Isolation of a precipitating antigen associated with bovine leukosis

A precipitating antigen was isolated from bovine leukosis C-type particles. It was purified by ultracentrifugation, isoelectric focusing and sedimentation in sucrose gradients. The antigen — identified as a basic protein with a single polypeptide in the molecular weight range from 12 800 to 15 500 d — cross-reacted with antisera from bovine as well as ovine leukosis.

A second antigen has been found in cytoplasmic extracts of cultivated lymphocytes and in NP₄₀-treated bovine C-type particles.