LOCALIZATION OF VARICELLA-ZOSTER VIRUS GENE-21 PROTEIN IN VIRUS-INFECTED CELLS IN CULTURE

Although four varicella-zoster virus (VZV) genes have been shown to be transcribed in latently infected human ganglia, their role in the dev elopment and maintenance of latency is unknown. To study these VZV tra nscripts, we decided first to localize their expression products in pr oductively infected cells. We began with VZV gene 21, whose open readi ng frame (ORF) is 3,113 bp, We cloned the 5' and 3' ends and the predi cted antigenic segments of the ORF as 1292-, 1280-, and 880-bp DNA fra gments, respectively, into the prokaryotic expression vector pGEX-2T. The three VZV 21 ORFs were expressed as approximately 75-, 73-, and 59 -kDa glutathione S-transferase fusion proteins in Escherichia coli, To prepare polyclonal antibodies that would recognize all potential epit opes on the VZV gene 21 protein, rabbits were inoculated with a mixtur e of the three fusion proteins, and antisera were obtained and affinit y purified. Immunohistochemical and immunoelectron microscopic analyse s using these antibodies revealed VZV ORF 21 protein in both the nucle us and cytoplasm of VZV-infected cells. When these antibodies were app lied to purified VZV nucleocapsids, intense staining was seen in their central cores.