A study of varicella zoster virus glycoprotein C regulatory region response to viral activators in vitro.

A study was conducted to analyze the response of varicella zoster virus (VZV) glycoprotein C gene (ORF14) regulatory sequences downstream as well as upstream of the transcription site to VZV transactivators, IE4 and IE62 and p29, the single-stranded DNA binding protein, in vitro by transiently transfecting a permissive human melanoma cell line (Mewo). This glycoprotein has been shown to be an important factor in VZV pathogenesis and therefore the regulation of its expression has been of much interest. In this study, the promoter region of gC as well as another VZV glycoprotein, gI (as a positive control), was amplified and cloned into a promoter less plasmid expressing the luciferase gene as a reporter. The activities of the regulatory regions from both glycoproteins were assessed by quantifying the luciferase activity. The results show that the luciferase assay is a powerful means of measuring promoter activity; nevertheless, the promoter region and cognate downstream and upstream sequences of the true late gC gene were not responsive to these viral proteins, indicating that other viral/cellular factors and/or viral replication could be involved in gC synthesis during the VZV infection cycle.