Tenofovir Gel for Prevention of Herpes Simplex Virus Type 2 Acquisition: Findings From the VOICE Trial

BACKGROUND

Genital infection with herpes simplex virus type 2 (HSV-2) is common and increases risk of human immunodeficiency virus (HIV) transmission and acquisition. Pericoital use of tenofovir (TFV) gel provided protection from HSV-2 acquisition in the CAPRISA 004 study.

METHODS

We measured estimate of effect of vaginal TFV 1% gel in preventing HSV-2 acquisition among women in VOICE, randomized, double-blinded, placebo-controlled trial assessing daily use of oral and vaginal TFV for HIV-1 preexposure prophylaxis. The TFV level in plasma at the first quarterly visit was used as a measure of gel use.

RESULTS

Of 566 participants at risk for HSV-2 acquisition, 532 (94%) had first-quarter plasma TFV and end-of-study HSV-2 serologic data available. Over a follow-up period of 501 person-years, 92 incident cases of HSV-2 acquisition occurred: 77 were in women with no TFV detected in plasma, and 15 occurred in women with TFV detected in plasma (incidence, 20.6 cases/100 person-years [95% confidence interval [CI], 16.2-25.7] vs 11.9 cases/100 person-years [95% CI, 6.6-19.6], respectively). TFV detection in plasma was associated with a trend toward a reduced risk of HSV-2 seroconversion, with an unadjusted hazard ratio (HR) of 0.59 (95% CI, .34-1.02; P = .060) and a HR adjusted for site, age, having ≥2 male sex partners in the past 3 months, use of hormonal contraception, having anal sex in the past 3 months, and HIV status of 0.60 (95% CI, .33-1.08; P = .086).

CONCLUSIONS

Detection of TFV in plasma among TFV gel users was associated with a trend toward a reduced risk of HSV-2 acquisition, after controlling for sexual behavior and HIV-1 acquisition.

Comparison of Mucosal Markers of Human Immunodeficiency Virus Susceptibility in Healthy Premenopausal Versus Postmenopausal Women

The objective of this study was to characterize cervicovaginal (CV) mucosal factors modulating susceptibility to human immunodeficiency virus (HIV) acquisition in healthy premenopausal (PRE) and postmenopausal (POST) women before and after treatment with estradiol (E2). We compared CV mucosal epithelial histology and immune cells, vaginal microbiota, antimicrobial activity of and soluble mucosal protein concentrations in the CV fluid lavage (CVL), and p24 antigen production after ex vivo infection of ectocervical tissues with HIV-1_BaL among PRE women (n = 20) in the follicular and luteal phases of the menstrual cycle and POST women (n = 17) at baseline and after ∼1 month of treatment with 0.01% vaginal E2 cream. Compared to PRE women, we measured higher levels of p24 antigen after ex vivo infection in tissues from POST women. POST women had a significantly thinner vaginal epithelium with decreased tight junction proteins and a higher density of mucosal immune T cells and lower levels of CD1a antigen-presenting cells, antimicrobial peptides, and inflammatory cytokines in the CVL (p values <.05). POST women had higher vaginal pH and lower vaginal Lactobacilli (p values <.05) than PRE women. After vaginal E2 therapy, CV endpoints and ex vivo HIV replication in POST tissues were similar to those observed in PRE tissues. The CV mucosa in POST women is thinned and compromised, with increased HIV-target immune cells and decreased antimicrobial factors, being more susceptible to HIV infection. After POST women receive topical E2 treatment, mucosal endpoints are similar to PRE levels.

Impact of targeted counseling on reported vaginal hygiene practices and bacterial vaginosis: the HIV Prevention Trials Network 035 study

The objective of this study was to describe the impact of intense counseling to reduce vaginal hygiene practices and its effect on bacterial vaginosis. A secondary data analysis of the HIV Prevention Trials Network 035 study was undertaken, focusing on HIV-negative, nonpregnant women who were at least 18 years old, in seven African sites and one US site. At enrollment and during follow-up quarterly visits, vaginal hygiene practices were determined by face-to-face administration of a behavioral assessment questionnaire. Vaginal hygiene practices were categorized as insertion into the vagina of (1) nothing, (2) water only, and (3) other substances with or without water. Each practice was quantified by frequency and type/combination of inserted substances. At quarterly visits, diagnosis of bacterial vaginosis was made using the Nugent score. Trends for vaginal hygiene practices and bacterial vaginosis were evaluated using generalized estimating equation models. A total of 3087 participants from the HIV Prevention Trials Network 035 study were eligible for this analysis. At enrollment, 1859 (60%) reported recent vaginal hygiene practices. By one year, this figure had decreased to 1019 (33%) with counseling. However, bacterial vaginosis prevalence remained consistent across the study observation period, with 36%-38% of women testing positive for the condition ( p for trend = 0.27). Overall, those who reported douching with water only (AOR = 1.03, 95%CI: 0.94-1.13) and those who reported inserting other substances (AOR= 0.98, 95%CI: 0.88-1.09) in the past quarter were not more likely to have bacterial vaginosis compared to those who reported no insertions. However, in South Africa, an increase in bacterial vaginosis was seen among those who reported inserting other substances (AOR: 1.48, 95%CI: 1.17, 1.88). In conclusion, targeted counseling against vaginal hygiene practices resulted in change in self-reported behavior but did not have an impact on bacterial vaginosis diagnosis in all but one site.

Bacterial Vaginosis and Subclinical Markers of Genital Tract Inflammation and Mucosal Immunity

Bacterial vaginosis (BV) has been linked to an increased risk of human immunodeficiency virus (HIV) acquisition and transmission in observational studies, but the underlying biological mechanisms are unknown. We measured biomarkers of subclinical vaginal inflammation, endogenous antimicrobial activity, and vaginal flora in women with BV and repeated sampling 1 week and 1 month after completion of metronidazole therapy. We also compared this cohort of women with BV to a healthy control cohort without BV. A longitudinal, open label study of 33 women with a Nugent score of 4 or higher was conducted. All women had genital swabs, cervicovaginal lavage (CVL) fluid, and cervicovaginal biopsies obtained at enrollment and received 7 days of metronidazole treatment. Repeat sampling was performed approximately 1 week and 1 month after completion of therapy. Participant's baseline samples were compared to a healthy, racially matched control group (n=13) without BV. The CVL from women with resolved BV (Nugent 0-3) had significantly higher anti-HIV activity, secretory leukocyte protease inhibitor (SLPI), and growth-related oncogene alpha (GRO-α) levels and their ectocervical tissues had significantly more CD8 cells in the epithelium. Women with persistent BV after treatment had significantly higher levels of interleukin-1β, tumor necrosis factor alpha (TNF-α), and intercellular adhesion molecule 1 (ICAM-1) in the CVL. At study entry, participants had significantly greater numbers of CCR5(+) immune cells and a higher CD4/CD8 ratio in ectocervical tissues prior to metronidazole treatment, compared to a racially matched cohort of women with a Nugent score of 0-3. These data indicate that BV is associated with changes in select soluble immune mediators, an increase in HIV target cells, and a reduction in endogenous antimicrobial activity, which may contribute to the increased risk of HIV acquisition.

Soluble Immune Mediators and Vaginal Bacteria Impact Innate Genital Mucosal Antimicrobial Activity in Young Women

INTRODUCTION

Innate activity against Escherichia coli in female genital secretions may represent contributions from vaginal bacteria and host soluble immune mediators. We analyzed the relationship between E. coli inhibitory activity, soluble immune mediators, and vaginal bacteria in participants in MTN-004, a placebo-controlled trial of VivaGel(®) , a candidate product for topical HIV pre-exposure prophylaxis.

METHODS

Escherichia coli inhibitory activity was quantified by colony reduction assay. Endocervical concentrations of interleukin (IL)-1β, IL-6, IL-12p40, macrophage inflammatory protein (MIP)-1α, granulocyte-macrophage colony-stimulating factor (GM-CSF), lactoferrin, and secretory leukocyte protease inhibitor (SLPI) were quantified to generate a cumulative mediator score. Vaginal bacteria were characterized by quantitative cultures.

RESULTS

In the two placebo arms, higher soluble immune mediator score was associated with greater E. coli inhibitory activity (β = 17.49, 95% CI [12.77, 22.21] and β = 13.28, 95% CI [4.76, 21.80]). However, in the VivaGel arm, higher concentrations of E. coli (β = -3.80, 95% CI [-6.36, -1.25]) and group B Streptococcus (β = -3.91, 95% CI [-6.21, -1.60]) were associated with reduced E. coli inhibitory activity.

CONCLUSIONS

Both host mediators and vaginal bacteria impact E. coli inhibition in genital secretions. The relative contributions of host mediators and bacteria varied between women who used VivaGel vs placebos.

First phase 1 double-blind, placebo-controlled, randomized rectal microbicide trial using UC781 gel with a novel index of ex vivo efficacy

OBJECTIVES

Successful control of the HIV/AIDS pandemic requires reduction of HIV-1 transmission at sexually-exposed mucosae. No prevention studies of the higher-risk rectal compartment exist. We report the first-in-field Phase 1 trial of a rectally-applied, vaginally-formulated microbicide gel with the RT-inhibitor UC781 measuring clinical and mucosal safety, acceptability and plasma drug levels. A first-in-Phase 1 assessment of preliminary pharmacodynamics was included by measuring changes in ex vivo HIV-1 suppression in rectal biopsy tissue after exposure to product in vivo.

METHODS

HIV-1 seronegative, sexually-abstinent men and women (N = 36) were randomized in a double-blind, placebo-controlled trial comparing UC781 gel at two concentrations (0.1%, 0.25%) with placebo gel (1∶1∶1). Baseline, single-dose exposure and a separate, 7-day at-home dosing were assessed. Safety and acceptability were primary endpoints. Changes in colorectal mucosal markers and UC781 plasma drug levels were secondary endpoints; ex vivo biopsy infectibility was an ancillary endpoint.

RESULTS

All 36 subjects enrolled completed the 7-14 week trial (100% retention) including 3 flexible sigmoidoscopies, each with 28 biopsies (14 at 10 cm; 14 at 30 cm). There were 81 Grade 1 adverse events (AEs) and 8 Grade 2; no Grade 3, 4 or procedure-related AEs were reported. Acceptability was high, including likelihood of future use. No changes in mucosal immunoinflammatory markers were identified. Plasma levels of UC781 were not detected. Ex vivo infection of biopsies using two titers of HIV-1(BaL) showed marked suppression of p24 in tissues exposed in vivo to 0.25% UC781; strong trends of suppression were seen with the lower 0.1% UC781 concentration.

CONCLUSIONS

Single and 7-day topical rectal exposure to both concentrations of UC781 were safe with no significant AEs, high acceptability, no detected plasma drug levels and no significant mucosal changes. Ex vivo biopsy infections demonstrated marked suppression of HIV infectibility, identifying a potential early biomarker of efficacy. (Registered at ClinicalTrials.gov; #NCT00408538).

Microbial biofilms on the surface of intravaginal rings worn in non-human primates

Millions of intravaginal rings (IVRs) are used by women worldwide for contraception and for the treatment of vaginal atrophy. These devices also are suitable for local and systemic sustained release drug delivery, notably for antiviral agents in human immunodeficiency virus pre-exposure prophylaxis. Despite the widespread use of IVRs, no studies have examined whether surface-attached bacterial biofilms develop in vivo, an important consideration when determining the safety of these devices. The present study used scanning electron microscopy, fluorescence in situ hybridization and confocal laser scanning microscopy to study biofilms that formed on the surface of IVRs worn for 28 days by six female pig-tailed macaques, an excellent model organism for the human vaginal microbiome. Four of the IVRs released the nucleotide analogue reverse transcriptase inhibitor tenofovir at a controlled rate and the remaining two were unmedicated. Large areas of the ring surfaces were covered with monolayers of epithelial cells. Two bacterial biofilm phenotypes were found to develop on these monolayers and both had a broad diversity of bacterial cells closely associated with the extracellular material. Phenotype I, the more common of the two, consisted of tightly packed bacterial mats approximately 5 µm in thickness. Phenotype II was much thicker, typically 40 µm, and had an open architecture containing interwoven networks of uniform fibres. There was no significant difference in biofilm thickness and appearance between medicated and unmedicated IVRs. These preliminary results suggest that bacterial biofilms could be common on intravaginal devices worn for extended periods of time.

Protection of HIV neutralizing aptamers against rectal and vaginal nucleases: implications for RNA-based therapeutics

RNA-based drugs are an emerging class of therapeutics. They have the potential to regulate proteins, chromatin, as well as bind to specific proteins of interest in the form of aptamers. These aptamers are protected from nuclease attack by chemical modifications that enhance their stability for in vivo usage. However, nucleases are ubiquitous, and as we have yet to characterize the entire human microbiome it is likely that many nucleases are yet to be identified. Any novel, unusual enzymes present in vivo might reduce the efficacy of RNA-based therapeutics, even when they are chemically modified. We have previously identified an RNA-based aptamer capable of neutralizing a broad spectrum of clinical HIV-1 isolates and are developing it as a vaginal and rectal microbicide candidate. As a first step we addressed aptamer stability in the milieu of proteins present in these environments. Here we uncover a number of different nucleases that are able to rapidly degrade 2'-F-modified RNA. We demonstrate that the aptamer can be protected from the nuclease(s) present in the vaginal setting, without affecting its antiviral activity, by replacement of key positions with 2'-O-Me-modified nucleotides. Finally, we show that the aptamer can be protected from all nucleases present in both vaginal and rectal compartments using Zn(2+) cations. In conclusion we have derived a stable, antiviral RNA-based aptamer that could form the basis of a pre-exposure microbicide or be a valuable addition to the current tenofovir-based microbicide candidate undergoing clinical trials.

Use of DNA hybridization to detect vaginal pathogens associated with bacterial vaginosis among asymptomatic pregnant women

OBJECTIVE

The purpose of this study was to determine whether microbial DNA hybridization is a useful method to study bacterial vaginosis in asymptomatic pregnant women.

STUDY DESIGN

Vaginal specimens were collected at <26 weeks' gestation from 230 women, and analyzed for bacterial vaginosis by both Gram stain using Nugent criteria and DNA hybridization for Gardnerella vaginalis, Prevotella bivia, Bacteroides ureolyticus, and Mobiluncus curtisii. Results were analyzed using McNemar's paired test and chi-square test for trend, with significance set at P < .05.

RESULTS

By Gram stain, 60 (26.1%) of 230 were positive for bacterial vaginosis, and 134 (58.3%) were negative. By DNA hybridization, 99 (43%) were positive for at least 1 pathogen, and DNA results were significantly associated with Gram-stain results (P < .01). As the Nugent score progressed from normal to abnormal flora, the proportion with >1 pathogen detected by DNA hybridization increased significantly (P < .001).

CONCLUSION

DNA hybridization may be a useful method to study shifts in vaginal flora during pregnancy.

The effects of three nonoxynol-9 preparations on vaginal flora and epithelium

To evaluate the effects of nonoxynol-9 (N-9) on the vaginal flora and epithelium, 48 women (16 in each group) were evaluated by use of quantitative vaginal cultures and colposcopy. at baseline and at 0.5, 4, 24, 48, and 72 h after insertion of one of three N-9 preparations (4% gel [Conceptrol], 3.5% gel [Advantage-24], or a 28% vaginal contraceptive film). The proportion positive for H2O2+ or H2O2- lactobacilli did not change significantly with any of the preparations, but lactobacilli concentrations decreased transiently. Both the proportion of women with Gardnerella vaginalis and the concentration of G. vaginalis decreased transiently. The proportion of women with Escherichia coli increased with the 4% gel, and the concentration increased with all preparations. The number with anaerobic gram-negative rods increased, although the concentrations decreased. Symptoms and colposcopic abnormalities were rare. Changes in levels of vaginal bacteria were transient after single applications of N-9, but adverse effects may be enhanced with frequent, chronic use.

HIV-1 infection associated with abnormal vaginal flora morphology and bacterial vaginosis

BACKGROUND

In-vitro research has suggested that bacterial vaginosis may increase the survival of HIV-1 in the genital tract. Therefore, we investigated the association of HIV-1 infection with vaginal flora abnormalities, including bacterial vaginosis and depletion of lactobacilli, after adjustment for sexual activity and the presence of other sexually transmitted diseases (STDs).

METHODS

During the initial survey round of our community-based trial of STD control for HIV-1 prevention in rural Rakai District, southwestern Uganda, we selected 4718 women aged 15-59 years. They provided interview information, blood for HIV-1 and syphilis serology, urine for detection of Chlamydia trachomatis and Neisseria gonorrhoeae, and two self-administered vaginal swabs for culture of Trichomonas vaginalis and gram-stain detection of vaginal flora, classified by standardised, quantitative, morphological scoring. Scores 0-3 were normal vaginal flora (predominant lactobacilli). Higher scores suggested replacement of lactobacilli by gram-negative, anaerobic microorganisms (4-6 intermediate; 7-8 and 9-10 moderate and severe bacterial vaginosis).

FINDINGS

HIV-1 frequency was 14.2% among women with normal vaginal flora and 26.7% among those with severe bacterial vaginosis (p < 0.0001). We found an association between bacterial vaginosis and increased HIV-1 infection among younger women, but not among women older than 40 years; the association could not be explained by differences in sexual activity or concurrent infection with other STDs. The frequency of bacterial vaginosis was similar among HIV-1-infected women with symptoms (55.0%) and without symptoms (55.7%). The adjusted odds ratio of HIV-1 infection associated with any vaginal flora abnormality (scores 4-10) was 1.52 (95% CI 1.22-1.90), for moderate bacterial vaginosis (scores 7-8) it was 1.50 (1.18-1.89), and for severe bacterial vaginosis (scores 9-10) it was 2.08 (1.48-2.94).

INTERPRETATION

This cross-sectional study cannot show whether disturbed vaginal flora increases susceptibility to HIV-1 infection. Nevertheless, the increased frequency of HIV-1 associated with abnormal flora among younger women, for whom HIV-1 acquisition is likely to be recent, but not among older women, in whom HIV-1 is likely to have been acquired earlier, suggests that loss of lactobacilli or presence of bacterial vaginosis may increase susceptibility to HIV-1 acquisition. If this inference is correct, control of bacterial vaginosis could reduce HIV-1 transmission.