Cis and trans elements regulating expression of the varicella zoster virus gI gene.

We have identified cis- and trans-acting elements involved in the VZV IE62 protein-activated expression of the varicella zoster virus (VZV) gene which encodes the viral gI glycoprotein. The cis-acting elements include a non-canonical TATA box and a novel 19 base pair sequence located just upstream of the TATA element designated the "activating upstream sequence" or AUS. The AUS is a movable element and its presence results in IE62 activation of a chimeric promoter consisting of the VZV gC TATA box and the gI AUS. We have also determined that the VZV ORF 29 protein modulates the regulatory activity of the IE62 protein at the gI promoter. In combination with the IE62 transactivator, it yields a 10 to 15-fold increase in expression over the levels seen with the IE62 protein alone in T lymphocytes. The upmodulatory activity requires the presence of a 40 base pair sequence, designated the 29RE, which maps between positions -220 and -180 in the gI promoter. In this paper we review these and earlier findings from our laboratories concerning the regulation of the gI promoter.