Discordant varicella-zoster virus glycoprotein C expression and localization between cultured cells and human skin vesicles

Abstract

Because of its very low titer, varicella-zoster virus (VZV) infectivity is usually transferred by passage of trypsin dispersed infected cells. Previously, we observed that gC biosynthesis was markedly delayed in monolayers inoculated with cell free virus. In this report, we investigated the kinetics of gC expression in more detail and included studies of monolayers inoculated with trypsin dispersed infected cells, the more traditional method of VZV infection. Extensive imaging analyses disclosed that gC was detectable in some inoculum cells, but little gC biosynthesis occurred during the first 48 hpi in the newly infected underlying monolayer. In contrast, during the first 24–48 hpi, expression of VZV gE and gB was easily detectable. Using real-time RT-PCR, we found a delay in accumulation of VZV gC transcripts that paralleled the delay in expression of VZV gC protein. Treatment with hexamethylene bisacetamide (HMBA) increased expression of both gC protein and gC mRNA. HMBA treatment also increased virus titer by 4-fold, but paradoxically reduced plaque size in the titration assay. Finally, we examined skin vesicles from cases of chickenpox and zoster in humans and observed abundant amounts of gC expression. In short, this report documents an unexpected delay in both gC mRNA and protein production under all conditions of VZV infection of cultured cells.

Aberrant Virion Assembly and Limited Glycoprotein C Production in Varicella-Zoster Virus-Infected Neurons

“…The low abundance of VZV gC protein in infected neurons was paralleled by low levels of true late VZV gC transcripts compared to transcription of the VZV IE62 gene and the early-late VZV gE gene in infected neurons, suggesting that low VZV gC abundance in infected neurons is due to a block in virus transcription rather than translation. Reduced transcription of VZV gC compared to that of VZV IE62 and VZV gE in neurons and fibroblasts is consistent with previous observations of reduced VZV gC transcription in human melanoma cells (8,19). While VZV gC production is significantly reduced in both virus-infected neurons and nonneuronal cells in tissue culture, VZV gC is nevertheless abundant in vesicles (20).…”

Dysregulated Glycoprotein B-Mediated Cell-Cell Fusion Disrupts Varicella-Zoster Virus and Host Gene Transcription during Infection

“…These values were 3.8-to 7.8-fold lower than that for pOka and 4.4-to 9-fold lower than that for the wild-type-like gB[Y920F] mutant. The ORF14 transcript is considered to be produced very late during VZV infection (41,42). This decrease is consistent with the poor propagation of the hyperfusogenic mutants.…”

Varicella-Zoster Virus Infection Induces Autophagy in both Cultured Cells and Human Skin Vesicles

“…In both chicken pox and zoster, skin vesicles are the final site of VZV replication and virus formation. While the architecture of skin vesicles immunostained with a variety of anti-VZV antibodies has been previously delineated (41,49), the fact the zoster vesicles contain autophagosomes is an intriguing finding. The punctuate LC3B-positive autophagosomes were easily detected by confocal microscopy throughout the skin vesicles.…”

“…In an earlier report (49) we demonstrated that gE and gH were easily detected in vesicles. Recently, we documented that VZV gC was also expressed abundantly in skin vesicles, in contrast to the case for cultured cells (41). Skin vesicles were sectioned and labeled with a primary antibody against LC3B, followed by incubation with a fluorochrome-conjugated secondary antibody.…”