REPLACEMENT OF POSTTRANSCRIPTIONAL REGULATION IN SIVMAC239 GENERATED A REV-INDEPENDENT INFECTIOUS VIRUS ABLE TO PROPAGATE IN RHESUS PERIPHERAL-BLOOD MONONUCLEAR-CELLS

Lentiviruses control virion production via posttranscriptional regulat ion mediated by the viral Rev protein. In this study, we demonstrate t hat the Rev regulation of SIVmac239 can be replaced by the presence of the cis-acting transport element (CTE) of the type D simian retroviru ses 1 (SRV-1). To avoid the possibility of generating revertants, the Rev-independent SIV clones have both rev and the Rev responsive elemen t (RRE) destroyed by multiple point mutations that do not affect the o verlapping tat and env open reading frames. Virus stocks generated fro m these Rev-independent SIV molecular clones can infect and can be pro pagated in rhesus peripheral blood mononuclear cells (PBMCs). Therefor e, the Rev/RRE system of SIVmac239 can be replaced by the SRV-1 CTE as previously shown for HIV-1. In both rhesus and human primary cells, t he replicative capacity of the Rev-independent SIV is 10- to 20-fold l ower than that of the wild-type virus. Rhesus PBMC-derived virus stock s of the Rev-independent SIV have lower infectivity. Interestingly, in CEM x 174 cells, no difference in replicative capacity between wild-t ype and Rev-independent SIV has been observed. The Rev-independent SIV has a stable genotype after several passages in primary cells. The av ailability of such Rev-independent viruses will allow the study of the role of Rev in pathogenesis and the potential generation of attenuate d SIV strains. (C) 1997 Academic Press.