A nonproducer, interfering human immunodeficiency virus (HIV) type 1 provirus can be transduced through a murine leukemia virus-based retroviral vector: Recovery of an anti-HIV mouse/human pseudotype retrovirus

The expression of a human immunodeficiency virus (HIV) type 1 provirus (F2-HIV) cloned from a nonproducer, chronically infected CD4 down-regulated Hut-78 cell clone (F12) does not lead to the formation of viral particles and, upon transfection in HeLa CD4⁺ cells, confers resistance to HIV superinfection without affecting the CD4 receptor exposure. In an attempt to transfer the anti-HIV properties of F12-HIV into human primary cells, we constructed a Moloney murine leukemia virus-based retroviral vector containing an F12-HIV genome lacking the 3' long terminal repeat and part of the nef gene, which was expressed under the control of its 5' long terminal repeat. The F12-HIV genome was inserted in the orientation opposite to that of the murine leukemia virus transcriptional unit and was designated the N2/F12-HIV nef- antisense vector. Lymphoblastoid CEMss cells, as well as human peripheral blood lymphocytes, were successfully transduced by the recombinant retrovirus emerging from the producer PA317 clones. CEMss clones expressing the F12-HIV nef-antisense vector became resistant to HIV superinfection even at the highest utilized multiplicity of infection (10⁵ 50% tissue culture infective doses per 10⁶ cells). In transduced CEMss cells the viral interference induced by the F12-HIV expression is not due to CD4 HIV receptor down-regulation. Nonproducer, interfering HIV proviruses transduced into retroviral vectors may, therefore, provide an alternative strategy for the protection of CD4⁺ human primary cells from HIV infection, which strategy may be used in designating a safe and efficient gene therapy protocol for patients with AIDS.