A chimeric yellow fever/West Nile virus was compared to West Nile virus (WNV) alone as a biosafety-level-2 reagent in the plaque reduction neutralization test for determining WNV infection histories. Concordance was 96.3% among 188 avian and equine serum samples. Neutralizing antibody titers were frequently >2-fold lower using the chimera. http://www.ncbi.nlm.nih.gov/pubmed/19005021?dopt=Abstract