Abstract
There are currently five serologic assays available for detection of anti-Zika virus (ZIKV) IgM-class antibodies with U.S. Food and Drug Administration emergency use authorization. Among these are the Chembio DPP Zika IgM system (DPP Zika ICA; Chembio, Medford, NY), a rapid immunochromatographic assay (ICA), and the InBios ZIKV Detect 2.0 IgM antibody capture enzyme-linked immunosorbent assay (ZIKV 2.0 MAC-ELISA; InBios international, Inc., Seattle, WA), which has replaced the original InBios ZIKV Detect MAC-ELISA. We evaluated performance of these three serologic assays using 72 specimens characterized by plaque reduction neutralization testing (PRNT) for the presence or absence of neutralizing antibodies (NAbs) to ZIKV, dengue virus (DENV), and West Nile virus (WNV). The InBios ZIKV 2.0 MAC-ELISA was "presumptive Zika positive" in all 15 PRNT-confirmed ZIKV samples, while the Chembio DPP Zika ICA was nonreactive in three (20%) and the InBios ZIKV MAC-ELISA was negative in four (27%). The Chembio DPP Zika ICA and InBios ZIKV 2.0 MAC-ELISA showed >95% specificity in 22 ZIKV/DENV-seronegative specimens and in 13 samples positive for NAbs to non-ZIKV flaviviruses. Comparatively, the InBios ZIKV MAC-ELISA was "presumptive" or "possible Zika positive" in 8 of 12 WNV or DENV PRNT-positive samples and in 12 of 22 PRNT-seronegative sera. Our findings suggest that replacement of the InBios ZIKV MAC-ELISA with the InBios ZIKV 2.0 MAC-ELISA will lead to fewer samples requiring PRNT, minimizing unnecessary anxiety among patients ultimately determined to be seronegative for ZIKV and DENV by PRNT and alleviating some of the testing burden on laboratories performing PRNT.