In vivo competence of murine cytomegalovirus under the control of the human cytomegalovirus major immediate-early enhancer in the establishment of latency and reactivation.

The human cytomegalovirus (HCMV) major immediate-early enhancer has been postulated to play a pivotal role in the control of latency and reactivation. However, the absence of an animal model has obstructed a direct test of this hypothesis. Here we report on the establishment of an in vivo, experimentally tractable system for quantitatively investigating physiological functions of the HCMV enhancer. Using a neonate BALB/c mouse model, we show that a chimeric murine CMV under the control of the HCMV enhancer is competent in vivo, replicating in key organs of mice with acute CMV infection and exhibiting latency/reactivation features comparable for the most part to those of the parental and revertant viruses.