Antigen requirements and specificity of a microplate enzyme-linked immunosorbent assay (ELISA) for detecting infectious bronchitis viral antibodies in chicken serum

The conditions of a rapid, indirect-enzyme linked immunosorbent assay for Infectious Bronchitis Virus (IBV) antibodies have been established. Optimal sensitivity was obtained using 10 µg/ml protein concentration of the Mass 41 strain purified from infected allantoic fluid. Specificity was demonstrated with Newcastle Disease Virus (NDV) antigen-antibody system. Negligible crossreactions were observed. After bromelain or lipase treatment IBV had an ELISA reactivity similar to untreated particles suggesting that peripheral constituents of IBV play a minor role when whole virus is adsorbed on solid phase. The method offers a simple and specific antibody assay which could be used for the laboratory diagnosis of avian infectious bronchitis.