Table 4. The positively selected sites from selection pressure analysis of the NA gene of Thai seasonal influenza isolates.

Types/Subtypes	Global ω	No. of positively selected sites (codon position)
	by SLAC	SLAC	FEL	MEME
A(H1N1)seasonal	0.26	3 (77, 222, 452)	5 (77, 222, 249, 344, 452)	7 (7, 77, 222, 249, 266, 344, 452)
A(H1N1)pdm09	0.31	1 (463)	7 (13, 34, 48, 188, 270, 451, 463)	6 (13, 34, 48, 188, 366, 463)
A(H3N2)	0.24	4 (93, 215, 401, 468)	9 (4, 43, 93, 141, 150, 215, 401, 464, 468)	12 (4, 43, 93, 141, 181, 215, 267, 271, 401, 402, 464, 468)
B	0.30	3 (73, 395, 404)	9 (68, 73, 106, 220, 248, 358, 395, 404, 465)	13 (15, 27, 41, 51, 73, 106, 107, 219, 220, 358, 395, 404, 465)

Global ω denotes the ratio of nonsynonymous substitutions (dN) to synonymous substitutions (dS).

SLAC, single-likelihood ancestor counting; FEL, fixed effects likelihood; MEME, mixed effects model of evolution.