Bovine viral diarrhea virus types 1 and 2 antibody response in calves receiving modified live virus or inactivated vaccines.

Serums from calves receiving eight different commercial vaccines containing modified live virus (MLV) or inactivated bovine viral diarrhea virus (BVDV) immunogens were assayed for antibodies to types 1 and 2 BVDV strains. The immune response to the types 1 and 2 BVDV strains were evaluated in 48 calves receiving one of the eight vaccines for each group. For 7/8 vaccines, the BVDV vaccine immunogen was only type 1 whereas the remaining vaccine contained both types 1 and 2 immunogens. Calves administered MLV vaccine received only one dose at day 0, whereas those calves receiving the inactivated vaccines were administered two doses initially at days 0 and 28. Selected calves were revaccinated with only one dose at day 140. Animals vaccinated with type 1 vaccines developed titers to a broad range of type 1 BVDV, both cytopathic (CP) and noncytopathic (NCP) biotypes, with lower titers evident to type 2 BVDV strains. For some animals, the BVDV serum antibodies did not persist. Revaccination at day 140 induced a significant four-fold increase in animals with intermediate to low antibody titers. There did not appear to be any clear differences in antibody responses between type 1 MLV or inactivated vaccines. The calves receiving the inactivated vaccine containing types 1 and 2 had similar antibody levels to both types.