Clinical evaluation of new automated cytomegalovirus IgM and IgG assays for the Elecsys^® analyser platform

Cytomegalovirus (CMV) is a leading cause of physical and neurological abnormalities in newborns. Hence, the diagnosis of CMV infection in pregnant women is necessary in order to allow appropriate management of their pregnancy. New assays have been developed for the Roche Elecsys® immunoassay platform that detect CMV-specific immunoglobulin (Ig)M and IgG, with the IgM assay designed to target IgM produced at the start of infection rather than IgM persisting later in infection. This study aimed to evaluate the performance of the new assays compared with other commercial kits widely distributed in laboratories. The performance of the Elecsys and comparator CMV IgM and IgG assays was assessed using 967 preselected patient samples characterised by CMV infection status, as well as being compared using 1,668 unselected clinical samples. The Elecsys CMV IgM and IgG assays performed consistently with comparator assays using the preselected samples. The Elecsys CMV IgM assay showed improved sensitivity compared with the Enzygnost® assay in primary infection (91.2 % vs. 79.4 %) and improved specificity over the Architect® assay in potentially cross-reacting samples (94.1 % vs. 82.4 %). The Elecsys IgM assay reported fewer positive results in the later stages of CMV infection compared with ETI-CYTOK-M ELISA, while the Elecsys IgG assay reported slightly fewer negative results in the early stages of infection compared with ETI-CYTOK-G ELISA. There was good agreement between Elecsys and comparator assays using unselected clinical samples (range 90.4–99.4 %). The Elecsys CMV IgM and IgG assays compare well with routinely used assays and are suitable for clinical use.