Analysis of the antibody response to bovine respiratory syncytial virus proteins in calves.

The antibody response in calves to natural infections with bovine respiratory syncytial virus (BRSV) was analysed by radioimmunoprecipitation assays. Antibodies to virus proteins of Mr 200K (L), 87K (G), 46K (F1), 41K (N), 35K (P), 28K and 24K (F2), 27K (M), 22K and less than 14K could be identified. Recovery of 6- to 7-month-old calves from severe BRSV-associated disease was accompanied by the development of an antibody response to the virus, which was directed mainly o the F and N proteins. Calves of 2 to 3 weeks of age possessed moderate levels of maternal antibodies to BRSV particularly directed to the F and N proteins but became seriously ill after infection. The antibody response in these calves was severely suppressed. In the sera of 4- to 9-month-old calves that died in the course of infection, high antibody levels to the virus were found, which were directed at least to the F and N proteins. The presence or development of antibodies to the F and N proteins appears insufficient for protection against or recovery from BRSV infections.