Diagnostic and clinical observation on the infectious bronchitis virus strain Q1 in Italy.

This paper describes the diagnostic and clinical observations of an infectious bronchitis virus (IBV) variant, referred to as Q1, in clinically ill chickens in Italy. This IBV variant was described for the first time in 1998 in China. In the autumn of 2011 it caused a small-scale epidemic in nonvaccinated meat chickens in farms located in Northern Italy. The disease was characterized by increased mortality, kidney lesions and proventriculitis. Histopathological observations confirmed the nephritis and described an unusual erosive/necrotic proventriculitis with infiltration of lymphocytes, plasma cells and heterophils, as well as fibroplasia in the lamina propria. Despite these findings and the isolation of the Q1 IB virus directly from proventricular tissue, further studies are necessary to confirm the role of this IBV strain in the development of proventricular lesions. Phylogenetic analysis revealed that all the IBV isolates were very similar and probably had a common origin. The IBV Q1 variant appears to be now endemic in the North of Italy and at times it is detected in vaccinated backyard and commercial broiler farms. The importance of continuous monitoring in controlling the spread of known or emerging IBV variants is underlined.