Vaccination programs for the control of avian influenza (AI) in poultry have limitations due to the problem of differentiating between vaccinated and virus-infected birds. The use of AI vaccination in poultry would have greater worldwide acceptance if reliable tests that clearly discriminated between naturally infected and vaccinated-only animals (DIVA) were available. In this study, to differentiate avian influenza virus (AIV)-infected chickens vs. chickens immunized with inactivated avian influenza virus, a commercial ELISA Kit (IDEXX) was used. Using HI as the reference method, the sensitivity of the commercial ELISA kit was 100% and its specificity was 100%. In the present study, we demonstrated that, 3 weeks after infection or vaccination, sera from both infected and vaccinated groups were tested positive and the difference in mean optical density between vaccinated and challenged birds, as detected by a commercial ELISA kit (IDEXX), was very small. Therefore, this assay cannot distinguish infected from vaccinated poultry.
Avian influenza virus (AIV); DIVA; commercial ELISA
