Structural studies on oncornavirus-related sequences in chicken genomic DNA: Two-step analyses of EcoRI and Bgl I restriction digests and tentative mapping of a ubiquitous endogenous provirus

DNA from a variety of uninfected chicken cell types has been analyzed by using restriction endonuclease digestion and RPC-5 ion-exchange chromatography followed by agarose gel electrophoresis. Endogenous retrovirus sequences were detected by using a ³²P-labeled avian leukosis viral RNA probe. One simple pattern was identified in an individual containing unexpressed endogenous proviral genes (gs^-chf^-phenotype for group-specific antigens and chicken helper factor) that was common to all individuals studied. A tentative restriction map has been derived for this and one other gs^-chf^-endogenous provirus. Other gs^-chf^-individuals and individuals with other phenotypes (e.g., gs⁺chf⁺and gs(L) chf(hE) showed more complicated patterns that often included additional bands and thus probably additional proviruses. RNA from an avian sarcoma virus was used to detect cellular sequences (sarc) homologous to the viral transforming gene (src). Results have revealed that a single restriction endonuclease EcoRI fragment of 13 x 10⁶ daltons contains the majority of these sequences and confirm that they are not adjacent to the endogenous provirus.