Phylogenetic characterization of the partial hemagglutinin protein genes of three avian influenza viruses (H9N2) isolated in Ahvaz broiler flocks during 2011-2013

Since 1998, Iranian poultry industry has been affected by avian influenza (AI) virus,subtype H9N2. The association of high mortality with these outbreaks in the field raised the specter of a possible new genetic modified AI virus. In this study, three AI viruses (H9N2) isolated from the broiler flocks with high mortality rates were characterized. The 488bp PCR products containing the midle site of hemagglutinin (HA) protein were generated and sequenced to determine molecular characterization of the isolates. Sequence analysis of main region of HAl gene of three isolates showed that isolates were identical at the nucleotide as well as amino acid levels. Phylogenetic analysis of 488 bp nucleotide region of the PCR products revealed that Iranian AI viruses had very close relationship to each other indicating these came from the common source. Moreover, the maximum amino acid sequence similarity of these viruses was observed with AI viruses from India (99 & 97%), Tunisia (99%), respectively. Overall, the results indicate that the current status of Iranian AI viruses resembles to other Eurasian H9N2 viruses and in spite of different nucleotide sequences among the viruses there is no evidence for existence of new AI pathotype.