Mononucleosis is usually caused by this virus, EBV for short
Children can get the virus, but it often goes unnoticed... [DOC] [TLE] Mononucleosis (Mono)-Cause - WebMD [PAR] Much less commonly, a mono-like illness is caused by different viruses, such as 
hepatitis B, rubella, ... Mono is usually caused by the Epstein-Barr virus (EBV).