Restriction endonuclease mapping of linear unintegrated proviral DNA of bovine leukemia virus.

A detailed restriction map was deduced for the genome of the exogenous bovine leukemia virus. The cleavage sites for nine restriction enzymes were mapped. The unintegrated linear viral DNA intermediate that is produced by infection of permissive cells with bovine leukemia virus was isolated. The linear viral DNA had a unique restriction map, indicating that it is not a set of random circular permutations of the RNA genome. From hybridization with a 3'-enriched probe, the DNA restriction map was aligned relative to the 5'-to-3' orientation of the viral RNA. Restriction enzyme analysis of integrated bovine leukemia virus information present in animals with enzootic bovine leukosis provided evidence for the existence of genetic variants of the virus.