title: [Adamantane resistance among influenza A (H3N2) viruses isolated from the mainland of China].
abstract: BACKGROUND
  To study the incidence of adamantane resistance among influenza A (H3N2) viruses isolated from the mainland of China since 1989 through our influenza surveillance system, and to provide more information for the clinical usage of adamantane drugs.
  
  
  METHODS
  Totally 584 influenza A (H3N2) virus strains were randomly selected from our surveillance network since 1989, the adamantane drug resistance related gene M2 of all 584 strains was sequenced, and the drug sensitivity of viruses was also assayed by using biological methods in cells.
  
  
  RESULTS
  No adamantane resistant strains were detected among the strains isolated from 1989 to 1999, but there was a surprisingly increased resistance rate of 56% in 2003 compared with 3.4% in 2002, and in 2005 the resistance rate increased to 77.6%.
  
  
  CONCLUSIONS
  Over 50% of virus among the strains isolated showed adamantane resistance since 2003, and the incidence rate is increasing.
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: Yu
authors.initials: Y
authors.lastname: Lan
authors.forename: Zi
authors.initials: Z
authors.lastname: Li
authors.forename: Li-bo
authors.initials: LB
authors.lastname: Dong
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhang
authors.forename: Le-ying
authors.initials: LY
authors.lastname: Wen
authors.forename: Yan-ming
authors.initials: YM
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Yuan-ji
authors.initials: YJ
authors.lastname: Guo
authors.forename: Yue-long
authors.initials: YL
authors.lastname: Shu
mesh_terms: D000218:Adamantane / Q000494:pharmacology*; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D002642:Chick Embryo; D002681:China; D024882:Drug Resistance, Viral; D053122:Influenza A Virus, H3N2 Subtype / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D012367:RNA, Viral / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014763:Viral Matrix Proteins / Q000235:genetics; D000086082:Viroporin Proteins
chemical_list: D000218:Adamantane; D000998:Antiviral Agents; D012367:RNA, Viral; D014763:Viral Matrix Proteins; C488937:M2 protein, Influenza A virus; D000086082:Viroporin Proteins