Hong Kong H1N1 With Tamflu and Adamantane Resistance
Recombinomics Commentary 15:55
January 5, 2009

Partial MP sequences from H1N1 isolates in Hong Kong were released today at Genbank (A/Hong Kong/942/2008, A/Hong Kong/1052/2008, A/Hong Kong/1313/2008) .  The MP sequences confirm that these isolates are resistant to Tamiflu (oseltamivir) and well as the adamantanes (S31N in M2).  This result was not unexpected, because the NA sequences released earlier had H274Y and the HA sequences were clade 2C.

The HA sequences were closely related to the clade 2C prototype sequence, Hong Kong/2652, and this sub-clade has S31N.  However, since one of the NA sequences was clade 2B, and S31N has not been reported in clade 2B, it was possible than one or more MP gene segments were also from clade 2B and would be adamantine sensitive. 

However, all three partial (200 BP) were identical to each other, as well as public 2C sequences, including Hong Kong/2652.  S31N has become fixed in clade 2C, and all clade 2C isolates last season and this season in the United States had S31N.  Similarly, all clade 2B isolates in the United States this season have H274Y, so the co-circulation of clade 2B and clade 2C in Hong Kong could lead to recombination between the two sub-clades, leading to resistance to both classes of anti-virals (neuramindase inhibitors and ion channel blockers).

The sequences released from Hong Kong has confirmed that this has happened in H1N1 isolates collected between March and June of 2008.

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