The Physical State of Hybrid Genomes Containing Simian Virus 40 and Bovine Papilloma Virus DNA Sequences in Transformed Clonal Cell Lines

TO test whether the covalent linkage of simian virus 40 (SV40) A gene DNA sequences might lead to integration of bovine papilloma virus type 1 (BPV-1) DNA sequences, recombinant pBR322 plasmids containing both the transforming region of the BPV-I genome and the SV40 A gene were used for transformation f rodent cells. Plasmids containing both regions transformed with higher efficiency than plasmids containing either egion alone. Various clonal cell lines were established and examined with regard to the physical state and the expression of the viral DNA sequences. BPV-1 RNA sequences were detected and the SV40 T-antigen was expressed. The plasmid sequences persisted in all cases in an unintegrated state. In no case was it possible to find evidence for integration of BPV-1 sequences. Both tissue culture cells transformed by bovine papillomavirus type 1 (BPV-1) and cells in solid tumours that were induced by BPV-1 contain only non-integrated viral genome