Bovine parainfluenza-3 virus proteins recognized by antibodies of aerosol-exposed calves.

Bovine parainfluenza-3 (BPI-3) virus proteins were radiolabeled with [35S]methionine. Control serum containing antibodies to BPI-3 virus obtained from calves that had been immunized by aerosol exposure and by IM inoculation and sera of cattle that were exposed to BPI-3 virus by aerosol only were used to immunoprecipitate BPI-3 virus proteins. The immunoprecipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Viral proteins with estimated molecular weights of 72,000, 70,000, and 58,000 were recognized by the control serum and the sera from calves exposed to BPI-3 virus only by aerosol. These proteins were the hemagglutinin/neuraminidase, nucleoprotein, and fusion protein. The results indicated that a single aerosol exposure to BPI-3 virus induces antibodies to the same BPI-3 virus proteins as do combined aerosol and parenteral inoculations with the virus.