Use of a recombinant envelope protein subunit antigen for specific serological diagnosis of West Nile virus infection

Serological diagnosis of West Nile virus (WNV) infection is complicated by extensive antigenic crossreactivity with other closely related flaviviruses, such as St. Louis encephalitis virus. Here we describe a recombinant, bacterially expressed antigen equivalent to structural domain III of the WNV envelope protein that has allowed clear discrimination of antibody responses to WNV from those against other related flaviviruses in indirect enzyme-linked inummosorbent assays using standardized control antisera and field-collected samples.