Molecular basis of antigenic variation between the glycoproteins C of respiratory bovine herpesvirus 1 (BHV-1) and neurovirulent BHV-5

Abstract

Herpesvirus glycoprotein C (gC) functions as a major virus attachment protein. The gC sequence of the neurovirulent bovine herpesvirus type 5 (BHV-5) virus was determined and compared with the gC sequence of the nonneurovirulent BHV-1. Alignment of the predicted amino acid sequences of BHV-1 and BHV-5 gC ORFs showed that the amino-terminal third of the protein differed between the two viruses. Whole or subgenomic fragments of gC coding regions from both viruses were expressed as trpE—gC fusion proteins in Escherichia coli to map linear epitopes defined by type-specific murine monoclonal antibodies (MAbs). Based on the reactivity of BHV-1-specific MAbs with the recombinant proteins, two epitopes were mapped between BHV-1 gC residues 22 and 172. Unidirectional deletion of these residues at the carboxy end mapped one within residues 22–69 and the other within residues 103–122. Two BHV-5-specific MAbs identified an epitope coding region within BHV-5 gC residues 31–78. Bovine antisera against BHV-1 and BHV-5 showed specificity to BHV-1 gC residues 22–69 and to BHV-5 gC residues 31–78, respectively, in a type-specific manner.