Homogeneity and complexity of avian oncornavirus proviral DNA determined by molecular hybridization.

The homogeneity of DNA complementary to the 35S RNA subunit of avian myeloblastosis virus (AMV) has been demonstrated by single or multistep hybridization. For multistep hybridizations, 35S AMV RNA was preselected for its ability to hybridize either to unfractionated leukemic DNA or to leukemic DNA enriched for unique or for reiterated sequences. These experiments indicate that the viral genome is complementary to DNA sequences with a low reiteration frequency. Competition experiments confirm the absence of fast-hybridizing sequences in viral DNA. Computer analyses of the data reveal that there are two to four copies of viral DNA in infected cells.