Animal Model for Testing SIV Latency Reversal Strategies

University Of Pittsburgh At Pittsburgh, Pittsburgh PA

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Abstract

? DESCRIPTION (provided by applicant): The case of the Berlin patient demonstrated that a cure for HIV infection is feasible. Meanwhile, the burden of the HIV epidemic, which spreads unabated, as such that for every HIV-infected person that starts antiretroviral therapy (ART), two new people become infected, fuels the global consensus that a cure for HIV is needed to curb the epidemic. A priority for cure research is the development of relevant animal models for preclinical assessment of new therapeutic strategies aimed at eliminating latently HIV-infected cells. We developed such an animal model and we plan to use it in this application to investigate strategies for reversing viral latency. Key features of this model include complete control of SIVsab replication in 100% of rhesus macaques (RMs) in the absence of ART with viral control achieved through effective cellular immune responses. The main strength of the model is that it permits a rapid, low cost screening of new therapeutic strategies aimed at depleting viral reservoirs in vivo without the need to boost cellular immune responses or the complexity of multidrug ART. As such, the model is shown to be fast, reliable and versatile for cure research and provides an ideal setting for testing the flush and kill strategies. In preliminary studies w have shown that SIVsab can be reactivated in controller RMs both ex vivo and in vivo. We will use this new SIVsab/RM system to test our hypothesis that the administration of a combination of LRAs will increase their efficacy in reducing the reservoir as compared to administration of individual LRAs, reduce the doses, reduce toxicity and thus allow a prolonged administration which might be needed to eliminate the reservoir. To this goal, we will combine two LRAs belonging to the currently available classes of LRAs: a histone deacetylation inhibitor (HDACi)-Romidepsin and a protein kinase C activator (PKC)-prostratin to reactivate the virus from the reservoir in controller RMs. Results obtained in this in vivo screening system will be confirmed in a conventional nonhuman primate model (SIVmac-infected RMs on ART) that more closely reproduce the characteristic of the majority of HIV-infected patients, including cytotoxic T lymphocyte dysfunction. By comparing and contrasting the impact of LRA administration on the reservoir in these two models that differ in terms of immune dysfunction and CTL functionality, we will validate the concept of flush and kill and test its efficacy in relevant in vivo systems. This proposal has strong translational potential. We propose an approach that might result in the reduction of the dose of LRAs thus allowing prolonged administration which may be needed to eliminate viral reservoir.