Virus-specific RNA in Cells Productively Infected or Transformed by Polyoma Virus

The rudiments of polyoma virus transcription have been established during the past 8 years. Small amounts of RNA, which hybridize to polyoma DNA, are made early during productive infection of mouse cells, while far larger quantities are synthesized at late times subsequent to the initiation of viral DNA replication (Benjamin 1966; Cheevers et al. 1970; Weil et al. 1967; Hudson et al. 1970). Hybridization competition experiments (Hudson et al. 1970; Glover 1974) suggest that there is control of transcription coupled to DNA replication: viral RNA sequences found at early times continue to be transcribed throughout the infectious cycle, but virus-specific RNA made late includes additional sequences not present prior to the onset of viral DNA synthesis. We shall refer to polyoma RNA synthesized before viral DNA replication as "early" RNA, to that made exclusively after replication as "specifically late" RNA, and to the entire population synthesized at late times as...