title: Genetic variation in the hemagglutinin of A(H1N1) 09pdm and A(H3N2) influenza viruses in the Beijing area from 2009 to 2014.
abstract: BACKGROUND
  A(H1N1) 09pdm and A(H3N2) influenza viruses are the main cause of occasional influenza pandemics and seasonal influenza epidemics around the world. Unfortunately, the understanding of long-term genetic variation in these viruses remains limited.
  
  
  METHODS
  In this study, hemagglutinin genes from 90 A(H1N1) 09pdm and 48 A(H3N2) influenza viruses in the Beijing area from 2009 to 2014 were sequenced and analyzed.
  
  
  RESULTS
  The hemagglutinin genes in A(H1N1) 09pdm and A(H3N2) shared nucleotide similarity that ranged from 93.06% - 99.88% and 98.68% - 99.29%, respectively, compared with current vaccine strains. 10 and 7 amino acid mutations in antigenic sites were identified in these two strains, respectively. In addition, a new site 177 glycosylation, which did not exist in previous circulating strains, was identified in 3 A(H1N1) 09pdm isolates.
  
  
  CONCLUSIONS
  This study demonstrated the continued evolution of seasonal influenza viruses in the Beijing area, indicating that an update of the vaccine is needed, especially for A(H1N1) 09pdm influenza virus.
authors.forename: Yang
authors.initials: Y
authors.lastname: Pan
authors.forename: Weixian
authors.initials: W
authors.lastname: Shi
authors.forename: Peng
authors.initials: P
authors.lastname: Yang
authors.forename: Shuangsheng
authors.initials: S
authors.lastname: Wu
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Peng
authors.forename: Shujuan
authors.initials: S
authors.lastname: Cui
authors.forename: Daitao
authors.initials: D
authors.lastname: Zhang
authors.forename: Guilan
authors.initials: G
authors.lastname: Lu
authors.forename: Jiachen
authors.initials: J
authors.lastname: Zhao
authors.forename: Yimeng
authors.initials: Y
authors.lastname: Liu
authors.forename: Quanyi
authors.initials: Q
authors.lastname: Wang
mesh_terms: D002681:China; D019295:Computational Biology; D058872:Epidemics; D000939:Epitopes / Q000737:chemistry; D014644:Genetic Variation; D006031:Glycosylation; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D053122:Influenza A Virus, H3N2 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000821:virology; D009711:Nucleotides / Q000235:genetics; D016366:Open Reading Frames; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics
chemical_list: D000939:Epitopes; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D009711:Nucleotides; D012367:RNA, Viral