title: Recombinant DNA molecules comprising bovine papilloma virus type 1 DNA linked to plasmid DNA are maintained in a plasmidial state both in rodent fibroblasts and in bacterial cells.
abstract: Transformed cells obtained after transfecting FR3T3 rat fibroblasts with DNA of bovine papilloma virus type 1 ( BPV1 ) maintained only free copies of the viral genome. Transfection with BPV1 DNA inserted in a bacterial plasmid (pBR322 or pML2 ) did not produce transformants at a detectable rate, unless the viral sequences had been first excised from the plasmid. In contrast, transfer of the same plasmids by polyethylene glycol-induced fusion of bacterial protoplasts with FR3T3 rat or C127 mouse cells led to significant transformation frequencies. A total of eight cell lines were studied, three rat and five mouse transformants, obtained with various BPV1 - pML2 recombinants. In all cell lines, both BPV1 and plasmid sequences were maintained as non-integrated molecules, predominantly as oligomeric forms of the transforming DNA. In the three rat transformants and in two of the mouse lines, parts of the non-transforming viral region and some bacterial sequences were deleted. In the remaining three mouse lines, the monomeric repeat was a non-rearranged plasmid molecule which could be re-established as a plasmid in Escherichia coli after cleavage with "one-cut" restriction endonucleases and circularization of the molecule.
mesh_terms: D000818:Animals; D001483:Base Sequence; D052688:Bovine papillomavirus 1 / Q000235:genetics*; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004279:DNA, Viral / Q000235:genetics; D005347:Fibroblasts / Q000502:physiology; D051379:Mice; D009693:Nucleic Acid Hybridization; D027383:Papillomaviridae / Q000235:genetics*; D010957:Plasmids; D051381:Rats; D011916:Rats, Inbred F344; D014162:Transfection
chemical_list: D004272:DNA, Mitochondrial; D004279:DNA, Viral; D004262:DNA Restriction Enzymes