Regulation of human cytomegalovirus US3 gene transcription by a cis-repressive sequence.

Regulation of immediate-early gene expression in human cytomegalovirus is subject to complex controls. The major immediate-early (mIE) gene is regulated by both positive and negative regulatory signals, including autoregulation mediated by a cis-repressive sequence. A second immediate-early gene, the US3 gene, is transcribed with kinetic similar to those of the mIE gene. I have identified an element present in the US3 gene located from -1 to -13 (relative to the start site of transcription) that mediates a decrease in US3 transcription. The US3 element resembles the cis-repressive element of the mIE gene in sequence, position, and function. The common theme of negative regulation of immediate-early genes shortly after infection suggests that a decrease in the level of immediate-early proteins may be critical for viral replication.