Short communication decreased incidence of dual infections in South african subtype C-infected women compared to a cohort ten years earlier

HIV Coinfection Provides Insights for the Design of Vaccine Cocktails to Elicit Broadly Neutralizing Antibodies

Induction of broadly neutralizing antibodies (bNAbs) to HIV and other diverse pathogens will likely require the use of multiple immunogens. An understanding of the dynamics of antibody development to multiple diverse but related antigens would facilitate the rational design of immunization strategies. Here, we characterize, in detail, the development of neutralizing antibodies in three individuals coinfected with several divergent HIV variants. Two of these coinfected individuals developed additive or cross-neutralizing antibody responses. However, interference was observed in the third case, with neutralizing antibody responses to one viral variant arising to the near exclusion of neutralizing responses to the other. Longitudinal characterization of the diversity in the Envelope glycoprotein trimer (Env) structure showed that in the individual who developed the broadest neutralizing antibodies, circulating viruses shared a conserved epitope on the trimer apex that was targeted by cross-neutralizing antibodies. In contrast, in the other two individuals, diversity was distributed across Env. Taken together, these data highlight that multiple related immunogens can result in immune interference. However, they also suggest that immunogen cocktails presenting shared, conserved neutralizing epitopes in a variable background may focus broadly neutralizing antibody responses to these targets. IMPORTANCE Despite being the focus of extensive research, we still do not know how to reproducibly elicit cross-neutralizing antibodies against variable pathogens by vaccination. Here, we characterize the antibody responses in people coinfected with more than one HIV variant, providing insights into how the use of antigen "cocktails" might affect the breadth of the elicited neutralizing antibody response and how the relatedness of the antigens may shape this.

Short Communication: A Recombinant Variant with Increased Envelope Entry Efficiency Emerged During Early Infection of an HIV-1 Subtype C Dual Infected Rapid Progressor

Mutations in functionally constrained sites of the HIV envelope (Env) can affect entry efficiency and are potential targets for vaccine and drug design. We investigated Du151, a dual-infected individual with rapid disease progression. At her death 19 months postinfection (mpi), she was infected with a recombinant variant, which outgrew both parental viruses. We aimed to determine whether the recombinant virus had enhanced Env entry efficiency compared to the parental viruses and to identify the functional determinant. We generated 15 env clones at 1, 2, 8, and 19 mpi. Pseudovirus carrying a recombinant Env clone (PSV clone), C18 (19 mpi), had significantly higher entry efficiency compared to the parents, suggesting that the recombinant virus had enhanced fitness. To identify the functional determinant, we compared two recombinant PSV clones (C18 and C63)-differing in entry efficiency (2-fold) and by four and three amino acids in gp120 and gp41, respectively. The increased entry efficiency of a C18-gp41 PSV chimera indicated that the three amino acids in the C18 gp41 region were involved (K658, G671, and F717). Site-directed mutagenesis of the three amino acids of C63 showed that a single amino acid mutation, R658K, increased pseudovirion entry efficiency. The introduction of R658 into two PSV clones (C1 and C18) decreased their entry efficiency, suggesting that R658 carries a fitness cost. Thus, our data suggest that a recombinant virus emerged at 19 mpi with enhanced Env entry efficiency. Therefore, K658 in gp41 could in part be a contributing factor to the increased viral load and rapid disease progression of Du151.

A cross-sectional study on the relationship of age, gestational age and HIV infection to bacterial vaginosis and genital mycoplasma infection

OBJECTIVES

Pregnant women are especially at risk of developing complications when infected with reproductive tract infections (RTIs). The objective of this study was to determine the prevalence of bacterial vaginosis (BV) and genital mycoplasmas in pregnant women and investigate the associations between BV, genital mycoplasmas, HIV infection, age and gestational age.

DESIGN

Cross-sectional study with descriptive and analytical components.

SETTING

Antenatal clinic of a tertiary academic hospital in South Africa.

PARTICIPANTS

220 pregnant women older than 18 were included in the study and provided self-collected vaginal swabs.

PRIMARY AND SECONDARY OUTCOMES

BV and genital mycoplasma colonisation and/or infection in women of differing age, gestational period and HIV status.

RESULTS

The prevalence of BV was 17.7% (39/220) (95% CI 12.9 to 23.4), intermediate vaginal flora (IVF) 15% (33/220) (95% CI 10.56 to 20.42), and the overall prevalence of genital mycoplasmas was 84% (185/220) (95% CI 78.47 to 88.58). BV was significantly associated with HIV infection with an OR of 2.84 (95% CI 1.08 to 7.46 and p value=0.034). However, BV was inversely associated with gestational age with an OR of 0.08 (95% CI 0.01 to 0.42 and p value=0.003) for second trimester pregnancies and an OR of 0.03 (95% CI 0.01 to 0.17 and p value<0.001) for third trimester pregnancies using the first trimester as reference. IVF was significantly associated with HIV infection with an OR of 2.7 (95% CI 1.07 to 6.79 and p value=0.035) but not with age or gestational age. Genital mycoplasmas were not significantly associated with age, gestational age, HIV status, BV flora or IVF.

CONCLUSIONS

The high infection rate of genital mycoplasmas and the association of BV with HIV found in this study reiterate the importance of screening for these RTIs in high-risk groups such as pregnant women.

Differences in HIV type 1 neutralization breadth in 2 geographically distinct cohorts in Africa

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.

Virological and immunological factors associated with HIV-1 differential disease progression in HLA-B 58:01-positive individuals

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 p24(Gag) 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.