EBV (Epstein Barr Virus) affects 80% of adults and is implicated in diseases, such as infectious mononucleosis (IM) and B cell lymphomas. It is a Herpes virus and has the ability to establish a latent infection. Although primary infection during childhood with EBV is usually asymptomatic, in older adolescents and young adults between 50 to 65% of primary infections result in disease such as IM. Infection by EBV is characterised by antibodies to distinct antigenic complexes, the combination of which is diagnostic of the stage of EBV infection. The antibody types are described as:

VIRAL CAPSID ANTIGEN (VCA): Antibodies to VCA are detectable in the early course of disease. The levels of antibody rise early and peak after 3-4 weeks. Whilst commonly Anti-VCA IgM then declines and completely disappears or persists at only very low levels, high levels of Anti-VCA IgG persist for life.

EBV-INDUCED NUCLEAR ANTIGEN (EBNA): EBNA is a multicomponent antigen complex, the major component EBNA-1 has been purified and sequenced. EBNA-1 antibodies are diagnostic for acute and convalescent stages in IM. EBNA-1 IgG is rarely seen in acute IM and rises during convalescence. The antibodies plateau between 3 to 12 months and normally persist for life.

EBV INDUCED EARLY ANTIGEN (EA): This non-structural complex is required for viral replication and production of complete virions. The EA complex is divided into two components: (a) the EA-D (diffuse component) and (b) EA-R (restricted component).

IgG antibodies to the EA complex can be found in early or late stages of IM.