Figure. Phylogenetic analysis of the hemagglutinin gene (A), neuraminidase gene (B), and matrix gene (C) of influenza virus (H1N1). The 3 clade 2C viruses with double resistance are indicated by circles, the 3 clade 2B viruses with amantadine resistance are indicated by triangles, and A/Brisbane/59/2007 and A/Hong Kong/2652/2006 are indicated by squares. Scale bars indicate 0.5% difference in nucleotide sequence.
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