Avian infectious bronchitis is a highly contagious acute viral disease in chickens caused by infectious bronchitis virus (IBV). As a member of the genus Gammacoronavirus, IBV has a remarkably high mutation and recombination rate, leading to numerous types and variants that differ from each other in pathogenicity. Although the site of entry of IBV is the upper respiratory tract, where the initial infection occurs, the virus can spread systemically, replicating in the epithelial cells of many organs and causing injuries of the kidneys and female reproductive tract. As IBV isolates present high antigenic and immunogenic diversity, that do not cross-protect, it is very difficult to control. Attenuated live vaccines are used in broilers and inactivated vaccines are typically used in future layers.