Establishment of serological assays to investigate the incidence of West Nile and Wesselsbron flavivirus infections in Africa

Abstract

The burden of WNV and association with neurological disease was identified through syndromic surveillance in animals and humans using available serological tools. WSLB virus was identified in two samples (an equine and a bird) in South Africa for the first time since 2008. Additionally, ELISA’s were developed testing for IgG and IgM antibodies in equines, humans, cattle, and a species-independent assay for WNV and WSLB using the NS1 antigen, which differs from the commercial ELISA’s available that targets the E protein. The human WNV IgM and IgG ELISA showed very promising results, while the equine WNV ELISA’s had quite high background and this could be due to the different target antigen or the use of a baculovirus expressed protein with commercial antibodies. The cattle WNV IgM ELISA also showed good results and can possibly be implemented in the lab. The WSLB ELISA’s were only developed and optimized with rabbit sera, since a clinical sample lacked neutralizing antibodies for use in the assay. Unfortunately, the baculovirus expression of the NS1 protein was unsuccessful.