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RESEARCH PRODUCT

566. Selective and Stable Transduction of Human CD4+ T Cells In Vivo Upon Systemic Administration of CD4-Targeted Lentiviral Vectors

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Playing a central role in both innate and adaptive immunity, CD4+ T cells are the key target for genetic modifications in basic research and immunotherapy. Specific and stable delivery of therapeutic genes into these cells is therefore highly desirable. Here, we describe novel lentiviral vectors (CD4-LV) that have been rendered selective for human or simian CD4+ cells by surface engineering. This novel CD4-LV was highly specific and effective in genetic modification of human CD4+ T cells both in vitro and in vivo. When applied to peripheral blood mononuclear cells (PBMC), CD4-LV transduced CD4+ but not CD4− cells. Notably, also unstimulated T cells were stably genetically modified. Upon systemic or intrasplenic administration into mice reconstituted with human PBMC or hematopoietic stem cells, reporter gene expression was predominantly detected in lymphoid organs. Evaluation of GFP expression in organ-derived cells and blood by flow cytometry demonstrated exclusive gene transfer into CD4+ human lymphocytes. In bone marrow and spleen memory T cells were preferentially hit. Towards potential therapeutic applications, we show that CD4-LV can deliver genes protecting T cells from infection with HIV-1 or encoding chimeric antigen receptors thereby inducing tumor cell killing. This study demonstrates for the first time highly selective and stable gene delivery into human CD4+ T lymphocytes upon in vivo administration of lentiviral vectors, opening an avenue towards novel strategies in immunotherapy.