Genetic Analysis of Hemagglutinin Protein of H9N2 Isolated from Live Bird Markets in Tehran Province in 2007-2008

Background and Aims: Influenza A virus subtype H9N2 have continued to circulate in domestic poultry farms in Asia since 1998. The virus circulates in live bird markets, missing link in epidemiology of avian influenza. Regarding previous studies on H9N2 viruses of Iran and having no data on this subject in Iranian live bird markets this study was conducted to analyze genetically hemagglutinin protein of H9N1 virus. Methods: A total of 500 tracheal and cloacal swabs from clinically healthy birds of Tehran's live bird markets were collected. Diagnostic RT-PCR was done on them using specific primers for subtype H9N2. Eight positive samples were selected for inoculation into 9-11 days SPF emberyonated eggs and the virus was grown and isolated. Amplification of the HA gene was carried out by PCR using two pairs of specific primers. PCR products were separated, purified and cloned. The products were sequenced and analyzed with M13 primers. They shared high amino acid homology with genes of other H9N2 viruses isolated previously in Asia and Iran. Results: H9N2 viruses isolated from live bird markets were highly similar to viruses isolated from industrial poultry being circulated as early as 2001. Conclusion: The results suggest that a common source of H9N2 viruses is circulating in Iran.