title: [Antigenic and genetic study of influenza virus (H1N1) circulated in China in 2004-2005].
abstract: BACKGROUND
  To analyze the genetic and antigenic characteristics of hemagglutinin (HA) gene of human influenza (H1N1) virus isolated from the mainland of China since 2004 to 2005.
  
  
  METHODS
  The single-way hemagglutination inhibition (HI) tests were used to test the antigenic characteristics, and the HA1 gene was sequenced based on the antigenic results.
  
  
  RESULTS
  The single-way HI results showed that no virus isolates had 4-folds greater HI titer compared with A/Shanghai/1/1999 (H1N1) in 2004, but there was 6.3% virus had 4-fold greater difference in 2005. The HA1 sequence data showed that the H1N1 virus had the following amino acid mutations such as 54 K > R, 90 T > K, 101 Y > H, 149 R > K, 169 V > A, 190 D > N, 212 R > K, 219 K > R, 245 W > R, 246 Y > F, 258 T > N, 318 V > A and the 54 and 190 amino acids located in antigenic group of HA1.
  
  
  CONCLUSIONS
  The H1N1 virus was changing in antigenic and genetic characteristics.
authors.affiliation: Chinese Influenza Center, Institute for Viral Disease Control and Prevention, State Key Laboratory for Infectious Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100052, China.
authors.forename: Cui-ling
authors.initials: CL
authors.lastname: Xu
authors.forename: Ni-juan
authors.initials: NJ
authors.lastname: Xiang
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhang
authors.forename: Le-ying
authors.initials: LY
authors.lastname: Wen
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhao
authors.forename: Zi
authors.initials: Z
authors.lastname: Li
authors.forename: Jun-feng
authors.initials: JF
authors.lastname: Guo
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Hong-jie
authors.initials: HJ
authors.lastname: Yu
authors.forename: Wei-zhong
authors.initials: WZ
authors.lastname: Yang
authors.forename: Yuan-ji
authors.initials: YJ
authors.lastname: Guo
authors.forename: Yue-long
authors.initials: YL
authors.lastname: Shu
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002460:Cell Line; D002681:China / Q000453:epidemiology; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000235:genetics* / Q000276:immunology*; D007251:Influenza, Human / Q000097:blood / Q000453:epidemiology / Q000821:virology*; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral