A human cytomegalovirus-based immunotherapy for HIV-1

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DESCRIPTION: The ultimate goal of this project is to develop an immunotherapy for human immunodeficiency virus (HIV)-1 based on a spread-deficient cytomegalovirus (CMV)-derived vaccine expressing "tailored" antigens designed for maximal coverage of clade B epitopes. In non-human primate models, rhesus CMV-vectored vaccines demonstrated unprecedented protection against highly virulent simian immunodeficiency virus (SIV). After initial infection, SI was ultimately cleared from protected animals suggesting that CMV-vectors can provide a therapeutic effect in infected individuals. CMV vectors are unique in multiple aspects: they can induce and maintain high levels of circulating and tissue-resident effector memory T cells even when vectors are spread-deficient in vivo. Moreover, in the absence of viral gene products that control T cell priming, CMV vectors induce T cells to unconventional epitopes including MHC-II restricted CD8+ T cells. Importantly, CMV vectors can be used repeatedly and in CMV-positive hosts without loss of immunogenicity. HIV sequence diversity poses a challenge to HIV vaccine design. However, unlike prophylactic vaccines which strive to achieve the broadest possible coverage of HIV sub-species, therapeutic vaccines can be tailored towards the actual strains present in an infected individual. In this proposal, we will therefore test the hypothesis that a tailored vaccine cocktail selected from a small vaccine panel containing HIV antigens optimized for T cell epitope coverage of a given HIV clade are superior with respect to inducing "relevant" T cell responses as compared to non-tailored approaches. We will use novel algorithms to design tailored antigens that maximize epitope-matches and we will insert these antigens into a new human CMV-vector backbone developed at TomegaVax during phase I of this proposal. We will monitor epitope specific T cell responses against specific HIV-strains using a recently developed NHP model for HCMV. Based on these results, we will design our final vaccine cocktail. To facilitate manufacturing of HCMV vectors under good manufacturing practices (GMP) we will generate a complementing master cell bank based on preliminary data showing, for the first time, HCMV growth in a cell type previously used for the manufacturing of unrelated viral vaccines. Upon completion of this project, we will have a designed, characterized, and developed a manufacturing strategy to generate clinical grade HCMV/HIV vector products.