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Volume 15, Number 12—December 2009

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

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

Main Article


Quasi-species of 274H and 274 Y pandemic (H1N1) 2009 virus from NPA samples and subsequent virus isolate A/Hong Kong/2369/2009 from MDCK cells conferring resistance to oseltamivir, Hong Kong, China*

Sample 274H, no. samples positive/no. tested (%) 274Y, no. samples positive/no. tested (%) IC50 for oseltamivir, nM IC50 for zanamivir, nM
NPA 45/95 (47.37) 50/95 (52.63) ND ND
MDCK cell culture 2/96 (2.08) 94/96 (97.92) 197.5 0.8

*50% inhibitory concentrations (IC50s) for oseltamivir and zanamivir were determined by using NA-Star influenza neuraminidase (NA) inhibitor resistance detection kits (Applied Biosystems, Foster City, CA, USA) according to the manufacturer’s instructions. Ratios of 274H and 274Y were evaluated by cloning neuraminidase (NA) gene PCR products from nasopharyngeal aspirate (NPA) samples or MDCK cell–cultured virus into the TA vector (Invitrogen, Carlsbad, CA, USA) and sequencing clones containing the NA gene. ND, not done.

Main Article

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