phylogenetic analysis of pb2 gene of h9n2 subtype of avian influenza viruses isolated from commercial chickens in tehran province of iran during 1998-2001

the pb2 protein of influenza a viruses has been shown as host range determinant. in this study pb2gene of five h9n2 isolates from tehran province during the period of 1998-2001 were partially amplifiedand sequenced to do phylogenetic study. iranian isolates could be classified in eurasian lineage according totheir pb2 gene sequences. the pb2 genes of these isolates are different from those of middle-east countriessuch as the uae, pakistan and saudi arabia, as well as india, and it is probable that their ancestors haveundergone reassortment with other subtypes. the nucleotide sequences of their pb2 are highly similar toeach other with 97.5-99.6% homology percentage showing the least mutations in their genes during theperiod of 1998 to 2001. the pb2 of the iranian isolates contain glutamic acid-(e) in position 627, asparticacid-(d) in 701 and serine-(s) in 714 as other avian isolates.