Efficacy of a modified-live virus vaccine administered to calves with maternal antibodies and challenged seven months later with a virulent bovine viral diarrhea type 2 virus

Abstract

A total of 22 commercial dairy calves were used to determine if vaccination of a modified-live bovine viral diarrhoea virus (BVDV) vaccine with adjuvants in the face of maternal antibody will protect calves from a virulent type 2 BVDV challenge within seven months post-vaccination, following the loss of maternal antibody. Neonatal calves were obtained prior to consuming colostrum and were randomly divided into three groups. Group 1 calves were fed an antibody-free colostrum supplement within six hours of birth. Calves in Group 2 and Group 3 were fed pooled colostrum obtained from cows vaccinated eight weeks prior to calving with a commercial inactivated combination vaccine containing BVDV1 and BVDV2. Group 2 calves were vaccinated at approximately 4.5 weeks of age with a commercial modified-live virus combination vaccine containing BVDV1 and BVDV2. Calves in Groups 1 and 3 were sham vaccinated. Seven months after vaccination, when calves in Group 3 became seronegative to BVDV2, calves in all three groups were challenged intranasally with virulent BVDV2, strain 1373. Calves that received colostrum and were vaccinated had only mild or no clinical diseases. Calves that did or did not receive colostrum and were sham vaccinated, developed severe diseases, with a 33-50% mortality rate. In this study, young calves vaccinated with a modified-live virus vaccine with adjuvants in the face of maternal antibody were protected against a virulent strain of BVDV.