. 2014 Dec 10;89(4):2442–2447. doi: 10.1128/JVI.02590-14

TABLE 2.

Selection pressures of H2N2 segments compared to their respective avian or H1N1 precursors

Origin and gene	Lineage	Global d_N/d_S			Branch model d_N/d_S			Sites under positive selection^a
		Mean	95% CI^d		Branch model d_N/d_S
		Mean	Lower	Upper	External	Internal	Internal/external ratio
Avian
HA	Human H2N2	0.448	0.402	0.497	0.287	0.272	0.948	5 (S72R/I; N181I; N192D/E/K; E211K/D; K217E^b)
	Avian H2N2	0.120	0.110	0.129	0.114	0.062	0.538	5 (S72R/I; N181I; N192D/E/K; E211K/D; K217E^b)
NA	Human H2N2	0.347	0.295	0.405	0.324	0.330	1.020
	Avian H2N2	0.170	0.158	0.182	0.473	0.210	0.444
PB1	Human H2N2	0.130	0.106	0.158	0.068	0.054	0.794
	Avian H2N2	0.031	0.028	0.035	0.111	0.080	0.723
Human
PB2	H2N2	0.116	0.094	0.142	0.067	0.045	0.671
	H1N1	0.072	0.061	0.083	0.079	0.052	0.655
PA	H2N2	0.147	0.119	0.179	0.112	0.098	0.871
	H1N1	0.085	0.074	0.097	0.076	0.066	0.880
NP	H2N2	0.221	0.181	0.267	0.133	0.123	0.924
	H1N1	0.165	0.132	0.204	0.166	0.104	0.627
M1	H2N2	0.224	0.167	0.291	0.161	0.083	0.513
	H1N1	0.128	0.105	0.154	0.157	0.073	0.467
M2^c	H2N2	0.309	0.187	0.475	0.163	0.115	0.708
	H1N1	0.405	0.322	0.502	0.534	0.435	0.814
NS1	H2N2	0.500	0.398	0.618	0.406	0.321	0.790
	H1N1	0.287	0.251	0.326	0.281	0.239	0.852
NS2^c	H2N2	0.300	0.200	0.428	0.371	0.569	1.534
	H1N1	0.215	0.170	0.268	0.182	0.192	1.053

Only sites that were significant in both the MEME method, with a P cutoff of <0.05, and the Tdg09 method, with a false discovery rate cutoff of <0.05, are reported.

Letters refer to single-letter amino acid abbreviations.

The MP and NS comprise two open reading frames with partial overlap, giving rise to two gene products of significant length. Selection pressures reflected in the overlapping part in either gene segment cannot be attributed to one of the two open reading frames, and the reported d_N/d_S values should be interpreted with caution.

CI, confidence interval.