[Adamantane resistance among influenza A (H3N2) viruses isolated from the mainland of China].
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.
Lan
Yu
Y
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.
Li
Zi
Z
Dong
Li-bo
LB
Zhang
Ye
Y
Wen
Le-ying
LY
Zhang
Yan-ming
YM
Wang
Min
M
Guo
Yuan-ji
YJ
Shu
Yue-long
YL
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
D000218:Adamantane; D000998:Antiviral Agents; D012367:RNA, Viral; D014763:Viral Matrix Proteins; C488937:M2 protein, Influenza A virus; D000086082:Viroporin Proteins