Identification of major antigenic proteins of bovine herpesvirus 1 and their correlation with virus neutralizing activity.

The polypeptides of an Australian isolate of bovine herpesvirus 1 were analysed by polyacrylamide gel electrophoresis, and Western blotting was used to identify those polypeptides which reacted most strongly with sera from infected animals. Approximately 20 polypeptides ranging in molecular weight from 11,000 to 240,000 daltons (11-240K) were identified by 35S-methionine labelling of virus and approximately half of these classed as glycoproteins using 14C-mannose and 3H-glucosamine incorporation into infected cells. Convalescent sera from cattle all reacted strongly with glycoprotein bands at 85 and 70K, with most sera also recognizing another band at 140-150K. The intensity of bands on the Western blot analyses was found to correlate well with neutralization titres of individual serum samples, indicating the involvement of these proteins in virus neutralization. The importance of the 70K glycoprotein was supported by the finding that, of 12 monoclonal antibodies studied, those 3 with the strongest neutralizing activity, were those which recognized a band at 70K in Western blot experiments.