Structure of simian immunodeficiency virus regulatory genes.

Three full-length cDNA clones were obtained from cells infected with the simian immunodeficiency virus (SIV) isolated from captive macaques (SIVMAC). Nucleotide sequence analyses suggested that these represented mRNA for the SIV MAC genes tat, rev (formerly, art/trs), and nef (formerly, 3'orf). The putative tat-specific clone was active in trans-activation of the SIV MAC long terminal repeat in COS-1 and Jurkat cells. In contrast, the human immunodeficiency virus 1 long terminal repeat was significantly trans-activated only in the COS-1 cells. This suggests that trans-activation by the SIV tat gene is modulated by cell-specific factors. The structure of all of the clones suggested an mRNA splicing pattern more complex than that described for human immunodeficiency virus 1.