VARICELLA-ZOSTER VIRUS MEMBRANE ANTIGENS

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Varicella-zoster virus (VZV), a human herpesvirus, is the causative agent for two clinically distinct diseases: varicella (chickenpox) and shingles (zoster). Although rarely life-threatening in normal individuals, primary (varicella) and reactivated (zoster) infections are a major concern for cancer and organ transplant patients who are undergoing immunosuppressive therapy. In many cases, VZV infections necessitate changes in the chemotherapeutic regimen to minimize the risk of a disseminated, life-threatening infection. Because of the serious consequences of VZV infection in these immunocompromised patients, clinical trials are underway in the USA and Japan to test the efficacy of immunization with live, attenuated strains of VZV. Despite its importance as a human pathogen, we have only an incomplete understanding of the biology, biochemistry and structure of VZV, and of the immune response to infection. Such information is a prerequisite for the eventual full understanding of the pathogenesis of the diseases caused by VZV and the mechanisms of recovery and of reactivation. The experiments described in this proposal are designed to obtain basic information about the VZV envelope glycoproteins, the probable targets of the immune response. The complete panel of mouse monoclonal antibodies to the VZV glycoproteins, which is available in this laboratory, will be used to: (1) analyze the post-translational modifications of the VZV glycoproteins (O-linked glycosylation, palmitylation, sulfation, phosphorylation and proteolysis); (2) examine the biosynthesis and processing of the glycoproteins; (3) to purify each of the glycoproteins in undenatured form by classical and immunoaffinity procedures; and (4) identify the HSV and VZV glycoproteins which are serologically crossreactive. The purified glycoproteins will be used to analyze the VZV glycoprotein specificities of the neutralizing antibodies present in VZV-immune globulin (VZIG). Passive immunization with VZIG is used clinically to protect immunocompromised children from severe, life-threatening varicella. The techniques employed will include: immuno-precipitation, SDS-PAGE, pulse-chase labeling, 2-D gels, partial proteolytic mapping, Western immunoblotting, immunoaffinity chromatography and paper and high performance liquid chromatography (HPLC). These studies will yield reagents and information that are necessary for future analysis of the immune responses to VZV infection, for development of better screening methods for VZIG production, for mapping the glycoproteins to the viral genome, and for possible development of a DNA-free subunit vaccine.