Objectives: Avian adenoviruses (AAV) are a very diverse group of pathogens causing a variety of asymptomatic and clinical presentations in poultry flocks. AAV have been associated with inclusion body hepatitis (IBH) and hydropericardium syndrome (HPS), respiratory disease, necrotizing pancreatitis, gizzard erosions and immunosuppression. Affected flocks may exhibit high mortality rates, liver damage, IBH/HPS and secondary infections due to immunosuppression. IBH/HPS has been reported as an economically important, emerging disease of broiler chickens in several countries. This preliminary study was conducted to molecularly detect avian adenoviruses in broiler flocks showing IBH, liver lesions and respiratory syndrome in Northeast Iran. Materials & Methods: In total, 60 tissue samples were collected as follows: 20 samples from flocks suspected to IBH and liver lesions, 20 samples from flocks showing respiratory syndrome and 20 samples from clinically healthy flocks. DNA was extracted from liver, lung and hydropericardium fluid. Extracted DNA was subjected to PCR assay. PCR products were sequenced to confirm the identity of avian adenoviruse. The nucleotide sequence data were analyzed using programs and services provided by NCBI. Results & Conclusion: Five samples out of 20 samples collected from flocks with IBH (5 samples) or liver lesions (15 samples) and one sample out of 20 samples from flocks showing respiratory syndrome were positive. All samples collected from suspected IBH cases were positive, but samples from liver lesions were negative. None of the 20 samples from clinically healthy samples were positive. Based on sequence data adenoviruses belonged to group of Avian adenoviruses. This preliminary investigation do only confirms the presence of avian adenoviruses in broiler flocks in Iran. To show the prevalence and the significance of avian adenoviruses in clinical and subclinical syndromes, more works are needed. To our knowledge, this study might be the first report of Fowl Adenovirus infection in Iranian broiler flocks.

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