Acyclovir and transmission of HIV-1 from persons infected with HIV-1 and HSV-2

Host genetic and viral determinants of HIV-1 RNA set point among HIV-1 seroconverters from sub-saharan Africa

We quantified the collective impact of source partner HIV-1 RNA levels, human leukocyte antigen (HLA) alleles, and innate responses through Toll-like receptor (TLR) alleles on the HIV-1 set point. Data came from HIV-1 seroconverters in African HIV-1 serodiscordant couple cohorts. Linear regression was used to determine associations with set point and R(2) to estimate variation explained by covariates. The strongest predictors of set point were HLA alleles (B*53:01, B*14:01, and B*27:03) and plasma HIV-1 levels of the transmitting partner, which explained 13% and 10% of variation in set point, respectively. HLA-A concordance between partners and TLR polymorphisms (TLR2 rs3804100 and TLR7 rs179012) also were associated with set point, explaining 6% and 5% of the variation, respectively. Overall, these factors and genital factors of the transmitter (i.e., male circumcision, bacterial vaginosis, and use of acyclovir) explained 46% of variation in set point. We found that both innate and adaptive immune responses, together with plasma HIV-1 levels of the transmitting partner, explain almost half of the variation in viral load set point.

IMPORTANCE

After HIV-1 infection, uncontrolled virus replication leads to a rapid increase in HIV-1 concentrations. Once host immune responses develop, however, HIV-1 levels reach a peak and subsequently decline until they reach a stable level that may persist for years. This stable HIV-1 set point represents an equilibrium between the virus and host responses and is predictive of later disease progression and transmission potential. Understanding how host and virus factors interact to determine HIV-1 set point may elucidate novel mechanisms or biological pathways for treating HIV-1 infection. We identified host and virus factors that predict HIV-1 set point in people who recently acquired HIV-1, finding that both innate and adaptive immune responses, along with factors that likely influence HIV-1 virulence and inoculum, explain ∼46% of the variation in HIV-1 set point.

Estimating the cost-effectiveness of pre-exposure prophylaxis to reduce HIV-1 and HSV-2 incidence in HIV-serodiscordant couples in South Africa

OBJECTIVE

To estimate the cost-effectiveness of daily oral tenofovir-based PrEP, with a protective effect against HSV-2 as well as HIV-1, among HIV-1 serodiscordant couples in South Africa.

METHODS

We incorporated HSV-2 acquisition, transmission, and interaction with HIV-1 into a microsimulation model of heterosexual HIV-1 serodiscordant couples in South Africa, with use of PrEP for the HIV-1 uninfected partner prior to ART initiation for the HIV-1 1infected partner, and for one year thereafter.

RESULTS

We estimate the cost per disability-adjusted life-year (DALY) averted for two scenarios, one in which PrEP has no effect on reducing HSV-2 acquisition, and one in which there is a 33% reduction. After a twenty-year intervention, the cost per DALY averted is estimated to be $10,383 and $9,757, respectively--a 6% reduction, given the additional benefit of reduced HSV-2 acquisition. If all couples are discordant for both HIV-1 and HSV-2, the cost per DALY averted falls to $1,445, which shows that the impact is limited by HSV-2 concordance in couples.

CONCLUSION

After a 20-year PrEP intervention, the cost per DALY averted with a reduction in HSV-2 is estimated to be modestly lower than without any effect, providing an increase of health benefits in addition to HIV-1 prevention at no extra cost. The small degree of the effect is in part due to a high prevalence of HSV-2 infection in HIV-1 serodiscordant couples in South Africa.

Global estimates of prevalent and incident herpes simplex virus type 2 infections in 2012

Background

Herpes simplex virus type 2 (HSV-2) infection causes significant disease globally. Adolescent and adult infection may present as painful genital ulcers. Neonatal infection has high morbidity and mortality. Additionally, HSV-2 likely contributes substantially to the spread of HIV infection. The global burden of HSV-2 infection was last estimated for 2003. Here we present new global estimates for 2012 of the burden of prevalent (existing) and incident (new) HSV-2 infection among females and males aged 15–49 years, using updated methodology to adjust for test performance and estimate by World Health Organization (WHO) region.

Methods and Findings

We conducted a literature review of HSV-2 prevalence studies world-wide since 2000. We then fitted a model with constant HSV-2 incidence by age to pooled HSV-2 prevalence values by age and sex. Prevalence values were adjusted for test sensitivity and specificity. The model estimated prevalence and incidence by sex for each WHO region to obtain global burden estimates. Uncertainty bounds were computed by refitting the model to reflect the variation in the underlying prevalence data. In 2012, we estimate that there were 417 million people aged 15–49 years (range: 274–678 million) living with HSV-2 infection world-wide (11.3% global prevalence), of whom 267 million were women. We also estimate that in 2012, 19.2 million (range: 13.0–28.6 million) individuals aged 15–49 years were newly-infected (0.5% of all individuals globally). The highest burden was in Africa. However, despite lower prevalence, South-East Asia and Western Pacific regions also contributed large numbers to the global totals because of large population sizes.

Conclusions

The global burden of HSV-2 infection is large, leaving over 400 million people at increased risk of genital ulcer disease, HIV acquisition, and transmission of HSV-2 to partners or neonates. These estimates highlight the critical need for development of vaccines, microbicides, and other new HSV prevention strategies.

Hormonal contraception and the risk of HIV acquisition: an individual participant data meta-analysis

BACKGROUND

Observational studies of a putative association between hormonal contraception (HC) and HIV acquisition have produced conflicting results. We conducted an individual participant data (IPD) meta-analysis of studies from sub-Saharan Africa to compare the incidence of HIV infection in women using combined oral contraceptives (COCs) or the injectable progestins depot-medroxyprogesterone acetate (DMPA) or norethisterone enanthate (NET-EN) with women not using HC.

METHODS AND FINDINGS

Eligible studies measured HC exposure and incident HIV infection prospectively using standardized measures, enrolled women aged 15-49 y, recorded ≥15 incident HIV infections, and measured prespecified covariates. Our primary analysis estimated the adjusted hazard ratio (aHR) using two-stage random effects meta-analysis, controlling for region, marital status, age, number of sex partners, and condom use. We included 18 studies, including 37,124 women (43,613 woman-years) and 1,830 incident HIV infections. Relative to no HC use, the aHR for HIV acquisition was 1.50 (95% CI 1.24-1.83) for DMPA use, 1.24 (95% CI 0.84-1.82) for NET-EN use, and 1.03 (95% CI 0.88-1.20) for COC use. Between-study heterogeneity was mild (I(2) < 50%). DMPA use was associated with increased HIV acquisition compared with COC use (aHR 1.43, 95% CI 1.23-1.67) and NET-EN use (aHR 1.32, 95% CI 1.08-1.61). Effect estimates were attenuated for studies at lower risk of methodological bias (compared with no HC use, aHR for DMPA use 1.22, 95% CI 0.99-1.50; for NET-EN use 0.67, 95% CI 0.47-0.96; and for COC use 0.91, 95% CI 0.73-1.41) compared to those at higher risk of bias (p(interaction) = 0.003). Neither age nor herpes simplex virus type 2 infection status modified the HC-HIV relationship.

CONCLUSIONS

This IPD meta-analysis found no evidence that COC or NET-EN use increases women's risk of HIV but adds to the evidence that DMPA may increase HIV risk, underscoring the need for additional safe and effective contraceptive options for women at high HIV risk. A randomized controlled trial would provide more definitive evidence about the effects of hormonal contraception, particularly DMPA, on HIV risk.

The experiences of HIV-serodiscordant couples in Soweto, South Africa

INTRODUCTION

The study was carried out in a single township in South Africa with a sample size of seven human immunodeficiency virus (HIV)-serodiscordant couples.

BACKGROUND

South Africa has the highest number of HIV cases in the world, with an estimated 6.4 million of its inhabitants living with this infection. Most people in stable relationships are unaware of the HIV serostatuses of their partners. Many people with an HIV partner are also generally unaware of their own HIV serostatuses. There is a high risk of acquisition of the HIV among couples in HIV-serodiscordant relationships. Yet, there is a dearth of research on HIV-serodiscordant couples.

AIM

To explore the experiences and knowledge of HIV-serodiscordant couples on HIV serodiscordance.

METHODS

A qualitative design of interpretative phenomenological analysis was used. Data were collected from seven HIV-serodiscordant couples using a semi-structured interview format. Data were analysed thematically using the principles of interpretative phenomenological analysis.

RESULTS

Three superordinate themes emerged from data analysis: experiences of stress, effects of HIV serodiscordance on couples and knowledge of HIV serodiscordance. The study outcomes were based on retrospective accounts of couples' experiences of HIV serodiscordance. Such accounts are subject to memory bias.

CONCLUSION

HIV-serodiscordant relationships are riddled with stress. Couples and nurses' knowledge and understanding of the concept of HIV serodiscordance is limited. Such limitation may negatively influence the quality of care and support offered to couples in these relationships.

IMPLICATIONS FOR NURSING AND HEALTH POLICY

HIV-serodiscordant couples need to be educated on this phenomenon. Nurses also need to be offered training on how to support and care for couples in these relationships. Such training should be shaped by couples' health-seeking behaviours and cultural norms. Specific guidelines and policy on HIV serodiscordance should be developed to ensure consistency in care provision and enhance uptake of support services.

Sero-prevalence of herpes simplex type 2 virus (HSV-2) and HIV infection in Kampala, Uganda

BACKGROUND

Prevalence of herpes simplex type 2 virus (HSV-2) is high worldwide. Previous studies in Uganda were rural or in women. We estimated age and sex-specific sero-prevalence of HSV-2 in Kampala, Uganda.

METHODS

Using two-stage random sampling stratified on population density, a survey of persons 15-65 years was conducted. Type-specific serological tests for HSV-2, HSV-1(HerpeSelect2 and 1 ELISA), HIV (Rapid tests and ELISA), syphilis (RPR and TPHA) were done. Additional prevalence analysis included post-stratification weighting on the Uganda 2002 Census gender distribution.

RESULTS

Among 1124 persons, HSV-2 prevalence was 58% (95% CI: 55, 60), HSV-1; 98% (95% CI: 97.6, 99.1), HIV; 17.7% (95% CI: 14.8, 19.2) and syphilis; 1.7% (95% CI: 1.4, 1.9). Weighted HSV-2 prevalence was 53.8% (Women; 63.8%, men; 43.2%), similar to unweighted data. Weighted HIV prevalence was 20.7% in women, 8.6% in men. Of 165 HIV infected persons, 85.4% had HSV-2. Risk factors for HSV-2 were being a woman (OR 2.0; 95% CI: 1.42, 2.78), age (OR 3.3; 95% CI: 2.43, 4.53), education (OR 1.70; 95% CI: 1.34, 2.34) and HIV (OR 4.5; 95% CI: 2.70, 7.50).

CONCLUSION

Prevalence of HSV-2 and HIV was high especially in women. Syphilis was rare. Awareness of herpes was low. Interventions in young people are needed.

HSV-2-driven increase in the expression of α4β7 correlates with increased susceptibility to vaginal SHIV(SF162P3) infection

The availability of highly susceptible HIV target cells that can rapidly reach the mucosal lymphoid tissues may increase the chances of an otherwise rare transmission event to occur. Expression of α4β7 is required for trafficking of immune cells to gut inductive sites where HIV can expand and it is expressed at high level on cells particularly susceptible to HIV infection. We hypothesized that HSV-2 modulates the expression of α4β7 and other homing receptors in the vaginal tissue and that this correlates with the increased risk of HIV acquisition in HSV-2 positive individuals. To test this hypothesis we used an in vivo rhesus macaque (RM) model of HSV-2 vaginal infection and a new ex vivo model of macaque vaginal explants. In vivo we found that HSV-2 latently infected RMs appeared to be more susceptible to vaginal SHIVSF162P3 infection, had higher frequency of α4β7high CD4+ T cells in the vaginal tissue and higher expression of α4β7 and CD11c on vaginal DCs. Similarly, ex vivo HSV-2 infection increased the susceptibility of the vaginal tissue to SHIVSF162P3. HSV-2 infection increased the frequencies of α4β7high CD4+ T cells and this directly correlated with HSV-2 replication. A higher amount of inflammatory cytokines in vaginal fluids of the HSV-2 infected animals was similar to those found in the supernatants of the infected explants. Remarkably, the HSV-2-driven increase in the frequency of α4β7high CD4+ T cells directly correlated with SHIV replication in the HSV-2 infected tissues. Our results suggest that the HSV-2-driven increase in availability of CD4+ T cells and DCs that express high levels of α4β7 is associated with the increase in susceptibility to SHIV due to HSV-2. This may persists in absence of HSV-2 shedding. Hence, higher availability of α4β7 positive HIV target cells in the vaginal tissue may constitute a risk factor for HIV transmission.

Plasma cytokine levels and risk of HIV type 1 (HIV-1) transmission and acquisition: a nested case-control study among HIV-1-serodiscordant couples

BACKGROUND

A heightened proinflammatory state has been hypothesized to enhance human immunodeficiency virus type 1 (HIV-1) transmission - both susceptibility of HIV-1-exposed persons and infectiousness of HIV-1-infected persons.

METHODS

Using prospective data from heterosexual African couples with HIV-1 serodiscordance, we conducted a nested case-control analysis to assess the relationship between cytokine concentrations and the risk of HIV-1 acquisition. Case couples (n = 120) were initially serodiscordant couples in which HIV-1 was transmitted to the seronegative partner during the study; control couples (n = 321) were serodiscordant couples in which HIV-1 was not transmitted to the seronegative partner. Differences in a panel of 30 cytokines were measured using plasma specimens from both HIV-1-susceptible and HIV-1-infected partners. Plasma was collected before seroconversion for cases.

RESULTS

For both HIV-1-infected and HIV-1-susceptible partners, cases and controls had significantly different mean responses in cytokine panels (P < .001, by the Hotelling T(2) test), suggesting a broadly different pattern of immune activation for couples in which HIV-1 was transmitted, compared with couples without transmission. Individually, log10 mean concentrations of interleukin 10 (IL-10) and CXCL10 were significantly higher for both HIV-1-susceptible and HIV-1-infected case partners, compared with HIV-1-susceptible and HIV-1-infected control partners (P < .01 for all comparisons). In multivariate analysis, HIV-1 transmission was significantly associated with elevated CXCL10 concentrations in HIV-1-susceptible partners (P = .001) and with elevated IL-10 concentrations in HIV-1-infected partners (P = .02).

CONCLUSIONS

Immune activation, as measured by levels of cytokine markers, particularly elevated levels of IL-10 and CXCL1, are associated with increased HIV-1 susceptibility and infectiousness.

Assessment of a new web-based sexual concurrency measurement tool for men who have sex with men

BACKGROUND

Men who have sex with men (MSM) are the most affected risk group in the United States' human immunodeficiency virus (HIV) epidemic. Sexual concurrency, the overlapping of partnerships in time, accelerates HIV transmission in populations and has been documented at high levels among MSM. However, concurrency is challenging to measure empirically and variations in assessment techniques used (primarily the date overlap and direct question approaches) and the outcomes derived from them have led to heterogeneity and questionable validity of estimates among MSM and other populations.

OBJECTIVE

The aim was to evaluate a novel Web-based and interactive partnership-timing module designed for measuring concurrency among MSM, and to compare outcomes measured by the partnership-timing module to those of typical approaches in an online study of MSM.

METHODS

In an online study of MSM aged ≥18 years, we assessed concurrency by using the direct question method and by gathering the dates of first and last sex, with enhanced programming logic, for each reported partner in the previous 6 months. From these methods, we computed multiple concurrency cumulative prevalence outcomes: direct question, day resolution / date overlap, and month resolution / date overlap including both 1-month ties and excluding ties. We additionally computed variants of the UNAIDS point prevalence outcome. The partnership-timing module was also administered. It uses an interactive month resolution calendar to improve recall and follow-up questions to resolve temporal ambiguities, combines elements of the direct question and date overlap approaches. The agreement between the partnership-timing module and other concurrency outcomes was assessed with percent agreement, kappa statistic (κ), and matched odds ratios at the individual, dyad, and triad levels of analysis.

RESULTS

Among 2737 MSM who completed the partnership section of the partnership-timing module, 41.07% (1124/2737) of individuals had concurrent partners in the previous 6 months. The partnership-timing module had the highest degree of agreement with the direct question. Agreement was lower with date overlap outcomes (agreement range 79%-81%, κ range .55-.59) and lowest with the UNAIDS outcome at 5 months before interview (65% agreement, κ=.14, 95% CI .12-.16). All agreements declined after excluding individuals with 1 sex partner (always classified as not engaging in concurrency), although the highest agreement was still observed with the direct question technique (81% agreement, κ=.59, 95% CI .55-.63). Similar patterns in agreement were observed with dyad- and triad-level outcomes.

CONCLUSIONS

The partnership-timing module showed strong concurrency detection ability and agreement with previous measures. These levels of agreement were greater than others have reported among previous measures. The partnership-timing module may be well suited to quantifying concurrency among MSM at multiple levels of analysis.

The challenges and opportunities for the development of a T-cell epitope-based herpes simplex vaccine

Herpes simplex virus type 1 and type 2 (HSV-1 & HSV-2) infections have been prevalent since the ancient Greek times. To this day, they still affect a staggering number of over a billion individuals worldwide. HSV-1 infections are predominant than HSV-2 infections and cause potentially blinding ocular herpes, oro-facial herpes and encephalitis. HSV-2 infections cause painful genital herpes, encephalitis, and death in newborns. While prophylactic and therapeutic HSV vaccines remain urgently needed for centuries, their development has been difficult. During the most recent National Institute of Health (NIH) workshop titled "Next Generation Herpes Simplex Virus Vaccines: The Challenges and Opportunities", basic researchers, funding agencies, and pharmaceutical representatives gathered: (i) to assess the status of herpes vaccine research; and (ii) to identify the gaps and propose alternative approaches in developing a safe and efficient herpes vaccine. One "common denominator" among previously failed clinical herpes vaccine trials is that they either used a whole virus or a whole viral protein, which contain both "pathogenic symptomatic" and "protective asymptomatic" antigens and epitopes. In this report, we continue to advocate developing "asymptomatic" epitope-based sub-unit vaccine strategies that selectively incorporate "protective asymptomatic" epitopes which: (i) are exclusively recognized by effector memory CD4(+) and CD8(+) T cells (TEM cells) from "naturally" protected seropositive asymptomatic individuals; and (ii) protect human leukocyte antigen (HLA) transgenic animal models of ocular and genital herpes. We review the role of animal models in herpes vaccine development and discuss their current status, challenges, and prospects.

Systematic review of couple-based HIV intervention and prevention studies: advantages, gaps, and future directions

We conducted a systematic review of couple-based HIV biobehavioral (skills-building, VCT, and adherence) and biomedical (ART, circumcision) prevention and intervention studies designed to reduce sexual- and drug-risk behaviors and HIV transmission and acquisition. Of the 11,162 papers identified in the search, 93 peer-reviewed papers met the inclusion criteria and yielded a total of 33 studies conducted globally. Biobehavioral couple-based prevention and intervention studies have been efficacious in reducing sexual- and drug-risk behaviors, increasing access to HIV testing and care, and improving adherence. Biomedical couple-based studies were found to reduce HIV incidence among HIV-negative sex partners and viral load among HIV-positive partners. Despite much progress, couple-based HIV prevention and intervention studies remain limited; a number of methodological gaps exist and studies focusing on MSM, people who inject drugs, and sex workers are scarce.

Preconception care: preventing and treating infections

Introduction

Infections can impact the reproductive health of women and hence may influence pregnancy related outcomes for both the mother and the child. These infections range from sexually transmitted infections (STIs) to TORCHS infections to periodontal disease to systemic infections and may be transmitted to the fetus during pregnancy, labor, delivery or breastfeeding.

Methods

A systematic review and meta-analysis of the evidence was conducted to ascertain the possible impact of preconception care for adolescents, women and couples of reproductive age on MNCH outcomes. A comprehensive strategy was used to search electronic reference libraries, and both observational and clinical controlled trials were included. Cross-referencing and a separate search strategy for each preconception risk and intervention ensured wider study capture.

Results

Preconception behavioral interventions significantly declines re-infection or new STI rates by 35% (95% CI: 20-47%). Further, condom use has been shown to be the most effective way to prevent HIV infection (85% protection in prospective studies) through sexual intercourse. Intervention trials showed that preconception vaccination against tetanus averted a significant number of neonatal deaths (including those specifically due to tetanus) when compared to placebo in women receiving more than 1 dose of the vaccine (OR 0.28; 95% CI: 0.15-0.52); (OR 0.02; 95% CI: 0.00-0.28) respectively.

Conclusion

Preconception counseling should be offered to women of reproductive age as soon as they test HIV-positive, and conversely women of reproductive age should be screened with their partners before pregnancy. Risk assessment, screening, and treatment for specific infections should be a component of preconception care because there is convincing evidence that treatment of these infections before pregnancy prevents neonatal infections.

Preconception care: delivery strategies and packages for care

The notion of preconception care aims to target the existing risks before pregnancy, whereby resources may be used to improve reproductive health and optimize knowledge before conceiving. The preconception period provides an opportunity to intervene earlier to optimize the health of potential mothers (and fathers) and to prevent harmful exposures from affecting the developing fetus. These interventions include birth spacing and preventing teenage pregnancy, promotion of contraceptive use, optimization of weight and micronutrient status, prevention and management of infectious diseases, and screening for and managing chronic conditions. Given existing interventions and the need to organize services to optimize delivery of care in a logical and effective manner, interventions are frequently co-packaged or bundled together. This paper highlights packages of preconception interventions that can be combined and co-delivered to women through various delivery channels and provides a logical framework for development of such packages in varying contexts.

An intervention to support HIV preexposure prophylaxis adherence in HIV-serodiscordant couples in Uganda

BACKGROUND

Daily preexposure prophylaxis (PrEP) is an effective HIV prevention strategy, but adherence is required for maximum benefit. To date, there are no empirically supported PrEP adherence interventions. This article describes the process of developing a PrEP adherence intervention and presents results on its impact on adherence.

METHODS

The Partners PrEP Study was a placebo-controlled efficacy trial of daily oral tenofovir and emtricitabine/tenofovir PrEP among uninfected members of HIV-serodiscordant couples. An ancillary adherence study was conducted at 3 study sites in Uganda. Participants with <80% adherence as measured by unannounced pill count received an additional adherence counseling intervention based on Lifesteps, an evidence-based HIV treatment adherence intervention, based on principles of cognitive-behavioral theory.

FINDINGS

Of the 1147 HIV-seronegative participants enrolled in the ancillary adherence study, 168 (14.6%) triggered the adherence intervention. Of participants triggering the intervention, 62% were men; median age was 32.5 years. The median number of adherence counseling sessions was 10. Mean adherence during the month before the intervention was 75.7% and increased significantly to 84.1% in the month after the first intervention session (P < 0.001). The most frequently endorsed adherence barriers at session 1 were travel and forgetting.

INTERPRETATION

A PrEP adherence intervention was feasible in a clinical trial of PrEP in Uganda and PrEP adherence increased after the intervention. Future research should identify PrEP users with low adherence for enhanced adherence counseling and determine optimal implementation strategies for interventions to maximize PrEP effectiveness.

The effect of valacyclovir on HIV and HSV-2 in HIV-infected persons on antiretroviral therapy with previously unrecognised HSV-2

In the absence of antiretroviral therapy, valacyclovir may reduce HIV viral load and increase CD4+ T-lymphocyte count. We sought to evaluate the impact of valacyclovir on HIV and HSV-2 in co-infected patients receiving antiretroviral therapy with previously unrecognised HSV-2 infection. A prospective, randomised-controlled, 24-week trial of valacyclovir 1000 mg was performed. Mean CD4+ T-lymphocyte count at 24 weeks compared to baseline CD4+ T-lymphocyte count was the primary outcome. HIV viral load suppression, HSV-2 outbreaks and asymptomatic HSV-2 shedding were secondary outcomes. Participants were randomised to valacyclovir (N = 66) or placebo (N = 35). Study completion was 64%. There was no change in 24 weeks compared to baseline CD4+ T-lymphocyte count in either group (valacyclovir p = 0.91, placebo p = 0.59) or the proportion with HIV viral load suppression (valacyclovir p = 0.75, placebo p = 1.0). Genital HSV and asymptomatic HSV-2 shedding were rare. Valacyclovir had no effect on CD4+ T-lymphocyte count or HIV viral load in this population. Valacyclovir may reduce clinical outbreaks and asymptomatic HSV-2 shedding, but the rarity of these events, along with its lack of benefit on HIV, does not support its use in this clinical setting.

Prospects and perspectives for development of a vaccine against herpes simplex virus infections

Herpes simplex viruses 1 and 2 are human pathogens that lead to significant morbidity and mortality in certain clinical settings. The development of effective antiviral medications, however, has had little discernible impact on the epidemiology of these pathogens, largely because the majority of infections are clinically silent. Decades of work have gone into various candidate HSV vaccines, but to date none has demonstrated sufficient efficacy to warrant licensure. This review examines developments in HSV immunology and vaccine development published since 2010, and assesses the prospects for improved immunization strategies that may result in an effective, licensed vaccine in the near future.

HIV infection: epidemiology, pathogenesis, treatment, and prevention

HIV prevalence is increasing worldwide because people on antiretroviral therapy are living longer, although new infections decreased from 3.3 million in 2002, to 2.3 million in 2012. Global AIDS-related deaths peaked at 2.3 million in 2005, and decreased to 1.6 million by 2012. An estimated 9.7 million people in low-income and middle-income countries had started antiretroviral therapy by 2012. New insights into the mechanisms of latent infection and the importance of reservoirs of infection might eventually lead to a cure. The role of immune activation in the pathogenesis of non-AIDS clinical events (major causes of morbidity and mortality in people on antiretroviral therapy) is receiving increased recognition. Breakthroughs in the prevention of HIV important to public health include male medical circumcision, antiretrovirals to prevent mother-to-child transmission, antiretroviral therapy in people with HIV to prevent transmission, and antiretrovirals for pre-exposure prophylaxis. Research into other prevention interventions, notably vaccines and vaginal microbicides, is in progress.

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

Supplemental Digital Content is Available in the Text.

Objective:

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

Methods:

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

Results:

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

Conclusions:

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

HIV sexual transmission risk among serodiscordant couples: assessing the effects of combining prevention strategies

BACKGROUND

The number of strategies to prevent HIV transmission has increased following trials evaluating antiretroviral therapy (ART), preexposure prophylaxis (PrEP) and male circumcision. Serodiscordant couples need guidance on the effects of these strategies alone, and in combination with each other, on HIV transmission.

METHODS

We estimated the sexual risk of HIV transmission over 1-year and 10-year periods among male-male and male-female serodiscordant couples. We assumed the following reductions in transmission: 80% from consistent condom use; 54% from circumcision in the negative male partner of a heterosexual couple; 73% from circumcision in the negative partner of a male-male couple; 71% from PrEP in heterosexual couples; 44% from PrEP in male-male couples; and 96% from ART use by the HIV-infected partner.

FINDINGS

For couples using any single prevention strategy, a substantial cumulative risk of HIV transmission remained. For a male-female couple using only condoms, estimated risk over 10 years was 11%; for a male-male couple using only condoms, estimated risk was 76%. ART use by the HIV-infected partner was the most effective single strategy in reducing risk; among male-male couples, adding consistent condom use was necessary to keep the 10-year risk below 10%.

CONCLUSION

Focusing on 1-year and longer term transmission probabilities gives couples a better understanding of risk than those illustrated by data for a single sexual act. Long-term transmission probabilities to the negative partner in serodiscordant couples can be high, though these can be substantially reduced with the strategic use of preventive methods, especially those that include ART.

Impact of viral load and the duration of primary infection on HIV transmission: systematic review and meta-analysis

OBJECTIVES

HIV 'treatment as prevention' (TasP) describes early treatment of HIV-infected patients intended to reduce viral load and transmission. Crucial assumptions for estimating TasP's effectiveness are the underlying estimates of transmission risk. We aimed to determine transmission risk during primary infection, and describe the relation of HIV transmission risk to viral load.

DESIGN

A systematic review and meta-analysis.

METHODS

We searched PubMed and Embase databases for studies that established a relationship between viral load and transmission risk, or primary infection and transmission risk, in serodiscordant couples. We analysed assumptions about the relationship between viral load and transmission risk, and between duration of primary infection and transmission risk.

RESULTS

We found 36 eligible articles, based on six different study populations. Studies consistently found that higher viral loads lead to higher HIV transmission rates, but assumptions about the shape of this increase varied from exponential increase to saturation. The assumed duration of primary infection ranged from 1.5 to 12 months; for each additional month, the log10 transmission rate ratio between primary and asymptomatic infection decreased by 0.40.

CONCLUSION

Assumptions and estimates of the relationship between viral load and transmission risk, and the relationship between primary infection and transmission risk, vary substantially and predictions of TasP's effectiveness should take this uncertainty into account.

Impact of CMV therapy with valganciclovir on immune activation and the HIV viral load in semen and blood: an observational clinical study

BACKGROUND

The HIV RNA viral load (VL) in vaginal secretions and semen is an independent predictor of HIV transmission. Blood VL is associated with semen VL, and local mucosal factors, such as semen cytomegalovirus (CMV) reactivation, may play an important role.

METHODS

Twenty-one HIV-CMV-coinfected, antiretroviral-naive men received 900 mg of oral valganciclovir once daily for 2 weeks in an open-label study. Blood and semen were collected at baseline, after 2 weeks of valganciclovir, and 2 months after therapy completion. The primary end point was change in semen HIV levels at 2 weeks, and the secondary end points were change in semen HIV VL at 2 months and change in semen CMV levels.

RESULTS

The HIV VLs fell significantly at 2 weeks in semen (median 3.44-3.02 log10 copies/mL, P = 0.02) and blood (median 3.61-3.10 log10 copies/mL, P < 0.01) and returned to baseline after therapy completion (median 3.24 and 3.71 log10 copies/mL in semen and blood, respectively). Semen CMV levels also fell on treatment (median 2.13-1.62 log10 copies/mL, P < 0.01) and continued to fall after therapy completion (median 0.91 log10 copies/mL at week 8, P < 0.001 vs. baseline). The reduced semen CMV VL was associated with decreased semen T-cell activation and enhanced CMV-specific T-cell responses in blood; changes in the semen HIV VL were not associated with immune parameters.

CONCLUSIONS

Although valganciclovir therapy was associated with reduced HIV and semen CMV levels, these results suggest that the reduced HIV VL was a direct drug effect rather than a CMV antiviral effect or CMV-associated immune alterations.

Qualitative evaluation of a Positive Prevention training for health care providers in Mozambique

The rapid scale-up of HIV care and treatment in Mozambique has provided an opportunity to reach people living with HIV (PLHIV) with prevention interventions in HIV care and treatment settings. A three-day Positive Prevention (PP) training intervention for health care providers that focused on pressing issues for PLHIV in Mozambique was adapted and delivered at sites in three provinces. In-depth interviews were conducted with 31 providers trained in the PP curriculum. Qualitative data were used to assess the appropriateness of the training materials and approach, which lessons providers learned and were able to implement and which PP messages were still difficult to deliver. Providers reported gaining numerous insights from the training, including how to conduct a risk assessment and client-centered counseling, negotiating disclosure, partner testing, condom use, PMTCT, treatment adherence and approaches for positive living. Training topics not commonly mentioned included discordance counseling, STIs, family planning, alcohol and drug use, and frank sexual risk discussions. While areas for improvement exist, the PP training was useful in transferring skills to providers and is a viable component of HIV care. This evaluation helps identify areas where future PP trainings and specific strategies and messages can be refined for the Mozambican context.

Toward global prevention of sexually transmitted infections (STIs): the need for STI vaccines

An estimated 499 million curable sexually transmitted infections (STIs; gonorrhea, chlamydia, syphilis, and trichomoniasis) occurred globally in 2008. In addition, well over 500 million people are estimated to have a viral STI such as herpes simplex virus type 2 (HSV-2) or human papillomavirus (HPV) at any point in time. STIs result in a large global burden of sexual, reproductive, and maternal-child health consequences, including genital symptoms, pregnancy complications, cancer, infertility, and enhanced HIV transmission, as well as important psychosocial consequences and financial costs. STI control strategies based primarily on behavioral primary prevention and STI case management have had clear successes, but gains have not been universal. Current STI control is hampered or threatened by several behavioral, biological, and implementation challenges, including a large proportion of asymptomatic infections, lack of feasible diagnostic tests globally, antimicrobial resistance, repeat infections, and barriers to intervention access, availability, and scale-up. Vaccines against HPV and hepatitis B virus offer a new paradigm for STI control. Challenges to existing STI prevention efforts provide important reasons for working toward additional STI vaccines. We summarize the global epidemiology of STIs and STI-associated complications, examine challenges to existing STI prevention efforts, and discuss the need for new STI vaccines for future prevention efforts.

Cervicovaginal HIV-1 shedding in women taking antiretroviral therapy in Burkina Faso: a longitudinal study

BACKGROUND

Antiretroviral therapy (ART) reduces transmission of HIV-1. However, genital HIV-1 can be detected in patients on ART. We analyzed factors associated with genital HIV-1 shedding among high-risk women on ART in Burkina Faso.

METHODS

Plasma viral load (PVL) and enriched cervicovaginal lavage HIV-1 RNA were measured every 3-6 months for up to 8 years. Random-effects logistic and linear regression models were used to analyze associations of frequency and quantity of genital HIV-1 RNA with behavioral and biological factors, adjusting for within-woman correlation. The lower limit of detection of HIV-1 RNA in plasma and eCVL samples was 300 copies per milliliter.

RESULTS

One hundred and eighty-eight participants initiated ART from 2004 to 2011. PVL was detectable in 16% (171/1050) of visits, in 52% (90/174) of women. Cervicovaginal HIV-1 RNA was detectable in 16% (128/798) of visits with undetectable plasma HIV-1 RNA in 45% (77/170) of women. After adjusting for PVL, detectable cervicovaginal HIV-1 RNA was independently associated with abnormal vaginal discharge and use of nevirapine or zidovudine vs. efavirenz and stavudine, respectively; longer time on ART and hormonal contraception were not associated with increased shedding. The presence of bacterial vaginosis, herpes simplex virus-2 DNA, and the use of nevirapine vs efavirenz were independently associated with an increased quantity of cervicovaginal HIV-1 RNA.

CONCLUSIONS

Certain ART regimens, abnormal vaginal discharge, bacterial vaginosis, and genital herpes simplex virus-2 are associated with HIV-1 cervicovaginal shedding or quantity in women on ART after adjusting for PVL. This may reduce the effectiveness of ART as prevention in high-risk populations.

An inquiry into the molecular basis of HSV latency and reactivation

Herpes simplex virus (HSV) evolved an elegant strategy that enables the virus to impact a large fraction of the human population. The virus replicates at the portal of entry (mouth, genitals) and concurrently it is transported retrograde to sensory neurons. In sensory neurons it establishes a silent (latent) infection. A variety of stimuli can reactivate the virus. The reactivated virus is transmitted anterograde to a site at the portal of entry for transmission by physical contact between infected and uninfected tissues to other individuals. The central issue is how a virus that vigorously replicates and successfully blocks the innate immune defenses of the host at the portal of entry into the body remains silent in sensory neurons. The presentation focuses on three key issues: (a) current assessment of the impact of HSV on human health, (b) the mechanisms by which the virus overcomes a key host defense mechanism at the portal of entry into the body and yet is silenced in latently infected neurons, and (c) the mechanisms by which the virus reactivates.

Daily oral emtricitabine/tenofovir preexposure prophylaxis and herpes simplex virus type 2 among men who have sex with men

Background

In addition to protecting against HIV acquisition, antiretroviral preexposure prophylaxis (PrEP) using topical 1% tenofovir gel reduced Herpes simplex virus type 2 (HSV-2) acquisition by 51% among women in the CAPRISA 004 study. We examined the effect of daily oral emtricitabine/tenofovir (FTC/TDF) PrEP on HSV-2 seroincidence and ulcer occurrence among men who have sex with men (MSM) in the iPrEx trial.

Methods

HSV-2 serum testing was performed at screening and every six months. Among HSV-2-seronegative individuals, we used Cox regression models to estimate hazard ratios (HRs) of HSV-2 seroincidence associated with randomization to FTC/TDF. We used multiple imputation and Cox regression to estimate HRs for HSV-2 seroincidence accounting for drug exposure. We assessed ulcer occurrence among participants with prevalent or incident HSV-2 infection.

Results

Of the 2,499 participants, 1383 (55.3%) tested HSV-2-seronegative at baseline, 892 (35.7%) tested positive, 223 (8.9%) had indeterminate tests, and one test was not done. Of the 1,347 HSV-2-seronegative participants with follow-up, 125 (9.3%) had incident HSV-2 infection (5.9 per 100 person-years). Compared with participants receiving placebo, there was no difference in HSV-2 seroincidence among participants receiving FTC/TDF (HR 1.1, 95% CI: 0.8–1.5; P = 0.64) or among participants receiving FTC/TDF with a concentration of tenofovir diphosphate >16 per million viable cells (HR 1.0, 95% CI: 0.3–3.5; P = 0.95). Among participants with HSV-2 infection, the proportion with ≥1 moderate or severe ulcer adverse event was twice as high in the placebo vs. active arm (5.9% vs. 2.9%, P = 0.02), but there were no differences in the proportions with ≥1 clinical examination during which perianal or groin ulcers were identified.

Conclusions

Tenofovir in daily oral FTC/TDF PrEP may reduce the occurrence of ulcers in individuals with HSV-2 infection but does not protect against HSV-2 incidence among MSM.

Sources of HIV incidence among stable couples in sub-Saharan Africa

Introduction

The recent availability of efficacious prevention interventions among stable couples offers new opportunities for reducing HIV incidence in sub-Saharan Africa. Understanding the dynamics of HIV incidence among stable couples is critical to inform HIV prevention strategy across sub-Saharan Africa.

Methods

We quantified the sources of HIV incidence arising among stable couples in sub-Saharan Africa using a cohort-type mathematical model parameterized by nationally representative data. Uncertainty and sensitivity analyses were incorporated.

Results

HIV incidence arising among stable concordant HIV-negative couples contribute each year, on average, 29.4% of total HIV incidence; of those, 22.5% (range: 11.1%–39.8%) are infections acquired by one of the partners from sources external to the couple, less than 1% are infections acquired by both partners from external sources within a year and 6.8% (range: 3.6%–11.6%) are transmissions to the uninfected partner in the couple in less than a year after the other partner acquired the infection from an external source. The mean contribution of stable HIV sero-discordant couples to total HIV incidence is 30.4%, with most of those, 29.7% (range: 9.1%–47.9%), being due to HIV transmissions from the infected to the uninfected partner within the couple. The remaining incidence, 40.2% (range: 23.7%–64.6%), occurs among persons not in stable couples.

Conclusions

Close to two-thirds of total HIV incidence in sub-Saharan Africa occur among stable couples; however, only half of this incidence is attributed to HIV transmissions from the infected to the uninfected partner in the couple. The remaining incidence is acquired through extra-partner sex. Substantial reductions in HIV incidence can be achieved only through a prevention approach that targets all modes of HIV exposure among stable couples and among individuals not in stable couples.

In vitro Inactivation of Latent HSV by Targeted Mutagenesis Using an HSV-specific Homing Endonuclease

Following acute infection, herpes simplex virus (HSV) establishes latency in sensory neurons, from which it can reactivate and cause recurrent disease. Available antiviral therapies do not affect latent viral genomes; therefore, they do not prevent reactivation following therapy cessation. One possible curative approach involves the introduction of DNA double strand breaks in latent HSV genomes by rare-cutting endonucleases, leading to mutagenesis of essential viral genes. We tested this approach in an in vitro HSV latency model using the engineered homing endonuclease (HE) HSV1m5, which recognizes a sequence in the HSV-1 gene UL19, encoding the virion protein VP5. Coexpression of the 3'-exonuclease Trex2 with HEs increased HE-mediated mutagenesis frequencies up to sixfold. Following HSV1m5/Trex2 delivery with adeno-associated viral (AAV) vectors, the target site was mutated in latent HSV genomes with no detectable cell toxicity. Importantly, HSV production by latently infected cells after reactivation was decreased after HSV1m5/Trex2 exposure. Exposure to histone deacetylase inhibitors prior to HSV1m5/Trex2 treatment increased mutagenesis frequencies of latent HSV genomes another two- to fivefold, suggesting that chromatin modification may be a useful adjunct to gene-targeting approaches. These results support the continuing development of HEs and other nucleases (ZFNs, TALENs, CRISPRs) for cure of chronic viral infections.Molecular Therapy-Nucleic Acids (2014) 3, e1; doi:10.1038/mtna.2013.75; published online 4 February 2014.

Incident HIV during pregnancy and postpartum and risk of mother-to-child HIV transmission: a systematic review and meta-analysis

BACKGROUND

Women may have persistent risk of HIV acquisition during pregnancy and postpartum. Estimating risk of HIV during these periods is important to inform optimal prevention approaches. We performed a systematic review and meta-analysis to estimate maternal HIV incidence during pregnancy/postpartum and to compare mother-to-child HIV transmission (MTCT) risk among women with incident versus chronic infection.

METHODS AND FINDINGS

We searched PubMed, Embase, and AIDS-related conference abstracts between January 1, 1980, and October 31, 2013, for articles and abstracts describing HIV acquisition during pregnancy/postpartum. The inclusion criterion was studies with data on recent HIV during pregnancy/postpartum. Random effects models were constructed to pool HIV incidence rates, cumulative HIV incidence, hazard ratios (HRs), or odds ratios (ORs) summarizing the association between pregnancy/postpartum status and HIV incidence, and MTCT risk and rates. Overall, 1,176 studies met the search criteria, of which 78 met the inclusion criterion, and 47 contributed data. Using data from 19 cohorts representing 22,803 total person-years, the pooled HIV incidence rate during pregnancy/postpartum was 3.8/100 person-years (95% CI 3.0-4.6): 4.7/100 person-years during pregnancy and 2.9/100 person-years postpartum (p = 0.18). Pooled cumulative HIV incidence was significantly higher in African than non-African countries (3.6% versus 0.3%, respectively; p<0.001). Risk of HIV was not significantly higher among pregnant (HR 1.3, 95% CI 0.5-2.1) or postpartum women (HR 1.1, 95% CI 0.6-1.6) than among non-pregnant/non-postpartum women in five studies with available data. In African cohorts, MTCT risk was significantly higher among women with incident versus chronic HIV infection in the postpartum period (OR 2.9, 95% CI 2.2-3.9) or in pregnancy/postpartum periods combined (OR 2.3, 95% CI 1.2-4.4). However, the small number of studies limited power to detect associations and sources of heterogeneity.

CONCLUSIONS

Pregnancy and the postpartum period are times of persistent HIV risk, at rates similar to "high risk" cohorts. MTCT risk was elevated among women with incident infections. Detection and prevention of incident HIV in pregnancy/postpartum should be prioritized, and is critical to decrease MTCT.

A prospective study of the effect of pregnancy on CD4 counts and plasma HIV-1 RNA concentrations of antiretroviral-naive HIV-1-infected women

BACKGROUND

In HIV-1-infected women, CD4 count declines occur during pregnancy, which has been attributed to hemodilution. However, for women who have not initiated antiretroviral therapy, it is unclear if CD4 declines are sustained beyond pregnancy and accompanied by increased viral levels, which could indicate an effect of pregnancy on accelerating HIV-1 disease progression.

METHODS

In a prospective study among 2269 HIV-1-infected antiretroviral therapy-naive women from 7 African countries, we examined the effect of pregnancy on HIV-1 disease progression. We used linear mixed models to compare CD4 counts and plasma HIV-1 RNA concentrations between pregnant, postpartum, and nonpregnant periods.

RESULTS

Women contributed 3270 person-years of follow-up, during which time 476 women became pregnant. In adjusted analysis, CD4 counts were an average of 56 (95% confidence interval: 39 to 73) cells/mm lower during pregnant compared with nonpregnant periods and 70 (95% confidence interval: 53 to 88) cells/mm lower during pregnant compared with postpartum periods; these results were consistent when restricted to the subgroup of women who became pregnant. Plasma HIV-1 RNA concentrations were not different between pregnant and nonpregnant periods (P = 0.9) or pregnant and postpartum periods (P = 0.3). Neither CD4 counts nor plasma HIV-1 RNA levels were significantly different in postpartum compared with nonpregnant periods.

CONCLUSIONS

CD4 count declines among HIV-1-infected women during pregnancy are temporary and not sustained in postpartum periods. Pregnancy does not have a short-term impact on plasma HIV-1 RNA concentrations.

HSV-2 co-infection as a driver of HIV transmission among heterosexual non-injecting drug users in New York City

Objective

To examine herpes simplex virus 2 (HSV-2)/HIV co-infection as a contributing factor in the increase in HIV infection among non-injecting heroin and cocaine users in New York City.

Methods

Subjects were recruited from the Beth Israel Medical Center drug detoxification and methadone maintenance programs in New York City in 1995–1999 and 2005–2011. All reported current heroin and/or cocaine use and no injection drug use. A structured questionnaire was administered and serum samples collected for HIV and HSV-2 testing. Population-attributable risk percentages (PAR%s) were estimated for associations between HSV-2 and increased susceptibility to and increased transmissibility of HIV among female NIDUs.

Results

785 subjects were recruited from 1995–1999, and 1764 subjects from 2005–2011. HIV prevalence increased from 7% to 13%, with nearly uniform increases among all demographic subgroups. HSV-2/HIV co-infection was common in both time periods, with an average (over the two time periods) of 80% of HIV negative females infected with HSV-2, an average of 43% of HIV negative males infected with HSV-2; an average of 97% of HIV positive females also infected with HSV-2 and an average of 67% of HIV positive males also infected with HSV-2. The increase in HIV prevalence was predominantly an increase in HSV-2/HIV co-infection, with relatively little HIV mono-infection in either time period. The estimated PAR%s indicate that approximately half of HIV acquisition among females was caused by HSV-2 infection and approximately 60% of HIV transmission from females was due to HSV-2 co-infection.

Conclusions

The increase in HIV infection among these non-injecting drug users is better considered as an increase in HSV-2/HIV co-infection rather than simply an increase in HIV prevalence. Additional interventions (such as treatment as prevention and suppressing the effects of HSV-2 on HIV transmission) are needed to reduce further HIV transmission from HSV-2/HIV co-infected non-injecting drug users.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Biomedical HIV prevention research and epidemic control in Thailand: two sides of the same coin

For a country with a moderate adult HIV prevalence of just over 1% in 2012, Thailand is widely perceived as having made some extraordinary contributions to the global management of the HIV/AIDS pandemic. It has been promoted as a model of effective HIV control and applauded for its leadership in providing access to antiretroviral treatment. Thailand has also received international recognition for its contribution to biomedical HIV prevention research, which is generally perceived as exceptional. In this paper, Thailand's global role model function as an example of effective HIV/AIDS control and high-quality biomedical HIV prevention research is re-evaluated against the background of currently available data and more recent insights. The results indicate that Thailand's initial response in raising the level of the political significance of HIV/AIDS was indeed extraordinary, which probably prevented a much larger epidemic from occurring. However, this response transpired in unusual extraconstitutional circumstances and its effectiveness declined once the country returned to political normalcy. Available data confirm the country's more than exceptional contribution to biomedical HIV prevention research. Thailand has made a huge contribution to the global management and control of the HIV/AIDS pandemic.

Australian sexually transmissible infection and HIV testing guidelines for asymptomatic men who have sex with men 2014: a review of the evidence

Men who have sex with men (MSM) in Australia and overseas are disproportionately affected by sexually transmissible infections (STIs), including HIV. Many STIs are asymptomatic, so regular testing and management of asymptomatic MSM remains an important component of effective control. We reviewed articles from January 2009–May 2013 to inform the 2014 update of the 2010 Australian testing guidelines for asymptomatic MSM. Key changes include: a recommendation for pharyngeal chlamydia (Chlamydia trachomatis) testing, use of nucleic acid amplification tests alone for gonorrhoea (Neisseria gonorrhoeae) testing (without gonococcal culture), more frequent (up to four times a year) gonorrhoea and chlamydia testing in sexually active HIV-positive MSM, time required since last void for chlamydia first-void urine collection specified at 20 min, urethral meatal swab as an alternative to first-void urine for urethral chlamydia testing, and the use of electronic reminders to increase STI and HIV retesting rates among MSM.

Cost-effectiveness of provider-based HIV partner notification in urban Malawi

Provider-initiated partner notification for HIV effectively identifies new cases of HIV in sub-Saharan Africa, but is not widely implemented. Our objective was to determine whether provider-based HIV partner notification strategies are cost-effective for preventing HIV transmission compared with passive referral. We conducted a cost-effectiveness analysis using a decision-analytic model from the health system perspective during a 1-year period. Costs and outcomes of all strategies were estimated with a decision-tree model. The study setting was an urban sexually transmitted infection clinic in Lilongwe, Malawi, using a hypothetical cohort of 5000 sex partners of 3500 HIV-positive index cases. We evaluated three partner notification strategies: provider notification (provider attempts to notify indexes' locatable partners), contract notification (index given 1 week to notify partners then provider attempts notification) and passive referral (index is encouraged to notify partners, standard of care). Our main outcomes included cost (US dollars) per transmission averted, cost per new case identified and cost per partner tested. Based on estimated transmissions in a 5000-person cohort, provider and contract notification averted 27.9 and 27.5 new infections, respectively, compared with passive referral. The incremental cost-effectiveness ratio (ICER) was $3560 per HIV transmission averted for contract notification compared with passive referral. Provider notification was more expensive and slightly more effective than contract notification, yielding an ICER of $51 421 per transmission averted. ICERs were sensitive to the proportion of partners not contacted, but likely HIV positive and the probability of transmission if not on antiretroviral therapy. The costs per new case identified were $36 (provider), $18 (contract) and $8 (passive). The costs per partner tested were $19 (provider), $9 (contract) and $4 (passive). We conclude that, in this population, provider-based notification strategies are potentially cost-effective for identifying new cases of HIV. These strategies offer a simple, effective and easily implementable opportunity to control HIV transmission.

HIV sexual transmission is predominantly driven by single individuals rather than discordant couples: a model-based approach

Understanding the relative contribution to HIV transmission from different social groups is important for public-health policy. Information about the importance of stable serodiscordant couples (when one partner is infected but not the other) relative to contacts outside of stable partnerships in spreading disease can aid in designing and targeting interventions. However, the overall importance of within-couple transmission, and the determinants and correlates of this importance, are not well understood. Here, we explore how mechanistic factors – like partnership dynamics and rates of extra-couple transmission – affect various routes of transmission, using a compartmental model with parameters based on estimates from Sub-Saharan Africa. Under our assumptions, when sampling model parameters within a realistic range, we find that infection of uncoupled individuals is usually the predominant route (median 0.62, 2.5%–97.5% quantiles: 0.26–0.88), while transmission within discordant couples is usually important, but rarely represents the majority of transmissions (median 0.33, 2.5%–97.5% quantiles: 0.10–0.67). We find a strong correlation between long-term HIV prevalence and the contact rate of uncoupled individuals, implying that this rate may be a key driver of HIV prevalence. For a given level of prevalence, we find a negative correlation between the proportion of discordant couples and the within-couple transmission rate, indicating that low discordance in a population may reflect a relatively high rate of within-couple transmission. Transmission within or outside couples and among uncoupled individuals are all likely to be important in sustaining heterosexual HIV transmission in Sub-Saharan Africa. Hence, intervention policies should be broadly targeted when practical.

Toll-like receptor polymorphism associations with HIV-1 outcomes among sub-Saharan Africans

OBJECTIVE

We evaluated Toll-like receptors (TLRs) single nucleotide polymorphisms (SNPs) for associations with HIV-1 acquisition, set-point and disease progression in African couples.

METHODS

Seven candidate and 116 haplotype-tagging SNPs (tagSNPs) were genotyped in 504 HIV-1 infected cases, and 343 seronegative controls.

RESULTS

TLR9 1635A/G was associated with reduced HIV-1 acquisition among HIV-seronegative controls with high but not low HIV-1 exposure (odds ratio [OR] = 0.7; P = .03 and OR = 0.9, P = .5, respectively). TLR7 rs179012 and TLR2 597C/T reduced set-point; the latter modified by time since HIV-1 acquisition. TLR8 1A/G reduced disease progression.

CONCLUSIONS

TLR SNPs impact HIV-1 outcomes with epidemiologic factors modifying these relationships.

HIV treatment as prevention: the key to an AIDS-free generation

The presence of elevated HIV viral load within blood and genital secretions is a critical driver of transmission events. Long-term suppression of viral load to undetectable levels through the use of antiretroviral therapy is now standard practice for clinical management of HIV. Antiretroviral therapy therefore can play a key role as a means to curb HIV transmission. Results of a randomized clinical trial, in conjunction with several observational studies, have now confirmed that antiretroviral therapy markedly decreases HIV transmission risk. Mathematical models and population-based ecologic studies suggest that further expansion of antiretroviral coverage within current guidelines can play a major role in controlling the spread of HIV. Expansion of so-called "Treatment as Prevention" initiatives relies upon maximal uptake of the HIV continuum-of-care cascade to allow for successful identification of those not yet known to be HIV-infected, engagement of patients in appropriate care, and subsequently achieving sustained virologic suppression in patients with the use of antiretroviral therapy. Since 2010, the Joint United Nations AIDS (UNAIDS) program has called for the inclusion of antiretroviral treatment as a key pillar in the global strategy to control the spread of HIV infection. This has now been invigorated by the release of the World Health Organization's 2013 Consolidated Antiretroviral Therapy Guidelines, recommending treatment to be offered to all HIV-infected individuals with CD4 cell counts below 500/mm³, and, regardless of CD4 cell count, to serodiscordant couples, TB and HBV co-infected individuals, pregnant women, and children below the age of 5 years.

The risk of HIV transmission within HIV-1 sero-discordant couples appears to vary across sub-Saharan Africa

BACKGROUND

Representative and precise estimates for the annual risk of HIV transmission (ϕ) from the infected to the uninfected partner in a stable HIV-1 sero-discordant couple (SDC) are not available. Nevertheless, quantifying HIV infectiousness is critical to understanding HIV epidemiology and implementing prevention programs.

MATERIALS AND METHODS

We estimated ϕ and examined its variation across 23 countries in sub-Saharan Africa (SSA) by constructing and analyzing a mathematical model that describes HIV dynamics among SDCs. The model was parameterized using empirical measures such as those of the nationally representative Demographic and Health Surveys. Uncertainty and sensitivity analyses were conducted to assess the robustness of the findings.

RESULTS

We estimated a median ϕ of 11.1 per 100 person-years across SSA. A clustering based on HIV population prevalence was observed with a median ϕ of 7.5 per 100 person-years in low HIV prevalence countries (<5%) compared to 19.5 per 100 person-years in high prevalence countries (>5%). The association with HIV prevalence explained 67% of the variation in ϕ, and suggested an increase of 0.95 per 100 person-years in ϕ for every 1% increase in HIV prevalence.

CONCLUSIONS

Empirical measures from cohort studies appear to underestimate HIV infectiousness in SSA. The risk of HIV transmission among SDCs appears also to vary across SSA, and this may have contributed to the contrasting HIV epidemic trajectories in this continent.

Development of methods for cross-sectional HIV incidence estimation in a large, community randomized trial

Background

Accurate methods of HIV incidence determination are critically needed to monitor the epidemic and determine the population level impact of prevention trials. One such trial, Project Accept, a Phase III, community-randomized trial, evaluated the impact of enhanced, community-based voluntary counseling and testing on population-level HIV incidence. The primary endpoint of the trial was based on a single, cross-sectional, post-intervention HIV incidence assessment.

Methods and Findings

Test performance of HIV incidence determination was evaluated for 403 multi-assay algorithms [MAAs] that included the BED capture immunoassay [BED-CEIA] alone, an avidity assay alone, and combinations of these assays at different cutoff values with and without CD4 and viral load testing on samples from seven African cohorts (5,325 samples from 3,436 individuals with known duration of HIV infection [1 month to >10 years]). The mean window period (average time individuals appear positive for a given algorithm) and performance in estimating an incidence estimate (in terms of bias and variance) of these MAAs were evaluated in three simulated epidemic scenarios (stable, emerging and waning). The power of different test methods to detect a 35% reduction in incidence in the matched communities of Project Accept was also assessed. A MAA was identified that included BED-CEIA, the avidity assay, CD4 cell count, and viral load that had a window period of 259 days, accurately estimated HIV incidence in all three epidemic settings and provided sufficient power to detect an intervention effect in Project Accept.

Conclusions

In a Southern African setting, HIV incidence estimates and intervention effects can be accurately estimated from cross-sectional surveys using a MAA. The improved accuracy in cross-sectional incidence testing that a MAA provides is a powerful tool for HIV surveillance and program evaluation.

Summary measures of adherence using pill counts in two HIV prevention trials: the need for standardisation in reporting

For trials of user-dependent HIV prevention products, accurate adherence measurements are essential to interpret and compare results across trials. We used pill count data from two recent HIV prevention trials of herpes simplex virus type 2 (HSV-2) suppression, to show that estimates of adherence vary substantially depending on assumptions that are made in analysing pill count data. We associate calculated adherence with biological markers of anti-HSV-2 activity. In both trials, calculated adherence varied considerably, depending on the summary measure used, and the handling of intervals with apparent ‘over-adherence’ (fewer pills returned than expected), and unreturned pills. Intervals of apparent over-adherence were associated with reduced antiviral effects on biological markers of herpes reactivation, indicating these are likely to represent periods of non-adherence. Our results demonstrate the clear need for standardisation in reporting of adherence data that are based on pill counts.

Daily acyclovir to decrease herpes simplex virus type 2 (HSV-2) transmission from HSV-2/HIV-1 coinfected persons: a randomized controlled trial

BACKGROUND

Daily suppressive therapy with valacyclovir reduces risk of sexual transmission of herpes simplex virus type 2 (HSV-2) in HSV-2-serodiscordant heterosexual couples by 48%. Whether suppressive therapy reduces HSV-2 transmission from persons coinfected with HSV-2 and human immunodeficiency virus type 1 (HIV-1) is unknown.

METHODS

Within a randomized trial of daily acyclovir 400 mg twice daily in African HIV-1 serodiscordant couples, in which the HIV-1-infected partner was HSV-2 seropositive, we identified partnerships in which HIV-1-susceptible partners were HSV-2 seronegative to estimate the effect of acyclovir on risk of HSV-2 transmission.

RESULTS

We randomly assigned 911 HSV-2/HIV-1-serodiscordant couples to daily receipt of acyclovir or placebo. We observed 68 HSV-2 seroconversions, 40 and 28 in acyclovir and placebo groups, respectively (HSV-2 incidence, 5.1 cases per 100 person-years; hazard ratio [HR], 1.35 [95% confidence interval, .83-2.20]; P = .22). Among HSV-2-susceptible women, vaginal drying practices (adjusted HR, 44.35; P = .004) and unprotected sex (adjusted HR, 9.91; P = .002) were significant risk factors for HSV-2 acquisition; having more children was protective (adjusted HR, 0.47 per additional child; P = .012). Among HSV-2-susceptible men, only age ≤30 years was associated with increased risk of HSV-2 acquisition (P = .016).

CONCLUSIONS

Treatment of African HSV-2/HIV-1-infected persons with daily suppressive acyclovir did not decrease risk of HSV-2 transmission to susceptible partners. More-effective prevention strategies to reduce HSV-2 transmission from HIV-1-infected persons are needed.