Although the institution of anti-retroviral therapy (ART) has reduced morbidity and mortality from HIV infection, immune reconstitution is incomplete, virus persists in tissue reservoirs and rebound viremia occurs when treatment is halted. Recent findings that intermittent compliance with drug therapy can stimulate T cell responses has led to the concept that low-level antigenic stimulation through re-exposure to virus, or boosting of T cell responses via immunization, may facilitate control of viral replication as an adjunct to ART. An effective way to generate human T cell responses is by presenting antigens on dendritic cells (DCs), a system of antigen presenting cells (APCs) that stimulate innate and acquired immune responses. DCs pulsed with live or chemically inactivated (Aldrithiol-2 treated) HIV or SIV, efficiently induce HIV-specific CD4+ and CD8+ T cell responses from human cells in vitro. Aldrithiol-2 (AT-2) inactivates HIV infectivity without affecting the conformational and functional integrity of virion surface proteins. DCs pulsed with AT-2 inactivated SIV induced long term control of viremia in Chinese rhesus macaques chronically infected with SIVmac251. Furthermore, we have established the safety and immunogenicity of DCs in healthy individuals and more recently in HIV+ individuals. Based on these findings, we will determine whether DCs pulsed with AT-2 inactivated-HIV induce therapeutic immune responses in a cohort of chronically infected HIV+ individuals.
The specific aims are to: (1) optimize the capture, processing and presentation of AT-2 treated HIV by human DCs in vitro, as a prelude to clinical studies;(2) develop the methodology required to prepare sterile AT-2 inactivated autologous HIV from patients'monocytes on a level which meets regulatory requirements, and (3) to establish the immunogenicity of DCs pulsed with autologous AT-2 inactivated HIV in an ART suppressed, chronically infected HIV+ cohort. These studies will help determine whether non-replicating HIV, when delivered on DCs, induces durable CD4 and CD8 responses which facilitate control of viral replication, even after termination of ART.
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