In order to determine the transcripts of gpI and gpIV of varicella-zoster virus (VZV), RNA was isolated from human embryonic fibroblast cells infected with VZV and Northern blot analysis was carried out using cloned DNA probes of unique short region including gpI and gpIV genes. The analysis of RNA revealed two discrete transcripts of 3.6 and 2.15 kilobases (kb) and three transcripts of 3.6, 2.9, and 1.6kb which hybridized to DNA probes covering the gpI and gpIV region, respectively. Next, mRNAs were hybrid-selected, translated in vitro and the polypeptide products were immunoprecipitated with antibodies against these glycoproteins. The polypeptides with a molecular weight of 70, 000 (70K) and 37K which were in vitro translational products of mRNA hybrid-selected with the DNA clone covering gpI and gpIV were detected using antibodies against gpI and gpIV, respectively. The result showed that the 70K polypeptide is presumably the translational product of 2.15kb mRNA and the 37K polypeptide is that of 1.6kb mRNA. DNA fragment encoding gpI or gpIV was inserted into vaccinia virus DNA and the recombinant viruses, mO74 (gpI) and mO39 (gpIV), were used for immunological analysis. In consequence, the gpI derived from cells infected with mO74 showed antigenic characteristics similar to those of gpI from VZV-infected cells as determined from the immunoprecipitation pattern, although the molecular weight of each polypeptide was different, and antibody produced in rabbits infected with recombinant virus had a high neutralizing activity, when the reaction was performed with complement. This suggested that gpI plays an important role for protection and recovery from VZV infection.