A monoclonal antibody blocking ELISA for the detection of IBV antibodies in fowl

A murine monoclonal antibody (mAb) reacting with the spike protein of seven field and laboratory strains of Infectious Bronchitis Virus (IBV) was characterised. Neutralisation tests performed in chicken tracheal organ culture showed that the mAb is directed against a conserved neutralising epitope. A monoclonal antibody blocking ELISA (B-ELISA) was developed based on the mAb. The sensitivity and specificity of the test was evaluated by examining sera and egg yolk from IBV-free, vaccinated or naturally infected chickens from different European countries. The comparisons showed that the IBV blocking ELISA was very sensitive and more specific than the commercially available indirect ELISA and the haemagglutination-inhibition (HI) test. As part of the Swedish national health control program, more than 60,000 sera have been examined with the B-ELISA at the National Veterinary Institute (Sweden) since 1993. The test proved to be very specific in detecting the spread of disease during the Swedish IBV outbreaks in 1994.