Inhibition of HIV-1 infection by lentiviral vectors expressing Pol III-promoted anti-HIV RNAs

A primary advantage of lentiviral vectors is their ability to pass through the nuclear envelope into the cell nucleus thereby allowing transduction of nondividing cells. Using HIV-based lentiviral vectors, we delivered an anti-CCR5 ribozyme (CCR5RZ), a nucleolar localizing TAR RNA decoy, or Pol III-expressed siRNA genes into cultured and primary cells. The CCR5RZ is driven by the adenoviral VA1 Pol III promoter, while the human U6 snRNA Pol III-transcribed TAR decoy is embedded in a U16 snoRNA (designated U16TAR), and the siRNAs were expressed from the human U6 Pol III promoter. The transduction efficiencies of these vectors ranged from 96-98% in 293 cells to 15-20% in primary PBMCs. A combination of the CCR5RZ and U16TAR decoy in a single vector backbone gave enhanced protection against HIV-1 challenge in a selective survival assay in both primary T cells and CD34⁺-derived monocytes. The lentiviral vector backbone-expressed siRNAs also showed potent inhibition of p24 expression in PBMCs challenged with HIV-1. Overall our results demonstrate that the lentiviral-based vectors can efficiently deliver single constructs as well as combinations of Pol III therapeutic expression units into primary hematopoietic cells for anti-HIV gene therapy and hold promise for stem or T-cell-based gene therapy for HIV-1 infection.