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Testing the Efficacy of HIV Prevention Strategies in Nonhuman Primate Models



The field of HIV prevention has recently gained two new biomedical preventions: 1) a partially effective HIV vaccine, RV-144 delivered parenterally, and 2) partially effective pre-exposure prophylaxis (PrEP) in the form of a microbicide delivered as a vaginal gel, or as a daily, oral tablet. These preventions, while not yet approved for general use, are - either in the same form or in modified form - imminently scalable and likely to be implemented widely in upcoming years. CDC has been involved in evaluating and developing biomedical preventions such as these for many years, both in animal models and in humans. Historically, CDC has also provided guidance on implementation of vaccines, and through ACIP, will do so for HIV vaccines as they emerge.

It is likely that future HIV vaccine trials in humans will have to incorporate control arms with PrEP, be it by oral, vaginal or rectal delivery. The partial efficacy observed with a single intervention, whether it be a vaccine or PrEP, has escalated the need to assess if these two combined preventions will have additive, synergistic or possibly even negative/inhibitory effects. CDC researchers have used statistical models to explore these questions. However, animal models allow direct testing of the combined efficacy of partially effective prevention methods. CDC and the field of HIV prevention would gain immensely from such preclinical results. This could directly inform clinical trial designs, and also inform implementation of novel preventions.

Project Goal:  The goal of this project is to model, in non-human primates, combination preventions such as PrEP and candidate HIV vaccines, to determine if these combinations have neutral, additive, synergistic, inhibitory or other effects.

Vendors should have prior experience testing animal models of HIV, anti-retrovirals or microbicides for HIV prevention and HIV vaccines. Proposals should include studies of at least 2 preventions for HIV infection (such as PrEP and a candidate HIV vaccine) that are representative of products in the current pipeline for human use. Furthermore, proposals should include a timeline, and should incorporate statistical estimates or sample sizes for different study arms that will allow appropriately powered evaluation of additive, synergistic or other interactions. Proposals may be structured to test study arms sequentially. Experimental design should include ways to measure correlates of protection and mechanisms of interaction. Studies should be designed with the long-term goal of providing information that will guide either human clinical trials of combination prevention, implementation of combination preventions or both. 

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