CHARACTERIZATION OF GLYCOPROTEIN-B OF THE GAMMAHERPESVIRUS EQUINE HERPESVIRUS-2

Twenty-two monoclonal antibodies (MAbs) were generated to the gammaher pesvirus equine herpesvirus-2 (EHV-2). Using Western blot analysis, ei ght MAbs recognized an Escherichia coli glutathione S-transferase (GST )-glycoprotein B (gB) fusion protein and, using overlapping GST-SB fus ion proteins, a neutralization epitope was mapped to amino acids 29-74 . One of the gB-specific MAbs was used to characterize the glycosylati on and kinetics of synthesis of EHV-2 gB. EHV-2 gB is synthesized as a 97 kDa polypeptide that is co-translationally modified to a 130 kDa h igh-mannose precursor that forms a 260 kDa dimer shortly after synthes is. Each 130 kDa precursor is endoproteolytically cleaved to disulphid e-linked subunits of 75 and 58 kDa prior to further processing to comp lex oligosaccharide-containing subunits of 89 and 65/62 kDa. The 89 an d 65/62 kDa subunits of EHV-2 gB contain 39 and 17 kDa of N-linked oli gosaccharides, respectively, and do not contain any O-linked oligosacc harides. Western blot analysis of purified EHV-2 virions established t hat gB exists as a 320 kDa dimer in the virion envelope.