VCA IgM

EBNA IgG and VCA IgM (anti-Epstein-Barr virus capsid antigen IgM) are two types of antibodies produced by the body against the Epstein-Barr virus (EBV), which is responsible for mononucleosis. EBNA IgG is directed against an antigen of the virus nucleus (Epstein Barr nuclear antigen), while the VCA IgM is directed against an element of the envelope (capsid) of the virus (viral-capsid antigen). When a person is infected with EBV, VCA IgM appears first and disappears within 4 to 6 weeks. EBNA IgG test results are positive within a few months, usually after symptoms have disappeared, and remain positive for life.