Sequence from early region of polyoma virus DNA containing viral replication origin and encoding small, middle and (part of) large T antigens.

The sequence of about one third of the polyoma virus genome is presented. This sequence covers the origin of replication of two large plaque strains (A2 and A3) of polyoma virus. The two strains differ by 11 bp in the origin region. A model for replication is suggested. The sequence probably also covers the entire coding region of two of the polyoma virus early proteins--small and middle T antigens--as well as part of the coding region for large T antigen. Over a small region of the DNA, all three coding frames contain termination codons, which argues a need for spliced early messenger RNAs. In another region of the DNA, two coding frames can be used. Correlation with protein data suggests that one frame codes for part of middle T antigen and the other for part of large T antigen.