Sequence Analysis and Phylogenetic Study of Hemagglutinin Gene of H9N2 Subtype of Avian Influenza Virus Isolated during 1998-2002 in Iran

Sequence analysis and phylogenetic study of hemagglutinin (HA) gene of H9N2 subtype of avian influenza virus isolates (outbreaks of 1998-2002) in Tehran province (Iran) were studied. Two sets of forward and reverse primers in highly conserved regions, based on sequences of HA gene in Genbank, were designed. PCR products of a 430-bp fragment of 16 isolates were sequenced and then were aligned with the reported sequences in Genbank. Nucleotide sequence comparisons of HA gene from Iranian isolates showed 97-99% identity within the group, and 98% homology with the two isolates [A/Parakeet/Narita/92A/98 (H9N2)] and [A/Parakeet/Chiba/1/97 (H9N2)] from Pakistani parakeets imported to Japan. On the basis of phylogenetic evidence, it is proposed that the emergence of H9N2 avian influenza infection in Iran originated in Pakistan, and it was due to low quarantine measures in the international boundaries. Due to the high percentage of H9N2 homology isolates of Iran with other isolates, namley A/quail/HongKong/G1, in Genbank and based on published reports for high similarity with infecting human H5N1 isolates, it seems that the potential of Iranian avian influenza isolates to infect human should be considered