Specific protection against bovine leukemia virus infection conferred on cattle by the Romanian inactivated vaccine BL-VACC-RO.

The Romanian BL-VACC-RO vaccine against bovine leukemia virus (BLV) infection was prepared with ethylenimine-inactivated BLV obtained from persistently infected cell lines. Intramuscular administration of two vaccine doses (each containing 0.40 mg virus glycoprotein with adjuvant), 2 weeks apart, conferred protection against challenge infection with BLV on 18 of the 20 vaccinated calves. Two calves were not protected, in spite of their positive serologic response to vaccination. The results demonstrate the efficiency of the BL-VACC-RO vaccine in preventing BLV infection.