Evaluation of an epitope-blocking enzyme-linked immunosorbent assay for the detection of antibodies to influenza A virus in domestic and wild avian and mammalian species

Abstract

An epitope-blocking enzyme-linked immunosorbent assay (bELISA) was developed for the detection of antibodies to influenza A virus in taxonomically diverse domestic and wild vertebrate species. In contrast to the bELISAs published previously that require reagent production, manipulation by the end-user, or have not been evaluated for use with both mammalian and avian species, this assay is performed using commercially available recombinant nucleoprotein antigen and corresponding nucleoprotein-specific monoclonal antibody and has been shown to work with multiple avian and mammalian species. The efficacy of the bELISA as a serum screening assay was compared to the agar gel immunodiffusion (AGID) assay using 251 serum samples obtained from experimentally infected mallards ( Anas platyrhynchos) and raccoons ( Procyon lotor). The concordance between the AGID assay and bELISA was 94.1% (95% CI = 89.9, 98.3) for raccoons, and 71.2% (95% CI = 63.5, 78.9) for mallards and 82.8% (95% CI = 78.2, 87.3) overall. The bELISA was more sensitive than the AGID assay as demonstrated by the detection of antibodies to influenza A virus at earlier time points in experimental infection studies and at higher serial dilutions. The efficacy of the bELISA to monitor natural influenza A virus exposure was also compared to the AGID assay using an additional 745 serum samples from six avian species and six mammalian species. This bELISA provides a rapid, reliable, and inexpensive technique for large-scale surveillance of influenza A virus exposure in taxonomically diverse vertebrate species.