Evaluation of H9N2 avian influenza virus replication and tissue distribution in kazeroun poultry by Reverse Transcription – PCR

Objectives: H9N2 Avian influenza virus (AVI) infection is a major cause of economic losses in poultry industry. The purpose of this study was to Evaluate H9N2 avian influenza virus replication and tissue distribution in kazeroun poultryby Reverse Transcription – PCR.Materials & Methods: To determine replication and tissue distribution of influenza virus H9N2, 125 poultrywere randomly allotted including four experimental and one control groups (25 birds in each group). The birds, except for the control group (group 5), were challenged with a various concentration of A/Chicken/Iran/722/2000 (H9N2) virus isolate (10 8.5,10 7.5,10 4.5 and 10 0.5 EID50). On days 1, 3, 6, 9 and 12 post inoculations (PI) trachea, thymus, lung, spleen, kidney, small intestine and cecal tonsils were collected for molecular detection.Results & Conclusion: In groups 1 and 2 which received the highest viral dose (10 8.5 and10 7.5 EID50, respectively) clinical signs including depression, listlessness, sneezing and coughing, were observed in 3 and 6 days PI. In groups 1 and 2, viral RNA was detected in the trachea on days 1, 3, 6, 9 and 12 PI. The virus was also found in the lungs on 1, 3, 6, 9 and 12 days PI and in the pancreas on days1, 3 and 6 PI only in groups 1 and 2. The virus was also found in the kidney 6 day PI and in the thymus on days 1 and 12. Viral RNA not observed in 12 day PI in cecal tonsils. Small intestine were positive for virus RNA in days 1, 3 and 6 PI. In all days of sampling, virus RNA were detected in spleen specimens in group 1 and 2. These results indicate that H9N2 AIV could be detected in the respiratory and urinary systems and the spleen following intranasal/oral inoculation and in other organs depend upon viral dose and days passed after virus inoculation. Hence, more replication and tissue distribution of AI virus occur in high concentration of virus in time of inoculation.

کلیدواژه ها:

RT– PCR ، tissue distribution ، H9N2 ، kazeroun poultry