A unique pattern of integrated viral genes in hamster cells transformed by highly oncogenic human adenovirus 12

We have analyzed the viral DNA sequences persisting in HE C19, a clonal line of hamster embryo cells transformed in vitro by human adenovirus 12 (Ad 12), a member of highly oncogenic group A. Saturation-hybridization of in vitro labeled Ad 12 DNA (2-4 x 10(8) cpm/mug) with HE C19 DNA showed that 93-100% of viral DNA sequences are present in the transformed cell. Reassociation of Ad 12 32P-DNA in the presence of HE C19 DNA detected 8 viral genome equivalents per diploid quantity of cell DNA. REannealing each of the six Ad 12 EcoRl restriction DNA fragments with HE C19 DNA indicated that the sequences of each fragment are present in near equimolar quantities, 8-10.5 copies per cell. HE C19 DNA "networks" were prepared and shown to contain the same viral DNA sequences and in the same amounts as present in unfractionated transformed cell DNA; these data provide the first direct evidence that human adenovirus genes are covalently linked to cellular DNA. The presence of most, if not all, of the viral genes was demonstrated also in the Ad 12 hamster tumor cell line, HT-2. The pattern of integrated viral genes in these nonpermissive hamster cells transformed by Ad 12 is different from that described for cells transformed by group C and B human adenoviruses and for SV40.