نبذة مختصرة : Flaviviruses with a major impact in veterinary medicine are widely distributed (e.g. West Nile fever (WNF) has spread across the five continents and Japanese Encephalitis (JE) is reported in South-East Asia) and are mainly responsible for neurological diseases in humans and/or horses.After flavivirus infection, viremia in mammal hosts is generally short and consequently indirect methods are mostly used to diagnose flavivirus infections. However, frequent spatial overlapping in their circulation areas renders the interpretation of serological assays difficult. Indeed, cross-reactions between flaviviruses are observed in rapid serological tests such as in ELISA and immunofluorescence assays (IFA). Serological assay results should thus be confirmed by the tedious comparative virus neutralization test (VNT) using a panel of viruses known to circulate in the area. Moreover, the risk of emergence of new flaviviruses such as reported recently with the Zika virus in Brazil or in North America should be considered when studying flavivirus epidemiology.In the first section, a new strategy aiming at improving the serological diagnosis of flavivirus infections was developed using the multiplexing capacity of microsphere immunoassays (MIA). The flavivirus soluble envelope (sE) glycoprotein ectodomain is composed of three domains (D), e.g. DI, DII and DIII, with EDIII containing virus-specific epitopes. Recombinant EDIIIs of different flaviviruses were synthesized in the Drosophila S2 expression system. The microspheres coupled with rEDIIIs were assayed with equine and ovine sera from natural and experimental flavivirus infections or non-immune samples. Very encouraging results have been obtained and this innovative multiplex immunoassay based on flavivirus rEDIIIs appears to be a powerful alternative to ELISAs and VNTs for veterinary diagnosis of flavivirus-related diseases.MIA with WNV nonstructural 1 protein were also implemented to differentiate Infected from Vaccinated Animals (DIVA). Such a DIVA approach was only ...
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