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

Calogero Terregino (1) , Anna Toffan (1) , Maria Serena Beato (1) , Roberta de Nardi (1) , Amelio Meini (2) , Giovanni Ortali (3) , Marzia Mancin (4) , Ilaria Capua (1)

1 OIE/FAO and National reference laboratory for Avian Influenza and Newcastle disease, Virology laboratory
2 Intervet Italia S.r.l. part of Schering-Plough
3 A.I.A. SpA
4 Centro Regionale di Epidemiologia Veterinaria (CREV)

The aims of this study were to evaluate the pathogenicity of an Italian isolate of IBV QX strain in broiler and layer type chickens and to assess the level of protection induced in these birds by a vaccination programme including IB Massachusetts and 4/91 serotype vaccines. Forty-two one-day-old female SPF chicks (layer type) and forty-two one-day-old female commercial broilers were used. The present study confirms the ability of the IB QX strain to replicate in the respiratory as well as in the female urogenital tract. Vaccination protected SPF birds fully, with no lesions detected or virus isolated. In broilers, replication of the challenge virus was reduced significantly. Data presented herein indicate that vaccination at day-old and at day 14 of age using the Ma5 and 4/91 serotypes may provide a practical method to control the clinical signs and economic losses associated with QXIBV infections in commercial layers and broilers farms.

Mots clés: Life Sciences

Calogero Terregino, Anna Toffan, Maria Serena Beato, Roberta de Nardi, Amelio Meini, et al.. 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. Avian Pathology, 2008, 37 (05), pp.487-493. ⟨10.1080/03079450802356938⟩. ⟨hal-00540127⟩