RAT CYTOMEGALOVIRUS HAS A UNIQUE IMMEDIATE-EARLY GENE ENHANCER

The immediate early (IE) enhancer/promoter regions of human cytomegalo virus (HCMV), simian cytomegalovirus (SCMV), and murine cytomegaloviru s (MCMV) share the following characteristics: (1) they demonstrate hig h-level transcriptional properties, (2) multiple repetitive elements a re found throughout the enhancer region, and (3) consensus binding sit es for cellular transcription factors are frequently located within th e repetitive elements. Here we characterize the enhancer/promoter regi on of the major IE gene locus for rat cytomegalovirus (RCMV). The RCMV IE enhancer/promoter region is able to activate transcription at the same level as HCMV or MCMV IE enhancer/promoter regions. In contrast t o HCMV, MCMV, and SCMV, the RCMV IE enhancer/promoter region is almost completely lacking in repetitive elements and the only recognized con sensus binding sites for cellular transcription factors recognized by sequence are three CTF, two AP1, and one NF-KB binding sites. However, enhancing activity does not appear to be dependent on these individua l sites in transient transfection experiments, but is additive across the enhancer region. (C) 1996 Academic Press, Inc.