Cytomegalovirus ( from the Greek cyto - , `` cell '' , and - megalo - , `` large '' ) is a viral genus of the Herpesviruses group in humans it is commonly known as HCMV or Human Herpesvirus 5 ( HHV-5 ) . Cytomegalovirus ( from the Greek cyto - , `` cell '' , and - megalo - , `` large '' ) is a viral genus of the viral group known as Herpesviridae or herpesviruses .