A new enzyme immunoassay to detect antibodies to arboviruses in the blood of wild birds.

A new indirect enzyme immunoassay (EIA) was developed to screen wild bird sera for antibodies against western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses. The detector antibody was made by immunizing rabbits with serum proteins pooled from single species representatives of four bird orders and was conjugated with horseradish peroxidase to allow visualization with the ABTS substrate in an EIA plate reader set at 405 nm. The detector antibody recognized a wide range of bird species and was more accurate, sensitive, and specific than a hemaglutination inhibition test when compared to a plaque reduction neutralization test (PRNT). EIA positive sera frequently could not be confirmed by PRNT; however, practically all sera positive by PRNT also were positive by EIA. The new EIA has been incorporated into our field research program and has been used to economically screen over 10,000 wild bird sera from 124 species for antibodies against WEE and SLE.