Establishing a cohort at high risk of HIV infection in South Africa: challenges and experiences of the CAPRISA 002 acute infection study

Determination of the mean duration of recent infection and false recency rate for the HIV triplex multiplex bead assay

BACKGROUND

We developed the HIV Triplex multiplex bead assay to identify and serotype HIV infection with high sensitivity and specificity; and distinguish recent from long-term HIV-1 infections. It can facilitate accurate incidence estimation, while reducing the number of tests and blood collected, which is highly desirable for use in future studies and surveys. Using previously collected, treatment-naive longitudinal seroconversion HIV-1 positive panels and specimens from individuals infected for >12 months, we determined the assay's mean duration of recent infection (MDRI) and false-recency rate (FRR) respectively, at various mean fluorescent intensity (MFI) cutoffs.

METHODS

We tested seroconversion specimens (N = 814) from 142 individuals infected with HIV-1 subtypes B, C, or AE, and 1341 cross-sectional specimens from individuals infected >12 months. The MFI cutoffs of 1000 to 2000 were evaluated for recency classification, including an MFI of 1250 corresponding to the limiting antigen avidity enzyme immunoassay (LAg-EIA) cutoff of 1.5 normalized optical density for MDRI and FRR. We used four statistical methods: Methods 1 and 2 used the empirically balanced observation time approach. Method 2 MFI values were raised to power = 1.33, based on a repeated measures model to linearize the relationship between MFI and time points, whereas Method 1 was not linearized. Methods 3 and 4 employed quadratic and linear interpolations for each seroconversion panel. FRR was calculated by dividing the number of specimens misclassified as recent by the total number of specimens tested.

RESULTS

MDRI values ranged from 135-146 days at MFI = 1000 to 229-279 days at MFI = 2000 by the 4 methods. FRR varied from 0.15%-1.27% with increasing MFI cutoff. At MFI = 1250, the average MDRI of 4 methods was 169 days and ranged from 159-183 with overlapping 95% CIs and FRR = 0.52%.

CONCLUSION

The HIV Triplex assay demonstrates a longer dynamic range compared to current HIV recency assays with a low FRR for cutoffs examined. With a longer dynamic range and low FRR, the MDRI for recent infection can be extended as appropriate to detect more recent infections, increasing the value of incidence assays benefiting public health surveillance and future surveys.

The evolution of envelope function during coinfection with phylogenetically distinct human immunodeficiency virus

BACKGROUND

Coinfection with two phylogenetically distinct Human Immunodeficiency Virus-1 (HIV-1) variants might provide an opportunity for rapid viral expansion and the emergence of fit variants that drive disease progression. However, autologous neutralising immune responses are known to drive Envelope (Env) diversity which can either enhance replicative capacity, have no effect, or reduce viral fitness. This study investigated whether in vivo outgrowth of coinfecting variants was linked to pseudovirus and infectious molecular clones' infectivity to determine whether diversification resulted in more fit virus with the potential to increase disease progression.

RESULTS

For most participants, emergent recombinants displaced the co-transmitted variants and comprised the major population at 52 weeks postinfection with significantly higher entry efficiency than other co-circulating viruses. Our findings suggest that recombination within gp41 might have enhanced Env fusogenicity which contributed to the increase in pseudovirus entry efficiency. Finally, there was a significant correlation between pseudovirus entry efficiency and CD4 + T cell count, suggesting that the enhanced replicative capacity of recombinant variants could result in more virulent viruses.

CONCLUSION

Coinfection provides variants with the opportunity to undergo rapid recombination that results in more infectious virus. This highlights the importance of monitoring the replicative fitness of emergent viruses.

HIV incidence among women engaging in sex work in sub-Saharan Africa: a systematic review and meta-analysis

BACKGROUND

Women who engage in sex work in sub-Saharan Africa have a high risk of acquiring HIV infection. HIV incidence has declined among all women in sub-Saharan Africa, but trends among women who engage in sex work are poorly characterised. We synthesised data on HIV incidence among women who engage in sex work in sub-Saharan Africa and compared these with the total female population to understand relative incidence and trends over time.

METHODS

We searched MEDLINE, Embase, Global Health, and Google Scholar from Jan 1, 1990, to Feb 28, 2024, and grey literature for studies that reported empirical estimates of HIV incidence among women who engage in sex work in any sub-Saharan Africa country. We calculated incidence rate ratios (IRRs) compared with total female population incidence estimates matched for age, district, and year, did a meta-analysis of IRRs, and used a continuous mixed-effects model to estimate changes in IRR over time.

FINDINGS

From 32 studies done between 1985 and 2020, 2194 new HIV infections were observed among women who engage in sex work over 51 490 person-years. Median HIV incidence was 4·3 per 100 person years (IQR 2·8-7·0 per 100 person-years). Incidence among women who engage in sex work was eight times higher than matched total population women (IRR 7·8 [95% CI 5·1-11·8]), with larger relative difference in western and central Africa (19·9 [9·6-41·0]) than in eastern and southern Africa (4·9 [3·4-7·1]). There was no evidence that IRRs changed over time (IRR per 5 years: 0·9 [0·7-1·2]).

INTERPRETATION

Across sub-Saharan Africa, HIV incidence among women who engage in sex work remains disproportionately high compared with the total female population. However, constant relative incidence over time indicates HIV incidence among women who engage in sex work has declined at a similar rate. Location-specific data for women who engage in sex work incidence are sparse, but improved surveillance and standardisation of incidence measurement approaches could fill these gaps. Sustained and enhanced HIV prevention for women who engage in sex work is crucial to address continuing inequalities and ensure declines in new HIV infections.

FUNDING

Bill & Melinda Gates Foundation, UK Research and Innovation, National Institutes of Health.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Circulating immunoglobulins and transient lymphocytopenia in a sub-study of CAPRISA 012B, testing HIV monoclonal antibodies in a phase 1 trial

Acute, transient lymphocytopenia, not clinically significant was observed in the CAPRISA 012B phase 1 clinical trial following administration of broadly neutralizing antibodies (bnAb)-CAP256V2LS alone or with VRC07-523LS. Lymphocytopenia was assigned upon a > 50% decline in absolute lymphocyte counts following bnAb administration. We posited that systemic immunoglobulins (Igs), and cytokine profiles of eight women who developed lymphocytopenia were different to the 12 women without lymphocytopenia. Plasma Ig subclasses (IgG)/isotypes (IgM/IgA), and 27 cytokines were measured at enrolment (prior to bnAbs) and at days 1, 7, 28, 56 post-bnAb administration. IgG subclasses, IgM and total lymphocyte counts were significantly lower prior to bnAbs in women with gradable lymphocytopenia than those without. Gradable lymphocytopenia compared to non-lymphocytopenia women had significantly higher MIP-1β from enrolment up to day 56. TNF-α was significantly lower in gradable lymphocytopenia compared to non-lymphocytopenia women for enrolment, days 7, 28 and 56 except for day 1. Within the gradable and within the non-lymphocytopenia women, from enrolment to day 1, significantly elevated IL-6, IL-8, IP-10, MCP-1, G-CSF and IL-1RA were found. Additionally, within the gradable lymphocytopenia women, 9 additional cytokines (TNF-α, MIP-1α, MIP-1β, RANTES, Basic FGF, eotaxin, IFN-γ, IL-17A and IL-4) were significantly elevated at day 1 post-bnAbs compared to enrolment. This sub study presents preliminary findings to support the monitoring of baseline immunological markers including lymphocyte counts for assessing the development of transient lymphocytopenia. In high-risk settings conducting clinical trials testing bnAbs for HIV prevention, understanding factors that could amplify rates of lymphocytopenia, even if transient, remain undefined.

Increasing age and duration of sex work among female sex workers in South Africa and implications for HIV incidence estimation: Bayesian evidence synthesis and simulation exercise

Introduction

In sub-Saharan Africa, accurate estimates of the HIV epidemic in female sex workers are crucial for effective prevention and care strategies. These estimates are typically derived from mathematical models that assume certain demographic and behavioural characteristics like age and duration of sex work to remain constant over time. We reviewed this assumption for female sex workers in South Africa.

Methods

We reviewed studies that reported estimates on either the age or the duration of sex work among female sex workers in South Africa. We used Bayesian hierarchical models to synthesize reported estimates and to study time trends. In a simulation exercise, we also investigated the potential impact of the "constant age and sex work duration"-assumption on estimates of HIV incidence.

Results

We included 24 different studies, conducted between 1996 and 2019, contributing 42 estimates on female sex worker age and 27 estimates on sex work duration. There was evidence suggesting an increase in both the duration of sex work and the age of female sex workers over time. According to the fitted models, over each decade the expected duration of sex work increased by 55.6% (95%-credible interval [CrI]: 23.5%-93.9%) and the expected age of female sex workers increased by 14.3% (95%-CrI: 9.1%-19.1%). Over the 23-year period, the predicted mean duration of sex work increased from 2.7 years in 1996 to 7.4 years in 2019, while the predicted mean age increased from 26.4 years to 32.3 years. Allowing for these time trends in the simulation exercise resulted in a notable decline in estimated HIV incidence rate among sex workers over time. This decline was significantly more pronounced than when assuming a constant age and duration of sex work.

Conclusions

In South Africa, age and duration of sex work in female sex workers increased over time. While this trend might be influenced by factors like expanding community mobilization and improved rights advocacy, the ongoing criminalisation, stigmatisation of sex work and lack of alternative employment opportunities could also be contributing. It is important to account for these changes when estimating HIV indicators in female sex workers.

Advancing HIV cure research in low- and middle-income countries requires empowerment of the next generation of scientists

While low- and middle-income countries (LMICs), especially in Southern and Eastern Africa, bear the largest burden of the HIV globally, investigators working on the front lines in these regions are leading a limited number of research efforts, particularly related to HIV cure. Conducting HIV cure research in high-burden HIV LIMCs provides an unparalleled opportunity to formulate innovative research strategies, design trials tailored to the local context, evaluate clinical outcomes within key and vulnerable populations, meaningful involvement of stakeholders, and to shape policies in areas where HIV prevention and cure interventions can yield the most significant impact. Further, the high prevalence of infection, with varied HIV strains affecting large diverse populations, creates a unique environment for studies that would not be feasible in any other part of the world. This underscores the critical importance of addressing obstacles to unlock the full potential of research efforts in these regions. In this viewpoint, we identify significant challenges facing early career investigators in LMICs, particularly in Africa, that hinder their full engagement in HIV cure research. Drawing examples from the International AIDS Society's Research-for-Cure Academy, we provide practical recommendations to overcome barriers that include limited access to funding, effective mentors, educational and career development opportunities, coupled with inadequate investment in infrastructure that contribute towards the limited number of investigators from high-burden HIV LIMCs who are spearheading cutting-edge cure research. Addressing these challenges is crucial to empower investigators who possess unique insights and expertise, and who are well positioned to lead HIV cure-related research efforts. We acknowledge and welcome initiatives that promote capacity building and knowledge exchange between early-career investigators in LMICs and their peers and scientific leaders from high-income countries (HICs). Prioritizing investment in global collaboration and partnership will play a pivotal role in empowering the next generation of African scientists and clinicians. To expedite advancements of cure-related strategies that will be effective in high-burden HIV LMICs, we endorse the sustainable expansion of these pivotal initiatives in these regions, to enhance their effectiveness and hasten progress in the pursuit of a global HIV cure.

Two-step evolution of HIV-1 budding system leading to pandemic in the human population

The pandemic HIV-1, HIV-1 group M, emerged from a single spillover event of its ancestral lentivirus from a chimpanzee. During human-to-human spread worldwide, HIV-1 diversified into multiple subtypes. Here, our interdisciplinary investigation mainly sheds light on the evolutionary scenario of the viral budding system of HIV-1 subtype C (HIV-1C), a most successfully spread subtype. Of the two amino acid motifs for HIV-1 budding, the P(T/S)AP and YPxL motifs, HIV-1C loses the YPxL motif. Our data imply that HIV-1C might lose this motif to evade immune pressure. Additionally, the P(T/S)AP motif is duplicated dependently of the level of HIV-1 spread in the human population, and >20% of HIV-1C harbored the duplicated P(T/S)AP motif. We further show that the duplication of the P(T/S)AP motif is caused by the expansion of the CTG triplet repeat. Altogether, our results suggest that HIV-1 has experienced a two-step evolution of the viral budding process during human-to-human spread worldwide.

Incidence of herpes simplex virus type 2 positivity among women living with human immunodeficiency virus in South Africa

BACKGROUND

For women living with HIV (WLHIV), co-infection with herpes simplex virus type 2 (HSV-2) causes severe genital ulcers and presents additional challenges for their HIV care. To inform preventive strategies, we aimed to determine the incidence and risk factors of HSV-2 positivity in a prospective cohort of South African women.

METHODS

The CAPRISA 002 study enrolled women at acute HIV infection between 2004 and 2020. HSV-2 testing was conducted by multiplex polymerase chain reaction (PCR) assay on collected vaginal swabs up to twice annually during follow-up. We calculated incidence as the number of new cases per 100 person-years (PYs) and used Cox-proportional-hazard regression to identify factors associated with time-to-HSV-2 PCR positivity.

RESULTS

At enrolment, the median age of 171 women was 24 years, interquartile range (IQR 21-28), and the estimated median days since HIV infection was 42 (IQR 22-65). Of participants tested at enrolment, HSV-2 antibody prevalence was 81.4% (105/129), and 10.6% (12/113) were positive by PCR. Among 147 women with a prior negative HSV-2 PCR diagnosis, we observed 47 new HSV-2 PCR positive cases over 424.4 PYs of follow-up, yielding an incidence rate of 11.1 cases per-100-PYs. HSV-2 PCR positivity incidence was higher among younger women (<25 years: adjusted Hazard Ratio [aHR] = 5.91, 95%CI 3.02-11.6), those with bacterial vaginosis (BV) (Nugent score 7-10: aHR = 2.17, 95%CI 1.15-4.10) and lower CD4 counts (<500 cells/μl: aHR = 2.04, 95%CI 1.08-3.87).

CONCLUSION

After acute HIV infection in women, the incidence of HSV-2 PCR positivity was associated with younger age, BV diagnosis and lower CD4 count.

Host genetic variation at a locus near CHD1L impacts HIV sequence diversity in a South African population

IMPORTANCE

It has been previously shown that genetic variants near CHD1L on chromosome 1 are associated with reduced HIV VL in African populations. However, the impact of these variants on viral diversity and how they restrict viral replication are unknown. We report on a regional association analysis in a South African population and show evidence of selective pressure by variants near CHD1L on HIV RT and gag. Our findings provide further insight into how genetic variability at this locus contributes to host control of HIV in a South African population.

HIV incidence among women engaging in sex work in sub-Saharan Africa: a systematic review and meta-analysis

Introduction

HIV incidence among women in sub-Saharan Africa (SSA) has declined steadily, but it is unknown whether new infections among women who engage in sex work (WESW) have declined at a similar rate. We synthesised estimates of HIV incidence among WESW in SSA and compared these to the wider female population to understand levels and trends in incidence over time.

Methods

We searched Medline, Embase, Global Health, Popline, Web of Science, and Google Scholar from January 1990 to October 2022, and grey literature for estimates of HIV incidence among WESW in SSA. We included studies reporting empirical estimates in any SSA country. We calculated incidence rate ratios (IRR) compared to age-district-year matched total female population incidence estimates. We conducted a meta-analysis of IRRs and used a continuous mixed-effects model to estimate changes in IRR over time.

Results

From 32 studies between 1985 and 2020, 2,194 new HIV infections were observed in WESW over 51,000 person-years (py). Median HIV incidence was 4.3/100py (IQR 2.8-7.0/100py), declining from a median of 5.96/100py between 1985 and 1995 to a median of 3.2/100py between 2010 and 2020. Incidence among WESW was nine times higher than in matched total population women (RR 8.6, 95%CI: 5.7-12.9), and greater in Western and Central Africa (RR 22.4, 95%CI: 11.3-44.3) than in Eastern and Southern Africa (RR 5.3, 95%CI: 3.7-7.6). Annual changes in log IRRs were minimal (-0.1% 95%CI: -6.9 to +6.8%).

Conclusions

Across SSA, HIV incidence among WESW remains disproportionately high compared to the total female population but showed similar rates of decline between 1990 and 2020. Improved surveillance and standardisation of approaches to obtain empirical estimates of sex worker incidence would enable a clearer understanding of whether we are on track to meet global targets for this population and better support data-driven HIV prevention programming.

Extended safety and tolerability of subcutaneous CAP256V2LS and VRC07-523LS in HIV-negative women: study protocol for the randomised, placebo-controlled double-blinded, phase 2 CAPRISA 012C trial

INTRODUCTION

Women-controlled HIV prevention technologies that overcome adherence challenges of available daily oral pre-exposure prophylaxis and give women a choice of options are urgently needed. Broadly neutralising monoclonal antibodies (bnAbs) administered passively may offer a valuable non-antiretroviral biological intervention for HIV prevention. Animal and human studies have demonstrated that bnAbs which neutralise HIV can prevent infection. The optimal plasma antibody concentrations to confer protection against HIV infection in humans is under intense study. The Centre for the AIDS Programme of Research in South Africa (CAPRISA) 012C trial will evaluate extended safety and pharmacokinetics of CAP256V2LS and VRC07-523LS among young HIV-negative South African and Zambian women. The study design also allows for an evaluation of a signal of HIV prevention efficacy.

METHODS AND ANALYSIS

CAPRISA 012 is a series of trials with three distinct protocols. The completed CAPRISA 012A and 012B phase 1 trials provided critical data for the CAPRISA 012C trial, which is divided into parts A and B. In part A, 90 participants were randomised to receive both CAP256V2LS and VRC07-523LS at 20 mg/kg or placebo, subcutaneously every 16 or 24 weeks. Part B will enrol 900 participants in South Africa and Zambia who will be randomised in a 1:1 ratio and receive an initial loading dose of 1.2 g of CAP256V2LS and VRC07-523LS or placebo followed by 600 mg of CAP256V2LS and 1.2 g of VRC07-523LS or placebo subcutaneously every 6 months. Safety will be assessed by frequency and severity of reactogenicity and other related adverse events. Pharmacokinetics of both antibodies will be measured in systemic and mucosal compartments over time, while participants will be monitored for breakthrough HIV infections.

ETHICS AND DISSEMINATION OF STUDY FINDINGS

The University of KwaZulu-Natal Biomedical Research Ethics Committee and South African Health Products Regulatory Authority have approved the trial (BREC/00002492/2021, SAHPRA20210317). Results will be disseminated through conference presentations, peer-reviewed publications and the clinical trial registry.

TRIAL REGISTRATION NUMBER

PACTR202112683307570.

Blood monocyte and dendritic cell profiles among people living with HIV with Mycobacterium tuberculosis co-infection

BACKGROUND

Understanding the complex interactions of the immune response mediated by Mycobacterium tuberculosis and HIV co-infection is fundamental to disease biomarker discovery, vaccine, and drug development. Using flow cytometry, we characterized the frequencies and phenotypic differences in monocytes and dendritic cell populations using peripheral blood mononuclear cells from individuals with recurrent, active pulmonary tuberculosis with and without coexisting HIV infection (CAPRISA 011, Clinicaltrials.gov, NCT02114684, 29/01/2014) and compared them to samples from HIV positive individuals and healthy controls. Additionally, we assessed the associations between the frequency of monocyte and dendritic cell subsets and time to culture conversion and cavitary disease in patients with active TB using a cox proportional hazards and logistic regression models.

RESULTS

Compared to healthy controls, the frequency of total monocytes (HLA-DR + CD14 +) was significantly higher in the TB/HIV and TB groups and the frequency of dendritic cells (HLA-DR + CD14-) was significantly higher in TB/HIV and HIV groups. We observed significant variation in the expression of CCR2, CD40, CD11b, CD86, CD163, CX3CR1 across different cell subsets in the four study groups. Increase in CCR2, CD11b and CD40 was associated with active TB infection, while decrease in CX3CR1 and increase in CD163 was associated with HIV infection. Expression of CX3CR1 (aHR 0.98, 95% CI 0.963 - 0.997, p = 0.019) on non-classical monocytes associated with longer time to TB culture conversion in the multivariable model correcting for randomization arm, age, sex, HIV status, lung cavitation, alcohol use, smoking and BMI. Higher surface expression of CD86 (aOR 1.017, 95% CI 1.001 - 1.032, p = 0.033) on intermediate monocytes associated with the presence of lung cavitation, while higher expression of transitional monocytes (aOR 0.944, 95% CI 0.892 - 0.999, p = 0.047) associated with the absence of lung cavitation in the multivariable model.

CONCLUSION

These data provide valuable insight into the heterogenous role of monocyte and dendritic cells in TB and HIV infections.

Incidence, recurrence, and prevalence of bacterial vaginosis from acute to chronic HIV infection in a prospective cohort of women in South Africa

PURPOSE

We investigated the incidence, recurrence, prevalence, and risk factors for bacterial vaginosis (BV) diagnosis starting from acute HIV infection among South African women.

METHODS

The Centre for the AIDS Programme of Research in South Africa 002 study tested and treated women for BV (Nugent score 7-10) once/twice annually from acute to chronic HIV infection (2004-2020). We estimated BV incidence as the number of new cases and recurrence as the number of subsequent diagnoses per 100 person-years (PYs). We fitted Anderson-Gil Cox-proportional-hazard regression models to determine factors associated with BV incidence or recurrence.

RESULTS

Of 235 participants, the median age at enrollment was 25 years (Inter Quartile Range [IQR] 22-29). BV prevalence at enrollment was 50.6%. BV incidence was 23.9 cases per 100 PYs, and recurrence was 51.3 cases per 100 PYs. BV incidence/recurrence was associated with younger age (<25 years: adjusted hazard ratio [aHR] 1.70, 95% confidence interval [CI] 1.27-2.27), detectable HIV viral load (aHR 1.54, 95% CI 1.27-1.87) and lower CD4 count (<350 cells/μL: aHR 1.33, 95% CI 1.01-1.76).

CONCLUSIONS

Our findings underscore the need for early antiretroviral treatment initiation with diagnostic BV and sexually transmitted infection care, especially among younger women.

Safety and pharmacokinetics of escalating doses of neutralising monoclonal antibody CAP256V2LS administered with and without VRC07-523LS in HIV-negative women in South Africa (CAPRISA 012B): a phase 1, dose-escalation, randomised controlled trial

BACKGROUND

Young women in sub-Saharan Africa continue to bear a high burden of HIV infection. Combination anti-HIV monoclonal antibodies are a potential HIV prevention technology that could overcome adherence challenges of daily oral pre-exposure prophylaxis. In this phase 1 clinical trial we aimed to determine the safety and pharmacokinetic profile of the broadly neutralising monoclonal antibody CAP256V2LS.

METHODS

CAPRISA 012B, a first-in-human dose-escalation phase 1 trial evaluated the safety, pharmacokinetics, and neutralisation activity of CAP256V2LS alone and in combination with VRC07-523LS in young HIV-negative women in Durban, South Africa. Groups 1 and 2 were open label with CAP256V2LS administered at 5 mg/kg and 10 mg/kg intravenously and 5 mg/kg, 10 mg/kg, and 20 mg/kg subcutaneously. In group 3, participants were randomly allocated to receive a combination of CAP256V2LS and VRC07-523LS at 10 mg/kg and 20 mg/kg subcutaneously comixed with ENHANZE, a recombinant human hyaluronidase. Once safety was established in the first three participants, dose escalation took place sequentially following review of safety data. Primary endpoints were the proportion of participants with mild, moderate, and severe reactogenicity or adverse events, graded as per the Division of AIDS toxicity grading. The trial is registered on the Pan African Clinical Trial Registry, PACTR202003767867253, and is recruiting.

FINDINGS

From July 13, 2020, to Jan 13, 2021, 42 HIV-negative women, aged 18-45 years, were enrolled. All 42 participants, eight with intravenous and 34 with subcutaneous administration, completed the trial. There were no serious adverse events or dose-limiting toxicities. Most commonly reported symptoms following intravenous administration were headaches in seven (88%) and nausea in four (50%) participants. Commonly reported symptoms following subcutaneous administration were headache in 31 (91%), chills in 25 (74%), and malaise or fatigue in 19 (56%) participants. Adverse events included transient lymphocytopenia in eight (19%), proteinuria in nine (21%), elevated aspartate aminotransferase in ten (24%), and alanine aminotransferase in five (12%) participants.

INTERPRETATION

CAP256V2LS administered alone and in combination with VRC07-523LS was safe with favourable pharmacokinetics and neutralisation activity, supporting further assessment in larger clinical studies.

FUNDING

European and Developing Countries Clinical Trials Partnership, South African Medical Research Council, and South African Department of Science and Innovation.

The Prevalence, Incidence, and Risk Factors for HIV Among Female Sex Workers-A Cohort Being Prepared for a Phase IIb HIV Vaccine Trial in Dar es Salaam, Tanzania

BACKGROUND

A cohort of female sex workers (FSWs) was established to determine HIV prevalence and incidence, and associated factors in preparation for a phase IIb HIV vaccine and pre-exposure prophylaxis trial (PrEPVacc).

SETTING

A cohort of FSWs in Dar es Salaam, Tanzania.

METHODS

FSWs aged 18-45 years were recruited using a respondent-driven sampling method. Social demographic data, HIV risk behavioral assessments, and blood samples for testing of HIV, syphilis, hepatitis B (HBV), and hepatitis C (HCV) infections were collected at baseline and then at 3, 6, 9, and 12 months. Poisson regressions were used to estimate the prevalence ratios for factors associated with HIV prevalence and to estimate the 12-month HIV incidence rate.

RESULTS

Between October and December 2018, a total of 773 FSWs were screened for eligibility and 700 were enrolled. The baseline prevalence of HIV, syphilis, HBV, and HCV was 7.6%, 1.2%, 1.7%, and 1.0%, respectively. HIV prevalence was associated with older age, using illicit drugs, and being infected with syphilis, HBV, or HCV. Attendance at 12 months was 80% (562/700). Twenty-one FSWs seroconverted during follow-up, giving a 12-month HIV incidence rate of 3.45 per 100 person-years at risk (95% CI; 2.25-5.28/100 person-years at risk). The HIV incidence rate was higher among FSWs aged 18-24 years, FSWs who used drugs, and those diagnosed with syphilis, HBV, or HCV.

CONCLUSION

The high HIV incidence rate and retention rate among FSWs enrolled into the cohort demonstrate that this population is suitable for participation in HIV prevention trials.

Dependence on a variable residue limits the breadth of an HIV MPER neutralizing antibody, despite convergent evolution with broadly neutralizing antibodies

Broadly neutralizing antibodies (bNAbs) that target the membrane-proximal external region (MPER) of HIV gp41 envelope, such as 4E10, VRC42.01 and PGZL1, can neutralize >80% of viruses. These three MPER-directed monoclonal antibodies share germline antibody genes (IGHV1-69 and IGKV3-20) and form a bNAb epitope class. Furthermore, convergent evolution within these two lineages towards a ^111.2GW^111.3 motif in the CDRH3 is known to enhance neutralization potency. We have previously isolated an MPER neutralizing antibody, CAP206-CH12, that uses these same germline heavy and light chain genes but lacks breadth (neutralizing only 6% of heterologous viruses). Longitudinal sequencing of the CAP206-CH12 lineage over three years revealed similar convergent evolution towards ^111.2GW^111.3 among some lineage members. Mutagenesis of CAP206-CH12 from ^111.2GL^111.3 to ^111.2GW^111.3 and the introduction of the double GWGW motif into CAP206-CH12 modestly improved neutralization potency (2.5–3-fold) but did not reach the levels of potency of VRC42.01, 4E10 or PGZL1. To explore the lack of potency/breadth, viral mutagenesis was performed to map the CAP206-CH12 epitope. This indicated that CAP206-CH12 is dependent on D⁶⁷⁴, a highly variable residue at the solvent-exposed elbow of MPER. In contrast, VRC42.01, PGZL1 and 4E10 were dependent on highly conserved residues (W⁶⁷², F⁶⁷³, T⁶⁷⁶, and W⁶⁸⁰) facing the hydrophobic patch of the MPER. Therefore, while CAP206-CH12, VRC42.01, PGZL1 and 4E10 share germline genes and show some evidence of convergent evolution, their dependence on different amino acids, which impacts orientation of binding to the MPER, result in differences in breadth and potency. These data have implications for the design of HIV vaccines directed at the MPER epitope.

Germline-targeting immunogens are a promising HIV vaccine design strategy. This approach is reliant on the identification of broadly neutralizing antibody (bNAb) classes, which use the same germline antibody genes to target the same viral epitopes. Here, we compare four HIV Envelope MPER-directed antibodies (4E10, VRC42.01, PGZL1 and CAP206-CH12) that despite having shared antibody genes, show distinct neutralization profiles. We show that CAP206-CH12 is dependent on a highly variable residue in the MPER, which results in low neutralization breadth. In contrast, the 4E10, PGZL1 and VRC42.01 mAbs are dependent on highly conserved residues in the MPER, resulting in exceptional neutralization breadth. Our data suggest that while shared germline genes within bNAb epitope classes are required, in some cases these are not sufficient to produce neutralization breadth, and MPER immunogens will need to trigger responses to conserved sites.

Burden of sexually transmitted infections from acute HIV infection among women in South Africa: Evidence from a prospective cohort study

PURPOSE

HIV and other sexually transmitted infections (STIs) often co-occur. However, less evidence exists on the long-term STI dynamics among persons living with HIV in sub-Saharan Africa to inform interventions. We investigated the incidence, prevalence and factors associated with STIs, starting from acute HIV infection in a cohort of South African women.

METHODS

The CAPRISA002 study enrolled women with acute HIV infection and performed STI testing and treatment 1-2 times annually from 2004-2020. We estimated STI incidence, re-infection, and prevalence trends before and after antiretroviral treatment (ART). We fitted Cox regression models to identify factors associated with STIs.

RESULTS

We followed up 235 women (median age = 25 years, IQR 22-29) for 7.5 years (IQR 5.7-10.8). New STI and re-infection cases per 100 person-years (PYs) were 5.1 and 9.5 for Neisseria gonorrhoeae (NG), 7.4 and 14.7 for Chlamydia trachomatis (CT), 8.0 and 26.6 for Trichomonas vaginalis (TV), 7.7 and 16.7 for Mycoplasma genitalium (MG) and 25.2 and 37.3 for any STI. STI incidence, was associated with HIV log₁₀ viral load (AHR = 1.24, 95% CI 1.06-1.44), active syphilis (AHR = 16.55, 95% CI 7.49-36.55), a positive HSV-2 PCR (AHR = 1.54, 95% CI 1.01-2.35), bacterial vaginosis (AHR = 1.48, 95% CI 1.01-2.18), recent regular sexual partners at enrolment (one vs none: AHR = 2.62, 95% CI 1.41-4.87; two plus vs none: AHR = 3.68, 95% CI 1.79-7.59) and age (5-year fold: AHR = 0.80, 95% CI 0.70-0.92).

CONCLUSION

The persistent STI/HIV co-infection burden among South African women highlights that early HIV diagnosis and ART initiation needs to be combined with better STI care for women and their partners to prevent HIV and STI transmission.

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.

Pregnancy rates and outcomes in a longitudinal HIV cohort in the context of evolving antiretroviral treatment provision in South Africa

BACKGROUND

In South Africa, women continue to face a high burden of Human Immunodeficiency Virus (HIV) infection and the possible complications thereof during pregnancy. We assessed pregnancy incidence rates and outcomes in a longitudinal HIV cohort study over a 15-year period.

METHODS

We evaluated pregnancies among women ≥ 18 years between 2004 and 2019 in the CAPRISA 002 study. We analysed pregnancy rates following HIV acquisition, CD4 counts and HIV viral load dynamics and pregnancy outcomes. We used linear regression to assess if the mean CD4 and log10 viral load close to delivery increases or decreases linearly across three different timepoints.

RESULTS

In total 245 women enrolled into the HIV negative study phase, 225 into the HIV infection phase and 232 in the antiretroviral therapy (ART) phase. Median follow-up time was 2.0 years [Interquartile Range (IQR) 0.8-2.0] during the HIV negative phase, 2.6 years; (IQR) 1.2-4.8] during HIV infection and 3.7 years (IQR 1.8-5.0) on ART, with maximum follow-up time of 2, 10 and 6 years respectively. Overall, 169 pregnancies occurred in 140 women, of which 16 pregnancies were observed during acute or early HIV infection [Incidence Rate (IR) 8.0 per 100 women-years; 95% confidence interval (CI): 4.6-12.9], 48 during established infection [IR 9.3; (CI 6.8-12.3)] and 68 on ART [IR 8.9; (CI: 7.0 - 11.4)]. Birth outcomes from 155/169 (91.7%) pregnancies were 118 (76.1%) full term live births, 17 (10.9%) premature live births, 9 (5.8%) therapeutic/elective miscarriages, 8 (5.1%) spontaneous miscarriages and 3 (1.9%) spontaneous foetal deaths or stillbirths. Six mother-to-child transmission events occurred, with four documented prior to 2008. Over time, mean CD4 count in pregnant women increased from 395 cells/µL (2004-2009) to 543 cells/µL (2010-2014) and to 696 cells/µL (2015-2019), p < 0.001. Conversely, the viral load declined from 4.2 log10 copies/ml to 2.5 log10 copies/ml and to 1.2 log10 copies/ml (p < 0.001) for the corresponding periods.

CONCLUSIONS

Pregnancy rates following HIV acquisition were high, emphasising a need for timeous ART provision and contraception counselling in women recently diagnosed with HIV. CD4 count and HIV viral load trajectories reflect improvements in treatment guidance for pregnant women over time.

Estimation of HIV incidence from analysis of HIV prevalence patterns by age and years since starting sex work among female sex workers in Zimbabwe

OBJECTIVES

To estimate HIV incidence among female sex workers (FSW) in Zimbabwe: using HIV prevalence by age and number of years since started selling sex (YSSS).

DESIGN

We pooled data from FSW aged 18-39 participating in respondent-driven sampling surveys conducted in Zimbabwe between 2011-2017.

METHODS

For each year of age, we estimated: HIV prevalence (Pt) and the change in HIV prevalence from the previous age (Pt-Pt-1). We then estimated the rate of new HIV infections during that year of age: It = Pt-Pt-1/(1-Pt-1), and calculated HIV incidence for 18-24 and 25-39 year-olds separately as the weighted average of It. We estimated HIV incidence for FSW 1-5 years and 6-15 years since first selling sex using the same approach, and compared HIV prevalence among FSW first selling sex at their current age with the general population.

RESULTS

Among 9,906 women, 50.2% were HIV positive. Based on HIV prevalence increases by age, we estimated an HIV incidence of 6.3/100 person-years at risk (pyar) (95%CI 5.3,7.6) among 18-24 year-olds, and 3.3/100 pyar (95% CI 1.3,4.2) among 25-39 year-olds. Based on prevalence increases by YSSS, HIV incidence was 5.3/100 pyar (95% CI 4.3,8.5) between 1-5 years since first selling sex, and 2.1/100 pyar (95% CI -1.3, 7.2) between 6-15 years.

CONCLUSIONS

Our analysis is consistent with very high HIV incidence among FSW in Zimbabwe, especially among those who are young and recently started selling sex. There is a critical need to engage young entrants into sex work in interventions that reduce their HIV risk.

Pre-infection plasma cytokines and chemokines as predictors of HIV disease progression

Previous studies have highlighted the role of pre-infection systemic inflammation on HIV acquisition risk, but the extent to which it predicts disease progression outcomes is less studied. Here we examined the relationship between pre-infection plasma cytokine expression and the rate of HIV disease progression in South African women who seroconverted during the CAPRISA 004 tenofovir gel trial. Bio-Plex 200 system was used to measure the expression of 47 cytokines/chemokines in 69 seroconvertors from the CAPRISA 004 trial. Cox proportional hazards regression analyses were used to measure associations between cytokine expression and CD4 decline prior to antiretroviral therapy initiation. Linear regression models were used to assess whether pre-infection cytokine expression were predictors of disease progression outcomes including peak and set-point viral load and CD4:CD8 ratio at less and greater than180 days post infection. Several cytokines were associated with increased peak HIV viral load (including IL-16, SCGFβ, MCP-3, IL-12p40, SCF, IFNα2 and IL-2). The strongest association with peak viral load was observed for SCGFβ, which was also inversely associated with lowest CD4:CD8 ratio < 180 days post infection and faster CD4 decline below 500 cells/µl (adjusted HR 4.537, 95% CI 1.475–13.954; p = 0.008) in multivariable analysis adjusting for age, study site, contraception, baseline HSV-2 status and trial arm allocation. Our results show that pre-infection systemic immune responses could play a role in HIV disease progression, especially in the early stages of infection.

Application of quantile mixed-effects model in modeling CD4 count from HIV-infected patients in KwaZulu-Natal South Africa

BACKGROUND

The CD4 cell count signifies the health of an individual's immune system. The use of data-driven models enables clinicians to accurately interpret potential information, examine the progression of CD4 count, and deal with patient heterogeneity due to patient-specific effects. Quantile-based regression models can be used to illustrate the entire conditional distribution of an outcome and identify various covariates effects at the respective location.

METHODS

This study uses the quantile mixed-effects model that assumes an asymmetric Laplace distribution for the error term. The model also incorporated multiple random effects to consider the correlation among observations. The exact maximum likelihood estimation was implemented using the Stochastic Approximation of the Expectation-Maximization algorithm to estimate the parameters. This study used the Centre of the AIDS Programme of Research in South Africa (CAPRISA) 002 Acute Infection Study data. In this study, the response variable is the longitudinal CD4 count from HIV-infected patients who were initiated on Highly Active Antiretroviral Therapy (HAART), and the explanatory variables are relevant baseline characteristics of the patients.

RESULTS

The analysis obtained robust parameters estimates at various locations of the conditional distribution. For instance, our result showed that baseline BMI (at [Formula: see text] 0.05: [Formula: see text]), baseline viral load (at [Formula: see text] 0.05: [Formula: see text] [Formula: see text]), and post-HAART initiation (at [Formula: see text] 0.05: [Formula: see text]) were major significant factors of CD4 count across fitted quantiles.

CONCLUSIONS

CD4 cell recovery in response to post-HAART initiation across all fitted quantile levels was observed. Compared to HIV-infected patients with low viral load levels at baseline, HIV-infected patients enrolled in the treatment with a high viral load level at baseline showed a significant negative effect on CD4 cell counts at upper quantiles. HIV-infected patients registered with high BMI at baseline had improved CD4 cell count after treatment, but physicians should not ignore this group of patients clinically. It is also crucial for physicians to closely monitor patients with a low BMI before and after starting HAART.

Ethical considerations for HIV remission clinical research involving participants diagnosed during acute HIV infection

HIV remission clinical researchers are increasingly seeking study participants who are diagnosed and treated during acute HIV infection—the brief period between infection and the point when the body creates detectable HIV antibodies. This earliest stage of infection is often marked by flu-like illness and may be an especially tumultuous period of confusion, guilt, anger, and uncertainty. Such experiences may present added ethical challenges for HIV research recruitment, participation, and retention. The purpose of this paper is to identify potential ethical challenges associated with involving acutely diagnosed people living with HIV in remission research and considerations for how to mitigate them. We identify three domains of potential ethical concern for clinicians, researchers, and ethics committee members to consider: 1) Recruitment and informed consent; (2) Transmission risks and partner protection; and (3) Ancillary and continuing care. We discuss each of these domains with the aim of inspiring further work to advance the ethical conduct of HIV remission research. For example, experiences of confusion and uncertainty regarding illness and diagnosis during acute HIV infection may complicate informed consent procedures in studies that seek to recruit directly after diagnosis. To address this, it may be appropriate to use staged re-consent procedures or comprehension assessment. Responsible conduct of research requires a broad understanding of acute HIV infection that encompasses its biomedical, psychological, social, and behavioral dimensions. We argue that the lived experience of acute HIV infection may introduce ethical concerns that researchers and reviewers should address during study design and ethical approval.

ADCC-mediating non-neutralizing antibodies can exert immune pressure in early HIV-1 infection

Despite antibody-dependent cellular cytotoxicity (ADCC) responses being implicated in protection from HIV-1 infection, there is limited evidence that they control virus replication. The high mutability of HIV-1 enables the virus to rapidly adapt, and thus evidence of viral escape is a very sensitive approach to demonstrate the importance of this response. To enable us to deconvolute ADCC escape from neutralizing antibody (nAb) escape, we identified individuals soon after infection with detectable ADCC responses, but no nAb responses. We evaluated the kinetics of ADCC and nAb responses, and viral escape, in five recently HIV-1-infected individuals. In one individual we detected viruses that escaped from ADCC responses but were sensitive to nAbs. In the remaining four participants, we did not find evidence of viral evolution exclusively associated with ADCC-mediating non-neutralizing Abs (nnAbs). However, in all individuals escape from nAbs was rapid, occurred at very low titers, and in three of five cases we found evidence of viral escape before detectable nAb responses. These data show that ADCC-mediating nnAbs can drive immune escape in early infection, but that nAbs were far more effective. This suggests that if ADCC responses have a protective role, their impact is limited after systemic virus dissemination.

Immunological Correlates of the HIV-1 Replication-Competent Reservoir Size

Understanding what shapes the latent human immunodeficiency virus type 1 (HIV-1) reservoir is critical for developing strategies for cure. We measured frequency of persistent HIV-1 infection after 5 years of suppressive antiretroviral therapy initiated during chronic infection. Pretreatment CD8+ T-cell activation, nadir CD4 count, and CD4:CD8 ratio predicted reservoir size.

Additive quantile mixed effects modelling with application to longitudinal CD4 count data

Quantile regression offers an invaluable tool to discern effects that would be missed by other conventional regression models, which are solely based on modeling conditional mean. Quantile regression for mixed-effects models has become practical for longitudinal data analysis due to the recent computational advances and the ready availability of efficient linear programming algorithms. Recently, quantile regression has also been extended to additive mixed-effects models, providing an efficient and flexible framework for nonparametric as well as parametric longitudinal forms of data analysis focused on features of the outcome beyond its central tendency. This study applies the additive quantile mixed model to analyze the longitudinal CD4 count of HIV-infected patients enrolled in a follow-up study at the Centre of the AIDS Programme of Research in South Africa. The objective of the study is to justify how the procedure developed can obtain robust nonlinear and linear effects at different conditional distribution locations. With respect to time and baseline BMI effect, the study shows a significant nonlinear effect on CD4 count across all fitted quantiles. Furthermore, across all fitted quantiles, the effect of the parametric covariates of baseline viral load, place of residence, and the number of sexual partners was found to be major significant factors on the progression of patients' CD4 count who had been initiated on the Highly Active Antiretroviral Therapy study.

Proviral Turnover During Untreated HIV Infection Is Dynamic and Variable Between Hosts, Impacting Reservoir Composition on ART

Human immunodeficiency virus (HIV) can persist as an integrated provirus, in a transcriptionally repressed state, within infected cells. This small yet enduring pool of cellular reservoirs that harbor replication-competent HIV is the main barrier to cure. Entry of viral sequences into cellular reservoirs begins shortly after infection, and cells containing integrated proviral DNA are extremely stable once suppressive antiretroviral therapy (ART) is initiated. During untreated HIV infection however, reservoir turnover is likely to be more dynamic. Understanding these dynamics is important because the longevity of the persisting proviral pool during untreated infection dictates reservoir composition at ART initiation. If the persisting proviral pool turns over slowly pre-ART, then HIV sequences seeded into it during early infection would have a high likelihood of persisting for long periods. However, if pre-ART turnover was rapid, the persisting proviral pool would rapidly shift toward recently circulating HIV sequences. One-way to estimate this turnover rate is from the age distributions of proviruses sampled shortly after therapy initiation: this is because, at the time of sampling, the majority of proviral turnover would have already occurred prior to ART. Recently, methods to estimate a provirus’ age from its sequence have made this possible. Using data from 12 individuals with HIV subtype C for whom proviral ages had been determined phylogenetically, we estimated that the average proviral half-life during untreated infection was 0.78 (range 0.45–2.38) years, which is >15 times faster than that of proviral DNA during suppressive ART. We further show that proviral turnover during untreated infection correlates with both viral setpoint and rate of CD4+ T-cell decline during this period. Overall, our results support dynamic proviral turnover pre-ART in most individuals, which helps explain why many individuals’ reservoirs are skewed toward younger HIV sequences. Broadly, our findings are consistent with the notion that active viral replication creates an environment less favorable to proviral persistence, while viral suppression creates conditions more favorable to persistence, where ART stabilizes the proviral pool by dramatically slowing its rate of decay. Strategies to inhibit this stabilizing effect and/or to enhance reservoir turnover during ART could represent additional strategies to reduce the HIV reservoir.

Broadly Neutralizing Antibodies for HIV-1 Prevention

Given the absence of an effective vaccine for protection against HIV-1 infection, passive immunization strategies that utilize potent broadly neutralizing antibodies (bnAbs) to block acquisition of HIV-1 are being rigorously pursued in the clinical setting. bnAbs have demonstrated robust protection in preclinical animal models, and several leading bnAb candidates have shown favorable safety and pharmacokinetic profiles when tested individually or in combinations in early phase human clinical trials. Furthermore, passive administration of bnAbs in HIV-1 infected individuals has resulted in prolonged suppression of viral rebound following interruption of combination antiretroviral therapy, and robust antiviral activity when administered to viremic individuals. Recent results from the first efficacy trials testing repeated intravenous administrations of the anti-CD4 binding site bnAb VRC01 have demonstrated positive proof of concept that bnAb passive immunization can confer protection against HIV-1 infection in humans, but have also highlighted the considerable barriers that remain for such strategies to effectively contribute to control of the epidemic. In this review, we discuss the current status of clinical studies evaluating bnAbs for HIV-1 prevention, highlight lessons learned from the recent Antibody Mediated Prevention (AMP) efficacy trials, and provide an overview of strategies being employed to improve the breadth, potency, and durability of antiviral protection.

Epigenetic Regulation of BST-2 Expression Levels and the Effect on HIV-1 Pathogenesis

HIV-1 must overcome host antiviral restriction factors for efficient replication. We hypothesized that elevated levels of bone marrow stromal cell antigen 2 (BST-2), a potent host restriction factor that interferes with HIV-1 particle release in some human cells and is antagonized by the viral protein Vpu, may associate with viral control. Using cryopreserved samples, from HIV-1 seronegative and seropositive Black women, we measured in vitro expression levels of BST-2 mRNA using a real-time PCR assay and protein levels were validated by Western blotting. The expression level of BST-2 showed an association with viral control within two independent cohorts of Black HIV infected females (r=-0.53, p=0.015, [n =21]; and r=-0.62, p=0.0006, [n=28]). DNA methylation was identified as a mechanism regulating BST-2 levels, where increased BST-2 methylation results in lower expression levels and associates with worse HIV disease outcome. We further demonstrate the ability to regulate BST-2 levels using a DNA hypomethylation drug. Our results suggest BST-2 as a factor for potential therapeutic intervention against HIV and other diseases known to involve BST-2.

Modelling CD4 counts before and after HAART for HIV infected patients in KwaZulu-Natal South Africa

BACKGROUND

This study aims to make use of a longitudinal data modelling approach to analyze data on the number of CD4+cell counts measured repeatedly in HIV-1 Subtype C infected women enrolled in the Acute Infection Study of the Centre for the AIDS Programme of Research in South Africa.

METHODOLOGY

This study uses data from the CAPRISA 002 Acute Infection Study, which was conducted in South Africa. This cohort study observed N=235 incident HIV-1 positive women whose disease biomarkers were measured repeatedly at least four times on each participant.

RESULTS

From the findings of this study, post-HAART initiation, baseline viral load, and the prevalence of obese nutrition status were found to be major significant factors on the prognosis CD4+ count of HIV-infected patients.

CONCLUSION

Effective HAART initiation immediately after HIV exposure is necessary to suppress the increase of viral loads to induce potential ART benefits that accrue over time. The data showed evidence of strong individual-specific effects on the evolution of CD4+ counts. Effective monitoring and modelling of disease biomarkers are essential to help inform methods that can be put in place to suppress viral loads for maximum ART benefits that can be accrued over time at an individual level.

Assessing the safety and pharmacokinetics of the anti-HIV monoclonal antibody CAP256V2LS alone and in combination with VRC07-523LS and PGT121 in South African women: study protocol for the first-in-human CAPRISA 012B phase I clinical trial

INTRODUCTION

New HIV prevention strategies are urgently required. The discovery of broadly neutralising antibodies (bNAbs) has provided the opportunity to evaluate passive immunisation as a potential prevention strategy and facilitate vaccine development. Since 2014, several bNAbs have been isolated from a clade C-infected South African donor, CAPRISA 256. One particular bNAb, CAP256-VRC26.25, was found to be extremely potent, with good coverage against clade C viruses, the dominant HIV clade in sub-Saharan Africa. Challenge studies in non-human primates demonstrated that this antibody was fully protective even at extremely low doses. This bNAb was subsequently structurally engineered and the clinical variant is now referred to as CAP256V2LS.

METHODS AND ANALYSIS

CAPRISA 012B is the second of three trials in the CAPRISA 012 bNAb trial programme. It is a first-in-human, phase I study to assess the safety and pharmacokinetics of CAP256V2LS. The study is divided into four groups. Group 1 is a dose escalation of CAP256V2LS administered intravenously to HIV-negative and HIV-positive women. Group 2 is a dose escalation of CAP256V2LS administered subcutaneously (SC), with and without the dispersing agent recombinant human hyaluronidase (rHuPH20) as single or repeat doses in HIV-negative women. Groups 3 and 4 are randomised placebo controlled to assess two (CAP256V2LS+VRC07-523LS; CAP256V2LS+PGT121) and three (CAP256V2LS+VRC07-523LS+PGT121) bNAb combinations administered SC to HIV-negative women. Safety will be assessed by the frequency of reactogenicity and adverse events related to the study product. Pharmacokinetic disposition of CAP256V2LS alone and in combination with VRC07-523LS and PGT121 will be assessed via dose subgroups and route of administration.

ETHICS AND DISSEMINATION

The University of KwaZulu-Natal Biomedical Research Ethics Committee (BREC) and the South African Health Products Regulatory Authority (SAHPRA) have granted regulatory approval (trial reference numbers: BREC00000857/2019 and SAHPRA 20200123). Trial results will be disseminated through conference presentations, peer-reviewed publications and the clinical trial registry.

TRIAL REGISTRATION NUMBER

PACTR202003767867253; Pre-results.

Antibody Isotype Switching as a Mechanism to Counter HIV Neutralization Escape

Neutralizing antibodies (nAbs) to highly variable viral pathogens show remarkable diversification during infection, resulting in an “arms race” between virus and host. Studies of nAb lineages have shown how somatic hypermutation (SHM) in immunoglobulin (Ig)-variable regions enables maturing antibodies to neutralize emerging viral escape variants. However, the Ig-constant region (which determines isotype) can also influence epitope recognition. Here, we use longitudinal deep sequencing of an HIV-directed nAb lineage, CAP88-CH06, and identify several co-circulating isotypes (IgG3, IgG1, IgA1, IgG2, and IgA2), some of which share identical variable regions. First, we show that IgG3 and IgA1 isotypes are better able to neutralize longitudinal autologous viruses and epitope mutants than can IgG1. Second, detrimental class-switch recombination (CSR) events that resulted in reduced neutralization can be rescued by further CSR, which we term “switch redemption.” Thus, CSR represents an additional immunological mechanism to counter viral escape from HIV-specific antibody responses.

Scheepers et al. show within an HIV-specific antibody lineage that isotypes confer variable ability to neutralize emerging viral escape variants. This suggests that class switching, in addition to somatic hypermutation of immunoglobulin-variable regions, contributes to antibody maturation during infection.

Negative binomial mixed models for analyzing longitudinal CD4 count data

It is of great interest for a biomedical analyst or an investigator to correctly model the CD4 cell count or disease biomarkers of a patient in the presence of covariates or factors determining the disease progression over time. The Poisson mixed-effects models (PMM) can be an appropriate choice for repeated count data. However, this model is not realistic because of the restriction that the mean and variance are equal. Therefore, the PMM is replaced by the negative binomial mixed-effects model (NBMM). The later model effectively manages the over-dispersion of the longitudinal data. We evaluate and compare the proposed models and their application to the number of CD4 cells of HIV-Infected patients recruited in the CAPRISA 002 Acute Infection Study. The results display that the NBMM has appropriate properties and outperforms the PMM in terms of handling over-dispersion of the data. Multiple imputation techniques are also used to handle missing values in the dataset to get valid inferences for parameter estimates. In addition, the results imply that the effect of baseline BMI, HAART initiation, baseline viral load, and the number of sexual partners were significantly associated with the patient's CD4 count in both fitted models. Comparison, discussion, and conclusion of the results of the fitted models complete the study.

The replication-competent HIV-1 latent reservoir is primarily established near the time of therapy initiation

Although antiretroviral therapy (ART) is highly effective at suppressing HIV-1 replication, the virus persists as a latent reservoir in resting CD4⁺ T cells during therapy. This reservoir forms even when ART is initiated early after infection, but the dynamics of its formation are largely unknown. The viral reservoirs of individuals who initiate ART during chronic infection are generally larger and genetically more diverse than those of individuals who initiate therapy during acute infection, consistent with the hypothesis that the reservoir is formed continuously throughout untreated infection. To determine when viruses enter the latent reservoir, we compared sequences of replication-competent viruses from resting peripheral CD4⁺ T cells from nine HIV-positive women on therapy to viral sequences circulating in blood collected longitudinally before therapy. We found that, on average, 71% of the unique viruses induced from the post-therapy latent reservoir were most genetically similar to viruses replicating just before ART initiation. This proportion is far greater than would be expected if the reservoir formed continuously and was always long lived. We conclude that ART alters the host environment in a way that allows the formation or stabilization of most of the long-lived latent HIV-1 reservoir, which points to new strategies targeted at limiting the formation of the reservoir around the time of therapy initiation.

Longitudinal analysis of subtype C envelope tropism for memory CD4+ T cell subsets over the first 3 years of untreated HIV-1 infection

Background

HIV-1 infects a wide range of CD4⁺ T cells with different phenotypic properties and differing expression levels of entry coreceptors. We sought to determine the viral tropism of subtype C (C-HIV) Envelope (Env) clones for different CD4⁺ T cell subsets and whether tropism changes during acute to chronic disease progression. HIV-1 envs were amplified from the plasma of five C-HIV infected women from three untreated time points; less than 2 months, 1-year and 3-years post-infection. Pseudoviruses were generated from Env clones, phenotyped for coreceptor usage and CD4⁺ T cell subset tropism was measured by flow cytometry.

Results

A total of 50 C-HIV envs were cloned and screened for functionality in pseudovirus infection assays. Phylogenetic and variable region characteristic analysis demonstrated evolution in envs between time points. We found 45 pseudoviruses were functional and all used CCR5 to mediate entry into NP2/CD4/CCR5 cells. In vitro infection assays showed transitional memory (TM) and effector memory (EM) CD4⁺ T cells were more frequently infected (median: 46% and 25% of total infected CD4⁺ T cells respectively) than naïve, stem cell memory, central memory and terminally differentiated cells. This was not due to these subsets contributing a higher proportion of the CD4⁺ T cell pool, rather these subsets were more susceptible to infection (median: 5.38% EM and 2.15% TM cells infected), consistent with heightened CCR5 expression on EM and TM cells. No inter- or intra-participant changes in CD4⁺ T cell subset tropism were observed across the three-time points.

Conclusions

CD4⁺ T cell subsets that express more CCR5 were more susceptible to infection with C-HIV Envs, suggesting that these may be the major cellular targets during the first 3 years of infection. Moreover, we found that viral tropism for different CD4⁺ T cell subsets in vitro did not change between Envs cloned from acute to chronic disease stages. Finally, central memory, naïve and stem cell memory CD4⁺ T cell subsets were susceptible to infection, albeit inefficiently by Envs from all time-points, suggesting that direct infection of these cells may help establish the latent reservoir early in infection.

Modelling HIV disease process and progression in seroconversion among South Africa women: using transition-specific parametric multi-state model

BACKGROUND

HIV infected patients may experience many intermediate events including between-event transition throughout their follow up. Through modelling these transitions, we can gain a deeper understanding of HIV disease process and progression and of factors that influence the disease process and progression pathway. In this work, we present transition-specific parametric multi-state models to describe HIV disease process and progression.

METHODS

The data is from an ongoing prospective cohort study conducted amongst adult women who were HIV-infected in KwaZulu-Natal, South Africa. Participants were enrolled during the acute HIV infection phase and then followed up during chronic infection, up to ART initiation.

RESULTS

Transition specific distributions for multi-state models, including a variety of accelerated failure time (AFT) models and proportional hazards (PH) models, were presented and compared in this study. The analysis revealed that women enrolling with a CD4 count less than 350 cells/mm3 (severe and advanced disease stages) had a far lower chance of immune recovery, and a considerably higher chance of immune deterioration, compared to women enrolling with a CD4 count of 350 cells/mm3 or more (normal and mild disease stages). Our analyses also showed that older age, higher educational levels, higher scores for red blood cell counts, higher mononuclear scores, higher granulocytes scores, and higher physical health scores, all had a significant effect on a shortened time to immunological recovery, while women with many sex partners, higher viral load and larger family size had a significant effect on accelerating time to immune deterioration.

CONCLUSION

Multi-state modelling of transition-specific distributions offers a flexible tool for the study of demographic and clinical characteristics' effects on the entire disease progression pathway. It is hoped that the article will help applied researchers to familiarize themselves with the models, including interpretation of results.

Multilevel ordinal model for CD4 count trends in seroconversion among South Africa women

BACKGROUND

Ordinal health longitudinal response variables have distributions that make them unsuitable for many popular statistical models that assume normality. We present a multilevel growth model that may be more suitable for medical ordinal longitudinal outcomes than are statistical models that assume normality and continuous measurements.

METHODS

The data is from an ongoing prospective cohort study conducted amongst adult women who are HIV-infected patients in Kwazulu-Natal, South Africa. Participants were enrolled into the acute infection, then into early infection subsequently into established infection and afterward on cART. Generalized linear multilevel models were applied.

RESULTS

Multilevel ordinal non-proportional and proportional-odds growth models were presented and compared. We observed that the effects of covariates can't be assumed identical across the three cumulative logits. Our analyses also revealed that the rate of change of immune recovery of patients increased as the follow-up time increases. Patients with stable sexual partners, middle-aged, cART initiation, and higher educational levels were more likely to have better immunological stages with time. Similarly, patients having high electrolytes component scores, higher red blood cell indices scores, higher physical health scores, higher psychological well-being scores, a higher level of independence scores, and lower viral load more likely to have better immunological stages through the follow-up time.

CONCLUSION

It can be concluded that the multilevel non-proportional-odds method provides a flexible modeling alternative when the proportional-odds assumption of equal effects of the predictor variables at every stage of the response variable is violated. Having higher clinical parameter scores, higher QoL scores, higher educational levels, and stable sexual partners were found to be the significant factors for trends of CD4 count recovery.

Modeling Viral Suppression, Viral Rebound and State-Specific Duration of HIV Patients with CD4 Count Adjustment: Parametric Multistate Frailty Model Approach

INTRODUCTION

Combination antiretroviral therapy has become the standard care of human immunodeficiency virus (HIV)-infected patients and has further led to a dramatically decreased progression probability to acquired immune deficiency syndrome (AIDS) for patients under such a therapy. However, responses of the patients to this therapy have recorded heterogeneous complexity and high dynamism. In this paper, we simultaneously model long-term viral suppression, viral rebound, and state-specific duration of HIV-infected patients.

METHODS

Full-parametric and semi-parametric Markov multistate models were applied to assess the effects of covariates namely TB co-infection, educational status, marital status, age, quality of life (QoL) scores, white and red blood cell parameters, and liver enzyme abnormality on long-term viral suppression, viral rebound and state-specific duration for HIV-infected individuals before and after treatment. Furthermore, two models, one including and another excluding the effect of the frailty, were presented and compared in this study.

RESULTS

Results from the diagnostic plots, Akaike information criterion (AIC) and likelihood ratio test showed that the Weibull multistate frailty model fitted significantly better than the exponential and semi-parametric multistate models. Viral rebound was found to be significantly associated with many sex partners, higher eosinophils count, younger age, lower educational level, higher monocyte counts, having abnormal neutrophils count, and higher liver enzyme abnormality. Furthermore, viral suppression was also found to be significantly associated with higher QoL scores, and having a stable sex partner. The analysis result also showed that patients with a stable sex partner, higher educational levels, higher QoL scores, lower eosinophils count, lower monocyte counts, and higher RBC indices were more likely to spend more time in undetectable viral load state.

CONCLUSIONS

To achieve and maintain the UNAIDS 90% suppression targets, additional interventions are required to optimize antiretroviral therapy outcomes, specifically targeting those with poor clinical characteristics, lower education, younger age, and those with many sex partners. From a methodological perspective, the parametric multistate approach with frailty is a flexible approach for modeling time-varying variables, allowing for dealing with heterogeneity between the sequence of transitions, as well as allowing for a reasonable degree of flexibility with a few additional parameters, which then aids in gaining a better insight into how factors change over time.

Human Immunodeficiency Virus Incidence Among Women at High-Risk of Human Immunodeficiency Virus Infection Attending a Dedicated Clinic in Kampala, Uganda: 2008-2017

BACKGROUND

High attrition and irregular testing for human immunodeficiency virus (HIV) in cohort studies for high-risk populations can bias incidence estimates. We compare incidence trends for high-risk women attending a dedicated HIV prevention and treatment clinic, using common methods for assigning when seroconversion occurs and whether seroconversion occurs among those with attrition.

METHODS

Between April 2008 and May 2009, women were enrolled into cohort 1 and from January 2013 into cohort 2, then scheduled for follow-up once every 3 months. Incidence trends based on assuming a midpoint in the seroconversion interval were compared with those of assigning a random-point. We also compared estimates based on the random-point with and without multiple imputation (MI) of serostatuses for participants with attrition.

RESULTS

By May 2017, 3084 HIV-negative women had been enrolled with 18,364 clinic visits. Before attrition, 27.6% (6990 of 25,354) were missed visits. By August 2017, 65.8% (426 of 647) of those enrolled in cohort 1 and 49.0% (1194 of 2437) in cohort 2 were defined with attrition. Among women with 1 or more follow-up visit, 93 of 605 in cohort 1 and 77 of 1601 in cohort 2 seroconverted. Periods with longer seroconversion intervals appeared to have noticeable differences in incidences when comparing the midpoint and random-point values. The MI for attrition is likely to have overestimated incidence after escalated attrition of participants. Based on random-point without MI for attrition, incidence at end of observation was 3.8/100 person-years in cohort 1 and 1.8/100 in cohort 2.

CONCLUSIONS

The random-point approach attenuated variation in incidence observed using midpoint. The high incidence after years of ongoing prevention efforts in this vulnerable population should be investigated to further reduce incidence.

Modelling immune deterioration, immune recovery and state-specific duration of HIV-infected women with viral load adjustment: using parametric multistate model

BACKGROUND

CD4 cell and viral load count are highly correlated surrogate markers of human immunodeficiency virus (HIV) disease progression. In modelling the progression of HIV, previous studies mostly dealt with either CD4 cell counts or viral load alone. In this work, both biomarkers are in included one model, in order to study possible factors that affect the intensities of immune deterioration, immune recovery and state-specific duration of HIV-infected women.

METHODS

The data is from an ongoing prospective cohort study conducted among antiretroviral treatment (ART) naïve HIV-infected women in the province of KwaZulu-Natal, South Africa. Participants were enrolled in the acute HIV infection phase, then followed-up during chronic infection up to ART initiation. Full-parametric and semi-parametric Markov models were applied. Furthermore, the effect of the inclusion and exclusion viral load in the model was assessed.

RESULTS

Inclusion of a viral load component improves the efficiency of the model. The analysis results showed that patients who reported a stable sexual partner, having a higher educational level, higher physical health score and having a high mononuclear component score are more likely to spend more time in a good HIV state (particularly normal disease state). Patients with TB co-infection, with anemia, having a high liver abnormality score and patients who reported many sexual partners, had a significant increase in the intensities of immunological deterioration transitions. On the other hand, having high weight, higher education level, higher quality of life score, having high RBC parameters, high granulocyte component scores and high mononuclear component scores, significantly increased the intensities of immunological recovery transitions.

CONCLUSION

Inclusion of both CD4 cell count based disease progression states and viral load, in the time-homogeneous Markov model, assisted in modeling the complete disease progression of HIV/AIDS. Higher quality of life (QoL) domain scores, good clinical characteristics, stable sexual partner and higher educational level were found to be predictive factors for transition and length of stay in sequential adversity of HIV/AIDS.

Modelling of viral load dynamics and CD4 cell count progression in an antiretroviral naive cohort: using a joint linear mixed and multistate Markov model

Background

Patients infected with HIV may experience a succession of clinical stages before the disease diagnosis and their health status may be followed-up by tracking disease biomarkers. In this study, we present a joint multistate model for predicting the clinical progression of HIV infection which takes into account the viral load and CD4 count biomarkers.

Methods

The data is from an ongoing prospective cohort study conducted among antiretroviral treatment (ART) naïve HIV-infected women in the province of KwaZulu-Natal, South Africa. We presented a joint model that consists of two related submodels: a Markov multistate model for CD4 cell count transitions and a linear mixed effect model for longitudinal viral load dynamics.

Results

Viral load dynamics significantly affect the transition intensities of HIV/AIDS disease progression. The analysis also showed that patients with relatively high educational levels (β = − 0.004; 95% confidence interval [CI]:-0.207, − 0.064), high RBC indices scores (β = − 0.01; 95%CI:-0.017, − 0.002) and high physical health scores (β = − 0.001; 95%CI:-0.026, − 0.003) were significantly were associated with a lower rate of viral load increase over time. Patients with TB co-infection (β = 0.002; 95%CI:0.001, 0.004), having many sex partners (β = 0.007; 95%CI:0.003, 0.011), being younger age (β = 0.008; 95%CI:0.003, 0.012) and high liver abnormality scores (β = 0.004; 95%CI:0.001, 0.01) were associated with a higher rate of viral load increase over time. Moreover, patients with many sex partners (β = − 0.61; 95%CI:-0.94, − 0.28) and with a high liver abnormality score (β = − 0.17; 95%CI:-0.30, − 0.05) showed significantly reduced intensities of immunological recovery transitions. Furthermore, a high weight, high education levels, high QoL scores, high RBC parameters and being of middle age significantly increased the intensities of immunological recovery transitions.

Conclusion

Overall, from a clinical perspective, QoL measurement items, being of a younger age, clinical attributes, marital status, and educational status are associated with the current state of the patient, and are an important contributing factor to extend survival of the patients and guide clinical interventions. From a methodological perspective, it can be concluded that a joint multistate model approach provides wide-ranging information about the progression and assists to provide specific dynamic predictions and increasingly precise knowledge of diseases.

Multivariate multilevel modeling of quality of life dynamics of HIV infected patients

BACKGROUND

Longitudinal quality of life (QoL) is an important outcome in many chronic illness studies aiming to evaluate the efficiency of care both at the patient and health system level. Although many QoL studies involve multiple correlated hierarchical outcome measures, very few of them use multivariate modeling. In this work, we modeled the long-term dynamics of QoL scores accounting for the correlation between the QoL scores in a multilevel multivariate framework and to compare the effects of covariates across the outcomes.

METHODS

The data is from an ongoing prospective cohort study conducted amongst adult women who were HIV-infected and on the treatment in Kwazulu-Natal, South Africa. Independent and related QoL outcome multivariate multilevel models were presented and compared.

RESULTS

The analysis showed that related outcome multivariate multilevel models fit better for our data used. Our analyses also revealed that higher educational levels, middle age, stable sex partners and higher weights had a significant effect on better improvements in the rate of change of QoL scores of HIV infected patients. Similarly, patients without TB co-infection, without thrombocytopenia, with lower viral load, with higher CD4 cell count levels, with higher electrolytes component score, with higher red blood cell (RBC) component score and with lower liver abnormality component score, were associated with significantly improved the rate of change of QoL, amongst HIV infected patients.

CONCLUSION

It is hoped that the article will help applied researchers to familiarize themselves with the models and including interpretation of results. Furthermore, three issues are highlighted: model building of multivariate multilevel outcomes, how this model can be used to assess multivariate assumptions, involving fixed effects (for example, to examine the size of the covariate effect varying across QoL domain scores) and random effects (for example, to examine the rate of change in one response variable associated to changes in the other).

Trends and Adaptive Optimal Set Points of CD4+ Count Clinical Covariates at Each Phase of the HIV Disease Progression

In response to invasion by the human immunodeficiency virus (HIV), the self-regulatory immune system attempts to restore the CD4+ count fluctuations. Consequently, many clinical covariates are bound to adapt too, but little is known about their corresponding new optimal set points. It has been reported that there exist few strongest clinical covariates of the CD4+ count. The objective of this study is to harness them for a streamlined application of multidimensional viewing lens (statistical models) to zoom into the behavioural patterns of the adaptive optimal set points. We further postulated that the optimal set points of some of the strongest covariates are possibly controlled by dietary conditions or otherwise to enhance the CD4+ count. This study investigated post-HIV infection (acute to therapy phases) records of 237 patients involving repeated measurements of 17 CD4+ count clinical covariates that were found to be the strongest. The overall trends showed either downwards, upwards, or irregular behaviour. Phase-specific trends were mostly different and unimaginable, with LDH and red blood cells producing the most complex CD4+ count behaviour. The approximate optimal set points for dietary-related covariates were total protein 60-100 g/L (acute phase), <85 g/L (early phase), <75 g/L (established phase), and >85 g/L (ART phase), whilst albumin approx. 30-50 g/L (acute), >45 g/L (early and established), and <37 g/L (ART). Sodium was desirable at approx. <45 mEq/L (acute and early), <132 mEq/L (established), and >134 mEq/L (ART). Overall, desirable approximates were albumin >42 g/L, total protein <75 g/L, and sodium <137 mEq/L. We conclude that the optimal set points of the strongest CD4+ count clinical covariates tended to drift and adapt to either new ranges or overlapped with the known reference ranges to positively influence the CD4+ cell counts. Recommendation for phase-specific CD4+ cell count influence in adaptation to HIV invasion includes monitoring of the strongest covariates related to dietary conditions (sodium, albumin, and total protein), tissue oxygenation (red blood cells and its haematocrit), and hormonal control (LDH and ALP).

Effect of HIV Envelope Vaccination on the Subsequent Antibody Response to HIV Infection

Analysis of breakthrough HIV-1 infections could elucidate whether prior vaccination primes relevant immune responses. Here, we measured HIV-specific antibody responses in 14 South African volunteers who acquired HIV infection after participating in phase 1/2 trials of envelope-containing immunogens. Serum samples were collected annually following HIV-1 infection from participants in trials HVTN 073 (subtype C, DNA/MVA, phase 1 trial, n = 1), HVTN 086 (subtype C, DNA/MVA/gp140 protein, phase 1 trial, n = 2), and HVTN 204 (multisubtype, DNA/adenovirus serotype 5 [Ad5], phase 2 trial, n = 7) and 4 placebo recipients. Binding and neutralizing antibody responses to Env proteins and peptides were determined pre- and post-HIV infection using an enzyme-linked immunosorbent assay and the TZM-bl cell neutralization assay, respectively. HIV-infected South African individuals served as unvaccinated controls. Binding antibodies to gp41, V3, V2, the membrane-proximal external region (MPER), and the CD4 binding site were detected from the first year of HIV-1 subtype C infection, and the levels were similar in vaccinated and placebo recipients. Neutralizing antibody responses against tier 1A viruses were detected in all participants, with the highest titers being to a subtype C virus, MW965.26. No responses were observed just prior to infection, indicating that vaccine-primed HIV-specific antibodies had waned. Sporadic neutralization activity against tier 2 isolates was observed after 2 to 3 years of HIV infection, but these responses were similar in the vaccinated and placebo groups as well as the unvaccinated controls. Our data suggest that prior vaccination with these immunogens did not alter the antibody responses to HIV-1 infection, nor did it accelerate the development of HIV neutralization breadth.IMPORTANCE There is a wealth of information on HIV-specific vaccine-induced immune responses among HIV-uninfected participants; however, data on immune responses among participants who acquire HIV after vaccination are limited. Here we show that HIV-specific binding antibody responses in individuals with breakthrough HIV infections were not affected by prior vaccination with HIV envelope-containing immunogens. We also found that these vectored vaccines did not prime tier 2 virus-neutralizing antibody responses, which are thought to be required for prevention against HIV acquisition, or accelerate the development of neutralization breadth. Although this study is limited, such studies can provide insights into whether vaccine-elicited antibody responses are boosted by HIV infection to acquire broader neutralizing activity, which may help to identify antigens relevant to the design of more effective vaccines.

Selective transmission of some HIV-1 subtype C variants might depend on Envelope stimulating dendritic cells to secrete IL-10

Envelope (Env) phenotype(s) that provide transmitted founders (TF) with a selective advantage during HIV-1 transmission would be the ideal target for preventative therapy. We generated Env clones from four individuals infected with a single virus and one participant infected with multiple variants at transmission and compared phenotype with matched Envs from chronic infection (CI). When we determined whether pseudovirus (PSV) of the five TF and thirteen matched CI Env clones differed in their ability to 1) enter TZM-bl cells, 2) bind DC-SIGN, and 3) trans-infect CD4+ cells there was no association between time post-infection and variation in Env phenotype. However, when we compared the ability of PSV to induce monocyte-derived dendritic cells (MDDCs) to secrete Interleukin-10 (IL-10), we found that only TF Envs from single variant transmission cases induced MDDCs to secrete either higher or similar levels of IL-10 as the CI clones. Furthermore, interaction between MDDC DC-SIGN and Env was required for secretion of IL-10. When variants were grouped according to time post-infection, TF PSV induced the release of higher levels of IL-10 than their CI counterparts although this relationship varied across MDDC donors. The selection of variants during transmission is therefore likely a complex event dependent on both virus and host genetics. Our findings suggest that, potentially due to overall variation in N-glycosylation across variants, nuanced differences in binding of TF Env to DC-SIGN might trigger alternative DC immune responses (IRs) in the female genital tract (FGT) that favour HIV-1 survival and facilitate transmission.

Tactile Contact as a Marketing Tool for Improving an HIV/STD Education Program's Compliance / Retention with Crack Cocaine Users

BACKGROUND

This research brief reports results from an exploratory pilot study on the use of socially acceptable touch in a public setting that accompanies a request to improve program compliance with "street level" crack cocaine users.

METHODS

Study participants consisted of 120 crack cocaine-using participants in a larger community-based HIV/STD prevention and research program targeting at-risk African-Americans. They were required to return for a series of four booster health education sessions over 2-5 days and 6 month and 1 year follow-up assessments. The most difficult aspect of this program was no-shows for the second booster session; study participants who attended at least two sessions were much more likely to attend all sessions and complete the entire lengthy program. The program director randomly approached some participants after the first visit in a public setting and briefly touched them as part of a handshake; then, the director asked them to return for their follow-up sessions. Whether they were approached or not was random. Analysis comprised descriptive and non-parametric statistics.

RESULTS

Ninety-three percent of participants who were asked to return and were touched returned for the second session; only 75% returned who had been asked to do so but were not touched. A statistically significant difference favored being touched and complying, as measured by second-session returning participants (p < .01), though it appeared the touch / request had more of a preventive than a promotional effect. Extraneous demographic and background factors were ruled out with the exception of age (older participants), which contributed slightly.

CONCLUSIONS

Results suggest that a request "anchored" to a socially acceptable public touch is promising in terms of improving program participation and engagement. Limitations and implications for future research are discussed.

Antibody-Dependent Cellular Cytotoxicity (ADCC)-Mediating Antibodies Constrain Neutralizing Antibody Escape Pathway

Both neutralization and antibody-dependent cellular cytotoxicity (ADCC) may be required for effective protection against HIV-1 infection. While there is extensive information on the targets of early neutralizing antibody (nAb) responses, much less is known about the targets of ADCC responses, which are more difficult to characterize. In four individuals recruited during acute HIV-infection, ADCC responses were detected 3-7 weeks prior to nAb responses. To determine the relative influence of ADCC and nAb responses on virus evolution, we performed an in-depth investigation of one individual (CAP63) who showed the highest nAb and ADCC responses. Both nAbs and ADCC antibodies targeted the V4 region of the Env, although there were some differences in epitope recognition. We identified accelerated viral evolution in this region concurrent with emergence of nAb activity, but not ADCC activity. Deep sequencing demonstrated that most nAb escape mutations were strongly selected for, however one nAb escape mutation that rendered the virus highly susceptible to autologous ADCC responses, was suppressed despite not affecting viral fitness. This escape mutation also rendered the virus more sensitive to autologous responses, as well as monoclonal antibodies targeting CD4-induced epitopes, compared to the wildtype virus. In conclusion, ADCC responses and nAbs in donor CAP63 recognized overlapping but unique epitopes in the V4 region, and while ADCC activity was present prior to nAbs, it did not drive viral evolution during this time. However, ADCC responses may select against nAb escape pathways that expose other common ADCC epitopes thereby restricting viral replication and expansion.

V2-Directed Vaccine-like Antibodies from HIV-1 Infection Identify an Additional K169-Binding Light Chain Motif with Broad ADCC Activity

Antibodies that bind residue K169 in the V2 region of the HIV-1 envelope correlated with reduced risk of infection in the RV144 vaccine trial but were restricted to two ED-motif-encoding light chain genes. Here, we identify an HIV-infected donor with high-titer V2 peptide-binding antibodies and isolate two antibody lineages (CAP228-16H/19F and CAP228-3D) that mediate potent antibody-dependent cell-mediated cytotoxicity (ADCC). Both lineages use the IGHV5-51 heavy chain germline gene, similar to the RV144 antibody CH58, but one lineage (CAP228-16H/19F) uses a light chain without the ED motif. A cocrystal structure of CAP228-16H bound to a V2 peptide identified a IGLV3-21 gene-encoded DDxD motif that is used to bind K169, with a mechanism that allows CAP228-16H to recognize more globally relevant V2 immunotypes. Overall, these data further our understanding of the development of cross-reactive, V2-binding, antiviral antibodies and effectively expand the human light chain repertoire able to respond to RV144-like immunogens.

IgG3 enhances neutralization potency and Fc effector function of an HIV V2-specific broadly neutralizing antibody

Broadly neutralizing antibodies (bNAbs) protect against HIV infection in non-human primates and their efficacy may be enhanced through interaction with Fc receptors on immune cells. Antibody isotype is a modulator of this binding with the IgG3 subclass mediating potent Fc effector function and is associated with HIV vaccine efficacy and HIV control. BNAb functions are typically assessed independently of the constant region with which they are naturally expressed. To examine the role of natural isotype in the context of a bNAb lineage we studied CAP256, an HIV-infected individual that mounted a potent V2-specific bNAb response. CAP256 expressed persistently high levels of plasma IgG3 which we found mediated both broad neutralizing activity and potent Fc function. Sequencing of germline DNA and the constant regions of V2-directed bNAbs from this donor revealed the expression of a novel IGHG3 allele as well as IGHG3*17, an allele that produces IgG3 antibodies with increased plasma half-life. Both allelic variants were used to generate CAP256-VRC26.25 and CAP256-VRC26.29 IgG3 bNAbs and these were compared to IgG1 versions. IgG3 variants were shown to have significantly higher phagocytosis and trogocytosis compared to IgG1 versions, which corresponded to increased affinity for FcγRIIa. Neutralization potency was also significantly higher for IgG3 bNAbs, particularly against viruses lacking the N160 glycan. By exchanging hinge regions between subclass variants, we showed that hinge length modulated both neutralization potency and Fc function. This study showed that co-operation between the variable and natural IgG3 constant regions enhanced the polyfunctionality of antibodies, indicating the value of leveraging genetic variation which could be exploited for passive immunity.

Recruitment using respondent driven sampling, risk behaviors assessment and willingness of young female sex workers (18-25 years) in Dar Es Salaam, Tanzania to participate in HIV vaccine trials

Background

Despite the present HIV preventive and treatment programs, the prevalence of HIV is still high in eastern and southern Africa, among young women and populations at high.

risk for HIV transmission such as sex workers. There is a need to prepare a suitable population that will participate in efficacy HIV vaccine trials to determine the efficacy of HIV vaccines that had proven to be safe and immune potent.

Methods

It was a cross-sectional study that recruited 600 female sex workers using respondent-driven sampling in Dar es Salaam. The study examined recruitment approaches, risk behaviors and willingness of young female sex workers to participate in an HIV vaccine trial. Descriptive statistics described risk behaviors and willingness of the participants to participate in efficacy HIV vaccine trials. The logistic regression model computed the likelihood of willingness to participate in the trials with selected variables.

Results

The study demonstrated 53% were less than 20 years old, 96% were single, and 22% lived in brothels. Eighty percent of the participants started selling sex at the age between 15 and 19 years old, 61% used illicit drugs for the first time when they were less than 20 years old, 24% had anal sex ever. Eighty-nine percent had more than 20-lifetime sexual partners, and 56% had unprotected sexual intercourse with sex clients. Ninety-one percent expressed a willingness to participate in the HIV vaccine trial. Sixty-one percent did not need permission from anyone for participating in a trial. Ninety-one percent expressed willingness to participate in the efficacy of HIV vaccine trial. In the logistic regression model, willingness was significantly associated with the need to ask permission for participation in HIV vaccine trial from sex agent.

Conclusion

Respondent-driven sampling provided a rapid means of reaching young female sex workers who reported high-risk behaviors. The majority expressed a high level of willingness to participate in the HIV vaccine trial which was marginally correlated to the need to seek consent for participation in the trial from the sex brokers. Future HIV vaccine trials involving this population should consider involving the brokers in the trials because they form an essential part of the community for the participants.