Avian Leukosis Virus is a common naturally occurring neoplastic disease affecting chickens. AL is of great economic significance not only because of tumor production, but decreased egg production and increased mortality. Due to its long incubation period, AL affects mostly breeders and commercial egg layers. Enlargement of the bursa and liver may be detected by palpitation in advanced cases.1 Avian viruses in serum can be detected by the Enzyme Linked Immunosorbant Assay (ELISA). The levels of viral protein p27 in serum and egg albumen, as well as the disease status of entire flocks can be monitored using ELISA. 

Rabbit anti p27 antibody is bound to a microwell. Diluted sera or egg albumen is added to the microwell and incubated. Any p27 viral proteins present in the serum will bind to the Rabbit anti p27 antibody on the microwell forming a p27 antibody-antigen complex. After washing away any unbound material, anti-p27 IgG Alkaline Phosphatase conjugate is added to the microwell. The conjugate will bind to the p27 antibody-antigen 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.