Antibody Responses of Young Calves to Inactivated Viral Vaccines

Abstract

The ability of maternal antibodies to interfere with active immunization of young animals by vaccination has been realized for many years. The development of vaccines that would overcome this effect could contribute greatly to the prevention of viral diseases of cattle. Major advances have been made in the quality of commercial inactivated virus vaccines to increase their efficacy. Therefore, three of these vaccines were evaluated for immunogenicity in young calves with residual maternal antibodies. Groups of 30 calves were administered each of the vaccines at the start of the experimentation and were administered a second dose 32 days later. Serum was obtained from these calves and 30 calves in a nonvaccinated control group prior to vaccination and at 32, 61, 97 and 125 days thereafter. The sera were tested for antibody levels with virus neutralization tests. Antibody responses to viruses included in two of the vaccines were extremely limited and restricted to animals with low maternal antibody titers. The third vaccine overcame suppression by maternal antibodies and elicited responses clearly differentiated from antibody levels in the control group of calves. Mean antibody titers were significantly higher in this vaccinated group of calves when compared to unvaccinated calves or animals in the other two vaccinated groups at 61, 97 and 125 days.