Veterinary Archives, Vol. 80 No. 2, 2010.
Original scientific paper
Natural co-infection caused by avian influenza H9 subtype and infectious bronchitis viruses in broiler chicken farms
Saeed Seifi
; School of Veterinary Medicine, Mazandaran University, Amol, Iran
Keramat Asasi
; Poultry Research Center, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
Ali Mohammadi
; Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
Abstract
Although H9N2 AIV (Avian Influenza Virus) is pathotyped as a low pathogenic avian influenza virus, our extensive field experiences over the last decade show serious disease and high mortality in broiler chicken associated with this subtype in many regions of Iran. One of the possible explanations for such 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 co-infections of H9N2 AIV and infectious bronchitis viruses in broiler chicken flocks in Fars province, Iran. Tracheal samples were taken from chickens in 30 closely monitored broiler flocks suffering from respiratory disease with mortality higher than normal range. RT-PCR was performed using primers 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 the mortality rate in co-infected flocks was significantly higher than others (P<0.05).
Keywords
avian influenza; infectious bronchitis; co-infection
Hrčak ID:
56716
URI
Publication date:
26.4.2010.
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