The current status of live attenuated varicella vaccine.- Evidence for frequent reactivation of the Oka varicella vaccine strain in healthy vaccines.- Investigation of varicellazoster virus variation by heteroduplex mobility assay.- Varicella-zoster virus with a lost gE epitope: evidence for immunological pressure by the human antibody response.- Biologic and geographic differences between vaccine and clinical varicella-zoster virus isolates.- Comparison of DNA sequence and transactivation activity of open reading frame 62 of Oka varicella vaccine and its parental viruses.- Cis and trans elements regulating expression of the varicella-zoster virus gI gene.- Interactions among structural proteins of varicella-zoster virus.- The role of varicella-zoster virus immediate-early proteins in latency and their potential use as components of vaccines.- Mutagenesis of the varicella-zoster virus genome: lessons learned.- Immune evasion mechanisms of varicella-zoster virus.- Pathway of viral spread in herpes zoster: detection of the protein encoded by open reading frame 63 of varicella-zoster virus in biopsy specimens.- Vaccination against cytomegalovirus.- Varicella-zoster virus in human and rat tissue specimens.- In vitro measurement of human T cell responses to varicella zoster virus antigen.- Use of varicella vaccines to prevent herpes zoster in older individuals.- Immunization of the elderly to boost immunity against varicella-zoster virus (VZV) as assessed by VZV skin test reaction.- Varicella-zoster virus immunity and prevention: a conference perspective.

Under sponsorship of the National Institutes of Health of Japan, an international conference entitled "Immunity and Prevention of Herpes Zoster" was held in 1 Osaka, Japan, March 8-10, 1999. Attendees included basic and clinical investi­ gators from Asia, Europe, and North America. The meeting was organized to explore progress made in basic virology and molecular understanding of varicella zoster (VZV), and to provide information on current knowledge of latency of VZV in humans. Updates on the immunology responses of humans to VZV, and a description of the current status of varicella vaccine worldwide were also included. In addition, the possibility of prevent­ ing zoster in people latently infected with wild-type VZV by immunizing them with varicella vaccine was presented. The papers in this volume include written summaries of most of the presentations given at that conference. Coincidentally but appropriately, the conference marked the twenty-fifth or "silver anniversary" of the first publication of the development and use of live varicella vaccine to prevent varicella, by Takahashi and his colleagues. Because varicella vaccine is the first herpesvirus vaccine licensed in use for humans, it is of special interest to all individuals who studied these pathogens. In view of the interest in developing vaccines against other herpes viruses, there was also a presentation on the current status of vaccines against cytomegaloviruses (CMV) at the conference.