Plasma viral loads during early HIV-1 infection are similar in subtype C- and non-subtype C-infected African seroconverters

High monoclonal neutralization titers reduced breakthrough HIV-1 viral loads in the Antibody Mediated Prevention trials

The Antibody Mediated Prevention (AMP) trials (NCT02716675 and NCT02568215) demonstrated that passive administration of the broadly neutralizing monoclonal antibody VRC01 could prevent some HIV-1 acquisition events. Here, we use mathematical modeling in a post hoc analysis to demonstrate that VRC01 influenced viral loads in AMP participants who acquired HIV. Instantaneous inhibitory potential (IIP), which integrates VRC01 serum concentration and VRC01 sensitivity of acquired viruses in terms of both IC50 and IC80, follows a dose-response relationship with first positive viral load (p = 0.03), which is particularly strong above a threshold of IIP = 1.6 (r = -0.6, p = 2e-4). Mathematical modeling reveals that VRC01 activity predicted from in vitro IC80s and serum VRC01 concentrations overestimates in vivo neutralization by 600-fold (95% CI: 300-1200). The trained model projects that even if future therapeutic HIV trials of combination monoclonal antibodies do not always prevent acquisition, reductions in viremia and reservoir size could be expected.

Per-pathogen virulence of HIV-1 subtypes A, C and D

HIV-1 subtypes differ in their clinical manifestations and the speed in which they spread. In particular, the frequency of subtype C is increasing relative to subtypes A and D. We investigate whether HIV-1 subtypes A, C and D differ in their per-pathogen virulence and to what extend this explains the difference in spread between these subtypes. We use data from the hormonal contraception and HIV-1 genital shedding and disease progression among women with primary HIV infection study. For each study participant, we determine the set-point viral load value, CD4⁺ T cell level after primary infection and CD4⁺ T cell decline. Based on both the CD4⁺ T cell count after primary infection and CD4⁺ T cell decline, we estimate the time until AIDS. We then obtain our newly introduced measure of virulence as the inverse of the estimated time until AIDS. After fitting a model to the measured virulence and set-point viral load values, we tested if this relation varies per subtype. We found that subtype C has a significantly higher per-pathogen virulence than subtype A. Based on an evolutionary model, we then hypothesize that differences in the primary length of infection period cause the observed variation in the speed of spread of the subtypes.

HIV risk associated with serum medroxyprogesterone acetate levels among women in East and southern Africa

BACKGROUND

Some observational studies have found increased HIV risk associated with self-reported use of injectable depot medroxyprogesterone acetate. Testing blood samples for medroxyprogesterone acetate (MPA), the progestin in depot medroxyprogesterone acetate, permits validation of self-reported data, and exploration of whether potential HIV risk is correlated with MPA levels, which are highest soon after injection.

METHODS

We conducted a case-control study testing archived serum from women who participated in three longitudinal studies of HIV prevention in East and southern Africa. Case samples, from women who acquired HIV, were from visits that occurred at or immediately prior to the first evidence of HIV infection. Secondary analyses restricted to case samples collected within 15 and 30 days of the estimated date of HIV infection. Matched control samples were from women who remained HIV uninfected. We used multivariable conditional logistic regression to compare exogenous hormone levels, quantified through mass spectrometry, among cases and controls.

RESULTS

When restricted to cases with samples collected within 15 days or less of estimated date of HIV infection, MPA detection was more frequent among women who acquired HIV (adjusted odds ratio = 2.75, 95% confidence interval 1.22-6.19). In this subset, the increase in HIV risk was only among samples with MPA detected at a low level of 0.02-0.50 ng/ml: 36.7% of cases and 9.4% of controls, adjusted odds ratio = 6.03, 95% confidence interval 2.50-14.54.

CONCLUSION

Detection of MPA at low levels close to the estimated time of HIV acquisition was significantly more frequent among women who acquired HIV. Studies are needed that explore biological mechanisms elicited by any MPA level and HIV risk.

Increased Risk of HIV Acquisition Among Women Throughout Pregnancy and During the Postpartum Period: A Prospective Per-Coital-Act Analysis Among Women With HIV-Infected Partners

Background

Understanding the absolute and relative risk of human immunodeficiency virus type 1 (HIV) acquisition during pregnancy and the postpartum period can inform HIV prevention strategies for women.

Methods

We used a complementary log-log model and data from 2751 HIV-serodiscordant couples to compare the probability of HIV acquisition among women per sex act during early pregnancy, late pregnancy, the postpartum period, and the nonpregnant period.

Results

At total of 686 pregnancies were identified, and 82 incident HIV infections occurred. After adjustment for condom use, age, preexposure prophylaxis (PrEP) use, and HIV viral load, the per-act probability of HIV acquisition was higher in late pregnancy (adjusted relative risk [aRR], 2.82; P = .01) and the postpartum period (aRR, 3.97; P = .01) as compared to that during nonpregnant period. For a 25-year-old woman not taking PrEP, the HIV acquisition probability per condomless sex act with an HIV-infected male partner with a viral load of 10 000 copies/mL was 0.0011 (95% confidence interval [CI] 0.005-0.0019), 0.0022 (95% CI, 0.0004-0.0093), 0.0030 (95% CI, 0.0007-0.0108), and 0.0042 (95% CI, 0.0007-0.0177) during the nonpregnant period, early pregnancy, late pregnancy, and the postpartum period, respectively.

Conclusion

The HIV acquisition probability per condomless sex act steadily increased during pregnancy and was highest during the postpartum period, suggesting that biological changes during pregnancy and the postpartum period increase HIV susceptibility among women.

Prediction of extended high viremia among newly HIV-1-infected persons in sub-Saharan Africa

Objective

Prompt identification of newly HIV-infected persons, particularly those who are most at risk of extended high viremia (EHV), allows important clinical and transmission prevention benefits. We sought to determine whether EHV could be predicted during early HIV infection (EHI) from clinical, demographic, and laboratory indicators in a large HIV-1 incidence study in Africa.

Design

Adults acquiring HIV-1 infection were enrolled in an EHI study assessing acute retroviral syndrome (ARS) symptoms and viral dynamics.

Methods

Estimated date of infection (EDI) was based on a positive plasma viral load or p24 antigen test prior to seroconversion, or the mid-point between negative and positive serological tests. EHV was defined as mean untreated viral load ≥5 log₁₀ copies/ml 130–330 days post-EDI. We used logistic regression to develop risk score algorithms for predicting EHV based on sex, age, number of ARS symptoms, and CD4 and viral load at diagnosis.

Results

Models based on the full set of five predictors had excellent performance both in the full population (c-statistic = 0.80) and when confined to persons with each of three HIV-1 subtypes (c-statistic = 0.80–0.83 within subtypes A, C, and D). Reduced models containing only 2–4 predictors performed similarly. In a risk score algorithm based on the final full-population model, predictor scores were one for male sex and enrollment CD4<350 cells/mm³, and two for having enrollment viral load >4.9 log₁₀ copies/ml. With a risk score cut-point of two, this algorithm was 85% sensitive (95% CI: 76%-91%) and 61% specific (55%-68%) in predicting EHV.

Conclusions

Simple risk score algorithms can reliably identify persons with EHI in sub-Saharan Africa who are likely to sustain high viral loads if treatment is delayed. These algorithms may be useful for prioritizing intensified efforts around care linkage and retention, treatment initiation, adherence support, and partner services to optimize clinical and prevention outcomes.

HIV disease progression among women following seroconversion during a tenofovir-based HIV prevention trial

Background

Little is known regarding HIV disease outcomes among individuals who become infected with HIV while receiving antiretroviral medications for prevention. We compared HIV disease parameters among women who seroconverted while receiving tenofovir-containing oral or vaginal pre-exposure prophylaxis (PrEP) to placebo.

Methods

Participants with HIV seroconversion in a randomized placebo-controlled trial of oral tenofovir, oral tenofovir/emtricitabine, and vaginal tenofovir gel (MTN-003) were followed in a longitudinal cohort study (MTN-015). The effect of oral and vaginal tenofovir-containing PrEP on HIV disease progression was compared to placebo using linear mixed effects and Cox proportional hazard models, as appropriate. Additional analyses were performed to compare the outcomes among participants with detectable tenofovir or emtricitabine in plasma at the first quarterly visit in MTN-003.

Results

A total of 224 participants were included in the analysis; 93% from South Africa and 94% clade C virus. No differences in HIV RNA at steady state or the trajectory over 12 months were observed for each active arm compared to placebo; tenofovir gel recipients had higher CD4⁺ T cell counts (722 vs 596 cells/mm³; p = 0.02) at 90 days after estimated HIV seroconversion and higher average rates of change over 12 months compared to placebo (-181 vs -92 cells/mm³ per year; p = 0.08). With a median follow-up of 31 months, no significant differences were observed for time to CD4⁺ T cell count ≤350 cells/mm³, or the composite endpoint of CD4⁺ T cells ≤350 cells/mm³, initiation of antiretroviral therapy or death for each active arm compared to placebo. Additionally, there were no significant differences in the HIV RNA or CD4+ T cell counts at baseline, the change to month 12, or any disease progression outcomes among participants with oral drug detected and no oral drug detected compared to placebo.

Conclusions

No clinically significant differences in HIV seroconversion outcomes were observed among women randomized to tenofovir-containing oral or vaginal PrEP regimens, however low overall adherence limits the generalizability of these findings.

Southern Africa: the Highest Priority Region for HIV Prevention and Care Interventions

The global HIV pandemic began to expand rapidly in southern Africa a decade later than was noted in central Africa, Europe, the Caribbean, and North America. Multiple factors played a role in this rapid expansion which led Southern Africa to become the most heavily afflicted region for HIV/AIDS globally. In this issue of Current HIV/AIDS Reports, investigators with active research interests in the region have reviewed key elements of the causes of and responses to the epidemic. Putative causes of the high HIV prevalence in the region are discussed, including host and viral biology, human behavior, politics and policy, structural factors, health services, health workforce, migration, traditional healers' role, and other issues. Regional epidemiological trends are described and forecasted. Issues related to the continuum of HIV care and treatment are highlighted. We hope that the reviews will prove useful to those policymakers, health care workers, and scientists who are striving to reduce the burden of HIV in the southern African region, as well as prove insightful for key issues of broader global relevance.

Variants in host viral replication cycle genes are associated with heterosexual HIV-1 acquisition in Africans

Supplemental Digital Content is Available in the Text.

Objective:

We evaluated genetic variants in 51 candidate genes encoding proteins that interact with HIV-1 during the virus life cycle for association with HIV-1 outcomes in an African cohort.

Methods:

Using a nested case–control study within a cohort of heterosexual HIV-1–serodiscordant couples, we genotyped 475 haplotype-tagging single-nucleotide polymorphisms (tagSNPs) and 18 SNPs previously associated with HIV-1 transmission and/or progression (candidate SNPs) in 51 host genes. We used logistic and Cox proportional hazard regression with adjustment for sex, age, and population stratification to detect SNP associations with HIV-1 acquisition, plasma HIV-1 set point, and a composite measure of HIV-1 disease progression. Significant thresholds for tagSNP, but not candidate SNP, associations were subjected to Bonferroni correction for multiple testing.

Results:

We evaluated 491 HIV-1–infected and 335 HIV-1–uninfected individuals for 493 SNPs, 459 of which passed quality control filters. Candidate SNP PPIA rs8177826 and tagSNP SMARCB1 rs6003904 were significantly associated with HIV-1 acquisition risk (odds ratio = 0.14, P = 0.03, and odds ratio = 2.11, P_corr = 0.01, respectively). Furthermore, the TT genotype for CCR5 rs1799988 was associated with a mean 0.2 log₁₀ copies per milliliter lower plasma HIV-1 RNA set point (P = 0.04). We also identified significant associations with HIV-1 disease progression for variants in FUT2 and MBL2.

Conclusions:

Using a targeted gene approach, we identified variants in host genes whose protein products interact with HIV-1 during the virus replication cycle and were associated with HIV-1 outcomes in this African cohort.

How does population viral load vary with the evolution of a large HIV epidemic in sub-Saharan Africa?

Using mathematical modelling, we describe the temporal evolution of population HIV-1 viral load in Tanzania throughout the epidemic. Population log₁₀ viral load was found to be stable and not sensitive to epidemic dynamics. However, even modest increases in antiretroviral therapy (ART) coverage were reflected as appreciable reductions in population log₁₀ viral load. As ART coverage expands in sub-Saharan Africa, population log₁₀ viral load will increasingly become a powerful proxy for monitoring ART implementation and HIV incidence trends.

HIV-1 subtype C is not associated with higher risk of heterosexual HIV-1 transmission: a multinational study among HIV-1 serodiscordant couples

BACKGROUND

HIV-1 subtype C has emerged as the most prevalent strain of HIV-1 worldwide, leading to speculation that subtype C may be more transmissible than other subtypes. We compared the risk of HIV-1 transmission for subtype C versus non-C subtypes (A, D, G and recombinant forms) among heterosexual African HIV-1 serodiscordant couples.

METHODS

We conducted a nested case-control analysis using data from two prospective cohort studies of heterosexual HIV-1 serodiscordant couples from six countries in eastern and southern Africa. Cases (N = 121) included incident HIV-1 transmissions that were established as linked within the serodiscordant partnership by viral sequencing; controls (N = 501) were nontransmitting HIV-1-infected partners. Subtype was determined for partial env and gag genes. Multiple logistic regression controlled for age and gender of the HIV-1-nfected partner and self-reported unprotected sex. Plasma and genital HIV-1 RNA concentrations were compared between subtype C and non-C subtypes using generalized estimating equations.

RESULTS

HIV-1 subtype C was not associated with increased risk of HIV-1 transmission compared with non-C subtypes: env adjusted odds ratio (adjOR) 1.14 [95% confidence interval (CI) 0.74-1.75, P = 0.6] and gag adjOR 0.98 (95% CI 0.63-1.52, P = 0.9). Plasma and genital HIV-1 RNA levels did not differ significantly for subtype C versus non-C.

CONCLUSION

In a geographically diverse population of heterosexual African HIV-1 serodiscordant couples, subtype C was not associated with greater risk of HIV-1 transmission compared with non-C subtypes, arguing against the hypothesis that subtype C is more transmissible compared with other common subtypes.

Faster progression to AIDS and AIDS-related death among seroincident individuals infected with recombinant HIV-1 A3/CRF02_AG compared with sub-subtype A3

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) is divided into subtypes and circulating recombinant forms (CRFs) but the impact of subtype/CRF on disease progression is not fully understood.

METHODS

We determined the HIV-1 subtype/CRF of 152 seroincident individuals from Guinea-Bissau, based on the C2-V3 region of env. Disease progression was measured as time from estimated seroconversion to AIDS and AIDS-related death. Hazard ratios (HRs) were calculated using a Cox proportional hazard model, adjusting for gender and age at seroconversion.

RESULTS

The major subtypes/CRFs identified were CRF02_AG (53%), A3 (29%), and A3/02 (a recombinant of A3 and CRF02_AG) (13%). Infection with A3/02 was associated with a close to 3-fold increased risk of AIDS and AIDS-related death compared to A3 (HR = 2.6 [P = 0.011] and 2.9 [P = 0.032], respectively). The estimated time from seroconversion to AIDS and AIDS-related death was 5.0 and 8.0 years for A3/02, 6.2 and 9.0 years for CRF02_AG, and 7.2 and 11.3 years for A3.

CONCLUSION

Our results show that there are differences in disease progression between HIV-1 A-like subtypes/CRFs. Individuals infected with A3/02 have among the fastest progression rates to AIDS reported to date. Determining the HIV-1 subtype of infected individuals could be important in the management of HIV-1 infections.

Future of phylogeny in HIV prevention

The success of the HIV Prevention Trials Network 052 trial has led to revisions in HIV-1 treatment guidelines. Antiretroviral therapy may reduce the risk of HIV-1 transmissions at the population level. The design of successful treatment as prevention interventions will be predicated on a comprehensive understanding of the spatial, temporal, and biological dynamics of heterosexual men who have sex with men and intravenous drug user epidemics. Viral phylogenetics can capture the underlying structure of transmission networks based on the genetic interrelatedness of viral sequences and cluster networks that could not be otherwise identified. This article describes the phylogenetic expansion of the Montreal men who have sex with men epidemic over the last decade. High rates of coclustering of primary infections are associated with 1 infection leading to 13 onward transmissions. Phylogeny substantiates the role of primary and recent stage infection in transmission dynamics, underlying the importance of timely diagnosis and immediate antiretroviral therapy initiation to avert transmission cascades.