Oral pre-exposure prophylaxis for HIV prevention.
ABSTRACT In the absence of an effective vaccine, HIV continues to spread worldwide, emphasizing the need for new biomedical interventions to limit its transmission. Appreciation of the challenges that HIV has to face to initiate an infection mucosally has spurred interest in evaluating the use of antiretroviral drugs to prevent infection. Recent animal studies using macaques or humanized mice models of mucosal transmission of SIV or HIV have shown that daily or intermittent pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) can exploit early virus vulnerabilities and effectively prevent establishment of infection. These preclinical findings have fueled interest in evaluating the safety and efficacy of PrEP in humans. We provide an overview of the rationale behind PrEP and discuss the next steps in PrEP research, including the need to better define the ability of current drugs to reach and accumulate in mucosal tissues and protect cells that are primary targets during early HIV infection.
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ABSTRACT: The last few years have witnessed a renewed commitment to HIV prevention. The evidence to support the use of antiretroviral therapy (ART) for prevention of new HIV infection in the form of Pre-exposure prophylaxis (PrEP) among men who have sex with men, transgender, people who inject drugs, heterosexual men and women and HIV-1 serodiscordant couples, or treatment as prevention (TasP) for serodiscordant couples have also grown. The need to explore the possible use of ART for HIV prevention in Nigeria has become imperative in view of its high HIV burden and the current slow pace of effort to achieve the universal target of reducing its HIV incidence by 50%. While PrEP and TasP are welcome addendum to the existing HIV prevention armamentarium, it is still important to conduct a demonstration project to identify strategies that can facilitate access to PrEP and TasP taking cognizance of the peculiar local challenges with respect to ART and HIV prevention commodity access. The country has therefore drawn a roadmap for itself on how to introduce ART for use for HIV prevention as either PrEP or TasP. This paper discusses the three year national roadmap that would enable the country generated the needed scientific evidence as well as extensive community support for use of ART for HIV prevention in Nigeria. This process includes the conduct of modeling and formative studies, and the implementation of a 24 months demonstration project. The outcome of the demonstration project would inform plans for the scale up of pre-exposure prophylaxis (PrEP) access for population(s) at high risk for HIV infection in Nigeria.African Journal of Reproductive Health 09/2014; 18(3):127.
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ABSTRACT: Objectives: This study evaluated the relationship between intracellular tenofovir diphosphate concentrations in peripheral blood mononuclear cells and prophylactic efficacy in a macaque model for HIV pre-exposure prophylaxis (PrEP). Methods: Macaques were challenged with simian HIV (SHIV) via rectal inoculation once weekly for up to 14 weeks. A control group (n = 34) received no drug, a second group (n = 6) received oral tenofovir disoproxil fumarate/emtricitabine 3 days before each virus challenge and a third group (n = 6) received the same dosing plus another dose 2 h after virus challenge. PBMCs were collected just before each weekly virus challenge. The relationship between tenofovir diphosphate in PBMCs and prophylactic efficacy was assessed with a Cox proportional hazards model. Results: The percentages of animals infected in the control, one-dose and two-dose groups were 97, 83 and 17, respectively. The mean (SD) steady-state tenofovir diphosphate concentration (fmol/10(6) cells) was 15.8 (7.6) in the one-dose group and 30.7 (10.1) in the two-dose group. Each 5 fmol tenofovir diphosphate/10(6) cells was associated with a 40% (95% CI 17%-56%) reduction in risk of SHIV acquisition, P = 0.002. The tenofovir diphosphate concentration associated with a 90% reduction in risk (EC90) was 22.6 fmol/10(6) cells (95% CI 13.8-60.8). Conclusions: The prophylactic EC90 for tenofovir diphosphate identified in macaques exposed rectally compares well with the EC90 previously identified in men who have sex with men (MSM; 16 fmol/10(6) cells, 95% CI 3-28). These results highlight the relevance of this model to inform human PrEP studies of oral tenofovir disoproxil fumarate/emtricitabine for MSM.Journal of Antimicrobial Chemotherapy 05/2014; 69(9). DOI:10.1093/jac/dku162 · 5.44 Impact Factor
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ABSTRACT: Background and MethodsA reservoir intravaginal ring (IVR) eluting tenofovir disoproxil fumarate (TDF) was evaluated for 6 months of continuous use in normally cycling female pigtailed macaques with monthly IVR exchanges to define pharmacokinetics and safety.Results and Conclusions Tenofovir levels in vaginal secretions and tissue remained consistent for 6 months with no adverse safety concerns.Journal of Medical Primatology 05/2014; 43(5). DOI:10.1111/jmp.12119 · 0.89 Impact Factor