INFECTIOUS bronchitis (IB) is a ubiquitous and highly contagious viral infection affecting chickens of all ages, which is known to cause severe economic losses to the industry. The viral agent is a coronavirus, a single-stranded RNA virus characterised by a well-documented capacity to modify its genome by both spontaneous mutation and genetic recombination. At the end of July 2011, samples from 15-day-old broilers from a farm located in north-east Italy were submitted to our laboratory for investigation. The birds had been vaccinated against IB (with the H120 strain …