Cell-type-dependent activation of the cellular EF-1α promoter by the varicella-zoster virus IE63 protein

The varicella-zoster virus (VZV) IE63 protein is abundantly expressed during productive viral infection and is one of six gene products that appear to be expressed during latency. We have found that the IE63 protein can activate expression from the cellular EF-1α promoter in the absence of other viral proteins. The VZV IE62 protein, in contrast, was not found to transactivate this promoter. These data indicate that IE63 can function independently of the IE62 protein to positively influence the cellular transcription apparatus. We show that IE63 activation of the EF-1α promoter is cell type dependent and have examined the effects of point mutations important for IE63 phosphorylation and virus viability on this activation.