摘要Objective:To study hemagglutinin genetic evolution of some Middle East(ME) 2009 H1N1 pdm isolates and compared them with prototype vaccine strain [A/California/07/2009 (H1N1)], which is used as a vaccine strain in the Northern Hemisphere2010-2011.Methods: Nucleotide and/or amino acid sequences ofHA gene of fifty-fourME 2009 H1N1 pdm isolates were retrieved from GenBank Database by using BasicBLAST engine. Phylogenetic trees were established for both nucleotide and amino acid sequences using the muscle algorithm of the computer programCLC free workbench 5.6.1 JREsoftware. Amino acids alignment was also done to compare sequences HA1 domains of HA genes of ME 2009 H1N1 pdm isolates (n=39) with amino acid sequence of prototype vaccine strain A/California/07/2009 (H1N1).Results: Phylogenetic analysis of amino acids and nucleotides of theHA gene of theME 2009 H1N1 pdm isolates confirmed their evolutionary position in cluster with prototype vaccine strain (A/California/07/2009 (H1N1)) which is used as vaccine strain in the Northern Hemisphere2010-2011. Antigenically, theME 2009 H1N1pdm isolates were homogeneous and closely related to prototype vaccine. Only a few amino acid substitutions in the HA among the ME2009 H1N1 pdm isolates were analyzed.Conclusions:The current influenza vaccine is expected to provide a good protection againstME 2009 H1N1 pdm because it contains strains withH1 HA [A/California/07/2009 (H1N1)]-like strain.