Avian Reoviruses (REO) are thought to be responsible for viral arthritis, stunting syndrome, respiratory disease, enteric disease, malabsorption syndrome, and osteoporosis. REO has also been isolated from non-diseased chickens. The nature, symptoms, and severity of REO induced diseases varies with host age, virulence, and route of exposure. Antibodies to avian viruses in serum can be detected by the Enzyme Linked Immunosorbant Assay (ELISA). The levels of REO 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-REO antibodies present in the serum will bind to the REO on the microwell forming an REO 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 REO 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.