Table 1. Amino acids in hemagglutinins from 2,562 highly pathogenic influenza A(H5N1) viruses isolated during 1996−2015 (excluding clade 2.3.4.4 viruses).

Position and amino acid	No. occurrences
18K	119
49N	301
57K	481
76K	16
76R	0
86R	5
98T	32
99L	57
118T	1
119L	0
123R	40
127P	329
128N	276
131T	49
133L	1,029
137A	545
144A	4
145S	1,873
160A	1,467
166I	160
173R	67
187N	117
193N	4
196K	183
199D	0
202V	75
222Q	2
227R	23
244H	316
267T	1,805
273M	10
277H	1
494K	0
500I	0