Purification of a glycoprotein from bovine leukemia virus (BLV).

A precipitating antigen of bovine leukemia virus was isolated by isoelectric focusing and Sephadex gel filtration. In SDS-polyacrylamide gel electrophoresis it was found to be a homogeneous protein with a relative molecular weight of 69000 daltons. Because of its relative molecular weight and staining characteristics it was designated as BLV gp69. A protein with the same molecular weight could also be demonstrated in BLV particles. In 34 out of 35 sera from cattle affected by enzootic bovine leukosis antibodies against gp69 were detected, whereas the sera from 197 animals, free of bovine leukosis, did not react in immunodiffusion test.