[Oseltamivir resistance among pandemic A(H1N1)2009 viruses between 2009 and 2011 in Guangzhou].
OBJECTIVE
To study the prevalence of oseltamivir-resistance among pandemic A (H1N1)2009 viruses isolated from patients in Guangzhou between 2009 and 2011, and to provide more information for clinical usage of oseltamivir.


METHODS
Totally 192 pandemic A (H1N1)2009 viruses isolated from patients in Guangzhou between July 2009 and April 2011 were studies. The HA and NA genes of all strains were sequenced to reveal the evolution of viruses, and the susceptibility of viruses to oseltamivir was tested in vitro.


RESULTS
One strain with a S247N mutation of the NA gene, which would make the virus resistant to oseltamivir, was found. The susceptibility (IC)50 of this viral strain to oseltamivir was 0.45 nmol/L, 2.5 times lower as compared to the wild-type strains. Phylogenetic analysis showed that this virus was not prevalent in Guangzhou from 2009-2011, and was not located in the same branch with the strains being epidemic in Australia and Singapore during the early seasons of 2011.


CONCLUSIONS
The resistance rate of pandemic A(H1N1)2009 viruses isolated from Guangzhou to oseltamivir was low, but surveillance on resistant strains needs to be strengthened to control resistant viruses imported from abroad.
State Key Laboratory of Respiratory Diseases(Guangzhou Medical University), the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China.
Wenda
W
Guan
Stephen K W
SK
Tsui
Simon M Y
SM
Lee
Zifeng
Z
Yang
Yi
Y
Luo
Xiaobo
X
Li
Shiguan
S
Wu
Yutao
Y
Wang
Hitoshi
H
Oshitani
Akira
A
Suzuki
Rongchang
R
Chen
State Key Laboratory of Respiratory Diseases(Guangzhou Medical University), the First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China. Email: nanshan@vip.163.com.
Nanshan
N
Zhong
D000293:Adolescent; D000328:Adult; D000368:Aged; D000998:Antiviral Agents / Q000494:pharmacology*; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D005814:Genes, Viral; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D007251:Influenza, Human / Q000188:drug therapy / Q000453:epidemiology* / Q000821:virology; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D009439:Neuraminidase / Q000235:genetics; D053139:Oseltamivir / Q000494:pharmacology*; D058873:Pandemics; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014764:Viral Proteins / Q000235:genetics; D055815:Young Adult
D000998:Antiviral Agents; D014764:Viral Proteins; D053139:Oseltamivir; D009439:Neuraminidase