Serologic Testing for Zika Virus: Comparison of Three Zika Virus IgM-Screening Enzyme-Linked Immunosorbent Assays and...

Serologic evaluation for Zika virus (ZIKV) infection currently includes an initial screen using an anti-ZIKV IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) followed by supplemental testing of specimens with nonnegative results by a plaque reduction neutralization test (PRNT). We compared the performance characteristics of three ELISAs for the detection of IgM class antibodies to ZIKV, including the Centers for Disease Control and Prevention (CDC) Zika MAC-ELISA, the InBios ZIKV Detect MAC-ELISA, and the Euroimmun anti-Zika Virus IgM ELISA. Additionally, we present our initial experiences with ZIKV serologic testing from a national reference laboratory perspective. Using both retrospectively and prospectively collected specimens from patients with possible ZIKV infection, we show that the CDC and InBios MAC-ELISAs perform comparably to each other, with positive agreement, negative agreement, and interrater kappa values ranging from 87.5% to 93.1%, 95.7% to 98.5%, and 0.52 to 0.83, respectively. In contrast, comparison of the Euroimmun ZIKV ELISA to either the CDC or InBios MAC-ELISAs resulted in positive agreement, negative agreement, and interrater kappa values ranging from 17.9% to 42.9%, 91.7% to 98.6%, and 0.10 to 0.39, respectively. Among the 19 prospective samples submitted for PRNT, nine were negative, eight specimens had neutralizing antibodies to a flavivirus (unable to be identified), and one sample each was confirmed for ZIKV or dengue virus infection. This study highlights the ongoing challenges associated with serologic diagnosis of ZIKV infection. Although the availability of a commercial serologic test for ZIKV has greatly expanded the national capacity for such testing, the need to further characterize and improve these assays, particularly with regard to specificity, remains.