Virus-secific transcription in 3T3 cells transformed by the ts-a mutant of polyoma virus.

Virus-specific RNA transcription has been measured in 3T3 cells transformed by the ts-a mutant of polyoma virus by RNA-excess hybridization to the separated strands of polyoma DNA. In two cloned sublines maintained at 39 degrees C, the nonpermissive temperature for the A gene function, RNA transcripts of a large fraction of the "early" strand are detected in both nuclear and cytoplasmic RNA fractions, but no "late" strand transcription is detected. Temperature shift to 31.5 degrees C, the permissive temperature, induces viral DNA replication and virus production accompanied by late strand transcription. In two independently derived noninducible cell lines, L strand transcription is never observed, even after cultivation at the permissive temperature. A smaller fraction of the E strand is transcribed in each noninducible cell than in its inducible parent, and this difference is further characterized as a lack of transcripts of portions of HpaII restriction endonuclease fragments 2 and 6.