Test Details: The Epstein-Barr virus (EBV) is a member of the herpes virus family. It causes an illness called infectious mononucleosis. This particular test aids in the diagnosis of EBV infections (infectious mononucleosis). EBV nuclear antigen (EBNA) IgG antibodies do not appear during the acute phase of infection but appear around 2-4 months after initial clinical presentation and typically persist for life. If EBNA antibody are positive, then it is likely that the person tested had a previous EBV infection.