The development of biomedical interventions to reduce acquisition of HIV-1 infection remains a global priority, however their potential effectiveness is challenged by very high HIV-1 envelope ...diversity. Two large prophylactic trials in high incidence, clade C epidemic regions in southern Africa are imminent; passive administration of the monoclonal antibody VRC01, and active immunization with a clade C modified RV144-like vaccines. We have created a large representative panel of C clade viruses to enable assessment of antibody responses to vaccines and natural infection in Southern Africa, and we investigated the genotypic and neutralization properties of recently transmitted clade C viruses to determine how viral diversity impacted antibody recognition. We further explore the implications of these findings for the potential effectiveness of these trials. A panel of 200 HIV-1 Envelope pseudoviruses was constructed from clade C viruses collected within the first 100 days following infection. Viruses collected pre-seroconversion were significantly more resistant to serum neutralization compared to post-seroconversion viruses (p = 0.001). Over 13 years of the study as the epidemic matured, HIV-1 diversified (p = 0.0009) and became more neutralization resistant to monoclonal antibodies VRC01, PG9 and 4E10. When tested at therapeutic levels (10ug/ml), VRC01 only neutralized 80% of viruses in the panel, although it did exhibit potent neutralization activity against sensitive viruses (IC50 titres of 0.42 μg/ml). The Gp120 amino acid similarity between the clade C panel and candidate C-clade vaccine protein boosts (Ce1086 and TV1) was 77%, which is 8% more distant than between CRF01_AE viruses and the RV144 CRF01_AE immunogen. Furthermore, two vaccine signature sites, K169 in V2 and I307 in V3, associated with reduced infection risk in RV144, occurred less frequently in clade C panel viruses than in CRF01_AE viruses from Thailand. Increased resistance of pre-seroconversion viruses and evidence of antigenic drift highlights the value of using panels of very recently transmitted viruses and suggests that interventions may need to be modified over time to track the changing epidemic. Furthermore, high divergence such as that observed in the older clade C epidemic in southern Africa may impact vaccine efficacy, although the correlates of infection risk are yet to be defined in the clade C setting. Findings from this study of acute/early clade C viruses will aid vaccine development, and enable identification of new broad and potent antibodies to combat the HIV-1 C-clade epidemic in southern Africa.
OBJECTIVE:Early studies in Cape Town identified independent HIV-1 epidemics, with distinct viral subtypes, among men who have sex with men (MSM) and the heterosexual population. However, few recent ...HIV-1 subtype data are available for MSM in South Africa. We examined HIV-1 subtypes among MSM in Cape Town.
DESIGN:Cross-sectional survey.
METHODS:Self-identified MSM were recruited from geographically and racially disparate communities across Cape Town. Participants completed behavioral questionnaires and underwent HIV testing. Virus isolated from infected participants underwent complete env gp160 sequencing, and HIV-1 subtypes were assigned through phylogenetic analysis.
RESULTS:In total, 194 HIV-infected MSM were enrolled67% black African, 24% colored, and 9% white men. More black African men identified as bisexual or heterosexual compared with other races. Overall, 31%–66% of men reported a recent partner of another race. HIV-1 subtypes were confirmed for 143 participants81% were subtype C, 14% B, 1% A1, 1% F2, and 3 recombinant viruses. Subtype C virus was associated with black African race (P = 0.003 compared with colored; P < 0.001 compared with white), men who identified as bisexual/heterosexual (P = 0.01), and reported a female sexual partner in the last year (P = 0.02). Compared with previous studies, an increasing prevalence of subtype C virus was noted among white MSM.
CONCLUSIONS:This molecular epidemiology study provides novel evidence of sexual network links between the heterosexual and MSM epidemics and between historically racially disparate communities. These findings provide insights into the drivers of HIV epidemics in different population groups and may have implications for prevention strategies.
In South Africa, adolescents constitute a key population at high risk of HIV acquisition. However, little is known about HIV transmission among students within schools. This study was undertaken to ...assess the risk factors for HIV infection and the extent of transmission among rural high school students. Between February and May 2012, consenting students from five randomly selected public sector high schools in rural KwaZulu-Natal participated in an anonymous cross-sectional survey. Dried blood spot samples were collected and tested for HIV. β-Human chorionic gonadotropin (βHCG) levels were measured in females for pregnancy. Family circumstances as well as sociodemographic and behavioral factors were assessed as potential risk factors. A subset (106/148, 72%) of HIV-positive samples underwent gag p17p24 sequencing for phylogenetic analysis. A total of 3,242 students (81.7% of enrolled students) participated. HIV prevalence was 6.8% 95% confidence interval (CI) 3.9-9.8% in girls and 2.7% (CI 1.6-3.8%) in boys adjusted odds ratio (aOR)=3.0, CI 2.4-3.8; p<0.001. HIV prevalence increased from 4.6% (95% CI 1.9-7.3) in the 12- to 15-year-old girls to 23.1% (95% CI 7.7-38.5) in girls over 20 years, while in boys HIV prevalence increased from 2.7% (95% CI 0.6-4.9) in the 12- to15-year-old boys to 11.1% (95% CI 2.7-19.4) in those over 20 years. Sequencing of samples obtained from students revealed only two clusters, suggesting within-school transmission and three interschool clusters, while the remainder was most likely acquired from sources other than those currently found in students attending the school concerned. HIV prevalence in both girls (aOR=3.6, CI 2.9-4.5; p<0.001) and boys (aOR=2.8, CI 1.2-6.2; p=0.01) was higher in those without a living biological mother. The high burden of HIV infection among students was not associated with intraschool transmission in this rural setting. Lack of a living parent is an important factor defining high risk in this group of adolescents.
To investigate whether distinct populations have differing human immunodeficiency virus type 1 (HIV) neutralizing antibody responses, we compared 20 women from Tanzania's HIV Superinfection Study ...(HISIS) cohort, who were infected multiple HIV subtypes, and 22 women from the Centre for the AIDS Programme of Research in South Africa (CAPRISA) cohort, who were infected exclusively with HIV subtype C. By 2 years after infection, 35% of HISIS subjects developed neutralization breadth, compared with 9% of CAPRISA subjects (P = .0131). Cumulative viral loads between 3 and 12 months were higher in the HISIS group (P = .046) and strongly associated with breadth (P<.0001). While viral load was the strongest predictor, other factors may play a role, as the odds of developing breadth remained higher in HISIS even after correction for viral load.
There is limited information on full-length genome sequences and the early evolution of transmitted HIV-1 subtype C viruses, which constitute the majority of viruses spread in Africa. The purpose of ...this study was to characterize the earliest changes across the genome of subtype C viruses following transmission, to better understand early control of viremia.
We derived the near full-length genome sequence responsible for clinical infection from five HIV subtype C-infected individuals with different disease progression profiles and tracked adaptation to immune responses in the first 6 months of infection.
Near full-length genomes were generated by single genome amplification and direct sequencing. Sequences were analyzed for amino acid mutations associated with cytotoxic T lymphocyte (CTL) or antibody-mediated immune pressure, and for reversion.
Fifty-five sequence changes associated with adaptation to the new host were identified, with 38% attributed to CTL pressure, 35% to antibody pressure, 16% to reversions and the remainder were unclassified. Mutations in CTL epitopes were most frequent in the first 5 weeks of infection, with the frequency declining over time with the decline in viral load. CTL escape predominantly occurred in nef, followed by pol and env. Shuffling/toggling of mutations was identified in 81% of CTL epitopes, with only 7% reaching fixation within the 6-month period.
There was rapid virus adaptation following transmission, predominantly driven by CTL pressure, with most changes occurring during high viremia. Rapid escape and complex escape pathways provide further challenges for vaccine protection.
Eliciting antibodies that neutralize a broad range of circulating HIV strains (broadly neutralizing antibodies bnAbs) represents a key priority for vaccine development. HIV superinfection ...(re-infection with a second strain following an established infection) has been associated with neutralization breadth, and can provide insights into how the immune system responds to sequential exposure to distinct HIV envelope glycoproteins (Env). Characterizing the neutralizing antibody (nAb) responses in four superinfected women revealed that superinfection does not boost memory nAb responses primed by the first infection or promote nAb responses to epitopes conserved in both infecting viruses. While one superinfected individual developed potent bnAbs, superinfection was likely not the driver as the nAb response did not target an epitope conserved in both viruses. Rather, sequential exposure led to nAbs specific to each Env but did not promote bnAb development. Thus, sequential immunization with heterologous Envs may not be sufficient to focus the immune response onto conserved epitopes.
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•HIV superinfection does not efficiently recruit cross-reactive memory B cells•Superinfection results in antibody responses specific to each infecting strain•No evidence that superinfection drives the development of bnAbs
HIV-infected individuals can be re-infected with a second strain (superinfection), providing a model that informs the use of sequential immunizations in future vaccines. Sheward et al. find that superinfection fails to boost memory B cells primed by the first infection and does not promote broadly neutralizing antibodies to HIV.
Abstract The Mbeya region of Tanzania has a genetically complex HIV epidemic with multiple subtypes and recombinant forms circulating, together with a high frequency of dual infections with more than ...one subtype. This study aimed to determine whether this impacted the HIV-1 transmission bottleneck. A total of 210 env sequences from 22 participants were generated from recently infected women from Mbeya using the single genome amplification approach. Participants were infected with subtypes C ( n = 9), A ( n = 4), or D ( n = 1), and recombinants AC ( n = 4), CD ( n = 2), AD ( n = 1), or ACD ( n = 1). Sixteen participants (73%) were infected with a single variant; five (23%) with multiple variants; and one (4%) was dually infected. Thus the frequency of single variant infections was similar to cohorts located in genetically restricted subtype B or C epidemics, suggesting that multiple circulating subtypes and unique recombinant forms do not have a significant impact on the transmission bottleneck.
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