Evaluation of five commercial enzyme immunoassays for the detection of human cytomegalovirus-specific IgM antibodies in the absence of a commerciallyavailable gold standard

In the recent years the number of commercially available immunoassays for t he detection of human cytomegalovirus (HCMV)-specific immunoglobulin M (IgM ) antibodies has rapidly increased. The aim of the present study was to eva luate five commercial immunoassays for the serological diagnosis of HCMV-in fection. These methods, namely the IMx CMV IgM assay, the AxSYM CMV IgM ass ay (both Abbott], the Gull CMV IgM, the CMV-IgM-ELA test PCS Medac and the Biotest Anti-HCMV recombinant IgM ELISA, were compared for their diagnostic effectiveness and interference with substances eventually producing cross- reactions with HCMV-IgM [Epstein-Barr-virus (EBV)-IgM, rheumatoid factor (R F)). In addition, repeated measurements on samples from kidney and heart tr ansplant recipients with active HCMV infection were examined to compare the temporal development of the HCMV-ISM measured with the five assay systems. Since there is no commercially available gold standard, it was assumed tha t the true classification, of whether the patient sample is HCMV-IgM positi ve or negative, was unknown. Hence sensitivity and specificity were assesse d based on a maximum likelihood approach using a "latent class" model. The cross-reactions were quantified by a Bayesian statistical model using prior information for the expected prevalences in the EBV-IgM and rheumatoid fac tor sample groups. The results of the study demonstrated that there are gre at differences in sensitivity and specificity as well as in cross-reactions with EBV-IgM and RF between the tested ELISAs.