Table 6.

Identification of amino acid substitutions in H3 antigenic sites of H3N2 viruses. Antigenic sites of H3 protein were compared to vaccine strains Brisbane/2007. Here, we are presenting changes in antigenic sites of viruses isolated following any modification in H3N2 vaccine strain (2012, 2014, 2015, 2016 and 2017). Dash (−) indicates amino acid similar to vaccine sequence while amino acids different than vaccine strain are indicated in italics. Bold amino acids denote amino acid changes found in vaccine strains recommended for subsequent season in comparison to Brisbane/2007. Similarity of antigenic sites between vaccine strain and circulating viruses is shown as percentages in the last column

H3																												Similarity to vaccine strains (%)
	A1		A2	A3						B1								B2		C1		C2		E1	D
	121		135	142		144		145		157		158		159			160	189	194	53		278		62	212		215
Brisbane/2007	N		T	R		N		N		L		K		F			K	N	L	D		N		E	T		P	A	B	C	E	D
2009	–		–	–		–		–		–		K	N	–			–	K	–	–		–		–	–	A	–	100	89.5	100	100	97
Perth/2009	N		T	R		K		N		L		N		F			K	K	L	D		N		K	T		S
2012	–		–	–		K	N	N	S	–		–		–			–	–	–	D	A	P		–	A		P	90	100	84	100	88
Victoria/2011	N		T	R		N		N		L		N		F			K	K	L	D		N		E	A		P
2014	–		–	G		–		S		L	S	–		F	Y	S	–	–	–	–		–		–	–		–	90	89.5	84	100	100
Texas/2012	N		T	R		N		N		L		N		F			K	K	L	D		K		E	A		P
2015	–		–	R	G	S		S		–		–		Y			T	–	–	–		–		–	–		–	86.3	89.5	100	100	100
Switzerland/2013	N		T	G		N		S		L		N		S			K	K	L	D		K		E	A		P
2016	N	K	–	G	R	S	K	–		–		–		F	Y		–	–	–	–	N	K	N	–	–		–	82	89.5	66.6	100	100
Hong Kong/2014	N		T	R		S		S		L		N		Y			K	K	P	D		K		E	A		P
2017	K		K	R	G	S	K	–		–		–		–			T	–	L	–		–		–	–		–	77	89.5	100	100	100