Targeting Antiapoptotic Signaling for Eradication of HIV Latent Reservoir

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Human immunodeficiency virus (HIV) infection creates a long-lived latent reservoir that is maintained during antiretroviral therapy (ART). With a half-life of approximately ~44 months, these latently-infected CD4 T cells threaten recrudescence even after prolonged treatment and are a major impediment to the eradication of virus reservoirs. Our long-term goals are to discover the mechanisms responsible for conveying the very long half-life of latent CD4 T cells and develop strategies to shorten the half-life to allow their elimination during a relevant time interval. We hypothesize that HIV developed a capacity to stimulate anti-apoptotic activities as a key part of the latency mechanism, which might account for the greatly increased half-life of reservoir cells. Some studies indicated that low-level viral gene expression exists in some of the latently infected cells or in many cases for part of the time, even if they are not releasing infectious virus. Low-levels of viral proteins might promote apoptosis resistance and long half-life. In this project, we focus on HIV Envelope and Nef proteins, both of which have proven antiapoptotic effects. Using an in vitro model of latency, we test whether Env or Nef-induces low-level MEK/Erk or PI3k/Akt signaling and whether specific signaling inhibitors eliminate the apoptosis resistance and help clear the latent cells. We already have substantial experience on Env:CD4 signaling and now add Nef protein as part of a new collaboration with Dr. Jonathan Karn, who is the CFAR mentor/collaborator of this project. Dr. Karn and his group are experts in HIV latency and successfully developed experimental systems for studying HIV latency in primary T cells. Using this system, we will establish latently infected CD4 T cells with several different HIV reporter viruses and test our hypothesis. Next, we will test whether specific inhibitors of MEK/Erk, PI3k/Akt or a combination of these drugs can help eliminate latent reservoir from PBMC of HIV infected patients receiving stable ART or with natural virus suppression (NVS). Signaling inhibitors for these pathways are the objects of intense research in cancer and several are already in human clinical trials so it is reasonable that our in vitro studies can provide the justification for animal models or clinical trials testing this approach.