Characterization of the immunogenic epitopes of Marek's disease virus glycoprotein B in recombinant fowlpox virus

Marek's disease virus (MDV) glycoprotein B (gB), a highly conserved immunogenic glycoprotein, plays an important role in protective immunity. When chickens were inoculated with a recombinant fowlpox virus (FPV) expressing gB, neutralizing antibodies were produced and the chickens were protected against challenge with pathogenic strains of MDV. We have shown that gB is initially synthesized as a glycosylated precursor(gp100), and then proteolytically cleaved to gp60 and gp49. Several chimeric gB genes were constructed by replacing either gp60 or gp49 of the serotype-l gB gene with the homologous region of a serotype-2 gB using a common restriction site. Recombinant FPVs with chimeric gB genes were analyzed for expression by immunoprecipitation and indirect immunofluorescence using serotype specific monoclonal antibodies. Results show the location of the immunogenic and protective epitopes to be on the gp49 moiety of the molecule.