Experimental co–infection of infectious bronchitis and low pathogenic avian influenza viruses (H9N2) aggravates morbidity and mortality in commercial broiler chickens
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Abstract
Outbreaks of respiratory diseases in commercial broiler chicken flocks have increased recently in Pakistan which is a major threat to Pakistan’s poultry industry. The aim of this study was the development of co-infection of infectious bronchitis (IB) and low pathogenic avian influenza viruses (H9N2) in commercial broiler chickens. For this purpose, commercial broiler chickens were challenged with IB virus and low pathogenic avian influenza virus (H9N2). A total of 180 Specific Pathogen Free (SPF) chicks were procured from the hatchery. All the chicks were divided into four groups i.e. A, B, C, and D each group having three replicates of 15 chicks. On the 23rd day of bird’s age, group A and B were intranasally challenged with IBV likewise, on day 26th, group B and C were challenged with H9N2 to produce co-infection, while group D served as a negative control. In group B, the clinical signs and symptoms appeared quickly and were persistent with high severity. The gross and histopathological lesions observed in lungs, trachea, liver, and kidneys were comparatively more severe in group B than in groups A and C, similarly, geometric mean titers (GMTs) of both IBV and H9N2 in group B were significantly higher (P<0.05) than that of groups A and C. Among the groups, a statistically significant increase in FCR of co-infected birds was observed. Based on these findings, it might be concluded that co-infection of IBV and H9N2 induced severe pathological lesions with high morbidity and mortality in poultry.
Keywords: Broiler chicken; Infectious bronchitis virus; Co-infection; Low pathogenic avian influenza virus (H9N2); Pathogenesisx