epstein-barr virus (ebv¸ human herpes virus 4)

a herpesvirus. EBV infection is common and usually asymptomatic in children, and may cause infectious mononucleosis ("kissing disease") in young adults. EBV lies dormant in the lymph nodes. It is associated with oral hairy leukoplakia, lymphoid interstitial pneumonitis and some types of cancer in people with suppressed immune systems.