STRUCTURAL STUDIES ON ONCORNAVIRUS-RELATED SEQUENCES IN CHICKEN GENOMIC DNA - 2-STEP ANALYSES OF ECO-RI AND BGL-I RESTRICTION DIGESTS AND TENTATIVE MAPPING OF A UBIQUITOUS ENDOGENOUS PROVIRUS

DNA from a variety of uninfected chicken cell types was analyzed by 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 was derived for this and 1 other gs- chf- endogenous provirus. Other gs- chf- individuals and individuals with other phenotypes (e.g., gs+ chf+ and gsL chfhE) 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). A single restriction endonuclease EcoRI fragment of 13 .times. 106 daltons contains the majority of these sequences and they are not adjacent to the endogenous provirus.