Immune Responses to Varicella-Zoster Virus

Knowledge about the host immune response to varicella-zoster virus (VZV) has expanded in parallel with progress in understanding the molecular virology of the virus and advances in basic immunology that have been achieved during the past two decade^.^,26 Early studies of immunity to VZV focused on the humoral immune response, analyzing IgG, IgM, and IgA antibodies that bind to the novel antigens synthesized in VZV-infected cells.54,Io5, 139 More recently, methods have been developed to assess cell-mediated immunity to VZV.4In addition to evaluating host responses to naturally acquired VZV infection, immunization of healthy and immunocompromised individuals with live attenuated varicella vaccine provides new opportunities to examine protective immunity against VZV.42,114The goal of studies of VZV immunity is to identify host factors that restrict the pathogenic potential of the virus so that the consequences of infection with this ubiquitous human herpesvirus can be effectively prevented.Assays of humoral and cell-mediated immune responses to VZV employ whole, unfractionated proteins recovered from tissue culture cells infected with the virus, usually referred to as VZV antigen, or specific protein reagents made by purification from VZV-infected cell extracts or expression of single VZV genes in vaccinia recombinant^.^, 56The use of whole VZV antigen permits the detection of immune re-