title: Evolutionary characterization of human H1N1 influenza virus hemagglutinin genes isolated from 1947 to 2009 in China.
abstract: OBJECTIVE
  Our aim was to reveal the molecular characteristics of human H1N1 influenza virus hemagglutinin (HA) genes from 1947 to 2009 in China.
  
  
  METHODS
  129 HA gene sequences were downloaded from NCBI's GenBank and analyzed by DNASTAR software. Additionally, the three-dimensional structure of HA protein was predicted by the SWISS-MODEL service.
  
  
  RESULTS
  First, 2009 Chinese HA genes were 99% identical to those of Mexican and American ones; their key sites remained highly conserved. Second, 50 Chinese strains from 1947 to 2009 clustered by the year of isolation, and 2009 strains had only 70% identity to 1947-2008 ones. Third, over the past 60 years, 3 receptor-binding (RB) sites and 2 of the 8 glycosylation sites (amino acids 279 and 290) underwent considerable changes while the cleavage sites remained stable. Fourth, the human HA sequences differed completely from swine and avian isolates. Finally, the mutation of cleavage sites can change the three-dimensional structures, but single mutations cannot.
  
  
  CONCLUSIONS
  Thus, in the past 60 years, Chinese H1N1 influenza HA genes kept stable with high affinity and low pathogenicity to human except changes in 2 glycosylation and 3 RB sites which were associated with the pandemic strength, range and host specificity of viruses.
authors.affiliation: Department of Infectious Diseases, Hangzhou Center for Disease Control and Prevention, Hangzhou, China.
authors.forename: She-Lan
authors.initials: SL
authors.lastname: Liu
authors.forename: Zhiruo
authors.initials: Z
authors.lastname: Zhang
authors.forename: Chengmin
authors.initials: C
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Dong
authors.forename: Hao
authors.initials: H
authors.lastname: Pan
authors.forename: Zhou
authors.initials: Z
authors.lastname: Sun
authors.forename: Xun-hui
authors.initials: XH
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Ruan
authors.forename: Li
authors.initials: L
authors.lastname: Xie
authors.forename: Jing
authors.initials: J
authors.lastname: Deng
authors.forename: Hong-Xuan
authors.initials: HX
authors.lastname: He
mesh_terms: D000595:Amino Acid Sequence; D002681:China; D016000:Cluster Analysis; D019143:Evolution, Molecular; D014644:Genetic Variation; D005838:Genotype; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D007251:Influenza, Human / Q000821:virology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010802:Phylogeny; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus