A Complement-Fixation Test for the Bovine Leukemia (C-Type) Virus

A complement-fixation (CF) testwas developed for identification of the bovine leukemia virus (BLV) in various tissue-culture preparations; serum from a sheep with an experimentally induced infection was used as the source of antibody. Virus antigen was successfully demonstrated in short-term lymphocyte suspension cultures from infected cattle, in fetal lamb spleen monolayer cultures infected in vitro, and in cell lines established from bovine lymphosarcomas. Specificity of the antiserum for BLV was determined by its failure to react with other syncytium-producing agents of cattle (bovine syncytial, herpes-like, and visna-Iike viruses). A modified CF test detected BLV antibodies in cattle sera. The changes were addition of 5% unheated normal bovine serum to the guinea pig complement and extension of the incubation period to 16 hours. Antibodies then were detected in 47 of 52 sera from cattle with lymphosarcoma. Titers ranged from 1∶4 to 1∶2048. All but one of the reacting sera also contained precipitating antibodies, as determined by agar gel immunodiffusion tests.