Detection of H9N2 avian influenza virus in various organs of experimentally infected chickens

H9N2 Avian influenza virus (AVI) infection is a major cause of economic losses in poultry industry. Therefore further study to explain the virus pathogenesis is necessary. In this study tissue tropism and dissemination of A/chicken/Iran/11T/99(H9N2) virus in various organs of specific pathogen free (SPF) chickens were investigated. Fifty 2-week-old chickens hatched from SPF eggs were divided randomly into two groups. Forty chicks in the experimental and ten chicks in the control group. Experimental chicks were inoculated intranasally-intraorally with the virus. Samples of lung, trachea, pancreas, thymus, spleen, brain, bursa of fabricius, proventriclus, cloaca and kidney were aseptically collected at 1, 3, 5, 7, 9 and 10 day post inoculation (DPI). A reverse transcriptase polymerase chain Reaction (RT-PCR) test was performed for virus detection. Viral RNA was detected in the respiratory system on days 3, 5 and 7 PI. The virus was also found in the kidney on days 3,5,7,9 PI and in the pancreas on days 3 and 5 PI. Viral RNA was observed only on day 5 PI in cloaca. The virus was not detected in the blood, brain and immune system. The virus was not found from any organs on day 10 PI. These results suggest that H9N2 AIV has tropism for respiratory, digestive and urinary system following intranasal/intraoral inoculation.   Key words: Avian influenza, H9N2, SPF, RT-PCR.