IMMUNOGENICITY OF PURIFIED VARICELLA ZOSTER VIRUS GLYCOPROTEINS

Abstract

Development of an effective, noninfectious subunit vaccine to the varicella zoster virus (VZV) will require identification of viral gene products critical for generating protective host responses. To better define the antigens which provoke immunity to VZV, viral glycoproteins (gps) were purified and tested for their ability to stimulate human lymphocytes. VZV specified gps were radiolabelled with [14C]-glucosamine then extracted from sonicates of infected cell monolayers using nonionic detergents. Mixed VZV gps were isolated by passing infected cell extracts over lentil lectin conjugated Sepharose and competitively eluting bound gps with α-methylmannoside. Gp I (98/62), gp II (140/66) and gp III (118), the predominant gps expressed in VZV-infected cells, were purified with murine monoclonal antibodies employing a novel avidin-biotin immunoaffinity method. Purity of the isolated VZV gps was confirmed by fluorography of SDS-PAGE gels. Both mixed viral gps (Stimulation Indices = 6-15) and individually purified gps (I, II, III) (SI = 3-8) induced proliferation by MNC from VZV-immune subjects. Responses observed were VZV-specific since proliferation failed to occur if MNC were obtained from VZV-susceptible individuals or if antigens were prepared from uninfected monolayers. Coculturing studies of separated MNC subpopulations indicated that responses to the gps represented proliferation by T4+ lymphocytes and required antigen presentation by adherent MNC. We conclude that virally encoded gps contain epitopes which stimulate VZV-specific proliferation by human T cells.