Cytomegalovirus (CMV) Antibody, IgG

Cytomegalovirus (CMV) Antibody, IgG is used to establish evidence of prior CMV infection or immunity and to assist in assessing suspected CMV disease when interpreted with CMV IgM and nucleic acid testing. The assay, also referred to as Anti-CMV IgG or Cytomegalovirus IgG antibody, aids in distinguishing CMV as a cause of mononucleosis-like illness when Epstein–Barr virus testing is negative. In preconception and prenatal settings, serostatus and, when performed, CMV IgG avidity help estimate the timing of infection and refine maternal–fetal risk stratification.

Cytomegalovirus is a human herpesvirus that establishes lifelong latency after initial infection with potential for reactivation. Transmission occurs through body fluids and can be passed from mother to child during pregnancy, delivery, or breastfeeding. In immunocompetent persons, primary infection is commonly silent or presents with a syndrome resembling infectious mononucleosis. During pregnancy, prior maternal immunity lowers the fetal risk, whereas a primary maternal infection carries the highest likelihood of congenital CMV. Approximately 10% of congenitally infected infants are symptomatic, with findings that can include microcephaly, intracranial calcifications, rash, and hepatosplenomegaly, and they may later develop sensorineural hearing loss or neurodevelopmental impairment. In the setting of immunodeficiency—such as advanced HIV infection or pharmacologic immunosuppression—CMV may produce severe end-organ disease, including retinitis, colitis, esophagitis, and encephalitis. CMV-specific IgG becomes detectable within weeks of primary infection and then persists. Early after acquisition, IgG avidity is low and matures to a high-avidity pattern over approximately three months, providing a tool to estimate the timing of infection when interpreted with other CMV assays.