Procedures for the haemagglutination and the haemagglutination inhibition tests for avian infectious bronchitis virus

Various aspects of production, storage and stability of the haemagglutination (HA) activity of infectious bronchitis virus (IBV) were studied. From the results obtained, a standard procedure for the production of IBV, HA and the HA and haemagglutination inhibition (HI) tests is suggested. The main points of the suggested procedure are: (1) the virus should be concentrated but not purified; (2) the virus should be treated with phospho-lipase C type 1 (PLC), at a final concentration of one unit/ml, for two hours at 37 degrees C; (3) the virus should be stored at 4 degrees C after PLC treatment; (4) HA and HI test plates should be kept at 4 degrees C and read 45-60 min after the addition of chicken red blood cells. Using the recommended standard procedure the HA and HI tests for IBV were as reproducible as the HA and HI tests for Newcastle disease virus.