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

<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>

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

Objective: 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. Methods: 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. Results: 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. Conclusions: Our findings demonstrated that the H9N2 viruses in Iran exhibit striking reassortment which has led to the generation of new genotypes.

[Sequence and phylogenetic analysis of nucleoprotein gene in Iranian H9N2 avian influenza viruses]

Survey of molecular characterization of nucleoprotein gene of H9N2 avian influenza viruses and determination of the genetic relationship of Iranian H9N2 viruses and other Asian viruses. The nucleoprotein [NP] genes from 4 isolates of H9N2 viruses isolated from commercial chickens in Iran during 2008-2009 were amplified by RT-PCR method and sequenced. Nucleotide sequences [orf] of the NP genes were used for phylogenetic tree construction. Nucleotide sequence analysis of the NP gene showed that the Iranian virus isolates did not exhibit insertions or deletions within nucleoprotein [NP] gene as compare with their prototype A/turkey/winconsin/66; however numerous point mutations were occurred in the gene length of these viruses similar to the previous Iranian strains. Nucleotide sequence analysis showed that these isolates are very closely related [96/7-99/6] and shared a homology of 91/9-92/3% and 91/5-92% with 2 human isolates A/HK/1073/99 and A/Hk/2108/2003, respectively. Phylogenetic analysis of the NP gene showed that all the NP genes of the Iranian H9N2 viruses fall into a single group within a G1-like sublineage which had contributed as donor of six internal genes to H5N1 a highly pathogenic avian influenza. The current study indicated that the NP gene of H9N2 influenza viruses circulating in Iran during the past years were well conserved. It seems that the differences between these Iranian virus isolates are the result of accumulation of point mutations among them