Avian infectious bronchitis virus (IBV) is a coronavirus which infects chickens, causing the associated disease, infectious bronchitis (IB). It is a highly infectious avian pathogen which affects the respiratory tract, gut, kidney and reproductive systems of chickens. Many IBV variants have been isolated around the world. IBV genotype Q1, genetically and serologically distinct from the classical IBVs, was also reported in China, the Middle East and Europe. This genotype is characterized by exhibiting in young layers proventriculitis and respiratory symptoms, but no kidney lesions.