Saturday, October 24, 2009

Oseltamivir-Resistant Influenza A Pandemic (H1N1) 2009 Virus, Hong Kong, China

[Comment: We had a case of a 16 year old out of China this past August, with Tamiflu Resistance. This is an ahead of print citation. I won't post the whole document, you can read it by clicking on the title. I've bolded the most important information]

DOI: 10.3201/eid1512.091057
Suggested citation for this article: Chen H, Cheung CL, Tai H, Zhao P, Chan JFW, Cheng VCC, et al. Oseltamivir-resistant influenza A pandemic (H1N1) 2009 virus, Hong Kong, China. Emerg Infect Dis. 2009 Dec; [Epub ahead of print]

Honglin Chen, Chung Lam Cheung, Hung Tai, Pengxi Zhao, Jasper F.W. Chan, Vincent C.C. Cheng, Kwok-Hung Chan, and Kwok-Yung Yuen
Author affiliation: The University of Hong Kong, Hong Kong Special Administrative Region, People’s Republic of China

Resistance to oseltamivir was observed in influenza A pandemic (H1N1) 2009 virus isolated from an untreated person in Hong Kong, China. Investigations showed a resistant virus with the neuraminidase (NA) 274Y genotype in quasi-species from a nasopharyngeal aspirate. Monitoring for the naturally occurring NA 274Y mutation in this virus is necessary


The patient in this study was not treated with oseltamivir. Therefore it is unlikely that the 274Y mutation was drug-induced.

Detection of mixed populations of 274Y and 274H in the NPA specimen before antiviral treatment suggests that the mutation occurs naturally, either before or during infection.

Although no experimental data exist that show the growth properties of this resistant variant, examination of the quasi-species population in the cell culture–propagated virus isolate showed that the 274Y variant has become the dominant population. This finding implies that the 274Y mutation does not compromise replication of pandemic (H1N1) 2009 virus in vitro.

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