of TG individuals, particularly related to HIV/AIDS.

In men at risk of HIV infection, IgM, IgG1, IgG3, and IgA reach the human foreskin epidermis

We profiled the humoral response in the penis, an area that has been minimally explored but may be relevant for protecting insertive men against HIV and other sexually acquired infections. Comparing paired tissue samples from 20 men at risk of HIV infection, foreskin contains less immunoglobulin A (IgA) and more IgG2 than colon. Using foreskin dermal and epidermal explants and paired plasma from 17 men, we examined Ig accumulation by normalizing Ig to human serum albumin (HSA) transudation. Dermal IgM, IgG2, IgA, and IgE ratios were greater than that in plasma, suggesting there is local antibody secretion at the dermis. Local Ig transcription was concentrated at the inner rather than the outer foreskin, and inner foreskin Ig ratios did not correlate with blood, indicating that localized production can contribute to the foreskin response. IgM, IgG1, IgG3, and IgA have preferential access to the foreskin epidermis, whereas IgG2, IgG4, and IgE are restricted to the dermis. Lastly, Ad5-specific IgA was selectively present in the colon, whereas foreskin Ad5 IgG was mainly derived from blood, and reached the inner epidermis at higher ratios than the outer (P<0.002). In summary, the foreskin antibody response combines local and systemic sources, and there is selective isotype accumulation in the epidermis.