Table 4. Amino acid substitutions, associated with mammalian host adaptation, receptor binding and antiviral resistance, in the proteins of the four imported H7N9 viruses.

Virus	Collection date	PB2		PB1-F2	HA		NA*		M2	NS1
	(mm/dd/yy)	627	701	66	226	228	119	292	31	92
A/Anhui/1/2013	03/20/2013	K	D	N	L	G	E	R	N	D
A/Taiwan/1/2013	04/24/2013	K	D	N	P	G	E	R/K #	N	D
A/Taiwan/3/2013	12/27/2013	K	D	N	L	G	E	R	N	D
A/Taiwan/1/2014	04/21/2014	K	D	N	L	G	E	R	N	D
A/Taiwan/2/2014	04/24/2014	E	N	N	L	G	E	R	N	D
Substitutions		E627K	D701N	N66S	Q226L	G228S	E119V	R292K	S31N	D92E

^#Mixed amino acid residues were detected.