Cytomegalovirus (CMV) Antibody, IgG

Cytomegalovirus (CMV) Antibody, IgG—also referred to as Anti-CMV IgG or CMV IgG antibodies—is used to document prior CMV exposure and current serostatus. When interpreted alongside CMV IgM and, when appropriate, IgG avidity, it assists in timing infection. It is employed preconceptionally and during pregnancy to establish maternal serostatus and categorize risk for congenital CMV, and it supports the workup of mononucleosis-like illness in the setting of negative Epstein–Barr virus testing. In immunocompromised individuals, serology defines baseline CMV status; however, confirmation of active CMV disease in this group typically relies on molecular or antigen-based detection rather than antibody testing.

Cytomegalovirus is a beta-herpesvirus that becomes latent after primary infection and can persist lifelong. Transmission occurs through exposure to saliva, urine, semen, and blood, and vertical transmission may occur in utero, during delivery, or through breastfeeding. In immunocompetent hosts, primary infection is frequently asymptomatic or presents with a mononucleosis-like illness; viral reactivation is more likely with immunosuppression. During pregnancy, primary maternal infection carries the greatest likelihood of congenital CMV. Approximately 10% of congenitally infected newborns are symptomatic; reported findings include microcephaly, intracranial calcifications, rash, hepatosplenomegaly, neurodevelopmental delay, and sensorineural hearing loss. Among immunocompromised patients, such as those with advanced HIV infection or transplant recipients, CMV disease can involve retinitis, colitis, esophagitis, pneumonitis, and encephalitis. CMV IgG develops within weeks after infection and persists for years to life. When combined with IgG avidity testing, serology can help distinguish recent from past infection: low avidity is characteristic early after primary infection and matures to high avidity over several months.