In the course of examining the trafficking pathways of varicella-zoster virus (VZV) glycoproteins gE, gI, gH, and gB, we discovered that all four are synthesized within 4 to 6 h postinfection (hpi) in cultured cells. Thereafter, they travel via the trans-Golgi network to the outer cell membrane. When we carried out a similar analysis on VZV gC, we observed little gC biosynthesis in the first 72 hpi. Further examination disclosed that gC was present in the inocula of infected cells, but no new gC biosynthesis occurred during the first 24 to 48 h thereafter, during which time new synthesis of gE, gH, and major capsid protein was easily detectable. Similarly, delayed gC biosynthesis was confirmed with three different VZV strains and two different cell lines. Bioinformatics analyses disclosed the presence of PBX/HOX consensus binding domains in the promoter/ enhancer regions of the genes for VZV gC and ORF4 protein (whose orthologs transactivate gC in other herpesviruses). Bioinformatics analysis also identified two HOXA9 activation regions on ORF4 protein. Treatment of infected cultures with chemicals known to induce the production of PBX/HOX transcription proteins, namely, hexamethylene bisacetamide (HMBA) and retinoic acid, led to more rapid gC biosynthesis. Immunoblotting demonstrated a fivefold increase in the HOXA9 protein after HMBA treatment. In summary, these results documented that gC was not produced during early VZV replication cycles, presumably related to a deficiency in the PBX/HOX transcription factors. Furthermore, these results explain the apparent spontaneous loss of VZV gC in some passaged viruses, as well as other anomalous gC results.Varicella-zoster virus (VZV) is a very cell-associated virus in cell culture. In addition, the infectivity titers are extremely low, usually less than 1,000,000 U per 25-cm 2 monolayer. Further, the virions produced in cell culture have an aberrant appearance. Explanations for these observations are a subject of continuing research. To this end, we have been investigating the biosynthesis and maturation of several VZV structural glycoproteins found in the envelope of the virion, especially the predominant gE/gI complex. These two glycoproteins are synthesized in the Golgi and then traffic through the trans-Golgi network en route to the outer plasma membrane within the expected 12-h replication cycle of an alphaherpesvirus. After endocytosis via their tyrosine-and dileucine-based motifs, they travel back to the trans-Golgi network (12). At this location, the glycoproteins appear to be incorporated into the virion assembly vacuoles. Two other major VZV glycoproteins, gH and gB, have similar endocytosis motifs and similar trafficking profiles.During the glycoprotein trafficking studies, VZV gC was used as a control because there are no obvious trafficking motifs in its short cytoplasmic tail (20). There have been clues that gC is important for virion production. The severe combined immunodeficient (SCID) mouse has become an important animal model for the investigation...