Enzyme Immunoassays for Measurement of Cytomegalovirus Immunoglobulin M Antibody

Abstract

The diagnosis of congenital cytomegalovirus (CMV) infection is often accomplished by the detection of circulating antibody directed against CMV. A method was devised for measuring CMV-specific IgM based on the isolation of IgM antibody by reaction with a solid phase coated with antihuman IgM. The determination of IgM antibody specific for CMV was accomplished by the addition of CMV or control antigen and enzyme-labeled CMV antibody (solid phase-IgM method). The sensitivity and specificity of this method were compared with those of a conventional form of solid-phase enzyme immunoassay in which CMV antigen is bound to the solid phase (solid phase-antigen method). Both assay systems were capable of detecting CMV-specific IgM antibody in the sera of 10 [human] babies with documented CMV infection and in the mothers of 4 of these babies. The solid phase-IgM method yielded negative results in all 66 sera available from babies who did not have congenital CMV infection. The solid phase-antigen system yielded false-positive results in 12 (18%) of these sera and in 8 of 12 sera obtained from patients with demonstrable rheumatoid factor. The solid phase-IgM system yielded negative results for the rheumatoid sera provided that appropriate control reactions were performed. The solid phase-IgM system is thus a specific and sensitive method for the determination of CMV IgM antibody.