Table 1.

Molecular analysis of A/Chicken/Guangdong/J1/2017(H7N9) and A/Chicken/Guangdong/J2/2017(H7N9).

Protein	Position	Mutation	Avian Strains		Human Strains			Biological feature altered by mutations
			CK/J1	CK/J2	GD/17SF006	QY/GIRD1	TW/1
NS1	42	P-S	S	S	S	S	S	P42S increases virulence in mice29
	92	D-E	D	D	D	D	D	Altered virulence in mice30
	205	N-S	S	S	S	S	S	Altered antiviral response in host31
	210	G-R	G	G	G	G	G	Altered antiviral response in host13
M2	31	S-N	N	N	N	N	N	S31N is known to confer resistance to amantadine and rimantadine32
NA	119	E-V	E	E	E	E	E	Oseltamivir resistance (N2 numbering)33
	222	I-L	I	I	I	I	I	Oseltamivir resistance (N2 numbering)33
	292	R-K	R	R	K	K	K	R292K is known to confer resistance to oseltamivir and zanamivir (N2 numbering)34
HA	CS	Basic aa insertion	PEVPKGKRTARGL	PEVPKGKRTARGL	PEVPKRKRTARGL	PEVPKRKRTARGL	PEVPKRKRTARGL
	138	S-A	A	A	A	A	A	S138A increases virus binding to α-2,6-linked sialic acid receptor (human receptor) (H3 numbering)20
	160	T-A	A	A	A	A	A	T160A increases binding to α-2,6-linked sialic acid receptor (human receptor) (H3 numbering)21
	186	G-V	V	V	V	V	V	G186V increases binding to α-2,6-linked sialic acid receptor (human receptor) (H3 numbering)22
	226	Q-L	Q	Q	Q	Q	Q	Q226L increases binding to α-2,6-linked sialic acid receptor (H3 numbering)25
	228	G-S	G	G	G	G	G	Increased binding to human-type influenza receptor (H3 numbering)35
PA	100	V-A	A	A	V	V	A	Species-associated signature positions36
	336	L-M	L	L	L	L	L	Increased polymerase activity in mice37
	356	K-R	K	R	R	R	R	Species-associated signature positions38
	409	S-N	N	N	N	N	N	Species-associated signature positions36
PB1	368	I-V	V	V	V	V	V	Increased transmission in ferrets18
PB1-F2	66	N-S	N	N	N	N	N	Induction of apoptosis39
PB2	627	E-K	E	E	K	K	K
	701	D-N	D	D	D	D	D	D701N increases adaptation to mammals18
	702	K-R	K	K	K	K	K	Species-associated signature positions40

Abbreviation: CK/J1, CK/J2, GD/17SF006, QY/GIRD1, TW/1 represent for IAV(H7N9) strains A/Chicken/Guangdong/J1/2017(H7N9), A/Chicken/Guangdong/J2/2017(H7N9), A/Guangdong/17SF006/2017(H7N9), A/Guangdong/GIRD1/2017(H7N9) and A/Taiwan/01/2017(H7N9) respectively. aa short for amino acids; HA short for hemagglutinin; H3 short for hemagglutinin subtype 3; M2 short for matrix 2 protein; NA short for neuraminidase; N2 short for neuraminidase subtype 2; NS short for non-structural protein; PA short for polymerase acidic protein; PB short for polymerase basic protein; PB1-F2 short for polymerase basic protein 1 alternate reading frame 2. Underlined characters indicating the different amino acids among viruses.