Characterization of B virus glycoprotein antibodies induced by DNA immunization

Genes encoding glycoproteins gB, gC, gD, gE, and gG of herpes B virus (species Cercopithecine herpesvirus 1) were cloned into mammalian expression vector pcDNA3.1/V5-His. Abilities of the plasmid constructs to express recombinant glycoproteins were confirmed by Western blot analysis of transfected CHO-K1 and COS-7 cells. Antibody production was induced in rabbits by intramuscular injections with the expression constructs at four-weekly intervals. Antibodies to gB were detected after the second DNA inoculation, while it took an additional plasmid injection to induce responses to gC, gD and gE. The gG plasmid failed to stimulate antibody production. Antisera ELISA titers varied greatly depending on the gene, with gB inducing highest (21,000) and gE inducing lowest (60) antibody titer. The induced antibodies were predominantly conformation-dependent. The gB, gC, and gD antisera contained HSV cross-neutralizing antibodies, but only gB antisera contained B virus neutralizing antibodies. The gB antisera cross-reacted with HSV antigens in Western blot, ELISA, dot-blot, plaque immunostaining and immunoprecipitation assays, whereas gD and gC antisera were mostly B virus-specific. Thus, polyclonal antibodies to B virus glycoproteins can be generated by DNA immunization and used as diagnostic and research reagents.