title: Pathogenicity of a QX strain of infectious bronchitis virus in specific pathogen free and commercial broiler chickens, and evaluation of protection induced by a vaccination programme based on the Ma5 and 4/91 serotypes.
abstract: The aims of this study were firstly to evaluate the pathogenicity of an Italian isolate of the QX strain of infectious bronchitis (IB) virus using 1-day-old female specific pathogen free chicks (layer type) and 1-day-old female commercial broiler type chickens, and secondly to assess the level of protection induced in these birds by a vaccination programme including the IB Massachusetts and 4/91 serotype live attenuated vaccines. Unvaccinated birds showed clinical signs of varying severity, predominantly affecting the upper respiratory tract. Vaccinated birds appeared healthy, with the exception of a very mild conjunctivitis affecting a limited number of the broilers. Vaccination fully protected specific pathogen free birds, since no histopathological lesions were observed, nor was virus detected following challenge. In broilers, replication of the challenge virus was not prevented but was significantly reduced. This study confirms that vaccination at 1 day old and at 14 days of age using the Ma5 and 4/91 IB vaccines may be instrumental in reducing the economic impact of QX IB virus infections in layer and broiler farms.
authors.affiliation: OIE/FAO and National Reference Laboratory for Newcastle Disease and Avian Influenza, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Universita 10, Legnaro (PD), Italy.
authors.forename: Calogero
authors.initials: C
authors.lastname: Terregino
authors.forename: Anna
authors.initials: A
authors.lastname: Toffan
authors.forename: Maria Serena
authors.initials: MS
authors.lastname: Beato
authors.forename: Roberta
authors.initials: R
authors.lastname: De Nardi
authors.forename: Marta
authors.initials: M
authors.lastname: Vascellari
authors.forename: Amelio
authors.initials: A
authors.lastname: Meini
authors.forename: Giovanni
authors.initials: G
authors.lastname: Ortali
authors.forename: Marzia
authors.initials: M
authors.lastname: Mancin
authors.forename: Ilaria
authors.initials: I
authors.lastname: Capua
mesh_terms: D000818:Animals; D002645:Chickens; D018352:Coronavirus Infections / Q000517:prevention & control* / Q000821:virology; D005260:Female; D001351:Infectious bronchitis virus / Q000145:classification* / Q000302:isolation & purification; D012703:Serotyping; D013047:Specific Pathogen-Free Organisms; D014132:Trachea / Q000648:ultrastructure / Q000821:virology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D014765:Viral Vaccines