Polypeptide specificity of the antibody response after primary and recurrent infection with bovine herpesvirus 1

The polypeptide specificities and defense mechanisms of the humoral immune response to bovine herpesvirus 1 were analyzed. Sequential serum samples taken from cows which were experimentally infected with bovine herpesvirus 1 were tested for their reactivity with individual bovine herpesvirus 1 polypeptides by immunoprecipitation, immunoblotting, and enzyme-linked immunosorbent assay. All bovine immune sera reacted with each of the three major bovine herpesvirus 1 glycoproteins, GVP 6/11a/16, GVP 3/9, and GVP 11b, during primary as well as recurrent infection. Among these glycoproteins, GVP 6/11a/16 induced the earliest and most consistent immune response. The levels of antibody to GVP 3/9 and GVP 11b varied among the animals, and they were slightly lower than the level of antibody to GVP 6/11a/16. Antibodies to several nonglycosylated polypeptides and two additional glycoproteins were also detected with the immunoblot assay. However, these antibodies were usually apparent only during recurrent infection, whereas they were undetectable or low during primary infection. The antibodies in the sera from all animals mediated virus neutralization and destruction of virus-infected cells by two immune mechanisms, e.g., antibody- and complement-mediated lysis and antibody-dependent cell-mediated cytotoxicity.