Characterization of neuraminidase gene of H9N2 influenza virus isolated from recent outbreaks in Iran

Introduction: Influenza viruses cause a variety of infections from high to low pathogenicity in hosts. Influenza virus Ais divided into subtypes based on two surface glycoproteins: the hemagglutinin (H) and the neuraminidase (N). Avian flu viruses do not normally infect humans, although, some sporadic human infections have been reported. The aim of this study was to identify and sequence the neuraminidase gene of Avian Influenza (AI) H9N2 virus isolated from recent outbreaks in Iran and comparative analyzing it with strains from other countries. Materials and Methods: Influenza viruses were passaged in embryonated eggs, and RNA extracted by RNX. TM kit. Using RT- PCR technique, cDNA preparation and amplification of N gene were done. The product was then assessed by electrophoresis and observed with UV, purified and sequenced. Results: Neuraminidase gene nucleotide sequence from six isolates from different parts of Iran were identified and recorded at the GenBank. Comparative analysis with reference strains carried out for these sequences. No mutation had been observed in cytoplasmic domain, however, four mutations had been occurred at transmembrane domain, which two of them were silent and two were actually substitution of hydrophobic amino acids with similar ones.  Conclusion: Nucleotide and amino acid analysis for the neuraminidase gene of H9N2 influenza virus of isolates obtained from different parts of Iran revealed similarities to other strains described from neighboring countries, such as Pakistan and Saudi Arabia. It seems like that they have common source with the same lineages.