Neutralizing monoclonal antibodies directed to infectious bovine rhinotracheitis virus.

Infectious bovine rhinotracheitis virus (IBRV) has been shown in this report to have thirty-three polypeptides. Ten of the eleven polypeptides which can be labeled with (3H)-glucosamine are located on the surface of the virus since they can be surface labeled with sodium boro(3H)hydride. In order to define the immunologically important viral proteins, monoclonal antibodies were prepared against the virus and selected for their ability to neutralize infectivity. Four such hybridoma lines were obtained for characterization of the antigens that elicit neutralizing antibodies. The viral polypeptides were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the specificity of each monoclonal antibody was determined by "Western" blot analysis and/or by immunoprecipitation of (35S)-methionine and (3H)-glucosamine labeled infected cell lysates by the monoclonal antibodies. One monoclonal antibody reacted with two glycoproteins, gp135 and gp78a, on the "Western" blot but immunoprecipitated three glycoproteins, gp135, gp78a, and gp54 from labeled infected cell lysates. The other three monoclonal antibodies immunoprecipitated a single glycoprotein, gp78b, from (3H)-glucosamine labeled infected cell lysates but not from (35S)-methionine labeled infected cell lysates.