Positive selection on hemagglutinin and neuraminidase genes of H1N1 influenza viruses

Table 1 Positively selected sites in hemagglutinin from viruses from different clusters

Dataset	Description	Number of sequences	Length of alignment (bp)	Number of sites under positive selection		Positively selected sites¹
						HA1		HA2
				SLAC	FEL	SLAC	FEL	SLAC	FEL
1.1	Avian strains	75	1647	0	0
1.2	North American swine strains	196	1647	0	1		138
1.3	Eurasian swine strains	90	1647	0	1				399
1.4	Seasonal human strains	1404	1647	8	8	82^B,94^B, 141^B,162^BG,186^B,187^BR,222^BR	82^B,94^B,160^BG,162^BG,186^B,187^BR,222^BR	451^T	451^T
1.5	Pandemic 2009 human strains	1891	1647	7	9	186^B,197,203,205^B,222^BR,223^B,261^BT	186^B,197,203,222^BR,261^BT		411^T,451^T,460^T,530^T

¹In these columns, B indicates that the site lies in the B-cell antigenic regions [18]. G means that it is a potential glycosylation site. T indicates that the site lies in the T-cell antigenic regions [19]. R indicates that it is a receptor-binding site [11]. We use the same numbering strategy as Deem and Pan [18] and start numbering from the amino acids DTLC.

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