Niedrig M, Sonnenberg K, Steinhagen K, Paweska JT (2007): Comparison of ELISA and immunoassays for measurement of IgG and IgM antibody to West Nile virus in human sera against virus neutralisation
J. Virol. Methods 139 (1): 103-105. Epub 2006 Nov 3.

Two commercial assays for the detection of IgG antibody to West Nile virus (WNV), an indirect enzyme-linked immunosorbent assay (I-ELISA) and indirect fluorescent antibody test (IFAT), were evaluated against the virus neutralisation test. Excellent agreement with the virus neutralisation was obtained with both tests, i.e., 99.5% by I-ELISA and 100% by IFAT. The well-known serological cross-reactivity within the family of the Flaviviridae was analysed using sera with known antibodies against dengue virus, tick borne encephalitis virus and yellow fever virus. IgM and/or IgG positive sera were examined for reactivity by WNV-ELISA and WNV-IFAT. While cross-reactivity between 0 and 18.2% was recorded with IgM positive sera, there was extensive cross-reactivity of 15.7-100% with IgG positive sera.