Bovine leucosis virus challenge infection of calves following application of BL-3 cells

8 calves were vaccinated 3 times with 1.5.10(7) BL-3 cells. 2 and 6 weeks, respectively, after the 3rd vaccination each 4 calves were subjected to a challenge infection with 2.5.10(5) blood lymphocytes of a BLV-infected cow. For control a challenge infection was performed on 3 non-vaccinated calves. The vaccination caused in all calves the appearance of complement-dependent cytotoxic antibodies against BL-3 cells but not of antibodies against BLV-gp51. After the challenge infection there occurred in the sera of all vaccinated calves and of all non-vaccinated control animals antibodies against gp51, and BLV could be demonstrated in the cultivated blood lymphocytes of all animals. Consequently, the application of BL-3 cells had no protective effect against the BLV infection.

Antibody production against BLV-p24 in calves following application of cell extracts from tumorous lymph nodes of cattle with enzootic bovine leukosis

In the cell extract from tumorous lymph nodes of bovine leukosis virus (BLV)-infected cattle (tumour cell extract) and from lymph nodes of BLV-free cattle (control cell extract) neither the gp51 nor the p24 antigens were detectable. The tumour cell extract contained receptors for the BLV antigens gp51 and p24. The immunogenicity of the cell extracts was tested in calves. All calves treated with the tumour cell extract developed antibodies against p24 but not against gp51. Administration of the control cell extract, in contrast, induced no antibodies against p24.