S. S. Abdool Karim

Quantitating the Multiplicity of Infection with Human Immunodeficiency Virus Type 1 Subtype C Reveals a Non-Poisson Distribution of Transmitted Variants

ABSTRACT Identifying the specific genetic characteristics of successfully transmitted variants may prove central to the development of effective vaccine and microbicide interventions. Although human immunodeficiency virus transmission is associated with a population bottleneck, the extent to which different factors influence the diversity of transmitted viruses is unclear. We estimate here the number of transmitted variants in 69 heterosexual men and women with primary subtype C infections. From 1,505 env sequences obtained using a single genome amplification approach we show that 78% of infections involved single variant transmission and 22% involved multiple variant transmissions (median of 3). We found evidence for mutations selected for cytotoxic-T-lymphocyte or antibody escape and a high prevalence of recombination in individuals infected with multiple variants representing another potential escape pathway in these individuals. In a combined analysis of 171 subtype B and C transmission events, we found that infection with more than one variant does not follow a Poisson distribution, indicating that transmission of individual virions cannot be seen as independent events, each occurring with low probability. While most transmissions resulted from a single infectious unit, multiple variant transmissions represent a significant fraction of transmission events, suggesting that there may be important mechanistic differences between these groups that are not yet understood.

Neutralizing Antibody Responses in Acute Human Immunodeficiency Virus Type 1 Subtype C Infection

ABSTRACT The study of the evolution and specificities of neutralizing antibodies during the course of human immunodeficiency virus type 1 (HIV-1) infection may be important in the discovery of possible targets for vaccine design. In this study, we assessed the autologous and heterologous neutralization responses of 14 HIV-1 subtype C-infected individuals, using envelope clones obtained within the first 2 months postinfection. Our data show that potent but relatively strain-specific neutralizing antibodies develop within 3 to 12 months of HIV-1 infection. The magnitude of this response was associated with shorter V1-to-V5 envelope lengths and fewer glycosylation sites, particularly in the V1-V2 region. Anti-MPER antibodies were detected in 4 of 14 individuals within a year of infection, while antibodies to CD4-induced (CD4i) epitopes developed to high titers in 12 participants, in most cases before the development of autologous neutralizing antibodies. However, neither anti-MPER nor anti-CD4i antibody specificity conferred neutralization breadth. These data provide insights into the kinetics, potency, breadth, and epitope specificity of neutralizing antibody responses in acute HIV-1 subtype C infection.

Informed consent for HIV testing in a South African hospital: is it truly informed and truly voluntary?

OBJECTIVE The purpose of this study was to assess informed consent to human immunodeficiency virus (HIV) testing in a perinatal HIV transmission study in a major referral hospital serving a largely Black population in South Africa. METHODS First-time antenatal clinic attenders who were randomly selected from those enrolled in the perinatal HIV study (n = 56) answered questionnaires before and after counseling. RESULTS Knowledge of HIV transmission and prevention, high at the outset, was little improved after counseling. The acceptance rate for HIV testing was high. Despite assurances that participation was voluntary, 88% of the women said they felt compelled to participate in the study. CONCLUSIONS Informed consent in this setting was truly informed but not truly voluntary.

Impact of on-site testing for maternal syphilis on treatment delays, treatment rates, and perinatal mortality in rural South Africa: a randomised controlled trial

Background: Syphilis remains a significant cause of preventable perinatal death in developing countries, with many women remaining untested and thus untreated. Syphilis testing in the clinic (on-site testing) may be a useful strategy to overcome this. We studied the impact of on-site syphilis testing on treatment delays and rates, and perinatal mortality. Methods: We conducted a cluster randomised controlled trial among seven pairs of primary healthcare clinics in rural South Africa, comparing on-site testing complemented by laboratory confirmation versus laboratory testing alone. Intervention clinics used the on-site test conducted by primary care nurses, with results and treatment available within an hour. Control clinics sent blood samples to the provincial laboratory, with results returned 2 weeks later. Results: Of 7134 women seeking antenatal care with available test results, 793 (11.1%) tested positive for syphilis. Women at intervention clinics completed treatment 16 days sooner on average (95% confidence interval: 11 to 21), though there was no significant difference in the proportion receiving adequate treatment at intervention (64%) and control (69%) clinics. There was also no significant difference in the proportion experiencing perinatal loss (3.3% v 5.1%; adjusted risk difference: −0.9%; 95% CI −4.4 to 2.7). Conclusions: Despite reducing treatment delays, the addition of on-site syphilis testing to existing laboratory testing services did not lead to higher treatment rates or reduce perinatal mortality. However on-site testing for syphilis may remain an important option for improving antenatal care in settings where laboratory facilities are not available.

Human TRIM5α expression levels and reduced susceptibility to HIV-1 infection.

BACKGROUND Human TRIM5alpha (TRIM5alphahu), a member of the tripartite motif protein family, displays some anti-human immunodeficiency virus type 1 (HIV-1) activity in vitro, although it is substantially less potent than its rhesus monkey counterpart (TRIM5alpharh). The effects of levels of TRIM5alphahu on prevention or control of HIV-1 infection in vivo are unknown. METHODS We used a quantitative real-time polymerase chain reaction (PCR) assay to measure levels of TRIM5alphahu expression in peripheral blood mononuclear cells (PBMCs) obtained from a cohort of individuals at high risk for HIV-1 infection in Durban, South Africa. Samples were available from 38 infected subjects (with all these samples obtained within 1 year of infection) and from 57 uninfected persons. Matched preinfection and postinfection samples were available from 13 individuals. RESULTS TRIM5alphahu messenger RNA levels were lower in the PBMCs of HIV-1-infected subjects than in those of uninfected subjects (P <.001). Seroconverters had lower preinfection levels of TRIM5alphahu than did nonseroconverters (P<.001). TRIM5alphahu levels did not change significantly after infection. There was no correlation between TRIM5alphahu levels and viral loads or CD4(+) T cell counts. CONCLUSIONS High expression of TRIM5alphahu is associated with reduced susceptibility to HIV-1 infection. Furthermore, infection is not associated with disregulation of TRIM5alphahu. TRIM5alphahu expression levels do not contribute to the control of primary HIV-1 viremia.

High HIV incidence and prevalence among young women in rural South Africa: developing a cohort for intervention trials

Objective: To measure prevalence and model incidence of HIV infection. Setting: 2013 consecutive pregnant women attending public sector antenatal clinics in 1997 in Hlabisa health district, South Africa. Historical seroprevalence data, 1992‐ 1995. Methods: Serum remaining from syphilis testing was tested anonymously for antibodies to HIV to determine seroprevalence. Two models, allowing for differential mortality between HIV‐positive and HIV‐negative people, were used. The first used serial seroprevalence data to estimate trends in annual incidence. The second, a maximum likelihood model, took account of changing force of infection and age‐dependent risk of infection, to estimate age‐specific HIV incidence in 1997. Multiple logistic regression provided adjusted odds ratios (OR) for risk factors for prevalent HIV infection. Results: Estimated annual HIV incidence increased from 4% in 1992/1993 to 10% in 1996/1997. In 1997, highest age‐specific incidence was 16% among women aged between 20 and 24 years. In 1997, overall prevalence was 26% (95% confidence interval [CI], 24%‐28%) and at 34% was highest among women aged between 20 and 24 years. Young age (<30 years; odds ratio [OR], 2.1; p = .001), unmarried status (OR 2.2; p = .001) and living in less remote parts of the district (OR 1.5; p = .002) were associated with HIV prevalence in univariate analysis. Associations were less strong in multivariate analysis. Partners migration status was not associated with HIV infection. Substantial heterogeneity of HIV prevalence by clinic was observed (range 17%‐31%; test for trend, p = .001). Conclusions: This community is experiencing an explosive HIV epidemic. Young, single women in the more developed parts of the district would form an appropriate cohort to test, and benefit from, interventions such as vaginal microbicides and HIV vaccines.

Screening for ‘window-period’ acute HIV infection among pregnant women in rural South Africa

The aim of this study was to evaluate the HIV‐1 RNA pooled nucleic acid amplification testing (NAAT) strategy to screen pregnant women in the ‘window period’ of acute HIV infection (AHI) in rural South Africa.

The influence of AIDS stigma and discrimination and social cohesion on HIV testing and willingness to disclose HIV in rural KwaZulu-Natal, South Africa

Abstract This study aims to understand the influence of AIDS stigma and discrimination, and social cohesion to HIV testing, and willingness to disclose an HIV status. A cross-sectional, interviewer administered survey (N=594) was conducted. Independent sample t-tests explored the mean differences between sex and age groups on stigma, discrimination, and social cohesion measurement. Logistic regression models were fitted with the above independent variables, and the binominal dependent variables: having had a test, willingness to have a test and disclose a positive status. The mean age of participants was 25.3 years and 60% were women. Only 28% had an HIV test, 63% were willing to have a test, and 82% reported a willingness to disclose an HIV status. High levels of stigma and discrimination were anticipated from the community, less so from their partners, and very little from families. Low levels of social distance exist towards people with HIV/AIDS, membership to social networks seems limited, and inadequate social support for people with HIV/AIDS was reported. The analysis indicates that AIDS stigma and discrimination, and inadequate social cohesion, limit access to voluntary counselling and testing (VCT), inhibit disclosure, and are, thus, barriers to care, support and prevention. Interventions need to extend the focus on information and education to strengthen social capital within a participatory and sustainable development framework.

Phase I Safety and Immunogenicity Evaluations of an Alphavirus Replicon HIV-1 Subtype C gag Vaccine in Healthy HIV-1-Uninfected Adults

ABSTRACT On the basis of positive preclinical data, we evaluated the safety and immunogenicity of an alphavirus replicon HIV-1 subtype C gag vaccine (AVX101), expressing a nonmyristoylated form of Gag, in two double-blind, randomized, placebo-controlled clinical trials in healthy HIV-1-uninfected adults. Escalating doses of AVX101 or placebo were administered subcutaneously to participants in the United States and Southern Africa. Because of vaccine stability issues, the first trial was halted prior to completion of all dose levels and a second trial was implemented. The second trial was also stopped prematurely due to documentation issues with the contract manufacturer. Safety and immunogenicity were evaluated through assessments of reactogenicity, reports of adverse events, and assessment of replication-competent and Venezuelan equine encephalitis (VEE) viremia. Immunogenicity was measured using the following assays: enzyme-linked immunosorbent assay (ELISA), chromium 51 (51Cr)-release cytotoxic T lymphocyte (CTL), gamma interferon (IFN-γ) ELISpot, intracellular cytokine staining (ICS), and lymphoproliferation assay (LPA). Anti-vector antibodies were also measured. AVX101 was well tolerated and exhibited only modest local reactogenicity. There were 5 serious adverse events reported during the trials; none were considered related to the study vaccine. In contrast to the preclinical data, immune responses in humans were limited. Only low levels of binding antibodies and T-cell responses were seen at the highest doses. This trial also highlighted the difficulties in developing a novel vector for HIV.

Virological and Immunological Factors Associated with HIV-1 Differential Disease Progression in HLA-B*58:01 Positive Individuals

ABSTRACT Molecular epidemiology studies have identified HLA-B*58:01 as a protective HIV allele. However, not all B*58:01-expressing persons exhibit slow HIV disease progression. We followed six HLA-B*58:01-positive, HIV subtype C-infected individuals for up to 31 months from the onset of infection and observed substantial variability in their clinical progression despite comparable total breadths of T cell responses. We therefore investigated additional immunological and virological factors that could explain their different disease trajectories. Cytotoxic T-lymphocyte (CTL) responses during acute infection predominantly targeted the TW10 and KF9 epitopes in p24Gag and Nef, respectively. Failure to target the TW10 epitope in one B*58:01-positive individual was associated with low CD4+ counts and rapid disease progression. Among those targeting TW10, escape mutations arose within 2 to 15 weeks of infection. Rapid escape was associated with preexisting compensatory mutations in the transmitted viruses, which were present at a high frequency (69%) in the study population. At 1 year postinfection, B*58:01-positive individuals who targeted and developed escape mutations in the TW10 epitope (n = 5) retained significantly higher CD4+ counts (P = 0.04), but not lower viral loads, than non-B*58:01-positive individuals (n = 17). The high population-level frequency of these compensatory mutations may be limiting the protective effect of the B*58:01 allele.