[New endogenous proviruses in the genome of brown Leghorn chickens]

Genetic differences and differences in localization of endogenous proviruses in chicken genomes were found in studies on endogenous provirus sequences in DNA of white and brown Leghorn chickens. In brown Leghorn DNA, proviruses both similar with Raus-associated virus (endogenous virus of white Leghorns) and differing from it in the pattern of hydrolysis by EcoRI restricting endonuclease were found, the latter occurring more frequently. Different sets of variously localized proviruses were found in DNA of individual chickens; none of the proviruses was found in DNA of all brown Leghorns examined. No single provirus common for chickens of the two species was found. The genetic diversity of endogenous proviruses observed in brown Leghorns indicates the possibility of coexistence in the chicken DNA of message on several significantly different endogenous viruses.