Regulation of simian virus 40 early and late gene transcription without viral DNA replication.

Primary cultures of African green monkey kidney cells were infected with the simian virus 40 temperature-sensitive mutant tsA58 at the nonpermissive temperature of 41 degrees C for 12 to 20 h. Under these conditions, a defective T antigen was produced and no viral DNA replication was detected. Viral transcription complexes were extracted from infected nuclei using Sarkosyl and the nascent chains of RNA elongated in vitro. Sixty to 70% of the viral RNA synthesized in vitro hybridized to late gene sequences. In contrast, 80 to 90% of the nuclear viral RNA labeled in vivo during a 15-min pulse with [3H]uridine hybridized to early gene sequences. This suggests that selective degradation of late gene transcripts occurs in vivo. The role of T antigen and viral DNA replication in regulation of simian virus 40 transcription is discussed.