Experimental gene therapy: the transfer of Tat-inducible interferon genes protects human cells against HIV-1 challenge in vitro and in vivo in severe combined immunodeficient mice.

ABSTRACT

OBJECTIVES: To evaluate in vitro and in vivo a strategy for gene therapy for AIDS based on the transfer on interferon (IFN)-alpha, -beta and -gamma genes to human cells. DESIGN: Human U937 promonocytic cells were stably transfected with Tat-inducible IFN expression vectors conferring an antiviral state against infection with HIV. METHODS: Transfected cells were either infected by HIV-1 in vitro or transplanted into severe combined immunodeficient (SCID) mice for an HIV challenge in vivo. RESULTS: U937 cell lines stably carrying IFN transgenes under the positive control of the HIV-1 Tat protein were highly resistant to HIV-1 replication in vitro. This antiviral resistance was associated with a strong induction of IFN synthesis immediately following the viral infection. HIV-1 proteins were found to be specifically trapped within the genetically modified cells. In contrast, all IFN-U937 cells permitted full HIV-2 replication. Transfected cells injected into SCID mice and challenged against HIV-1 were strongly resistant to infection when cells were transduced with IFN-alpha of IFN-beta genes. However, IFN-gamma-transfected cells permitted HIV-1 infection in vivo despite the induction of a high level of IFN-gamma secretion. The quantity of proviral DNA was 10(5)-fold lower in IFN-alpha- or IFN-beta-transfected U937 cells collected from these SCID mice than that in non-transfected cells. CONCLUSIONS: Our results substantiated the validity of a strategy, bases on the transfer of HIV-1-inducible IFN-alpha or IFN-beta genes, to confer antiviral resistance to human cells.