Bovine papilloma virus transcription: polyadenylated RNA species and assessment of the direction of transcription

Abstract

The bovine papilloma virus type 1 (BPV-1)-specific RNA species were identified in virus-induced bovine warts, hamster tumors, and transformed hamster and mouse cells. In each case two major species were present (1.1 and 1.3 kilobases [kb]). Also two species of 1.6 and 1.8 kb appearing in variable amounts were found. Only in the keratinized periphery of the warts, where virus replication takes place, was it possible to reveal an additional 2-kb RNA species. In this tissue, however, the 1.6-kb species was not detected. The basal part of a bovine wart contained an additional minor, 2.9-kb, BPV-1-specific RNA sequence. By hybridization with purified defined BPV-1 DNA fragments it was shown that most of the coding sequences of the 2-kb species were transcribed from a region between 0.02 and 0.19 map units. The majority of the coding sequences of the smaller species in transformed cells were located in the region between 0.31 and 0.61 map units. The putative 5' ends mapped between 0.72 and 0.96 map units. Oligodeoxythymidylic acid-primed [(32)P]cDNA was synthesized from various RNA preparations to generate probes for the detection of 3' termini of the polyadenylated BPV-1 RNAs. By hybridization across the BPV-1 genome only one signal between the map positions 0.30 and 0.40 was obtained when RNA from transformed cells and from a tumor was used as a template. In contrast, RNA from the periphery of a wart led to the detection of an additional signal which was confined to the region between 0.96 and 1.00 map units. From the arrangement of both the 3' termini and the coding areas along the viral genome it appears that several RNA species are transcribed from one DNA strand.