Rockstroh et al.
Specific detection and differentiation of tick-borne encephalitis and West Nile virus induced IgG antibodies in humans and horses.
Transbound. Emerg. Dis., 2019, in press, doi: 10.1111/tbe.13205
West Nile virus (WNV) is emerging into TBE endemic regions and due to cross-reacting epitopes in the glycoprotein E, serological analyses in place to detect IgG specific antibodies in hosts (humans and horses) harbor the risk for false-positive results. The authors have developed an ELISA based on a quadruple WNV and TBE virus E protein mutant protein with four mutations in the highly conserved fusion-loop region domain of the protein (which is the target for most cross-reacting antibodies) and recombinantly expressed in Drosophila S2 cells. This new assay has been analyzed for specificity, sensitivity and reproducibility with human and horse sera directed against various flaviviruses: TBE, WNV, Dengue, Usutu and Zika viruses.
WNV ELISAs with equine sera showed no cross-reactivity with TBE-positive samples resulting in 100% specificity and 87.9% sensitivity. Human sera tested on this WNV-ELISA or TBE-ELISA showed no cross-reactivity with Dengue, Usutu and Zika virus positive antibodies. However, residual cross-reactivity was observed with 14.7% of TBE-positive sera which resulted in a specificity of 94.4%. This new ELISA has the potential to make cumbersome virus neutralization assays for specific identification of flavivirus infections obsolete.