Infectious Bronchitis Virus (IBV) is a clinically acute, highly contagious viral disease affecting chickens of all ages. IBV has an incubation period of only 24 to 72 hours. The disease affects the respiratory and urogenital tract of chickens. Young chickens exhibit acute respiratory disease signs and lesions in the trachea. Mortality may be as high as 100%. Antibodies to avian viruses in serum can be detected by the Enzyme Linked Immunosorbant Assay (ELISA). The levels of IBV antibodies in serum, as well as the immune status of entire flocks can be monitored using ELISA. 

Inactivated antigen is bound to a microwell. Diluted sera is added to the microwell and incubated. Any anti-IBV antibodies present in the serum will bind to the IBV on the microwell forming an IBV antigen-antibody complex. After washing away any unbound material, anti-Chicken IgG Alkaline Phosphatase conjugate is added to the microwell. The conjugate will bind to the IBV antigen-antibody complex. After incubation any unbound conjugate is removed by washing. Enzyme substrate is then added to the microwell. The substrate reacts with any Alkaline Phosphatase present and forms a yellow product. In the final step the reaction is stopped, fixing the color. The intensity of the color is measured photometrically at 405 - 410 nm.