Neutralizing monoclonal antibodies to bovine viral diarrhoea virus bind to the 56K to 58K glycoprotein.

A panel of murine monoclonal antibodies (MAbs) against the two major glycoproteins of bovine viral diarrhoea virus (BDV) was produced and assayed by serum neutralization, radioimmunoprecipitation (RIP) and immunoblotting. Based on their viral polypeptide specificity and on their ability to neutralize viral infectivity, the MAbs in the panel were divided into three classes: Class 1 MAbs reacted with the 56K to 58K glycoprotein and neutralized the virus, class 2 MAbs recognized the 56K to 58K glycoprotein but were not neutralizing, and class 3 MAbs reacted with the 48K glycoprotein and did not neutralize the virus. These results identify the 56K to 58K protein as one of the envelope glycoproteins of BDV. Evidence was obtained indicating that it is responsible for the induction of neutralizing antibodies. No large uncleaved precursors of the 56K to 58K protein could be identified unequivocally by RIP of infected cell extracts, suggesting that this polypeptide is proteolytically processed cotranslationally. A subset of MAbs that reacted with BDV isolates of the noncytopathic biotypes yielded similar results, indicating that these findings are applicable to both biotypes of BDV.