INHIBITION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 BY RETROVIRAL VECTORS EXPRESSING ANTISENSE-TAR

The human immunodeficiency virus type-1 (HIV-1) Tat activation response (TAR) region is essential for Tat-mediated trans-activation of the HIV-I long terminal repeat (LTR), The TAR element is present on the 5' and 3' ends of all HIV-1 transcripts and is relatively conserved among different HIV-1 isolates. These properties make it an attractive target for anti-HIV-1 gene therapy strategies, We have constructed a Moloney murine leukemia-based retroviral vector that expresses a chimeric tRNA(i)Met-antisense TAR fusion transcript complementary to the HIV-1 TAR region. The potential of this anti-TAR retroviral vector to inhibit HIV-1 was initially tested by transient transfections with an HIV-1-LTR-Tat expression plasmid into HeLa-CAT cells, Anti-TAR inhibited Tat-mediated HIV-1 LTR-driven CAT reporter gene expression in a dose-dependent fashion, The antisense-TAR vector was then used to transduce the human SupT1 T cell line, Cotransfection of these SupT1 cells with a Tat expression plasmid plus an HIV-1 LTR-CAT reporter plasmid resulted in decreased CAT gene expression in comparison to control transduced SupT1 cells, The antisense-TAR engineered SupT1 cell line was then challenged with HIV-1(MN). HIV-1 viral production was inhibited in SupT1 cells transduced with the antisense-TAR retroviral vector, Greater inhibition of HIV-1 was observed with antisense-TAR as compared to antisense-Tat expressing retroviral vector, These observations suggest that antisense-TAR retroviral vectors are potentially useful for clinical anti-HIV-1 gene therapy.