Transcriptional organization of bovine papillomavirus type 1.

Multiple bovine papillomavirus type 1 (BPV-1)-specific polyadenylated RNA species in a BPV-1-infected bovine fibropapilloma were identified and mapped. All of the RNA species were transcribed from the same DNA strand of the BPV-1 genome. Five RNA species previously identified in BPV-1-transformed mouse cells were also present in the bovine fibropapilloma. These five species measured 1,050, 1,150, 1,700, 3,800, and 4,050 bases, mapped within the 69% transforming segment of the BPV-1 genome, and shared a 3' coterminus at 0.53 map units (m.u.). The 5' ends of the bodies of these distinct transcripts were located at ca. 0.03, 0.09, 0.34, 0.39, and 0.41 m.u. Additional polyadenylated RNA species not present in BPV-1-transformed mouse cells were specific for the BPV-1-infected bovine fibropapilloma and measured 1,700, 3,700, 3,800, 6,700, and 8,000 bases. These wart-specific species shared a 3' coterminus at 0.90 m.u. The 5' termini of the bodies of the 1,700- and 3,800-base species mapped at 0.71 and 0.42 m.u., respectively. Exonuclease VII analysis failed to reveal any internal splicing in these two species; however, the presence of small remote 5' leader sequences could not be ruled out. The 3,700-base species hybridized to DNA fragments from the 69% transforming segment as well as from the 31% nontransforming segment of the BPV-1 genome; however, this species was not precisely mapped. The 5' termini of the two largest RNA species (6,700 and 8,000 bases in size) were located at ca. 0.01 and 0.90 m.u., respectively. Since the 5' ends of these mapped adjacent to a TATAAA sequence which could possibly serve as an element of a transcriptional promoter, it is possible that one or both of these species represent nonspliced precursor RNA molecules.