A RECOMBINANT RETROVIRUS CARRYING A NON-PRODUCER HUMAN-IMMUNODEFICIENCY-VIRUS (HIV) TYPE-1 VARIANT INDUCES RESISTANCE TO SUPERINFECTING HIV

A human immunodeficiency virus (HIV) type 1-infected Hut-78 cell clone (F12) shows a peculiar phenotype: it exhibits an altered viral protei n pattern, is a non-producer and is resistant to homologous superinfec tion. To determine whether this phenotype is dependent upon the expres sion of the HIV-1 genome integrated therein, the SstI/SstI F12 proviru s [deprived of HIV long terminal repeats (LTRs)] was cloned and insert ed in the pLj retroviral vector bearing the neomycin (neo) and Genetic in resistance gene. CD4- HIV-susceptible CEMss cells (a CEM clone able to form large syncytia 2 to 3 days post-HIV infection) were infected with the recombinant retroviruses rescued from the F12/HIV-pLj-transfe cted (in either sense or antisense orientation) amphotropic packaging cells PA 317. Neo sense resistant gene clones showed approximately 10 copies of viral DNA/cell (without detectable major deletions) only in episomal form, low viral RNA expression and a viral protein pattern ch aracterized by an uncleaved gp160, no gp41 and little, if any, p55 gag precursor (as in F12 cells). Superinfection of these F12/HIV DNA-engi neered clones with HIV-1 resulted in a significant reduction in the yi eld of superinfecting HIV. This effect (more pronounced when the clone s were maintained under neo selective pressure) was observed in all fi ve retrovirus-infected clones exhibiting the presence and expression o f sense episomal F12/HIV DNA but not in two clones bearing an antisens e F12/HIV DNA or in one clone bearing only the pLj vector. These resul ts indicate that bio-engineered human CD4+ cells expressing the F12/HI V genome exhibit a significant resistance to HIV superinfection.