Extrachromosomal deer fibromavirus DNA in deer fibromas and virus-transformed mouse cells

The non-virus-producing fibromatous portions of five deer fibromas were examined for deer fibromavirus (DFV) DNA sequences. Liquid-phase hybridization revealed 100 to 330 copies per cell of the virus genome. Southern blot analysis of undigested deer tumor DNA preparations indicated that most of the DFV DNA was present as monomeric, unintegrated genomes; however, restriction enzyme digestion patterns suggest a small population of resistant DFV sequences. DFV DNA was also present in virus-transformed NIH/3T3 mouse cells as multiple, extrachromosomal genomes.