The regulation of transcription of viral and cellular genes by herpesvirus immediate-early gene products (review).

The expression of viral genes during infection of tissue culture cells by herpesviruses can be divided into three broad classes termed Immediate-Early (IE), early and late. The IE polypeptides include trans-acting regulators of gene expression; prior expression of IE gene products is essential for the activation of transcription from early gene promoters. During the past five years, the use of modern gene manipulation techniques, short-term transfection assays and in vitro methods has resulted in a significant increase in our understanding of the IE polypeptides. This review concentrates on the genetic, physical and functional properties of herpesvirus IE gene products with particular emphasis on those of herpes simplex virus type 1.