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

Abstract

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.

Figure 1.

Simple regression for the sample-to-negative control ratio values obtained with the 2 commercial enzyme-linked immunosorbent assays, including all tested samples (N = 295; adjusted R² = 0.7856, P < 0.001).