Abstract Drugs of abuse, such as methamphetamine (METH), can work in concert with specific anti- retroviral therapeutics and residual viral replication in HIV-infected brain, to drive the HIV-related brain pathology and neurocognitive dysfunction. The central hypothesis of this proposal is that HIV brain life cycle is influenced by exposure to METH, which facilitates the entry of HIV into the brain, establishing infection and latency, and, along with specific anti- retroviral drugs, contribute to neuroimmune activation and neuroinflammatory reactions. We will evaluate these events by focusing on novel and previously unexplored aspects of HIV biology at the blood-brain barrier (BBB). Based on our preliminary data, we propose that toll-like receptors 2 and 4 (TLR2/4) are critical players of cerebrovascular toxicity of METH, leading to dissembling of TJ protein complexes and facilitated HIV entry into the brain (Aim 1). We will next evaluate the mechanisms of METH-induced enhanced HIV replication and establishment of latent infection in BBB pericytes (Aim 2). Our pioneering findings indicated that BBB pericytes are permissive to HIV infection. In the current proposal, we will continue this novel research by focusing on the role of METH in active and latent infection in these cells. Because METH, HIV, and anti-retroviral drugs share mitochondrial dysfunction as one of the primary mechanisms of their cerebrovascular toxicity, an important part of the proposal will be devoted to exploring novel nanotechnologies aimed to target mitochondria for therapeutic protection (Aim 3). Thus, we will provide innovative therapeutic strategies to protect against cerebrovascular toxicity and neuroimmune activation, which are driven by METH and specific anti-retroviral drugs in HIV-infected brain. The proposed research is not only highly innovative, but it is likely to lead to the development of new translational knowledge for the clinic. This application will study novel and previously unrecognized mechanisms and pathogenesis underlying the development of brain infection by HIV, in the context of drug abuse and anti-retroviral strategies. With expertise in drug abuse research, BBB biology, HIV infection, and mitochondria targeting, we are uniquely positioned to perform the proposed, highly innovative project.