Genetic analysis of polymerase complex (PA, PB1 and PB2) genes of H9N2 avian influenza viruses from Iran (1999 to 2009)

ABSTRACT

<p><b>OBJECTIVE</b>To determine the molecular characterization of Polymerase complex (PA, PB1 and PB2) genes of H9N2 avian influenza viruses and the genetic relationship of Iranian H9N2 viruses and other Asian viruses.</p><p><b>METHODS</b>The Polymerase complex (PA, PB1 and PB2) genes from seven isolates of H9N2 viruses isolated from commercial chickens in Iran during 2008-2009 were amplified (by RT-PCR method) and sequenced. Nucleotide sequences (Open Reading Frame orf) of the PA, PB1 and PB2 genes were used for phylogenetic tree construction.</p><p><b>RESULTS</b>Most PB2 and PA genes of the H9N2 viruses isolated in 2008-2009 belonged to the unknown avian sublineage which grouped with the 2004 Pakistani H7N3 viruses. The PB1 genes of Iranian viruses indicated greater genetic diversity and shared a high level of similarity to PB1 genes from either H5 or H7 subtypes with compared to established H9N2 Eurasian sublineages.</p><p><b>CONCLUSIONS</b>Our findings demonstrated that the H9N2 viruses in Iran exhibit striking reassortment which has led to the generation of new genotypes.</p>