Expression of SV40 T antigen under control of adenovirus promoters

We have obtained novel adenovirus-SV40 recombinant viruses that express wild-type SV40 large T and small t antigens under the control of different adenovirus promoters. Hybrids were constructed in vitro with SV40 DNA that contains the entire early coding region but lacks the transcriptional promoter. Recombinants were isolated by a strong biological selection for viruses that express SV40 T antigen. Analysis of several recombinant genomes indicates that they contain the SV40 A gene inserted in a variety of positions and orientations in the adenoviral genome. Moreover, the set of hybrid transcripts reveals an unexpected variety of splicing patterns. Some hybrid mRNAs transcribed from the adenovirus late promoter appear to contain the adenovirus tripartite leader sequence. Other hybrid mRNAs were transcribed from adenovirus early promoters. All recombinant mRNAs contain intact SV40 early sequences that have normal splice patterns and produce wild-type T antigens. Biochemical characterization of SV40 T antigens overproduced by the hybrid viruses indicates that they are structurally indistinguishable from wild-type SV40 large T antigen and are functionally equivalent to the D2 protein.