The role of chemokines in the establishment of HIV latency

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DESCRIPTION (provided by applicant): The use of combination antiretroviral therapy (ART) for the treatment of HIV has resulted in a significant reduction in morbidity and mortality, however HIV infection cannot be eradicated with ART alone. The major barrier to eradication of HIV is persistent long lived latently infected resting CD4+ T-cells. Developing strategies to block the establishment of latent infection could be used in addition to ART to eliminate or accelerate the decay of latently infected CD4+ T-cells. Our overall hypothesis is that specific chemokines, molecules involved in controlling T cell migration and recirculation, are critical for facilitating latent infection in resting CD4+ T-cells. Our overall aim is to identify novel interventions to blok infection of resting CD4+ T-cells by targeting host and not viral factors. To address this, we will use a robust model we have recently developed to establish latency in vitro. In this model, resting CD4+ T-cells are incubated with chemokines that bind to chemokine receptors highly expressed on resting cells. After incubation with the relevant chemokines, cells are infected with HIV and high levels of integration and no virus production is observed, consistent with latent infection. Using this model of chemokine-induced latency, we will first determine whether the establishment of latency can be inhibited by either chemokine receptor or chemokine antagonists. Chemokine antagonists are chemokines with progressive truncation of the N-terminus end which acquire antagonist rather than agonist activity. We will specifically target chemokine receptors that we have shown are critical for HIV infection of resting CD4+ T-cells. These include CXCR3, CCR6 and CCR7. The chemokine receptor and chemokine antagonists will be evaluated alone and in combination in vitro. We will then define the mechanisms of how chemokines mediate efficient nuclear localization and integration in resting CD4+ T-cells. We will first identify the critical cytoskeletal pathways required for migration of the virus to the nucleus in a resting CD4+ T-cell. Using fluorescent microscopy we will identify whether the key pathways involve the actin or microtubule cytoskeleton. We will identify whether changes in the cytoskeleton facilitate nuclear localization in resting CD4+ T-cells and whether this is activated by a specific signaling event or simply by T-cell migration alone. Finally, we will explore the rol of the phophoinosito-3-kinase (PI3K) pathway in mediating efficient HIV integration in resting CD4+ T-cells. We will determine the relevant downstream proteins and specific nuclear factors that are important for facilitating integration. We will also define the sites of HIV integration i this model of latency and determine the relationship between integration and transcription factor binding sites. Overall, these studies may ultimately identify novel antiviral targets, specific for blocking latent infection of resting CD4+ T-cells.