Table 1. Amino acid substitutions identified after mouse adaptation of pandemic H1N1 2009 and oseltamivir-resistant variants.

Virus strain	Amino acid residue at position no.
	PB2		PB1		PA	HAa				NP	NAb
	158	714	105	721	97	119	153	183	222	101	274
CA/04/09	E	S	N	R	T	K	K	S	D	D	H
maCA04_A	E	S	N	R	T	K	K	P	G	Gc	H
maCA04_B	E	S	N	R	I	K	K	P	G	G	H
maCA04_C	E	S	T	K	T	E	K	P	G	G	H
maCA04_D	E	S	N	R	T	K	K	P	D	G	H
CA/04/09H274Y	E	S	N	R	T	K	K	S	D	D	Y
maCA04H274Y_A	G	S	N	R	T	K	E	P	G	G	Y
maCA04H274Y_B	E	R	N	R	T	K	E	P	G	G	Y
maCA04H274Y_C	E	S	N	R	T	K	E	P	G	G	Y
maCA04H274Y_D	G	S	N	R	T	K	E	P	G	G	Y

^a The number of the amino acid residue by H1 numbering. ^bThe number of the amino acid residue by N2 numbering. ^cThe boldface represents substitution of parental amino acid.