Volume 15, Number 6—June 2009
Dispatch
Oseltamivir- and Amantadine-Resistant Influenza Viruses A (H1N1)
Peter K.C. Cheng, Tommy W.C. Leung, Eric C.M. Ho, Peter C.K. Leung, Anita Y.Y. Ng, Mary Y.Y. Lai, and Wilina W.L. Lim
Table
Phylogenetic analysis of HA, NA, and M2 genes of influenza viruses A (H1N1) with different drug-resistance characteristics isolated in Hong Kong, January–June 2008*
| Characteristics | No. isolates | HA clade | NA clade | M2 clade | Mutation |
|---|---|---|---|---|---|
| Oseltamivir resistant (n = 84) | |||||
| Amantadine susceptible | 81 | 2B† | 2B | 2B | H274Y in NA |
| Amantadine resistant | 1 | 2C† | 2B | 2C | H274Y in NA, S31N in M2 |
| 2 |
2C |
2C |
2C |
H274Y in NA, S31N in M2 |
|
| Oseltamivir susceptible (n = 37) | |||||
| Amantadine susceptible | 20 | 2B | 2B | 2B | None |
| Amantadine resistant | 14 | 2C | 2C | 2C | S31N in M2 |
| 3 | 2B | 2B | 2C | S31N in M2 |
*HA, hemagglutinin; NA, neuraminidase; M2, matrix.
†Clade 2B or clade 2C indicates the gene specified has a nucleotide homology >99% to that of A/Brisbane/59/2007 or A/Hong Kong/2652/2006 virus, respectively.
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