Infectious bronchitis is an acute, highly contagious upper respiratory tract disease in chickens. In addition to respiratory signs, decreased egg production and egg quality are common, and nephritis can be caused by some strains. Attenuated live and killed vaccines are available, but different antigenic types of the avian coronavirus causing the disease do not cross-protect, complicating control efforts. Diagnostic tests include ELISA and HI testing for serum antibodies and virus detection by RT-PCR and virus isolation in embryonated eggs. Sequence analysis of the Spike gene is used to genetically type the virus.