Antiretroviral prophylaxis for HIV prevention in heterosexual men and women.

BACKGROUND: Antiretroviral preexposure prophylaxis is a promising approach for preventing human immunodeficiency virus type 1 (HIV-1) infection in heterosexual populations. METHODS: We conducted a randomized trial of oral antiretroviral therapy for use as preexposure prophylaxis among HIV-1-serodiscordant heterosexual couples from Kenya and Uganda. The HIV-1-seronegative partner in each couple was randomly assigned to one of three study regimens--once-daily tenofovir (TDF), combination tenofovir-emtricitabine (TDF-FTC), or matching placebo--and followed monthly for up to 36 months. At enrollment, the HIV-1-seropositive partners were not eligible for antiretroviral therapy, according to national guidelines. All couples received standard HIV-1 treatment and prevention services. RESULTS: We enrolled 4758 couples, of whom 4747 were followed: 1584 randomly assigned to TDF, 1579 to TDF-FTC, and 1584 to placebo. For 62% of the couples followed, the HIV-1-seronegative partner was male. Among HIV-1-seropositive participants, the median CD4 count was 495 cells per cubic millimeter (interquartile range, 375 to 662). A total of 82 HIV-1 infections occurred in seronegative participants during the study, 17 in the TDF group (incidence, 0.65 per 100 person-years), 13 in the TDF-FTC group (incidence, 0.50 per 100 person-years), and 52 in the placebo group (incidence, 1.99 per 100 person-years), indicating a relative reduction of 67% in the incidence of HIV-1 with TDF (95% confidence interval [CI], 44 to 81; P<0.001) and of 75% with TDF-FTC (95% CI, 55 to 87; P<0.001). Protective effects of TDF-FTC and TDF alone against HIV-1 were not significantly different (P=0.23), and both study medications significantly reduced the HIV-1 incidence among both men and women. The rate of serious adverse events was similar across the study groups. Eight participants receiving active treatment were found to have been infected with HIV-1 at baseline, and among these eight, antiretroviral resistance developed in two during the study. CONCLUSIONS: Oral TDF and TDF-FTC both protect against HIV-1 infection in heterosexual men and women. (Funded by the Bill and Melinda Gates Foundation; Partners PrEP ClinicalTrials.gov number, NCT00557245.).

Breadth of neutralizing antibody response to human immunodeficiency virus type 1 is affected by factors early in infection but does not influence disease progression.

The determinants of a broad neutralizing antibody (NAb) response and its effect on human immunodeficiency virus type 1 (HIV-1) disease progression are not well defined, partly because most prior studies of a broad NAb response were cross-sectional. We examined correlates of NAb response breadth among 70 HIV-infected, antiretroviral-naïve Kenyan women from a longitudinal seroincident cohort. NAb response breadth was measured 5 years after infection against five subtype A viruses and one subtype B virus. Greater NAb response breadth was associated with a higher viral load set point and greater HIV-1 env diversity early in infection. However, greater NAb response breadth was not associated with a delayed time to a CD4(+) T-cell count of <200, antiretroviral therapy, or death. Thus, a broad NAb response results from a high level of antigenic stimulation early in infection, which likely accounts for prior observations that greater NAb response breadth is associated with a higher viral load later in infection.

Initiation of antiretroviral therapy leads to a rapid decline in cervical and vaginal HIV-1 shedding.

BACKGROUND: Antiretroviral therapy (ART) may decrease HIV-1 infectivity in women by reducing genital HIV-1 shedding. OBJECTIVES: To evaluate the time course and magnitude of decay in cervical and vaginal HIV-1 shedding as women initiate ART. METHODS: This prospective, observational study of 20 antiretroviral-naive women initiating ART with stavudine, lamivudine, and nevirapine measured HIV-1 RNA in plasma, cervical secretions, and vaginal secretions. Qualitative polymerase chain reaction estimated HIV-1 DNA in cervical and vaginal samples. Perelson's two-phase viral decay model and non-linear random effects were used to compare RNA decay rates. Decreases in proviral DNA were evaluated using logistic regression and generalized estimating equations. RESULTS: Significant decreases in the quantity of HIV-1 RNA were observed by day 2 in plasma (P < 0.001), day 2 in cervical secretions (P = 0.001), and day 4 in vaginal secretions (P < 0.001). Modeled initial and subsequent RNA decay rates in plasma, cervical secretions, and vaginal secretions were 0.6, 0.8, and 1.2 log10 virions/day, and 0.04, 0.05, and 0.06 log10 virions/day, respectively. The initial decay rate for vaginal HIV-1 RNA was more rapid than for plasma RNA (P = 0.02). Detection of HIV-1 DNA decreased significantly in vaginal secretions during the first week (P < 0.001). At day 28, 10 women had detectable HIV-1 RNA or proviral DNA in genital secretions. CONCLUSIONS: Genital HIV-1 shedding decreased rapidly after ART initiation, consistent with a rapid decrease in infectivity. However, incomplete viral suppression in half of these women may indicate an ongoing risk of transmission.

High levels of cervical HIV-1 RNA during early HIV-1 infection.

Few data are available on genital tract viral replication early after HIV-1 acquisition, when infectivity is high. We compared cervical HIV-1 RNA from 60 women with paired samples from within 90 days after HIV-1 acquisition and at viral setpoint (4-24 months). Cervical HIV-1 was higher in early compared with setpoint samples (mean 3.43 versus 2.85 log10 copies/swab, P < 0.001). After adjusting for HIV-1-plasma RNA, cervical HIV-1 RNA from 30 days or less after infection was increased by 0.45 log10 copies/swab (P = 0.006).

The effect of hormonal contraception on genital tract shedding of HIV-1.

OBJECTIVE: A previous cross-sectional study reported that hormonal contraception may be associated with increased infectivity in HIV-1 infected women. We conducted a prospective study to determine if cervical shedding of HIV-1 increased after initiating hormonal contraception. DESIGN: Shedding of HIV-1 DNA (a marker of HIV-1 infected cells) and HIV-1 RNA were measured before and after initiating hormonal contraception. METHODS: HIV-1 seropositive women were recruited from a Kenyan family planning clinic. At baseline, cervical secretions were collected for HIV-1 DNA and RNA assays in women initiating hormonal contraception; follow-up samples were collected a median of 64 days later. RESULTS: One-hundred and one women chose depot medroxyprogesterone (Depo), 53 chose low-dose oral contraceptives (OC), seven high-dose OC, and 52 progesterone-only OC. At follow-up, there was a significant increase in the prevalence of cervical HIV-1 DNA detection [from 42% to 52%, odds ratio (OR), 1.62; 95% confidence interval (CI), 1.03-2.63) for all hormonal contraception combined, and a trend for an increase for each individual type. Although the prevalence of cervical HIV-1 RNA increased slightly (from 82% to 86%; OR, 1.56; 95% CI, 0.83-3.03), the concentration of cervical HIV-1 RNA did not change significantly overall (from 2.81 to 2.84 log10 copies/swab; P = 0.77) or for individual contraception types. CONCLUSIONS: A modest but significant increase in shedding of HIV-1 DNA but not of HIV-1 RNA was detected after starting hormonal contraception. Our results may have important implications regarding the infectivity of women using hormonal contraception, and highlight the need for epidemiologic studies of transmission rates from women using and not using hormonal contraception.

Virus load during primary Human Immunodeficiency Virus (HIV) type 1 infection is related to the severity of acute HIV illness in Kenyan women.

We evaluated the association between the severity of primary human immunodeficiency virus type 1 (HIV-1) illness and HIV-1 plasma virus load before seroconversion using stored plasma samples obtained from 74 prostitutes in Mombasa, Kenya. Fever, vomiting, headache, fatigue, arthralgia, myalgia, sore throat, skin rash, or being too sick to work were each associated with significantly higher virus loads before HIV-1 seroconversion, and each additional symptom or sign was associated with an increase in virus load of 0.4 log(10) copies/mL.

Viral linkage in HIV-1 seroconverters and their partners in an HIV-1 prevention clinical trial.

BACKGROUND: Characterization of viruses in HIV-1 transmission pairs will help identify biological determinants of infectiousness and evaluate candidate interventions to reduce transmission. Although HIV-1 sequencing is frequently used to substantiate linkage between newly HIV-1 infected individuals and their sexual partners in epidemiologic and forensic studies, viral sequencing is seldom applied in HIV-1 prevention trials. The Partners in Prevention HSV/HIV Transmission Study (ClinicalTrials.gov #NCT00194519) was a prospective randomized placebo-controlled trial that enrolled serodiscordant heterosexual couples to determine the efficacy of genital herpes suppression in reducing HIV-1 transmission; as part of the study analysis, HIV-1 sequences were examined for genetic linkage between seroconverters and their enrolled partners. METHODOLOGY/PRINCIPAL FINDINGS: We obtained partial consensus HIV-1 env and gag sequences from blood plasma for 151 transmission pairs and performed deep sequencing of env in some cases. We analyzed sequences with phylogenetic techniques and developed a Bayesian algorithm to evaluate the probability of linkage. For linkage, we required monophyletic clustering between enrolled partners' sequences and a Bayesian posterior probability of ≥ 50%. Adjudicators classified each seroconversion, finding 108 (71.5%) linked, 40 (26.5%) unlinked, and 3 (2.0%) indeterminate transmissions, with linkage determined by consensus env sequencing in 91 (84%). Male seroconverters had a higher frequency of unlinked transmissions than female seroconverters. The likelihood of transmission from the enrolled partner was related to time on study, with increasing numbers of unlinked transmissions occurring after longer observation periods. Finally, baseline viral load was found to be significantly higher among linked transmitters. CONCLUSIONS/SIGNIFICANCE: In this first use of HIV-1 sequencing to establish endpoints in a large clinical trial, more than one-fourth of transmissions were unlinked to the enrolled partner, illustrating the relevance of these methods in the design of future HIV-1 prevention trials in serodiscordant couples. A hierarchy of sequencing techniques, analysis methods, and expert adjudication contributed to the linkage determination process.

Characteristics of HIV-1 serodiscordant couples enrolled in a clinical trial of antiretroviral pre-exposure prophylaxis for HIV-1 prevention.

INTRODUCTION: Stable heterosexual HIV-1 serodiscordant couples in Africa have high HIV-1 transmission rates and are a critical population for evaluation of new HIV-1 prevention strategies. The Partners PrEP Study is a randomized, double-blind, placebo-controlled trial of tenofovir and emtricitabine-tenofovir pre-exposure prophylaxis to decrease HIV-1 acquisition within heterosexual HIV-1 serodiscordant couples. We describe the trial design and characteristics of the study cohort. METHODS: HIV-1 serodiscordant couples, in which the HIV-1 infected partner did not meet national guidelines for initiation of antiretroviral therapy, were enrolled at 9 research sites in Kenya and Uganda. The HIV-1 susceptible partner was randomized to daily oral tenofovir, emtricitabine-tenofovir, or matching placebo with monthly follow-up for 24-36 months. RESULTS: From July 2008 to November 2010, 7920 HIV-1 serodiscordant couples were screened and 4758 enrolled. For 62% (2966/4758) of enrolled couples, the HIV-1 susceptible partner was male. Median age was 33 years for HIV-1 susceptible and HIV-1 infected partners [IQR (28-40) and (26-39) respectively]. Most couples (98%) were married, with a median duration of partnership of 7.0 years (IQR 3.0-14.0) and recent knowledge of their serodiscordant status [median 0.4 years (IQR 0.1-2.0)]. During the month prior to enrollment, couples reported a median of 4 sex acts (IQR 2-8); 27% reported unprotected sex and 14% of male and 1% of female HIV-1 susceptible partners reported sex with outside partners. Among HIV-1 infected partners, the median plasma HIV-1 level was 3.94 log(10) copies/mL (IQR 3.31-4.53) and median CD4 count was 496 cells/µL (IQR 375-662); the majority (64%) had WHO stage 1 HIV-1 disease. CONCLUSIONS: Couples at high risk of HIV-1 transmission were rapidly recruited into the Partners PrEP Study, the largest efficacy trial of oral PrEP. (ClinicalTrials.gov NCT00557245).

HIV-1 evolution in gag and env is highly correlated but exhibits different relationships with viral load and the immune response.

OBJECTIVE: To evaluate relationships between HIV-1 evolution, including immune evasion, and markers of disease progression during chronic infection. DESIGN: HIV-1 evolution and disease progression markers were evaluated over approximately 5 years of infection among 37 Kenyan women from a prospective, seroincident cohort. Evolution was measured in two genes, gag and env, which are primary targets of cellular and humoral immune responses, respectively. METHODS: Proviral HIV-1 gag and env sequences were obtained from early and chronic infection when plasma viral load and CD4 cell counts were available. Human leukocyte antigen types were obtained to identify changes in gag cytotoxic T-lymphocyte epitopes. The breadth of the neutralizing antibody response was measured for each woman's plasma against a panel of six viruses. Tests of association were performed between virus evolution (diversity, divergence, and ratio of nonsynonymous to synonymous divergence), markers of disease progression (viral load and CD4 cell count), and immune parameters (gag cytotoxic T lymphocyte epitope mutation and neutralizing antibody breadth). RESULTS: HIV-1 gag and env diversity and divergence were highly correlated in early and late infection. Divergence in gag was strongly correlated with viral load, largely because of the accumulation of synonymous changes. Mutation in gag cytotoxic T-lymphocyte epitopes was associated with higher viral load. There was evidence for adaptive evolution in env, but the extent of env evolution was only weakly associated with neutralizing antibody breadth. CONCLUSION: Our results indicate that HIV-1 evolution in gag and env is highly correlated but exhibits gene-specific differences. The different immune pressures on these genes may partly explain differences in evolution and consequences for HIV-1 disease progression.

Subtype C Is associated with increased vaginal shedding of HIV-1.

The prevalence of human immunodeficiency virus (HIV)-1-infected cells and HIV-1 RNA levels in genital secretions and breast milk and the risk of mother-to-child transmission of HIV-1 were compared among subtypes A, C, and D in a Kenyan cohort. Pregnant women infected with subtype C were significantly more likely to shed HIV-1-infected vaginal cells than were those infected with subtype A or D (odds ratio [OR], 3.6 [95% confidence interval {CI}, 1.4-8.8]; P = .006). This relationship held after adjusting for age, CD4 cell count, and plasma HIV-1 RNA load (OR, 3.1 [95% CI, 1.1-8.6]; P = .03). These observations suggest that HIV-1 subtype influences mucosal shedding of HIV-1.

Short-term effect of zidovudine on plasma and genital human immunodeficiency virus type 1 and viral turnover in these compartments.

The effect of zidovudine on plasma and genital human immunodeficiency virus type 1 (HIV-1) was determined in 42 antiretroviral-naive HIV-1-seropositive women in Nairobi. After 7 days of zidovudine treatment, HIV-1 RNA levels decreased by 0.5 to 1.1 log(10) in plasma and genital secretions. HIV-1 RNA half-life following zidovudine treatment was 4.7, 1.3, and 0.9 days in plasma, cervix, and vagina, respectively, and significantly shorter in genital secretions than in plasma (P < 0.001). Defining the short-term effect of zidovudine on plasma and genital HIV-1 is important for improving perinatal HIV-1 interventions.

Comparison of human immunodeficiency virus type 1 viral loads in Kenyan women, men, and infants during primary and early infection.

Steady-state levels of human immunodeficiency virus type 1 (HIV-1) RNA in plasma reached at approximately 4 months postinfection are highly predictive of disease progression. Several studies have investigated viral levels in adults or infants during primary and early infection. However, no studies have directly compared these groups. We compared differences in peak and set point plasma HIV-1 RNA viral loads among antiretrovirus-naive Kenyan infants and adults for whom the timing of infection was well defined. Peak and set point viral loads were significantly higher in infants than in adults. We did not observe any gender-specific differences in viral set point in either adults or infants. However, infants who acquired HIV-1 in the first 2 months of life, either in utero, intrapartum, or through early breast milk transmission, had significantly higher set point HIV-1 RNA levels than infants who were infected after 2 months of age through late breast milk transmission or adults who were infected through heterosexual transmission.

Validation of performance of the gen-probe human immunodeficiency virus type 1 viral load assay with genital swabs and breast milk samples.

Human immunodeficiency type 1 (HIV-1) continues to spread at an alarming rate. The virus may be transmitted through blood, genital secretions, and breast milk, and higher levels of systemic virus in the index case, as measured by plasma RNA viral load, have been shown to correlate with increased risk of transmitting HIV-1 both vertically and sexually. Less is known about the correlation between transmission and HIV-1 levels in breast milk or genital secretions, in part because reliable quantitative assays to detect HIV-1 in these fluids are not available. Here we show that the Gen-Probe HIV-1 viral load assay can be used to accurately quantify viral load in expressed breast milk and in cervical and vaginal samples collected on swabs. Virus could be quantified from breast milk and swab samples spiked with known amounts of virus, including HIV-1 subtypes A, C, and D. As few as 10 copies of HIV-1 RNA could be detected above background threshold levels in > or =77% of assays performed with spiked breast milk supernatants and mock swabs. In genital swab samples from HIV-1-infected women, similar levels of HIV-1 RNA were consistently detected in duplicate swabs taken from the same woman on the same clinic visit, suggesting that the RNA values from a single swab sample can be used to measure genital viral load.

Injectable contraceptive use and genital ulcer disease during the early phase of HIV-1 infection increase plasma virus load in women.

We examined the association between host factors present near the time of human immunodeficiency virus type 1 (HIV-1) acquisition and subsequent virus loads, in a prospective cohort study of women in Mombasa, Kenya. Women were prospectively followed monthly before HIV-1 infection. One hundred sixty-one commercial sex workers who became infected with HIV-1 were followed for a median of 34 months, and 991 plasma samples collected > or =4 months after infection were tested for HIV-1 RNA. The median virus set point at 4 months after infection was 4.46 log10 copies/mL, and the average virus load increase during subsequent follow-up was 0.0094 log10 copies/mL/month. In a multivariate analysis that controlled for sexual behavior, the use of the injectable contraceptive depot medroxyprogesterone acetate (DMPA) at the time of HIV-1 infection was associated with a higher virus set point, and the presence of genital ulcer disease (GUD) during the early phase of HIV-1 infection was associated with greater change in virus load during follow-up. These findings suggest that, in women, the use of DMPA and the presence of GUD during the early phase of HIV-1 infection may influence the natural course of infection.