Genetic transformation of somatic cells. XI. The autonomic replication of the cloned DNA of the bovine papilloma virus in NIH/3T3 mouse fibroblasts and the changes in the growth characteristics of the transformed cells

Mouse fibroblasts NIH 3T3 were transfected with the plasmid pBPV (142-6) containing full genome of bovine papilloma virus 1, and focuses of morphological transformation were selected 2-3 weeks later. DNA molecules, containing BPV-1 sequences, were isolated from extrachromosomal fraction of transformed clones suggesting stable autonomous replication of BPV in 3T3 NIH cells. In some rescued plasmids deletions spanning E6, 7 genes of BPV were found. It is suggested that these genes are not essential for morphological transformation and autonomous replication in 3T3 NIH cells. BPV-transformed clones are able to grow in the medium containing low concentration (0.5%) of serum.