Antibody-binding sites on truncated forms of varicella-zoster virus gpI(gE) glycoprotein

Varicella-zoster virus (VZV)-seropositive human sera were shown to be reactive with the truncated VZV gpI(gE) candidate subunit vaccine (TgpI-511). To identify the location of antibody-binding sites (epitopes) on TgpI-511, three truncated forms of TgpI-511 glycoprotein (TgpI-124, TgpI-160, TgpI-316) DNA encoding the N-terminal region of this glycoprotein with amino acid residues of 124, 160 and 360, respectively, were inserted into the vaccinia virus genome. Infection of cells with recombinant vaccinia viruses resulted in the secretion of all three truncated gpI(gE) as well as TgpI-511 from the infected cells. Immunoprecipitation of these truncated glycoproteins with VZV-seropositive human sera and gpI(gE)-specific monoclonal antibodies identified the location of four new antibody-binding sites on the VZV TgpI-511 glycoprotein. In addition, tunicamycin treatment and O-glycanase digestion revealed the presence of both N-linked and O-linked oligosaccharides on TgpI-511. These results revealed the location of new epitopes on VZV TgpI-511 and demonstrated that the epitopes on TgpI-511 were recognized by human sera from VZV-seropositive individuals.