Complementation of a bovine papilloma virus low-copy-number mutant: evidence for a temporal requirement of the complementing gene.
We identified a bovine papilloma virus function encoded by the E6/E7 gene, which is required for both BPV high-copy-number replication and maintenance of transformation of cultured cells. A cDNA copy of this gene was isolated and expressed from a retrovirus vector. We found that complete complementation of a BPV low-copy-number mutant (dl576) by the cDNA encoding the E6/E7 gene was temporally dependent. When both the E6/E7 cDNA and dl576 were introduced together into cells, wild-type replication and stable transformation resulted. In contrast, introduction of the complementing cDNA into cells already carrying dl576 led to only partial amplification of the resident mutant DNA accompanied by a restoration of the transformed phenotype. These results, along with other findings, suggest that the establishment of BPV plasmid replication occurs in two stages: an initial amplification of the incoming DNA followed by stable homeostatic replication which maintains the existing copy number.
D000818:Animals; D052688:Bovine papillomavirus 1 / Q000235:genetics*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis; D005814:Genes, Viral; D005816:Genetic Complementation Test; D009154:Mutation; D027383:Papillomaviridae / Q000235:genetics*; D010957:Plasmids; D014162:Transfection
D004247:DNA