[Characteristics of new loci of endogenous proviruses in chickens].

The composition and structure of endogenous proviruses in the genome of Italian partridge chicken was studied by the blot-hybridization method using 32P-DNA of RAV-2 virus as a probe. Among 34 fowls examined, 5-contained no endogenous proviruses related to fowl leukemia viruses. DNA of the other fowls contained various combinations of 4 previously undescribed endogenous proviruses varying in structure and localization. None of them was identical in its structure with DNA of endogenous fowl virus RAV-0, all the four discovered loci have deletions. The origin, modes of genetic variability, and function of endogenous proviruses are discussed.