An Evaluation of Three Commercially Available Infectious Bursal Disease Vaccines

Abstract

Three commercially available infectious bursal disease vaccines, designated BV, BV-M, and LKT, were evaluated in chicks that were specific-pathogen-free and free of antibodies to infectious bursal disease virus (IBDV). For comparison, a pathogenic field isolate of the IBDV (FV) was also inoculated into 1-day-old and 3week-old chicks. At 5 weeks old, the mean virus-neutralizing (VN) antibody titers of the 3 vaccinated groups did not differ significantly (P< 0.05). At 7 weeks old the BV-induced VN titers were significantly higher (P<0.05) than the LKTand the BV-M-induced titers. Differences remained similarly significant (P<0.05) at 9 weeks old. Precipitating antibodies were consistently demonstrable in the serums of BV-vaccinated chickens at 5, 7, and 9 weeks old by the agar-gel precipitin (AGP) test, whereas many serums from the BVMand LKT-vaccinated birds had no detectable AGP reaction at 9 weeks old. Field virus exposure at 1 day or three weeks old resulted in high VN titers as well as persistent AGP reaction. The vaccine virus persisted in the bursa of Fabricius until birds were 9 weeks old in groups receiving LKT and BV vaccines but not in the group given the BV-M vaccine. Upon challenge with FV at 9 weeks old, the LKT and the BV-M vaccinated birds were better protected against bursal atrophy than the birds vaccinated with BV-strain. None of the vaccine viruses, when used according to the manufacturers' recommendations, or the FV, when given at 3 weeks old, caused significant (P<0.05) immunosuppression.