Characterization of African swine fever virus antigenic proteins by immunoprecipitation.

African swine fever virus is a large, complex virion in which numerous proteins have been identified by biochemical techniques. Few of these proteins have been shown to react with antibodies from recovered swine, leading to speculation that the immunological unreactivity of some viral proteins might explain the inability of immune sera from surviving animals to neutralize the virus. We used immunoprecipitation of radiolabeled viral proteins to examine these sera in more detail. Gradient sodium dodecyl sulphate polyacrylamide gel electrophoretic analysis of these immunoprecipitates revealed that at least 37 viral proteins participated in antigen-antibody reactions in this system. Differences in the molecular weights of some immunoprecipitable proteins were noted between different isolates of virus, between the same isolate grown in different cells, and between an isolate adapted to Vero cells and one not adapted to these cells.