Comparison of two commercial enzyme-linked immunosorbent assays for detection of Influenza A virus antibodies

Serologic tools for Influenza A virus (FLUAV) antibody testing of wild birds are currently limited. In the present study, 2 commercial enzyme-linked immunosorbent assays (ELISAs) for detection of FLUAV antibodies, the IDEXX AI MultiS-Screen Ab Test and the ID VET ID Screen Influenza A Antibody Competition, were compared. Sera obtained from mallards (Anas platyrhynchos), experimentally infected with 8 FLUAV subtypes (N = 48), and field serum samples, collected from 11 wild bird species (N = 247), were tested. Overall, a substantial agreement was obtained between the 2 assays as applied to both experimental (86.5% agreement, κ = 0.69) and field samples (89.9% agreement, κ = 0.78). Based on the current study, doubtful results obtained with the ID VET assay should be re-tested to confirm their antibody status. Additionally, increasing the incubation period for the ID VET assay increases the test sensitivity but also increases the likelihood of generating false-positive results. Overall, it is concluded that the 2 ELISAs can be used for FLUAV antibody screening in wild birds and that the sensitivity of the ID VET assay can be increased with slight modifications of the manufacturer's instructions.