Comparison of the 2009 pdm A(H1N1) influenza viruses collected in Japan before and during the peak phase of the pandemic.

Clusters and micro-clades (MC) 2 to 10 are named according to [17].
The sequences of Nagasaki/HA-58 and Hokkaido/256 that were not reported in [17] have been obtained from the Influenza Virus Resource database.
Synonymous and non-synonymous mutations in the partial sequences of HA and NA for the viruses presented in this table are summarized in Table S2.