Shanon Ellis

Increased Susceptibility to Vaginal Simian/Human Immunodeficiency Virus Transmission in Pig-tailed Macaques Coinfected With Chlamydia trachomatis and Trichomonas vaginalis

BACKGROUND Sexually transmitted infections (STIs) are associated with an increased risk of human immunodeficiency virus (HIV) infection, but their biological effect on HIV susceptibility is not fully understood. METHODS Female pig-tailed macaques inoculated with Chlamydia trachomatis and Trichomonas vaginalis (n = 9) or medium (controls; n = 7) were repeatedly challenged intravaginally with SHIVSF162p3. Virus levels were evaluated by real-time polymerase chain reaction, plasma and genital cytokine levels by Luminex assays, and STI clinical signs by colposcopy. RESULTS Simian/HIV (SHIV) susceptibility was enhanced in STI-positive macaques (P = .04, by the log-rank test; relative risk, 2.5 [95% confidence interval, 1.1-5.6]). All STI-positive macaques were SHIV infected, whereas 3 controls (43%) remained uninfected. Moreover, relative to STI-negative animals, SHIV infections occurred earlier in the menstrual cycle in STI-positive macaques (P = .01, by the Wilcoxon test). Levels of inflammatory cytokines (interferon γ, interleukin 6, and granulocyte colony-stimulating factor [G-CSF]) were higher in STI-positive macaques during STI inoculation and SHIV exposure periods (P ≤ .05, by the Wilcoxon test). CONCLUSIONS 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.

Depot-medroxyprogesterone acetate does not reduce the prophylactic efficacy of emtricitabine and tenofovir disoproxil fumarate in macaques.

Abstract: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 exposure on PrEP with emtricitabine/tenofovir disoproxil fumarate. Twelve pigtail macaques treated with DMPA were exposed vaginally to simian HIV once a week for up to 5 months and received either placebo (n = 6) or emtricitabine/tenofovir disoproxil fumarate (n = 6). All control macaques were infected, whereas the PrEP-treated animals remained protected (P = 0.0007). This model suggests that women using DMPA will fully benefit from PrEP.

Relationship of estimated SHIV acquisition time points during the menstrual cycle and thinning of vaginal epithelial layers in pigtail macaques

Background HIV acquisition in the female genital tract remains incompletely understood. Quantitative data on biological HIV risk factors, the influence of reproductive hormones, and infection risk are lacking. We evaluated vaginal epithelial thickness during the menstrual cycle in pigtail macaques (Macaca nemestrina). This model previously revealed increased susceptibility to vaginal infection during and after progesterone-dominated periods in the menstrual cycle. Methods Nucleated and nonnucleated (superficial) epithelial layers were quantitated throughout the menstrual cycle of 16 macaques. We examined the relationship with previously estimated vaginal SHIVSF162P3 acquisition time points in the cycle of 43 different animals repeatedly exposed to low virus doses. Results In the luteal phase (days 17 to cycle end), the mean vaginal epithelium thinned to 66% of mean follicular thickness (days 1–16; P = 0.007, Mann-Whitney test). Analyzing 4-day segments, the epithelium was thickest on days 9 to 12 and thinned to 31% thereof on days 29 to 32, with reductions of nucleated and nonnucleated layers to 36% and 15% of their previous thickness, respectively. The proportion of animals with estimated SHIV acquisition in each cycle segment correlated with nonnucleated layer thinning (Pearson r = 0.7, P < 0.05, linear regression analysis), but not nucleated layer thinning (Pearson r = 0.6, P = 0.15). Conclusions These data provide a detailed picture of dynamic cycle-related changes in the vaginal epithelium of pigtail macaques. Substantial thinning occurred in the superficial, nonnucleated layer, which maintains the vaginal microbiome. The findings support vaginal tissue architecture as susceptibility factor for infection and contribute to our understanding of innate resistance to SHIV infection.

Analysis of putative mucosal SHIV susceptibility factors during repeated DMPA treatments in pigtail macaques.

Depot‐medroxyprogesterone acetate (DMPA) has been associated in some studies with increased HIV susceptibility in women. We used a pigtail macaque model to document the effects of repeated DMPA treatments and their potential contribution to increased SHIV susceptibility.

Combination Emtricitabine and Tenofovir Disoproxil Fumarate Prevents Vaginal Simian/Human Immunodeficiency Virus Infection in Macaques Harboring Chlamydia trachomatis and Trichomonas vaginalis

Genital inflammation associated with sexually transmitted infections increases susceptibility to human immunodeficiency virus (HIV), but it is unclear whether the increased risk can reduce the efficacy of pre-exposure prophylaxis (PrEP). We investigated whether coinfection of macaques with Chlamydia trachomatis and Trichomonas vaginalis decreases the prophylactic efficacy of oral emtricitabine (FTC)/tenofovir disoproxil fumarate (TDF). Macaques were exposed to simian/human immunodeficiency virus (SHIV) vaginally each week for up to 16 weeks and received placebo or FTC/TDF pericoitally. All animals in the placebo group were infected with SHIV, while 4 of 6 PrEP recipients remained uninfected (P= .03). Oral FTC/TDF maintains efficacy in a macaque model of sexually transmitted coinfection, although the infection of 2 macaques signals a modest loss of PrEP activity.

Development of a rectal sexually transmitted infection – HIV coinfection model utilizing Chlamydia trachomatis and SHIVSF162p3

Rectal sexually transmitted infections (STIs) may increase HIV susceptibility in men who have sex with men (MSM), and Chlamydia trachomatis is prevalent among HIV‐positive MSM. To study STIs and HIV infection in MSM, we first evaluated whether cynomolgus macaques can sustain both C. trachomatis and SHIVSF162p3 infections.

Novel multipurpose pod-intravaginal ring for the prevention of HIV, HSV, and unintended pregnancy: Pharmacokinetic evaluation in a macaque model

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.

A Depot Medroxyprogesterone Acetate Dose That Models Human Use and Its Effect on Vaginal SHIV Acquisition Risk.

Introduction:Hormonal contraception with depot medroxyprogesterone acetate (DMPA) may increase HIV acquisition risk, but observational human studies are inconclusive, and animal models can help investigate this risk. In this study, we test the impact of a low DMPA dose, designed to resemble human contraceptive use, on Simian-Human Immunodeficiency Virus (SHIV) acquisition risk in pigtail macaques (Macaca nemestrina). Methods:Macaques metabolize DMPA faster than humans. We previously identified a per-weight DMPA dose and administration frequency that achieves long-lasting suppression of ovulation in macaques. Eight macaques were given 1.5-mg/kg DMPA monthly, whereas 11 were untreated controls. For comparison, women receive 150 mg (approximately 2 mg/kg) every 3 months. We exposed monkeys to 20 suboptimal SHIV challenges, designed to slowly infect half of controls and allow increased infection in the DMPA group. Results:It took a median 5.5 viral challenges to infect DMPA-treated macaques and 9 challenges for controls (P = 0.27; exact conditional logistic regression). The exact odds ratio was 2.2 (CI: 0.6 to 8.3). Ovulation was suppressed, and the vaginal epithelium was thinned after DMPA treatment in all animals (mean, 30 and 219 mm in DMPA-treated and control macaques, respectively, P = 0.03, t test using the Satterthwaite degrees-of-freedom approximation). Conclusions:SHIV infections in DMPA-treated macaques were 2.2 times those of controls, but this was not statistically significant. The result is remarkably similar to studies of human DMPA use, which have shown HIV risk increases of a similar magnitude and of variable significance. Taken together with previous studies of higher DMPA doses in macaques, the results suggest a dose-dependent effect of DMPA on Simian Immunodeficiency Virus (SIV) or SHIV acquisition.

Development of a rectal sexually transmitted infection (STI) Model in Rhesus macaques using Chlamydia trachomatis serovars E and L2

Rectal STI coinfection models enhance the understanding of rectal HIV transmission risk factors.

Development of a repeat-exposure penile SHIV infection model in macaques to evaluate biomedical preventions against HIV

Penile acquisition of HIV infection contributes substantially to the global epidemic. Our goal was to establish a preclinical macaque model of penile HIV infection for evaluating the efficacy of new HIV prevention modalities. Rhesus macaques were challenged once or twice weekly with consistent doses of SHIVsf162P3 (a chimeric simian-human immunodeficiency virus containing HIV env) ranging from 4–600 TCID50 (50% tissue culture infective dose), via two penile routes, until systemic SHIV infection was confirmed. One route exposed the inner foreskin, glans and urethral os to virus following deposition into the prepuce (foreskin) pouch. The second route introduced the virus non-traumatically into the distal urethra only. Single-route challenges resulted in dose-dependent rates of SHIV acquisition informing selection of optimal SHIV dosing. Concurrent SHIV challenges via the prepuce pouch (200 TCID50) and urethra (16 TCID50) resulted in infection of 100% (10/10) animals following a median of 2.5 virus exposures (range, 1–12). We describe the first rhesus macaque repeat-exposure SHIV challenge model of penile HIV acquisition. Utilization of the model should further our understanding of penile HIV infection and facilitate the development of new HIV prevention strategies for men.