Cytomegalovirus (CMV) Antibody, IgG

The Cytomegalovirus (CMV) Antibody, IgG test, also referred to as Anti-CMV IgG or CMV IgG antibody, is used to determine previous CMV infection and to assess immune status. In clinical scenarios suggestive of CMV, serologic status supports attribution of illness to CMV, particularly when Epstein–Barr virus testing is negative. In obstetric care, CMV IgG—used alone or with paired sera and/or IgG avidity—helps stratify the risk of congenital CMV. In immunocompromised hosts, CMV serology contributes to the diagnostic assessment of suspected CMV-related disease.

Cytomegalovirus is a human herpesvirus that establishes lifelong latency and can reactivate. Transmission occurs through saliva, urine, semen, and blood, and by vertical routes in utero, during delivery, or via breast milk. Primary infection in immunocompetent persons is often asymptomatic or manifests as a mononucleosis-like syndrome. During pregnancy, primary maternal infection is associated with the risk of congenital CMV; a subset of congenitally infected infants develop symptomatic disease with findings such as microcephaly, intracranial calcifications, rash, hepatosplenomegaly, and sensorineural hearing loss. IgG antibodies develop within weeks after primary infection and persist for years. IgG avidity increases over time and helps differentiate recent primary infection (low avidity) from past infection or reactivation (high avidity). Because maternal IgG crosses the placenta, neonatal IgG serology does not establish congenital infection.