Evaluation of baculovirus-expressed bovine herpesvirus-1 (BHV-1) glycoproteins for detection and analysis of BHV-1-specific antibody responses.

Baculovirus (Autographa californica nuclear polyhedrosis)-expressed bovine herpesvirus-1 (BHV-1) glycoproteins B (gB), gC, and gD were developed and characterized. The recombinant proteins retained their antigenic properties as determined by immunoblotting against monoclonal antibodies. The proteins were examined as antigens for detection of BHV-1 infection and for the analysis of antibody responses to the individual viral proteins. A total of 115 bovine serum samples were tested for their reactivity with individual recombinant proteins from baculovirus-infected Spodoptera frugiperda (SF-9) cell lysates by enzyme-linked immunosorbent assay (ELISA), western blotting, and dot blotting assays. These serum samples were previously tested for BHV-1-specific antibodies by virus neutralization (VN) at the veterinary diagnostic laboratory. All 90 serum samples tested positive with VN were positive by ELISA against gC and gD, separately. However, reactivities of sera against gB were generally low and inconsistent. On the other hand, out of 25 sera that were negative with VN, 22 sera were consistent and gave negative results against gC or gD by ELISA, whereas reactivities with gB were inconsistent. Similar results were obtained when the sera were tested by western blotting and dot blotting. The positive sera consistently reacted strongly against gC and to a lesser extent gD. These results suggest that baculovirus expressed gC from infected cell lysate can be used as a potential diagnostic antigen for detection of anti-gC-specific antibody responses in BHV-1 infected cattle.