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Evaluation of the indirect and IgM‐capture anti‐human cytomegalovirus IgM ELISA methods as confirmed by cytomegalovirus IgG avidity
Author(s) -
Ikuta Kazufumi,
Koshizuka Tetsuo,
Kanno Ryoko,
Inoue Naoki,
Kubo Takahiko,
Koyano Shin,
Suzutani Tatsuo
Publication year - 2019
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/1348-0421.12683
Subject(s) - cytomegalovirus , avidity , immunoglobulin m , immunology , antibody , human cytomegalovirus , virology , concordance , immunoglobulin g , betaherpesvirinae , biology , medicine , herpesviridae , virus , viral disease
Primary cytomegalovirus (CMV) infection during pregnancy often results in congenital CMV infection with severe clinical complications. IgM antibodies are one of the indices of primary infection. The IgG avidity index (AI) is also known to remain low for 3 months after primary infection. Here, we evaluated and compared the performance of CMV IgM and IgG avidity assays. Because sensitivity and specificity reportedly differ between CMV IgM kits, CMV IgM detection was compared between the two commercially available ELISA kits that are most commonly used in Japan. Sera for CMV IgM were first screened using a traditional indirect ELISA kit. Selected samples were then tested for CMV IgM and CMV AI using a CMV IgM‐capture ELISA kit and a CMV IgG avidity assay, respectively. The rate of concordance between the IgM kits was 89% (42/47), indicating the absence of any significant difference. Most of the CMV IgM‐positive plasma samples showed high CMV IgG AI; however, 18 commercially available plasma samples with low CMV IgG AI were all CMV IgM‐positive. One plausible explanation for this discrepancy is that the duration of low IgG AI is shorter than that of IgM positivity. Alternatively, CMV IgM tests may generate pseudo‐positive readouts in cases of congenital infection. Nevertheless, our study confirms that CMV IgG AI can be a reliable indicator of CMV primary infection.