A type-specific blocking ELISA for the detection of infectious bronchitis virus antibody

Infectious bronchitis virus (IBV) infection has been a major threat to the poultry industry worldwide. Current commercially available ELISA kits detect group-specific antibodies; however, to understand the status of field infection, a monoclonal antibody (mAb) blocking ELISA (b-ELISA) against local IBVs was developed. The selected mAb showed specificity to Taiwan IBV strains but had no cross-reactivity with the vaccine strain H120. Using the hemagglutination inhibition (HI) test as a standard, the cut-off value, sensitivity, and specificity of a b-ELISA using this mAb were evaluated in 390 field samples. The type-specificity of detection was validated using a panel of chicken hyperimmune sera. The results showed that the b-ELISA demonstrated high sensitivity (98.0%) and specificity (97.2%) of detection. The agreement between the results of the b-ELISA and the HI test was statistically significant (Kappa = 0.95), and there was no significant difference between these two methods (McNemar p = 0.72). The b-ELISA specifically detected Taiwan IBV serotypes but not three non-Taiwan IBV serotypes nor sera against other avian pathogens. This b-ELISA provides type-specific antibody detection of local IBV strains. It has the potential to serve as a rapid and reliable diagnostic method for IBV clinical infections in the field in Taiwan.