In this pigtail macaque model of DMPA and vaginal SHIV infection, we found little or no effect of DMPA on plasma viremia and mucosal virus shedding during acute infection. These results do not support a role of DMPA in increasing mucosal HIV shedding.

C. trachomatis and T. vaginalis infection increase the susceptibility to SHIV, likely because of prolonged genital tract inflammation. These novel data demonstrate a biological link between these nonulcerative STIs and the risk of SHIV infection, supporting epidemiological associations of HIV and STIs. This study establishes a macaque model for studies of high-risk HIV transmission and prevention.

All animals showed temporal vaginal epithelial thinning with loss of the non-nucleated layer, and vaginal pH changes post-DMPA injections.

Globally, women bear an uneven burden for sexual HIV acquisition. Results from two clinical trials evaluating intravaginal rings (IVRs) delivering the antiretroviral agent dapivirine have shown that protection from HIV infection can be achieved with this modality, but high adherence is essential. Multipurpose prevention technologies (MPTs) can potentially increase product adherence by offering protection against multiple vaginally transmitted infections and unintended pregnancy. Here we describe a coitally independent, long-acting pod-IVR MPT that could potentially prevent HIV and HSV infection as well as unintended pregnancy. The pharmacokinetics of MPT pod-IVRs delivering tenofovir alafenamide hemifumarate (TAF2) to prevent HIV, acyclovir (ACV) to prevent HSV, and etonogestrel (ENG) in combination with ethinyl estradiol (EE), FDA-approved hormonal contraceptives, were evaluated in pigtailed macaques (N = 6) over 35 days. Pod IVRs were exchanged at 14 days with the only modification being lower ENG release rates in the second IVR. Plasma progesterone was monitored weekly to determine the effect of ENG/EE on menstrual cycle. The mean in vivo release rates (mg d-1) for the two formulations over 30 days ranged as follows: TAF2 0.35–0.40; ACV 0.56–0.70; EE 0.03–0.08; ENG (high releasing) 0.63; and ENG (low releasing) 0.05. Mean peak progesterone levels were 4.4 ± 1.8 ng mL-1 prior to IVR insertion and 0.075 ± 0.064 ng mL-1 for 5 weeks after insertion, suggesting that systemic EE/ENG levels were sufficient to suppress menstruation. The TAF2 and ACV release rates and resulting vaginal tissue drug concentrations (medians: TFV, 2.4 ng mg-1; ACV, 0.2 ng mg-1) may be sufficient to protect against HIV and HSV infection, respectively. This proof of principle study demonstrates that MPT-pod IVRs could serve as a potent biomedical prevention tool to protect women’s sexual and reproductive health and may increase adherence to HIV PrEP even among younger high-risk populations.

Concerns that the injectable contraceptive depot-medroxyprogesterone acetate (DMPA) may increase the risk of HIV acquisition in women led to questions on whether DMPA could reduce efficacy of pre-exposure prophylaxis (PrEP) for HIV prevention. We used a macaque model to investigate the impact of prolonged DMPA on PrEP with FTC/TDF. Twelve pigtail macaques treated with DMPA were exposed vaginally to SHIV once a week for up to 5 months and received either placebo (n=6) or FTC/TDF (n=6). All control macaques were infected while the PrEP-treated animals remained protected (p=0.0007). This model suggests that women using DMPA will fully benefit from PrEP.