CHARACTERIZATION OF CDNAS SPECIES ENCODING THE TAT PROTEIN OF CAPRINEARTHRITIS-ENCEPHALITIS VIRUS

Two distinct species of caprine arthritis encephalitis virus (CAEV) ta t cDNAs were isolated early after infection of a Himalayan tahr cell l ine. Sequence analyses predicted that one cDNA (pCEV/el) represented a polycistronic transcript that encodes Tat and Rev as well as an N-ter minally truncated transmembrane protein and a protein, designated X, w hose function is unknown; whereas the other cDNA (pCEV/f1) encodes Tat and the env gene products, pCEV/el trans-activated a CAEV LTR-chloram phenicol acetyltransferase reporter gene in goat synovial membrane cel ls. This activity was shown to be encoded by the Tat open reading fram e by analysis of a deletion mutant. Because the pCAEV/f1 insert was un stable in plasmid form, its Tat activity could not be convincingly dem onstrated. The target sequences for Tat within the CAEV LTR were local ized to the Us region which, when placed in either orientation upstrea m of heterologous promoters, was able to confer responsiveness to Tat. (C) 1994 Academic Press, Inc.