Rethinking the heterosexual infectivity of HIV-1: a systematic review and meta-analysis

Comparison between a deep-learning and a pixel-based approach for the automated quantification of HIV target cells in foreskin tissue

The availability of target cells expressing the HIV receptors CD4 and CCR5 in genital tissue is a critical determinant of HIV susceptibility during sexual transmission. Quantification of immune cells in genital tissue is therefore an important outcome for studies on HIV susceptibility and prevention. Immunofluorescence microscopy allows for precise visualization of immune cells in mucosal tissues; however, this technique is limited in clinical studies by the lack of an accurate, unbiased, high-throughput image analysis method. Current pixel-based thresholding methods for cell counting struggle in tissue regions with high cell density and autofluorescence, both of which are common features in genital tissue. We describe a deep-learning approach using the publicly available StarDist method to count cells in immunofluorescence microscopy images of foreskin stained for nuclei, CD3, CD4, and CCR5. The accuracy of the model was comparable to manual counting (gold standard) and surpassed the capability of a previously described pixel-based cell counting method. We show that the performance of our deep-learning model is robust in tissue regions with high cell density and high autofluorescence. Moreover, we show that this deep-learning analysis method is both easy to implement and to adapt for the identification of other cell types in genital mucosal tissue.

Model-based predictions of protective HIV pre-exposure prophylaxis adherence levels in cisgender women

Most human immunodeficiency virus (HIV) infections occur in cisgender women in resource-limited settings. In women, self-protection with emtricitabine/tenofovir disoproxil fumarate pre-exposure prophylaxis (FTC/TDF-PrEP) constitutes a major pillar of HIV prevention. However, clinical trials in women had inconsistent outcomes, sparking uncertainty about adherence requirements and reluctance in evaluating on-demand regimens. We analyzed data from published FTC/TDF-PrEP trials to establish efficacy ranges in cisgender women. In a 'bottom-up' approach, we modeled hypotheses in the context of risk-group-specific, adherence-efficacy profiles and challenged those hypotheses with clinical data. We found that different clinical outcomes were related to the proportion of women taking the product, allowing coherent interpretation of the data. Our analysis showed that 90% protection was achieved when women took some product. We found that hypotheses of putative male/female differences were either not impactful or statistically inconsistent with clinical data. We propose that differing clinical outcomes could arise from pill-taking behavior rather than biological factors driving specific adherence requirements in cisgender women.

Combination HIV prevention during pregnancy and the post-partum period in Malawi and Zambia: a mathematical modelling analysis

INTRODUCTION

Despite widespread success in reducing vertical HIV transmission, most antenatal care (ANC) programmes in eastern and southern Africa have not emphasized primary prevention of maternal HIV acquisition during pregnancy and lactation/breastfeeding. We hypothesized that combination HIV prevention interventions initiated alongside ANC could substantially reduce maternal HIV incidence.

METHODS

We constructed a multi-state model describing male-to-female HIV transmission in steady heterosexual partnerships during pregnancy and lactation/breastfeeding, with initial conditions based on population distribution estimates for Malawi and Zambia in 2020. We modelled individual and joint increases in three HIV prevention strategies at or soon after ANC initiation: (1) HIV testing of male partners, resulting in HIV diagnosis and less condomless sex among those with previously undiagnosed HIV; (2) initiation (or re-initiation) of suppressive antiretroviral therapy (ART) for male partners with diagnosed but unsuppressed HIV; and (3) adherent pre-exposure prophylaxis (PrEP) for HIV-negative female ANC patients with HIV-diagnosed or unknown-status male partners. We estimated the percentage of within-couple, male-to-female HIV transmissions that could be averted during pregnancy and lactation/breastfeeding with these strategies, relative to base-case conditions in which 45% of undiagnosed male partners become newly HIV diagnosed via testing, 75% of male partners with diagnosed but unsuppressed HIV initiate/re-initiate ART and 0% of female ANC patients start PrEP.

RESULTS

Increasing uptake of any single strategy by 20 percentage points above base-case levels averted 10%-11% of maternal HIV acquisitions during pregnancy and lactation/breastfeeding in the model. Joint uptake increases of 20 percentage points in two interventions averted an estimated 19%-23% of transmissions, and with a 20-percentage-point increase in uptake of all three interventions, 29% were averted. Strategies achieving 95% male testing, 90% male ART initiation/re-initiation and 40% female PrEP use reduced incident infections by 45%.

CONCLUSIONS

Combination HIV prevention strategies provided alongside ANC and sustained through the post-partum period could substantially reduce maternal HIV incidence during pregnancy and lactation/breastfeeding in eastern and southern Africa.

Synthesis of protective oral PrEP adherence levels in cisgender women using convergent clinical- and bottom-up modeling

Globally, most HIV infections occur in heterosexual women in resource-limited settings. In these settings, female self-protection with generic emtricitabine/tenofovir disoproxil fumarate pre-exposure prophylaxis (FTC/TDF-PrEP) may constitute a major pillar of the HIV prevention portfolio. However, clinical trials in women had inconsistent outcomes, sparking uncertainty regarding risk-group specific adherence requirements and causing reluctance in testing and recommending on-demand regimen in women. We analyzed all FTC/TDF-PrEP trials to establish PrEP efficacy ranges in women. In a 'bottom-up' approach, we modeled hypotheses corroborating risk-group specific adherence-efficacy profiles. Finally, we used the clinical efficacy ranges to (in-)validate hypotheses. We found that different clinical outcomes could solely be explained by the proportion of enrolled participants not taking the product, allowing, for the first time, to unify clinical observations. This analysis showed that 90% protection was achieved, when women took some of the product. Using 'bottom-up' modelling, we found that hypotheses of putative male/female differences were either irrelevant, or statistically inconsistent with clinical data. Furthermore, our multiscale modelling indicated that 90% protection was achieved if oral FTC/TDF was taken at least twice weekly.

Association of mental health symptoms on HIV care outcomes and retention in treatment

OBJECTIVE

The purpose was to examine associations between HIV care engagement and mental health symptoms among persons living with HIV (PLWH) receiving ART. This study builds upon previous findings indicating a significant association between mental health and retention in HIV care,¹ while also advancing the literature by examining the impact of substance use on this link, as well as potential bidirectional associations.

METHOD

Participants of the current study were 493 patients who engaged in care and received antiviral therapy (ART) from Infectious Disease physicians between 2017 and 2019 in a large academic medical center.

RESULTS

Results from hierarchical regression analyses revealed that patients who missed more days of ART medication had higher depressive symptoms, even when accounting for the effect of demographic variables and alcohol use. Further, depressive symptoms predicted significant variance in number of "no show" visits, but was not individually predictive of ""no show"" visits beyond the effect of other HIV care outcomes (e.g., number of days of medication missed).

CONCLUSION

Findings reflect linkages among HIV treatment adherence, mental health, and substance use, and highlight the need to target mental health symptoms to improve outcomes among PLWH and prevent HIV transmission.

Brief Report: Dapivirine Ring HIV-1 Prevention Effectiveness for Women Engaged in Vaginal and Anal Intercourse: Insights From Mathematical Modeling

BACKGROUND

The dapivirine vaginal ring reduces the risk of HIV-1 acquisition in acts of vaginal intercourse (VI), and although it does not offer HIV-1 protection in acts of anal intercourse (AI), it may provide some overall risk reduction for women for whom most sex acts are vaginal. We estimated the protective effect of the ring among women with high ring adherence engaged in both VI and AI.

METHODS

We developed a microsimulation model using data from the MTN-020/ASPIRE trial. Among women who reported any AI, we estimated the proportion of all sex acts that were AI. Model scenarios varied this proportion among women engaged in both VI and AI from 5% to 30%, including the trial-observed median proportion of 6.3% of all acts being AI. In primary analyses, dapivirine ring efficacy was model-calibrated at 70% for vaginal exposures and assumed to be 0% for anal exposures.

RESULTS

Among highly adherent women for whom 6.3% of sex acts were AI, the ring reduced HIV-1 risk by 53% (interquartile range: 44, 60), with a decline to 26% (interquartile range: 16, 36) among women for whom 30% of acts were AI. Ring effectiveness was less than 40% among women for whom AI accounted for greater than 16% of all sex acts, although this represented less than 5% of all women in the ASPIRE trial.

CONCLUSIONS

For most women, including those who engage in AI, because most HIV-1 risk occurs in acts of vaginal sex, the dapivirine vaginal ring can provide important HIV-1 protection.

HIV/AIDS Mathematical Model of Triangle Transmission

In this paper, a mathematical analysis of the HIV/AIDS deterministic model studied in the paper called Mathematical Model of HIV/AIDS Considering Sexual Preferences Under Antiretroviral Therapy, a case study in the previous works preformed by Espitia is performed. The objective is to gain insight into the qualitative dynamics of the model determining the conditions for the persistence or effective control of the disease in the community through the study of basic properties such as positiveness and boundedness; the calculus of the basic reproduction number; stationary points such as disease-free equilibrium (DFE), boundary equilibrium (BE) and endemic equilibrium (EE); and the local stability (LAS) of disease-free equilibrium. The findings allow us to conclude that the best way to reduce contagion and consequently reach a DFE is thought to be the reduction in the rate of homosexual partners, as they are the most affected population by the virus and are therefore the most likely to become infected and spread it. Increasing the departure rate of infected individuals leads to a decrease in untreated infected heterosexual men and untreated infected women.

How to Safeguard University Students Against HIV Transmission? Results of a Cross-Sectional Study in Southern Italy

Introduction

Young people represent a growing share of the group living with HIV, and monitoring the sexual behaviors of this vulnerable age group is necessary to control and prevent the HIV/AIDS pandemic. The present study has been conducted to investigate the level of knowledge and attitudes toward HIV infection and sexual behaviors among a sample of undergraduate university students in Southern Italy.

Methods

Data were collected through an anonymous online questionnaire between 1st to 31st July 2020 and included questions on socio-demographic and sexual history characteristics, knowledge and attitudes toward HIV infection, sexual behaviors, and sources of information about HIV. The eligibility criteria for the study were: age between 18 and 30 years and registered as an undergraduate student at the university.

Results

Among the 1,318 students who completed the survey, 62.5% knew that HIV can be transmitted through blood, vaginal secretions and semen. The overall median knowledge score was 10, and the main determinants of knowledge were being younger and attending to medical or life science majors. Less than half of the students (45.8%) reported that they always wear a condom during any sexual activity. Predictors of consistent condom use were being younger, having a later sexual debut and a good knowledge score.

Conclusions

The study findings showed a not completely satisfactory level of knowledge and unsafe sex practices among university students. These results reiterate the need to tailor HIV prevention strategies among young individuals. Such a change could dispel misconceptions about HIV transmission and prevention that affect risk-taking sexual behaviors. These strategies may ultimately contribute to lessing the effect of HIV/AIDS transmission in Italy.

The Impact of Genital Ulcers on HIV Transmission Has Been Underestimated—A Critical Review

In the early 1990s, several observational studies determined that genital ulcer disease (GUD), in either the index or the exposed person, facilitates HIV transmission. Several meta-analyses have since presented associated risk ratios (RR) over the baseline per-act transmission probability (PATP) usually in the range of 2–5. Here we review all relevant observational studies and meta-analyses, and show that the estimation of RRs was, in most cases, biased by assuming the presence of GUD at any time during long follow-up periods, while active genital ulcers were present in a small proportion of the time. Only two studies measured the GUD co-factor effect in PATPs focusing on acts in which ulcers were present, and both found much higher RRs (in the range 11–112). We demonstrate that these high RRs can be reconciled with the studies on which currently accepted low RRs were based, if the calculations are restricted to the actual GUD episodes. Our results indicate that the effect of genital ulcers on the PATP of HIV might be much greater than currently accepted. We conclude that the medical community should work on the assumption that HIV risk is very high during active genital ulcers.

The impact of condom use on the HIV epidemic

Background: Condom promotion and supply was one the earliest interventions to be mobilized to address the HIV pandemic. Condoms are inexpensive and provide protection against transmission of HIV and other sexually transmitted diseases (STIs) as well as against unintended pregnancy. As many as 16 billion condoms may be used annually in all low- and middle-income countries (LMIC). In recent years the focus of HIV programs as been on testing and treatment and new technologies such as PrEP. Rates of condom use have stopped increasing short of UNAIDS targets and funding from donors is declining. Methods: We applied a mathematical HIV transmission model to 77 high HIV burden countries to estimate the number of HIV infections that would have occurred from 1990 to 2019 if condom use had remained at 1990 levels. Results: The results suggest that current levels of HIV would be five times higher without condom use and that the scale-up in condoms use averted about 117 million HIV infections. Conclusions: HIV programs should ensure that affordable condoms are consistently available and that the benefits of condom use are widely understood.

HIV transmitting mononuclear phagocytes; integrating the old and new

In tissue, mononuclear phagocytes (MNP) are comprised of Langerhans cells, dendritic cells, macrophages and monocyte-derived cells. They are the first immune cells to encounter HIV during transmission and transmit the virus to CD4 T cells as a consequence of their antigen presenting cell function. To understand the role these cells play in transmission, their phenotypic and functional characterisation is important. With advancements in high parameter single cell technologies, new MNPs subsets are continuously being discovered and their definition and classification is in a state of flux. This has important implications for our knowledge of HIV transmission, which requires a deeper understanding to design effective vaccines and better blocking strategies. Here we review the historical research of the role MNPs play in HIV transmission up to the present day and revaluate these studies in the context of our most recent understandings of the MNP system.

Newly Discovered Archival Data Show Coincidence of a Peak of Sexually Transmitted Diseases with the Early Epicenter of Pandemic HIV-1

To which extent STDs facilitated HIV-1 adaptation to humans, sparking the pandemic, is still unknown. We searched colonial medical records from 1906–1958 for Leopoldville, Belgian Congo, which was the initial epicenter of pandemic HIV-1, compiling counts of treated STD cases in both Africans and Europeans. Almost all Europeans were being treated, while for Africans, generalized treatment started only in 1929. Treated STD counts in Europeans thus reflect STD infection rates more accurately compared to counts in Africans. In Africans, the highest recorded STD treatment incidence was in 1929–1935, declining to low levels in the 1950s. In Europeans, the recorded treatment incidences were highest during the period 1910–1920, far exceeding those in Africans. Europeans were overwhelmingly male and had frequent sexual contact with African females. Consequently, high STD incidence among Europeans must have coincided with high prevalence and incidence in the city’s African population. The data strongly suggest the worst STD period was 1910–1920 for both Africans and Europeans, which coincides with the estimated origin of pandemic HIV-1. Given the strong effect of STD coinfections on HIV transmission, these new data support our hypothesis of a causal effect of STDs on the epidemic emergence of HIV-1.

The impact of condom use on the HIV epidemic

Background: Condom promotion and supply was one the earliest interventions to be mobilized to address the HIV pandemic. Condoms are inexpensive and provide protection against transmission of HIV and other sexually transmitted diseases (STIs) as well as against unintended pregnancy. As many as 16 billion condoms may be used annually in all low- and middle-income countries (LMIC). In recent years the focus of HIV programs as been on testing and treatment and new technologies such as PrEP. Rates of condom use have stopped increasing short of UNAIDS targets and funding from donors is declining. Methods: We applied a mathematical HIV transmission model to 77 high HIV burden countries to estimate the number of HIV infections that would have occurred from 1990 to 2019 if condom use had remained at 1990 levels. Results: The results suggest that current levels of HIV would be five times higher without condom use and that the scale-up in condoms use averted about 117 million HIV infections. Conclusions: HIV programs should ensure that affordable condoms are consistently available and that the benefits of condom use are widely understood.

Prevalence and Predictors of Syphilis in Female Sex Workers in Eastern China: Findings from Six Consecutive Cross-Sectional Surveys

Purpose

Female sex workers play an important role in transmitting HIV and syphilis from high-risk groups to the general population. However, epidemic trends and risk factors for syphilis in Chinese female sex workers (FSWs) remain unclear.

Methods

Using convenient sampling methods, 2482 FSWs were interviewed and tested for syphilis from 2014 to 2019, all of them were divided into two groups of high-grade FSWs and low-grade FSWs according to service solicited and clients price there were. Demographic data were collected and logistic regression analysis was used to identify risk factors for syphilis.

Results

43.67% of participants have received free condoms, 76.15% of them engaged in peer education of the 2482 FSWs tested for syphilis, 107 (4.31%) were positive. The prevalence of syphilis in high-grade FSWs was significantly lower than that in low-grade FSWs (3.14% and 5.62%, respectively).The overall prevalence of syphilis increased from 3.19% to4.47%. The percentage of FSWs received free condoms and engaged in peer education increased significantly. With upgraded awareness of syphilis, the number of FSWs having protected sex also increased significantly. It is also found that low-grade female sex workers are at greater risk of syphilis than those high-grade ones (odds ratio (OR) = 1.76, 95% CI 1.18–2.63, p < 0.05).

Conclusion

Great awareness of syphilis and the increased utilization of condom did not reduce the prevalence of syphilis, especially in low-grade FSWs group. More effective integrated interventions should be developed for such populations.

Human anogenital monocyte-derived dendritic cells and langerin+cDC2 are major HIV target cells

Tissue mononuclear phagocytes (MNP) are specialised in pathogen detection and antigen presentation. As such they deliver HIV to its primary target cells; CD4 T cells. Most MNP HIV transmission studies have focused on epithelial MNPs. However, as mucosal trauma and inflammation are now known to be strongly associated with HIV transmission, here we examine the role of sub-epithelial MNPs which are present in a diverse array of subsets. We show that HIV can penetrate the epithelial surface to interact with sub-epithelial resident MNPs in anogenital explants and define the full array of subsets that are present in the human anogenital and colorectal tissues that HIV may encounter during sexual transmission. In doing so we identify two subsets that preferentially take up HIV, become infected and transmit the virus to CD4 T cells; CD14⁺CD1c⁺ monocyte-derived dendritic cells and langerin-expressing conventional dendritic cells 2 (cDC2).

Increase in HIV incidence in women exposed to rape

OBJECTIVE

To determine the incidence of HIV acquisition in women postrape compared with a cohort of women who had not been raped.

DESIGN

A prospective cohort study.

METHODS

The Rape Impact Cohort Evaluation study based in Durban, South Africa, enrolled women aged 16-40 years from postrape care services, and a control group of women from Primary Healthcare services. Women who were HIV negative at baseline (441 in the rape-exposed group and 578 in the control group) were followed for 12-36 months with assessments every 3 months in the first year and every 6 months thereafter. Multivariable Cox regression models adjusted for baseline and time varying covariates were used to investigate the effect of rape exposure on HIV incidence over follow-up.

RESULTS

Eighty-six women acquired HIV during 1605.5 total person-years of follow-up, with an incident rate of 6.6 per 100 person-years [95% confidence interval (CI): 4.8-9.1] among the rape exposed group and 4.7 per 100 person-years (95% CI: 3.5-6.2) among control group. After controlling for confounders (age, previous trauma, social support, perceived stress, multiple partners and transactional sex with a casual partner), women exposed to rape had a 60% increased risk of acquiring HIV [adjusted hazard ratio: 1.59 (95% CI: 1.01-2.48)] compared with those not exposed. Survival analysis showed difference in HIV incident occurred after month 9.

CONCLUSION

Rape is a long-term risk factor for HIV acquisition. Rape survivors need both immediate and long-term HIV prevention and care.

Association of schistosomiasis and HIV infections: A systematic review and meta-analysis

Background:

Female genital schistosomiasis (FGS) affects up to 56 million women in sub-Saharan Africa and may increase risk of HIV infection.

Methods:

To assess the association of schistosomiasis with HIV infection, peer-reviewed literature published until 31 December 2018 was examined and a pooled estimate for the odds ratio was generated using Bayesian random effects models.

Results:

Of the 364 abstracts that were identified, 26 were included in the summary. Eight reported odds ratios of the association between schistosomiasis and HIV; one reported a transmission hazard ratio of 1.8 (95% CI, 1.2–2.6) among women and 1.4 (95% CI, 1.0–1.9) among men; 11 described the prevalence of schistosomiasis among HIV-positive people (range, 1.5–36.6%); and six reported the prevalence of HIV among people with schistosomiasis (range, 5.8–57.3%). Six studies were selected for quantitative analysis. The pooled estimate for the odds ratio of HIV among people with schistosomiasis was 2.3 (95% CI, 1.2–4.3).

Conclusions:

A significant association of schistosomiasis with HIV was found. However, a specific summary estimate for FGS could not be generated. A research agenda was provided to determine the effect of FGS on HIV infection. The WHO’s policy on mass drug administration for schistosomiasis may prevent HIV.

Understanding of Perceived Infectiousness and Its Influence on Sexual Behavior Among Individuals With Acute HIV Infection in Lilongwe, Malawi (HPTN 062)

We implemented HPTN 062, an acceptability and feasibility study of a motivational-interviewing (MI) intervention to reduce HIV transmission among individuals with acute HIV infection (AHI) in Lilongwe, Malawi. Participants were randomly assigned to receive either brief education or the MI intervention over 24 weeks; all participants received the same messages about AHI. We used mixed methods to assess participants' understanding of the association between AHI and viral load, and its connection to sexual behavior at 8 weeks. While most participants understood key aspects of AHI, MI-intervention participants gave substantially more detailed descriptions of their understanding. Nearly all participants, regardless of study arm, understood that they were highly infectious and would be very likely to transmit HIV after unprotected sex during AHI. Our findings suggest that messages about AHI delivered during the period of AHI are likely beneficial for ensuring that those with AHI understand their level of infectiousness and its association with forward transmission.

Evaluation of Post-Exposure Prophylaxis Utilization Among Human Immunodeficiency Virus Exposed Victims at University of Gondar Comprehensive Specialized Hospital, North West Ethiopia

Background

Human immunodeficiency virus (HIV) infection is a serious public health problem costing the lives of many people including healthcare workers worldwide. Ethiopia is one of the most seriously affected countries in sub-Saharan Africa, with a large number of people who are living with HIV/AIDS and AIDS -related deaths. Prevention of the virus transmission through the appropriate utilization of post exposure prophylaxis is one of the major strategies. Therefore, the aim of this study was to evaluate the utilization of post-exposure prophylaxis (PEP) among victims of HIV at the University of Gondar Comprehensive Specialized Hospital, north-west Ethiopia. A retrospective cross-sectional study was conducted from May 17, 2018, to May 24, 2018 and descriptive statistics were carried out to analyze the Data using SPSS version 20.

Results

From a total of 309 patients PEP was prescribed during the study period, of whom 239 (77.34%) were occupational victims and 55 (17.8%) were rape victims, with one missing data. Occupational victims were exposed by blood and blood product splashes and nurses and physicians were exposed almost equally, 14.24% and 13.92%, respectively. The majority of the victims were exposed at a health facility. Two hundred and eighty-five (92.23%) victims received prescriptions containing three-drug regimens, tenofovir + lamivudine + efavirenz, followed by 9 victims (2.91%) with two-drug regimens; zidovudine + lamivudine. There are no follow-up mechanisms as a result the completion rate and the outcome of PEP was not determined.

Conclusion

PEP was initiated within 72 hr, most within 24 hr. The adherence was unknown with poor follow-up despite the strong recommendations of the national and WHO guidelines.

Impact of Endemic Infections on HIV Susceptibility in Sub-Saharan Africa

Human immunodeficiency virus (HIV) remains a leading cause of global morbidity with the highest burden in Sub-Saharan Africa (SSA). For reasons that are incompletely understood, the likelihood of HIV transmission is several fold higher in SSA than in higher income countries, and most of these infections are acquired by young women. Residents of SSA are also exposed to a variety of endemic infections, such as malaria and various helminthiases that could influence mucosal and systemic immunology. Since these immune parameters are important determinants of HIV acquisition and progression, this review explores the possible effects of endemic infections on HIV susceptibility and summarizes current knowledge of the epidemiology and underlying immunological mechanisms by which endemic infections could impact HIV acquisition. A better understanding of the interaction between endemic infections and HIV may enhance HIV prevention programs in SSA.

HIV-1 genetic diversity and divergence and its correlation with disease progression among antiretroviral naïve recently infected individuals

HIV-1 genetic diversity evolution was deeply characterized during the first year of infection among recently-infected patients using deep sequencing technology and correlated with disease progression surrogate markers. RNA and DNA samples from twenty-five individuals (13 female) encoding the protease and reverse transcriptase regions of the pol gene, and the V3 region of the env gene were evaluated at recent infection and during established infection. Infection by a unique HIV-1 strain was inferred in 70.1% of the individuals, with no differences between genders. Infections by multiple strains were associated with higher viral loads and faster CD4⁺ T cell declines. Either low or high levels of viral loads accompanied low levels of genetic diversity and lower selective pressure. With massive sequence data from 3 distinct genomic HIV-1 regions from plasma and PBMCs over time, we propose a model for HIV-1 genetic diversity, which correlates to basal viral loads of patients.

Risk of sexual transmission of human immunodeficiency virus with antiretroviral therapy, suppressed viral load and condom use: a systematic review

BACKGROUND

The Public Health Agency of Canada reviewed sexual transmission of HIV between serodiscordant partners to support examination of the criminal justice system response to HIV nondisclosure by the Department of Justice of Canada. We sought to determine HIV transmission risk when an HIV-positive partner takes antiretroviral therapy, has a suppressed viral load or uses condoms.

METHODS

We conducted an overview and systematic review update by searching MEDLINE and other databases (Jan. 1, 2007, to Mar. 13, 2017; and Nov. 1, 2012, to Apr. 27, 2017, respectively). We considered reviews and studies about absolute risk of sexual transmission of HIV between serodiscordant partners to be eligible for inclusion. We used A Measurement Tool to Assess Systematic Reviews (AMSTAR) for review quality, Quality in Prognosis Studies (QUIPS) instrument for study risk of bias and then the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence across studies. We calculated HIV incidence per 100 person-years with 95% confidence intervals (CIs). We assigned risk categories according to potential for and evidence of HIV transmission.

RESULTS

We identified 12 reviews. We selected 1 review to estimate risk of HIV transmission for condom use without antiretroviral therapy (1.14 transmissions/100 person-years, 95% CI 0.56-2.04; low risk). We identified 11 studies with 23 transmissions over 10 511 person-years with antiretroviral therapy (0.22 transmissions/ 100 person-years, 95% CI 0.14-0.33; low risk). We found no transmissions with antiretroviral therapy and a viral load of less than 200 copies/mL across consecutive measurements 4 to 6 months apart (0.00 transmissions/100 person-years, 95% CI 0.00-0.28; negligible risk regardless of condom use).

INTERPRETATION

Based on high-quality evidence, there is a negligible risk of sexual transmission of HIV when an HIV-positive sex partner adheres to antiretroviral therapy and maintains a suppressed viral load of less than 200 copies/mL measured every 4 to 6 months. Sexual transmissions of HIV have occurred when viral load was more than 200 copies/mL with antiretroviral therapy or condoms alone were used, although the risk remains low. These findings will help to support patient and clinician decision-making, affect public health case management and contact tracing, and inform justice system responses to HIV nondisclosure.

Post-exposure prophylaxis for HIV infection in sexual assault victims

OBJECTIVES

Sexual assault (SA) is recognized as a public health problem of epidemic proportions. Guidelines recommend the administration of post-exposure prophylaxis (PEP) after an SA. However, few data are available about the feasibility of this strategy, and this study was conducted to assess this.

METHODS

We conducted a retrospective, longitudinal, observational study in SA victims attending the Hospital Clinic in Barcelona from 2006 to 2015. A total of 1695 SA victims attended the emergency room (ER), of whom 883 met the PEP criteria. Five follow-up visits were scheduled at days 1, 10, 28, 90 and 180 in the out-patient clinic. The primary endpoint was PEP completion rate at day 28. Secondary endpoints were loss to follow-up, treatment discontinuation, occurrence of adverse events (AEs) and rate of seroconversion.

RESULTS

The median age of participants was 25 years [interquartile range (IQR) 21-33 years] and 93% were female. The median interval between exposure and presentation at the ER was 13 h (IQR 6-24 h). The level of risk was appreciable in 47% (n = 466) of individuals. Of 883 patients receiving PEP, 631 lived in Catalonia. In this group, the PEP completion rate at day 28 was 29% (n = 183). The follow-up rate was 63% (n = 400) and 38% (n = 241) at days 1 and 28, respectively. Treatment discontinuation was present in 58 (15%) of 400 patients who attended at least the day 1 visit, the main reason being AEs (n = 35; 60%). AEs were reported in 226 (56%) patients, and were mainly gastrointestinal (n = 196; 49%). Only 211 (33%) patients returned for HIV testing at day 90. A single seroconversion was observed in a men who have sex with men (MSM) patient at day 120.

CONCLUSIONS

Follow-up and compliance rates in SA victims were poor. In addition, > 50% of the patients experienced AEs, which were the main reason for PEP interruption. Strategies to increase follow-up testing and new better tolerated drug regimens must be investigated to address these issues.

On the efficiency of HIV transmission: Insights through discrete time HIV models

There are different views on which of the two forms of viral spread is more efficient in vivo between cell-free and cell-associated virus. In this study, discrete time human immunodeficiency virus models are formulated and analysed with the goal of determining the form of viral spread that is more efficient in vivo. It is shown that on its own, cell-free viral spread cannot sustain an infection owing to the low infectivity of cell-free virus and cell-associated virus can sustain an infection because of the high infectivity of cell-associated virus. When acting concurrently, cell-associated virus is more efficient in spreading the infection upon exposure to the virus. However, in the long term, the two forms of viral spread contribute almost equally. Both forms of viral spread are shown to be able to initiate an infection.

Sexually transmitted infections and HIV in the era of antiretroviral treatment and prevention: the biologic basis for epidemiologic synergy

INTRODUCTION

HIV is a unique sexually transmitted infection (STI) that is greatly affected by other concomitant "classical" bacterial and viral STIs that cause genital ulcers and/or mucosal inflammation. STIs also serve as a marker for risky sexual behaviours. STIs increase infectiousness of people living with HIV by increasing the viral concentration in the genital tract, and by increasing the potential for HIV acquisition in people at risk for HIV. In addition, some STIs can increase blood HIV concentration and promote progression of disease. This review is designed to investigate the complex relationship between HIV and classical STIs.

DISCUSSION

Treatment of STIs with appropriate antibiotics reduces HIV in blood, semen and female genital secretions. However, community-based trials could not reliably reduce the spread of HIV by mass treatment of STIs. Introduction of antiretroviral agents for the treatment and prevention of HIV has led to renewed interest in the complex relationship between STIs and HIV. Antiretroviral treatment (ART) reduces the infectiousness of HIV and virtually eliminates the transmission of HIV in spite of concomitant or acquired STIs. However, while ART interrupts HIV transmission, it does not stop intermittent shedding of HIV in genital secretions. Such shedding of HIV is increased by STIs, although the viral copies are not likely replication competent or infectious. Pre-exposure prophylaxis (PrEP) of HIV with the combination of tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) prevents HIV acquisition in spite of concomitant STIs.

CONCLUSIONS

STIs remain pandemic, and the availability of ART may have led to an increase in STIs, as fear of HIV has diminished. Classical STIs present a huge worldwide health burden that cannot be separated from HIV, and they deserve far more attention than they currently receive.

Developing a dynamic HIV transmission model for 6 U.S. cities: An evidence synthesis

BACKGROUND

Dynamic HIV transmission models can provide evidence-based guidance on optimal combination implementation strategies to treat and prevent HIV/AIDS. However, these models can be extremely data intensive, and the availability of good-quality data characterizing regional microepidemics varies substantially within and across countries. We aim to provide a comprehensive and transparent description of an evidence synthesis process and reporting framework employed to populate and calibrate a dynamic, compartmental HIV transmission model for six US cities.

METHODS

We executed a mixed-method evidence synthesis strategy to populate model parameters in six categories: (i) initial HIV-negative and HIV-infected populations; (ii) parameters used to calculate the probability of HIV transmission; (iii) screening, diagnosis, treatment and HIV disease progression; (iv) HIV prevention programs; (v) the costs of medical care; and (vi) health utility weights for each stage of HIV disease progression. We identified parameters that required city-specific data and stratification by gender, risk group and race/ethnicity a priori and sought out databases for primary analysis to augment our evidence synthesis. We ranked the quality of each parameter using context- and domain-specific criteria and verified sources and assumptions with our scientific advisory committee.

FINDINGS

To inform the 1,667 parameters needed to populate our model, we synthesized evidence from 59 peer-reviewed publications and 24 public health and surveillance reports and executed primary analyses using 11 data sets. Of these 1,667 parameters, 1,517 (91%) were city-specific and 150 (9%) were common for all cities. Notably, 1,074 (64%), 201 (12%) and 312 (19%) parameters corresponded to categories (i), (ii) and (iii), respectively. Parameters ranked as best- to moderate-quality evidence comprised 39% of the common parameters and ranged from 56%-60% across cities for the city-specific parameters. We identified variation in parameter values across cities as well as within cities across risk and race/ethnic groups.

CONCLUSIONS

Better integration of modelling in decision making can be achieved by systematically reporting on the evidence synthesis process that is used to populate models, and by explicitly assessing the quality of data entered into the model. The effective communication of this process can help prioritize data collection of the most informative components of local HIV prevention and care services in order to reduce decision uncertainty and strengthen model conclusions.

Defining early SIV replication and dissemination dynamics following vaginal transmission

Understanding HIV transmission is critical to guide the development of prophylactic interventions to prevent infection. We used a nonhuman primate (NHP) model with a synthetic swarm of sequence-tagged variants of SIVmac239 ("SIVmac239X") and scheduled necropsy during primary infection (days 3 to 14 after challenge) to study viral dynamics and host responses to the establishment and dissemination of infection following vaginal challenge. We demonstrate that local replication was initiated at multiple sites within the female genital tract (FGT), with each site having multiple viral variants. Local replication and spread in the FGT preceded lymphatic dissemination. Innate viral restriction factors were observed but appeared to follow viral replication and were ineffective at blocking initial viral establishment and dissemination. However, major delays were observed in time to dissemination in animals and among different viral variants within the same animal. It will be important to assess how phenotypic differences affect early viral dynamics.

Barriers of Mucosal Entry of HIV/SIV

Most new HIV infections, over 80%, occur through sexual transmission. During sexual transmission, the virus must bypass specific female and male reproductive tract anatomical barriers to encounter viable target cells. Understanding the generally efficient ability of these barrier to exclude HIV and the precise mechanisms of HIV translocation beyond these genital barriers is essential for vaccine and novel therapeutic development. In this review, we explore the mucosal, barriers of cervico-vaginal and penile tissues that comprise the female and male reproductive tracts. The unique cellular assemblies f the squamous and columnar epithelium are illustrate highlighting their structure and function. Each anatomical tissue offers a unique barrier to virus entry in healthy individuals. Unfortunately barrier dysfunction can lead to HIV transmission. How these diverse mucosal barriers have the potential to fail is considered, highlighting those anatomical areas that are postulated to offer a weaker barrier and are; therefore, more susceptible to viral ingress. Risk factors, such as sexually transmitted infections, microbiome dysbiosis, and high progestin environments are also associated with increased acquisition of HIV. How these states may affect the integrity of mucosal barriers leading to HIV acquisition are discussed suggesting mechanisms of transmission and revealing potential targets for intervention.

Mucosa: Key Interactions Determining Sexual Transmission of the HIV Infection

In the context of HIV sexual transmission at the genital mucosa, initial interactions between the virus and the mucosal immunity determine the outcome of the exposure. Hence, these interactions have been deeply explored in attempts to undercover potential targets for developing preventative strategies. The knowledge gained has led to propose a hypothetical model for mucosal HIV transmission. Subsequent research studies on this topic further revealed new mechanisms and identified new host-HIV interactions. This review aims at integrating these findings to inform better and update the current model of HIV transmission. At the earliest stage of virus exposure, the epithelial integrity and the presence of antiviral factors are critical in preventing viral entry to the submucosa. However, the virus has been shown to enter to the submucosa in the presence of physical abrasion or via epithelial transmigration using paracellular passage or transcytosis mechanisms. The efficiency of these processes is greater with cell-associated viral inoculums and can be influenced by the presence of viral and immune factors, and by the structure of the exposed epithelium. Once the virus reaches the submucosa, dendritic cells and fibroblasts, as recently described, have been shown in vitro of being capable of facilitating the transfer of viral particles to susceptible cells, leading to viral dissemination, most likely in a trans-infection manner. The presence of activated CD4⁺ T cells in submucosa increases the probability of infection, where the predominant microbiota could be implicated through the modulation of an inflammatory microenvironment. Other factors such as genital fluids and hormones could also play an essential role in HIV transmission. Here, we review the most recent evidence described for mucosal HIV-transmission contributing with the understanding of this phenomenon.

Mechanistic framework predicts drug-class specific utility of antiretrovirals for HIV prophylaxis

Currently, there is no effective vaccine to halt HIV transmission. However, pre-exposure prophylaxis (PrEP) with the drug combination Truvada can substantially decrease HIV transmission in individuals at risk. Despite its benefits, Truvada-based PrEP is expensive and needs to be taken once-daily, which often leads to inadequate adherence and incomplete protection. These deficits may be overcome by next-generation PrEP regimen, including currently investigated long-acting formulations, or patent-expired drugs. However, poor translatability of animal- and ex vivo/in vitro experiments, and the necessity to conduct long-term (several years) human trials involving considerable sample sizes (N>1000 individuals) are major obstacles to rationalize drug-candidate selection. We developed a prophylaxis modelling tool that mechanistically considers the mode-of-action of all available drugs. We used the tool to screen antivirals for their prophylactic utility and identify lower bound effective concentrations that can guide dose selection in PrEP trials. While in vitro measurable drug potency usually guides PrEP trial design, we found that it may over-predict PrEP potency for all drug classes except reverse transcriptase inhibitors. While most drugs displayed graded concentration-prophylaxis profiles, protease inhibitors tended to switch between none- and complete protection. While several treatment-approved drugs could be ruled out as PrEP candidates based on lack-of-prophylactic efficacy, darunavir, efavirenz, nevirapine, etravirine and rilpivirine could more potently prevent infection than existing PrEP regimen (Truvada). Notably, some drugs from this candidate set are patent-expired and currently neglected for PrEP repurposing. A next step is to further trim this candidate set by ruling out compounds with ominous safety profiles, to assess different administration schemes in silico and to test the remaining candidates in human trials.

Pre-exposure prophylaxis (PrEP) is a novel, promising strategy to halt HIV transmission. PrEP with Truvada can substantially decrease the risk of infection. However, individuals often inadequately adhere to the once-daily regimen and the drug is expensive. These shortcomings may be overcome by next-generation PrEP compounds, including long-acting formulations. However, poor translatability of animal- and ex vivo/in vitro experiments, and difficulties in conducting long-term trials involving considerable sample sizes (N > 1000 individuals) make drug-candidate selection and optimization of administration schemes costly and often infeasible. We developed a simulation tool that mechanistically considers the mode-of-action of all antivirals. We used the tool to screen all available antivirals for their prophylactic utility and identified lower bound effective concentrations for designing PrEP dosing regimen in clinical trials. We found that in vitro measured drug potency may over-predict PrEP potency, for all antiviral classes except reverse transcriptase inhibitors. We could rule out a number of antivirals for PrEP repurposing and predicted that darunavir, efavirenz, nevirapine, etravirine and rilpivirine provide complete protection at clinically relevant concentrations. Further trimming of this candidate set by compound-safety and by assessing different implementation schemes is envisaged.

Higher prevalence of viral control in HIV-1-infected women in serodiscordant relationships

BACKGROUND

HIV-1-discordant couples that remain discordant despite repeated exposure may differ from the general population in their distribution of transmission risk factors, including low plasma viral load (PVL) in the infected partner even in the absence of antiretroviral therapy (ART).

METHODS

We followed two cohorts of HIV-1-infected Kenyan women: females in discordant couples (FDC) and female sex workers (FSW). We compared the distribution of undetectable (<150 copies/mL) and low PVL (<1,000 copies/mL) between the cohorts using bootstrap methods and exact Poisson regression.

RESULTS

We evaluated 296 FDC and 220 FSW. At baseline, FDC were more likely to have undetectable (RR = 6.94, bootstrap 95% CI: 3.47, 20.81) and low PVL (RR = 3.53, bootstrap 95% CI: 2.57, 5.65) than FSW. Similarly, both repeat undetectable PVL (RR = 9.36, bootstrap 95% CI: 6.04, 10.97) and repeat low (RR = 4.99, bootstrap 95% CI: 2.33, 14.04) PVL were more likely among FDC than FSW during follow-up.

DISCUSSION

We observed higher prevalence of viral control in FDC compared to FSW in the absence of ART, suggesting potentially higher prevalence of biological HIV resistance factors among discordant couples.

Does per-act HIV-1 transmission risk through anal sex vary by gender? An updated systematic review and meta-analysis

Quantifying HIV-1 transmission risk per-act of anal intercourse (AI) is important for HIV-1 prevention. We updated previous reviews by searching Medline and Embase to 02/2018. We derived pooled estimates of receptive AI (URAI) and insertive AI (UIAI) risk unprotected by condoms using random-effects models. Subgroup analyses were conducted by gender, study design, and whether antiretroviral treatment (ART) had been introduced by the time of the study. Two new relevant studies were identified, one of which met inclusion criteria, adding three new cohorts and increasing number of individuals/partnerships included from 1869 to 14 277. Four studies, all from high-income countries, were included. Pooled HIV-1 risk was higher for URAI (1.25%, 95% CI 0.55%-2.23%, N = 5, I²  = 87%) than UIAI (0.17%, 95 % CI 0.09%-0.26%, N = 3, I²  = 0%). The sole heterosexual URAI estimate (3.38%, 95% CI 1.85%-4.91%), from a study of 72 women published in a peer-reviewed journal, was significantly higher than the men-who-have-sex-with-men (MSM) pooled estimate (0.75%, 95% CI 0.56%-0.98%, N = 4, P < 0.0001) and higher than the only other heterosexual estimate identified (0.4%, 95% CI 0.08%-2.0%, based on 59 women, excluded for being a pre-2013 abstract). Pooled per-act URAI risk varied by study design (retrospective-partner studies: 2.56%, 95% CI 1.20%-4.42%, N = 2 (one MSM, one heterosexual); prospective studies: 0.71%, 95% CI 0.51%-0.93%, N = 3 MSM, P < 0.0001). URAI risk was lower for studies conducted in the ART era (0.75%, 95% CI 0.52%-1.03%) than pre-ART (1.67%, 95% CI 0.44%-3.67%) but not significantly so (P = 0.537). Prevention messages must emphasize that HIV-1 infectiousness through AI remains high, even in the ART era. Further studies, particularly among heterosexual populations and in resource-limited settings, are required to elucidate whether AI risk differs by gender, region and following population-level ART scale-up.

Early HIV infection predictions: role of viral replication errors

In order to prevent and/or control infections it is necessary to understand their early-time dynamics. However this is precisely the phase of HIV about which the least is known. To investigate the initial stages of HIV infection within a host we have developed a multi-type, continuous-time branching process model. This model is a stochastic extension of the standard viral dynamics model, under the assumption that the number of cell targets for viral infection is constant, biologically reasonable since, during the earliest stages of HIV infection, very few cells are infected relative to their total population size. We use our model to investigate three important clinical characteristics of early HIV infection following intravenous challenge: risk of infection, time to infection clearance (assuming failed infection), and time to infection detection. Our focus is on the impact of errors in viral replication that result in non-infectious virus production on these characteristics. Only a small fraction of circulating virus in any chronically infected individual is capable of infecting susceptible cells: estimates range from 1/10⁴ - 1/10³. Characterization and quantification of the processes by which virus becomes defective remains incomplete. We consider two mechanisms that result in defective virus: (1) Copying errors, i.e., lethal errors in reverse transcription, which introduce mutations into the HIV-1 proviral genome, some of which may cripple the viral genome produced, and (2) Packaging errors, i.e., errors during viral packaging, at the end of the viral replication cycle, which cause defective virus by packaging new virions without, for example, viral RNA or key proteins required for infectivity. We show that assumptions on mechanisms of defective virus production can significantly impact early HIV infection model predictions. For example, the risk of infection is orders of magnitude higher if all defective virus is associated with packaging errors, but infection is predicted to be detectable sooner following HIV exposure if all defective virus is associated with copying errors. Thus, in order to make reliable predictions of risk, clearance time, and detection time, better characterization of viral replication is required.

Expert consensus statement on the science of HIV in the context of criminal law

INTRODUCTION

Globally, prosecutions for non-disclosure, exposure or transmission of HIV frequently relate to sexual activity, biting, or spitting. This includes instances in which no harm was intended, HIV transmission did not occur, and HIV transmission was extremely unlikely or not possible. This suggests prosecutions are not always guided by the best available scientific and medical evidence.

DISCUSSION

Twenty scientists from regions across the world developed this Expert Consensus Statement to address the use of HIV science by the criminal justice system. A detailed analysis of the best available scientific and medical research data on HIV transmission, treatment effectiveness and forensic phylogenetic evidence was performed and described so it may be better understood in criminal law contexts. Description of the possibility of HIV transmission was limited to acts most often at issue in criminal cases. The possibility of HIV transmission during a single, specific act was positioned along a continuum of risk, noting that the possibility of HIV transmission varies according to a range of intersecting factors including viral load, condom use, and other risk reduction practices. Current evidence suggests the possibility of HIV transmission during a single episode of sex, biting or spitting ranges from no possibility to low possibility. Further research considered the positive health impact of modern antiretroviral therapies that have improved the life expectancy of most people living with HIV to a point similar to their HIV-negative counterparts, transforming HIV infection into a chronic, manageable health condition. Lastly, consideration of the use of scientific evidence in court found that phylogenetic analysis alone cannot prove beyond reasonable doubt that one person infected another although it can be used to exonerate a defendant.

CONCLUSIONS

The application of up-to-date scientific evidence in criminal cases has the potential to limit unjust prosecutions and convictions. The authors recommend that caution be exercised when considering prosecution, and encourage governments and those working in legal and judicial systems to pay close attention to the significant advances in HIV science that have occurred over the last three decades to ensure current scientific knowledge informs application of the law in cases related to HIV.

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

Background

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

Methods

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

Results

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

Conclusion

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

Pseudotyping of HIV-1 with Human T-Lymphotropic Virus 1 (HTLV-1) Envelope Glycoprotein during HIV-1-HTLV-1 Coinfection Facilitates Direct HIV-1 Infection of Female Genital Epithelial Cells: Implications for Sexual Transmission of HIV-1

Female genital epithelial cells cover the genital tract and provide the first line of protection against infection with sexually transmitted pathogenic viruses. These cells normally are impervious to HIV-1. We report that coinfection of cells by HIV-1 and another sexually transmitted virus, human T-lymphotropic virus 1 (HTLV-1), led to production of HIV-1 that had expanded cell tropism and was able to directly infect primary vaginal and cervical epithelial cells. HIV-1 infection of epithelial cells was blocked by neutralizing antibodies against the HTLV-1 envelope (Env) protein, indicating that the infection was mediated through HTLV-1 Env pseudotyping of HIV-1. Active replication of HIV-1 in epithelial cells was demonstrated by inhibition with anti-HIV-1 drugs. We demonstrated that HIV-1 derived from peripheral blood of HIV-1-HTLV-1-coinfected subjects could infect primary epithelial cells in an HTLV-1 Env-dependent manner. HIV-1 from subjects infected with HIV-1 alone was not able to infect epithelial cells. These results indicate that pseudotyping of HIV-1 with HTLV-1 Env can occur in vivo Our data further reveal that active replication of both HTLV-1 and HIV-1 is required for production of pseudotyped HIV-1. Our findings indicate that pseudotyping of HIV-1 with HTLV-1 Env in coinfected cells enabled HIV-1 to directly infect nonpermissive female genital epithelial cells. This phenomenon may represent a risk factor for enhanced sexual transmission of HIV-1 in regions where virus coinfection is common.IMPORTANCE Young women in certain regions of the world are at very high risk of acquiring HIV-1, and there is an urgent need to identify the factors that promote HIV-1 transmission. HIV-1 infection is frequently accompanied by infection with other pathogenic viruses. We demonstrate that coinfection of cells by HIV-1 and HTLV-1 can lead to production of HIV-1 pseudotyped with HTLV-1 Env that is able to directly infect female genital epithelial cells both in vitro and ex vivo Given the function of these epithelial cells as genital mucosal barriers to pathogenic virus transmission, the ability of HIV-1 pseudotyped with HTLV-1 Env to directly infect female genital epithelial cells represents a possible factor for increased risk of sexual transmission of HIV-1. This mechanism could be especially impactful in settings such as Sub-Saharan Africa and South America, where HIV-1 and HTLV-1 are both highly prevalent.

Genital inflammation undermines the effectiveness of tenofovir gel in preventing HIV acquisition in women

Several clinical trials have demonstrated that antiretroviral (ARV) drugs, taken as pre-exposure prophylaxis (PrEP), can prevent HIV infection¹, with the magnitude of protection ranging from -49 to 86%^2–11. While these divergent outcomes are thought to be due primarily to product adherence¹², biological factors likely contribute¹³. Despite selective recruitment of higher risk participants for prevention trials, HIV risk is heterogeneous, even within higher risk groups^14–16. To determine whether this heterogeneity could influence PrEP outcomes, we undertook a post-hoc prospective analysis of the CAPRISA 004 tenofovir 1% gel trial (n=774), one of the first trials to demonstrate protection against HIV infection. Concentrations of nine pro-inflammatory cytokines were measured in cervicovaginal lavages at >2,000 visits, and a graduated cytokine score was used to define genital inflammation. In women without genital inflammation, tenofovir was 57% protective against HIV (95% CI: 7 to 80%), compared to 3% (95% CI: −104 to 54%) if genital inflammation was present. Among high gel adherers, tenofovir protection was 75% (95% CI: 25 to 92%) in women without inflammation compared to −10% (95% CI: −184 to 57%) in women with inflammation. Host immune predictors of HIV risk may modify the effectiveness of HIV prevention tools; reducing genital inflammation in women may augment HIV prevention efforts.

Early antiretroviral therapy on reducing HIV transmission in China: strengths, weaknesses and next focus of the program

Early antiretroviral therapy (ART) initiation is a recommended public health approach for the prevention of HIV-1 transmission. In this cohort study, we included 13132 serodiscordant couples. ART was initiated for patients with CD4+ T cell counts less than 200 cells/uL, 350 cells/uL, and 500 cells/uL respectively. This divided the ART treated couples into three groups. Univariate and multivariate intention-to-treat analyses were performed to examine the association between the study groups. Early-ART initiation was associated with a 45% lower risk of partner infection than was late-ART initiation (AHR 0.55, 95% CI, 0.37–0.81). Mid-ART initiation was associated with a 39% lower risk of partner infection than was late-ART initiation (AHR 0.61, 95% CI, 0.48–0.78). However, the risk reduction between the early and mid-ART groups was not significant. Drug compliance (AHR 1.55, 95% CI 1.03–2.35) and increased baseline viral load (AHR 1.41, 95% CI 1.33–1.51) were associated with an increased risk of infections among partners in the treatment. Prevention of HIV transmission as a result of early ART initiation was feasible on national and regional scales; however, many factors, such as the motivation to commence ART, adherence, and attrition, may affect the impact of this strategy in programmatic settings.

High risk exposure to HIV among sexually active individuals who tested negative on rapid HIV Tests in the Tshwane District of South Africa-The importance of behavioural prevention measures

OBJECTIVE

To assess the prevalence of HIV risk behaviour among sexually active HIV sero-negative individuals in the Tshwane district of South Africa (SA).

METHODS

Demographic and HIV risk behaviour data were collected on a questionnaire from participants of a cross-sectional study that screened for early HIV infection using pooled nucleic acid amplification testing (NAAT). The study enrolled individuals who tested negative on rapid HIV tests performed at five HIV counseling and testing (HCT) clinics, which included four antenatal clinics and one general HCT clinic.

RESULTS

The study enrolled 9547 predominantly black participants (96.6%) with a median age of 27 years (interquartile range [IQR]: 23-31). There were 1661 non-pregnant and 7886 pregnant participants largely enrolled from the general and antenatal HCT clinics, respectively. NAAT detected HIV infection in 61 participants (0.6%; 95% confidence interval [CI]: 0.4-0.8) in the whole study. A high proportion of study participants, 62.8% and 63.0%, were unaware of their partner's HIV status; and also had high prevalence, 88.5% and 99.5%, of recent unprotected sex in the general and pregnant population, respectively. Consistent use of condoms was associated with protection against HIV infection in the general population. Trends of higher odds for HIV infection were observed with most demographic and HIV risk factors at univariate analysis, however, multivariate analysis did not show statistical significance for almost all these factors. A significantly lower risk of HIV infection was observed in circumcised men (p <0.001).

CONCLUSIONS

These data show that a large segment of sexually active people in the Tshwane district of SA have high risk exposure to HIV. The detection of newly diagnosed HIV infections in all study clinics reflects a wide distribution of individuals who are capable of sustaining HIV transmission in the setting where HIV risk behaviour is highly prevalent. A questionnaire that captures HIV risk behaviour would be useful during HIV counselling and testing to ensure that there is a systematic way of identifying HIV risk factors and that counselling is optimised for each individual. HIV risk behaviour surveillance could be used to inform relevant HIV prevention interventions that could be implemented at a community or population level.

An exact approach to calibrating infectious disease models to surveillance data: The case of HIV and HSV-2

When mathematical models of infectious diseases are used to inform health policy, an important first step is often to calibrate a model to disease surveillance data for a specific setting (or multiple settings). It is increasingly common to also perform sensitivity analyses to demonstrate the robustness, or lack thereof, of the modeling results. Doing so requires the modeler to find multiple parameter sets for which the model produces behavior that is consistent with the surveillance data. While frequently overlooked, the calibration process is nontrivial at best and can be inefficient, poorly communicated and a major hurdle to the overall reproducibility of modeling results. In this work, we describe a general approach to calibrating infectious disease models to surveillance data. The technique is able to match surveillance data to high accuracy in a very efficient manner as it is based on the Newton-Raphson method for solving nonlinear systems. To demonstrate its robustness, we use the calibration technique on multiple models for the interacting dynamics of HIV and HSV-2.

Treatment of HIV for the Prevention of Transmission in Discordant Couples and at the Population Level

The scientific breakthrough proving that antiretroviral therapy (ART) can halt heterosexual HIV transmission came in the form of a landmark clinical trial conducted among serodiscordant couples. Study findings immediately informed global recommendations for the use of treatment as prevention in serodiscordant couples. The extent to which these findings are generalizable to other key populations or to groups exposed to HIV through nonsexual transmission routes (i.e., anal intercourse or unsafe injection of drugs) has since driven a large body of research. This review explores the history of HIV research in serodiscordant couples, the implications for management of couples, subsequent research on treatment as prevention in other key populations, and challenges in community implementation of these strategies.

Factors Driving the HIV Epidemic in Southern Africa

The HIV pandemic has disproportionately impacted sub-Saharan Africa and Southern Africa in particular. The concurrent presence of overlapping epidemic drivers likely underpins how and why the HIV epidemic is so explosive in this region, with implications for understanding approaches to reduce transmission. In this review, we discuss the relative contribution and interaction between epidemic drivers in the Southern African context, including factors both distally and proximally associated with the likelihood and degree of exposure to HIV and factors that increase the probability of transmission when exposure occurs. In particular, we focus on young women as a key population in need of HIV prevention and highlight factors that increase their risk on several levels.

Modeling HIV disease progression and transmission at population-level: The potential impact of modifying disease progression in HIV treatment programs

INTRODUCTION

Mathematical models that incorporate HIV disease progression dynamics can estimate the potential impact of strategies that delay HIV disease progression and reduce infectiousness for persons not on antiretroviral therapy (ART). Suppressive treatment of HIV-positive persons co-infected with herpes simplex virus-2 (HSV-2) with valacyclovir, an HSV-2 antiviral, can lower HIV viral load, but the impact of partially-suppressive valacyclovir relative to fully-suppressive ART on population HIV transmission has not been estimated.

METHODS

We modeled HIV disease progression as a function of changes in viral load and CD4 count over time among ART naïve persons. The disease progression Markov model was nested within a dynamic model of HIV transmission at population level. We assumed that valacyclovir reduced HIV viral load by 1.23 log copies/μL, and that persons treated with valacyclovir initiated ART more rapidly when their CD4 fell below 500 due to retention in HIV care. We estimated the potential impact of valacyclovir on onward transmission of HIV in three scenarios of different ART and valacyclovir population coverage.

RESULTS

The average duration of HIV infection was 9.5 years. The duration of disease before reaching CD4 200cells/μL was 2.53 years longer for females than males. Relative to a baseline of ART initiation at CD4≤500cells/μL, the valacyclovir scenario resulted in 167,000 fewer HIV infections over ten years, with an incremental cost-effectiveness ratio (ICER) of $5276 per HIV infection averted. A Test and Treat scenario with 70% ART coverage and no valacyclovir resulted in 350,000 fewer HIV infections at an ICER of $2822 and $812 per HIV infection averted and QALY gained, respectively.

CONCLUSION

Even when compared with valacyclovir suppression, a drug that reduces HIV viral load, universal treatment for HIV is the optimal strategy for averting new infections and increasing public health benefit. Universal HIV treatment would most effectively and efficiently reduce the HIV burden.

The epidemic emergence of HIV: what novel enabling factors were involved?

Humans acquired retroviruses from simians, mainly through bushmeat handling. All epidemically successful HIV groups started to spread in early 20th century, contrasting with the antiquity of T-cell lymphotropic viruses, implying that novel enabling factors were involved in HIV emergence. Here we review the Parenteral Serial Transmission and the Enhanced Heterosexual Transmission hypotheses for the adaptation and early spread of HIV. Epidemic start roughly coincides in time with peak genital ulcer disease in cities, suggesting a major role for sexual transmission. Only ill-adapted and rare HIV groups emerged after approximately 1950, when injections and transfusions attained their maximal levels, suggesting that if parenteral serial transmission was necessary for HIV adaptation, it had to be complemented by sexual transmission for HIV to reach epidemic potential.

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Factors associated with inconsistent condom use among people living with HIV/Aids

OBJECTIVE

to analyze the prevalence and factors associated with inconsistent use of condoms among people living with HIV/ Aids (PLWHA).

METHOD

it is a cross-sectional study with 228, with individual interviews conducted in 2011. A multivariate analysis was performed with a logistic regression model.

RESULTS

143 participants met the inclusion criteria, and the prevalence of inconsistent condom use was 28.7%. However, there was greater adherence among men (79.3%). In the multivariate analysis, the independent variable daily use of alcohol (OR=11.02; 95% CI 1.84, 65.92; p = 0.021) was associated with inconsistent condom use. The chance of men making consistent condom use was higher than women (OR = 0.36, 95% CI 0.15, 0.81; p = 0.015).

CONCLUSION

the prevalence of inconsistent condom male use among PLWHA was low, however, evidenced greater compliance among men over women with a statistically significant difference and the daily use of alcohol was associated with inconsistent condom use.

Penile Anaerobic Dysbiosis as a Risk Factor for HIV Infection

Sexual transmission of HIV requires exposure to the virus and infection of activated mucosal immune cells, specifically CD4⁺ T cells or dendritic cells. The foreskin is a major site of viral entry in heterosexual transmission of HIV. Although the probability of acquiring HIV from a sexual encounter is low, the risk varies even after adjusting for known HIV risk factors. The genital microbiome may account for some of the variability in risk by interacting with the host immune system to trigger inflammatory responses that mediate the infection of mucosal immune cells. We conducted a case-control study of uncircumcised participants nested within a randomized-controlled trial of male circumcision in Rakai, Uganda. Using penile (coronal sulcus) swabs collected by study personnel at trial enrollment, we characterized the penile microbiome by sequencing and real-time PCR and cytokine levels by electrochemiluminescence assays. The absolute abundances of penile anaerobes at enrollment were associated with later risk of HIV seroconversion, with a 10-fold increase in Prevotella, Dialister, Finegoldia, and Peptoniphilus increasing the odds of HIV acquisition by 54 to 63%, after controlling for other known HIV risk factors. Increased abundances of anaerobic bacteria were also correlated with increased cytokines, including interleukin-8, which can trigger an inflammatory response that recruits susceptible immune cells, suggesting a mechanism underlying the increased risk. These same anaerobic genera can be shared between heterosexual partners and are associated with increased HIV acquisition in women, pointing to anaerobic dysbiosis in the genital microbiome and an accompanying inflammatory response as a novel, independent, and transmissible risk factor for HIV infection.IMPORTANCE We found that uncircumcised men who became infected by HIV during a 2-year clinical trial had higher levels of penile anaerobes than uncircumcised men who remained HIV negative. We also found that having higher levels of penile anaerobes was also associated with higher production of immune factors that recruit HIV target cells to the foreskin, suggesting that anaerobes may modify HIV risk by triggering inflammation. These anaerobes are known to be shared by heterosexual partners and are associated with HIV risk in women. Therefore, penile anaerobes may be a sexually transmissible risk factor for HIV, and modifying the penile microbiome could potentially reduce HIV acquisition in both men and women.

Sexual Behavior Latent Classes Among Men Who Have Sex With Men: Associations With Sexually Transmitted Infections

Men who have sex with men (MSM) are at disproportionate risk of acquisition of sexually transmitted infections (STIs). We used latent class analysis (LCA) to examine patterns of sexual behavior among MSM and how those patterns are related to STIs. We examined patterns of sexual behavior using behavioral and clinical data from a cross-sectional study of 235 MSM who presented to an urban sexual health clinic for STI testing. Analyzed data were collected using a combination of interviewer- and self-administered surveys and electronic health records. We used LCA to identify underlying subgroups of men based on their sexual behavior, described the demographics of the latent classes, and examined the association between the latent classes and STI status. We identified three latent classes of sexual behavior: Unprotected Anal Intercourse (UAI) Only (67%), Partner Seekers (14%), and Multiple Behaviors (19%). Men in the Multiple Behaviors class had a 67% probability of being STI positive, followed by men in the UAI Only class (27%) and men in the Partner Seekers class (22%). Examining the intersection of a variety of sexual practices indicates particular subgroups of MSM have the highest probability of being STI positive.