A study of natural co-infection caused by avian influenza (H9 subtype) and infection bronchitis viruses in broiler chicken farms showing respiratory signs

MAIN

©1994-2009 All Rights Reserved. Online Journal of Veterinary Research. You may not store these pages in any form except for your own personal use. All other usage or distribution is illegal under international copyright treaties. Permission to use any of these pages in any other way besides the before mentioned must be gained in writing from the publisher. This article is exclusively copyrighted in its entirety to OJVR publications. This article may be copied once but may not be, reproduced or re-transmitted without the express permission of the editor

OJVRTM

Online Journal of Veterinary Research©

Volume 13 (1):53-62, 2009

A study of natural co-infection caused by avian influenza (H9 subtype) and infection

bronchitis viruses in broiler chicken farms showing respiratory signs

Seifi S^1*, Asasi K², Mohammadi A³

¹Group of Veterinary Medicine, Chalous Branch, Islamic Azad University (IAU), Chalous,²Poultry Research Center and ³Depratement of Pathobiology School of Veterinary Medicine, Shiraz University, Shiraz, Iran

ABSTRACT

Seifi S, Asasi K, Mohammadi A, A study of natural co-infection caused by avian influenza (H9 subtype) and infection bronchitis viruses in broiler chicken farms showing respiratory signs, Online J Vet Res, 13(1):53-62, 2009. Although H9N2 AIV( Avian Influenza Virus) is pathotyped as low pathogenic avian influenza virus, our extensive field experiences during the last decade show serious disease and high mortality associated with this subtype in many regions of Iran. One of the possible explanations for such a high mortality and great economic losses could be mixed infection with other respiratory pathogens such as infectious bronchitis virus (IBV). This investigation was conducted to study the natural infection of H9N2 AIV and infectious bronchitis viruses, and to determine if co-infections occur in broiler chicken flocks in Fars province, Iran. The tracheal samples were taken from chickens in 30 closely monitored broiler flocks suffering from respiratory disease with a mortality rate above the normal range of 5%. RT-PCR was performed in order to detect the M protein and the H9 gene of avian influenza A. The multiplex nested RT-PCR was also performed to detect Massachusetts, 793B (4/91) and D274 serotypes of IBV in the samples. In this study, AIV and IBV were detected in 16 (53/3%) and 12 (40%) out of 30 flocks, respectively. The tracheal samples of 11 out of 12 flocks were positive for 4/91 strain of IBV and one for Massachusetts serotype. A mixed infection of AIV (H9 subtype) and IBV (4/91 serotype) was observed in four flocks with severe lesions and 20-30% mortality. The results of this study indicate the high occurrence of natural co-infection of AIV and IBV in Iranian broiler chicken farms showing respiratory signs and they show that mortality rate in co-infected flocks were significantly (p<0.05).higher than other flocks sampled.

Key words: Avian Influenza, Infectious Bronchitis, Co- infection

MAIN

FULL-TEXT(SUBSCRIPTION)