Regulation of human cytomegalovirus by retinoic acid.

Human cytomegalovirus (HCMV) may opportunistically use retinoic acid (RA), a physiologically essential control molecule of cellular differentiation, to advance its own replication. At present, it is not clear whether RA stimulation of HCMV replication is exclusively a differentiation driven event. We report that exposure of permissively infected primary human foreskin fibroblast cells to RA transcriptionally activates the viral major immediate-early promoter (MIEP) and enhances the production of infectious particles. These experiments implicate a direct involvement of RA in modulating HCMV activation.