Development and clinical evaluation of a recombinant-antigen-based cytomegalovirus immunoglobulin M automated immunoassay using the Abbott AxSYM analyzer

A new microparticle enzyme immunoassay (MEIA), the Cytomegalovirus (CMV) Im munoglobulin M (IgM) test, was developed on the Abbott AxSYM analyzer. This test uses recombinant CMV antigens derived from portions of four structura l and nonstructural proteins of CMV: pUL32 (pp150), pUL44 (pp52), pUL83 (pp 65), and pUL80a (pp38). A total of 1,608 specimens from random volunteer bl ood donors (n = 300), pregnant women (It = 1,118), transplant recipients (r t = 6), and patients with various clinical conditions and disease states (n = 184) were tested during development and evaluation of this new assay. In a preliminary clinical evaluation we tested specimens collected prospectiv ely from pregnant women (It = 799) and selected CMV IgM-positive archived s pecimens from pregnant women (n = 39), The results from the new CMV IgM imm unoasssy were compared to the results of a consensus interpretation of the results obtained with three commercial CMV IgM immunoassays. The results fo r specimens with discordant results were resolved by a CMV IgM immunoblot a ssay. The relative sensitivity; specificity, and agreement for the AxSYM CM V IgM assay were 94.29, 96.28, and 96.19%, respectively, and the resolved s ensitivity, specificity, and agreement were 95.83, 97.47, and 97.37%, respe ctively. We also tested serial specimens from women who experienced serocon version or a recent CMV infection during gestation (n 17) and potentially c ross-reactive specimens negative for CMV IgM antibody by the consensus test s (n = 184). The AxSYM CMV IgM assay was very sensitive for the detection o f CMV IgM during primary CMV infection, as shown by the detection of CMV Ig M at the same time as or just prior to the detection of CMV IgG. Specimens from individuals with lupus (rt = 16) or parovirus B19 infection (n = 6) or specimens containing hyper IgM (n = 9), hyper Ige (n = 8)? or rheumatoid f actor (n = 55) did not cross-react with the AxSYM assay. One specimen each from individuals infected with Epstein-Barr virus (n = 26), measles virus ( n = 10), herpes simplex virus (n = 12), or varicella-zoster virus (n = 13) infection, one specimen from an influenza vaccinee (n = 14), and one specim en containing antinuclear antibody cross-reacted with the assay. The overal l rate of cross-reactivity of the specimens with the assay was 33% (6 of 18 4). The AxSYM CMV IgM assay is a sensitive and specific assay far the detec tion of CMV-specific IgM.