Infectious bursal disease (IBD) is an acute and highly contagious disease caused by IBDV. IBDV mainly invades bursa, the central immune organ of chickens. It can cause infected chickens dead and the production performance drop. Birds which survive the disease are permanently immunosuppressed. Immunosuppresssion leads to vaccination failure and susceptibility to other infections and diseases, Newcastle disease, Marek's disease and IBV. The bird researchers have payed more attention to it. IBD has been one of...