Spread of H1N1 Tamiflu Resistance In Sapporo Japan

Sunday, December 29, 2013
By Paul Martin

December 29, 2013

The National Institute of Infectious Diseases in Tokyo has released a group of H1N1 sequences from Sapporo, Japan which are oseltamivir (Tamiflu) resistant due to H274Y. The samples were collected between November 15 and December 9 and Japan is to be commended for the rapid release of these important sequences (A/SAPPORO/107/2013, A/SAPPORO/114/2013, A/SAPPORO/TH1/2013, A/SAPPORO/116/2013, A/SAPPORO/119/2013, A/SAPPORO/120/2013) from children and adults (4M, 21M, 39F, 3M, 10M, 5M, respectively). All six sequences are closely related to each other, signaling clonal expansion.

Similar clonal expansion of sequences containing H274Y was seen in southern United States (Louisiana and Mississippi), but those sequences (A/Louisiana/07/2013, A/Louisiana/08/2013, A/Louisiana/10/2013, A/Louisiana/13/2013, A/Mississippi/11/2013) were distinct from the sequences in Sapporo, which are related to sequences in Hong Kong (A/Hong Kong/5008/2013) and the United States (A/Utah/09/2013). In contrast the H274Y sequences in Louisiana and Mississippi are related to sequences that have been widely detected in the US.

The onward transmission of H274Y in two sub-clade which are easily distinguished from each other, but related to sequences identified over a wide geographical area, raise concerns that H274Y will continue to spread, which was seen in seasonal H1N1 in the 2008-2009 season.

More sequences from Japan and the United States would be useful.

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