Table 1.

Length variation types (LVTs) in the NS1 protein of influenza A viruses (August 2009).

NS1 length aa (LVT)
Species	Subtype	202	212	215	217	219	220	223	224	225	230	232	237	Total
Avian	H1N1					6					71			77
Avian	H1N2					2					5			7
Avian	H3N2					14					49			63
Avian	H3N8				1						108			109
Avian	H4N6	1				1					101			103
Avian	H4N8										34		1	35
Avian	H5N1		2		8			72		1123	78	6		1289
Avian	H5N2				17						144			161
Avian	H5N9	2									4			6
Avian	N6N1	1			70						83			154
Avian	H6N2				42						79			121
Avian	H7N1	1					11		34		33			79
Avian	H7N2					1					156			157
Avian	H7N3				30						107		1	138
Avian	H9N2				393		3				171			567
Avian	H13N2										3		1	4
Human	H1N1	3			3	509*					720		104	1339
Human	H2N2				1		13				2		74	90
Human	H3N2					2	9				1825		167	2003
Human	H5N1			2						125	17			144
Human	H9N2				1						4			5
Swine	H1N1				5	109					53		3	170
Swine	H1N2				3	66					14			83
Swine	H2N3					2								2
Swine	H3N1					5					1			6
Swine	H3N2				6	34					48		11	99
Equine	H3N8				2	40					88			110
	Total	8	2	2	582	791	36	72	34	1248	3998	6	362	7141

^*Swine origin pandemic H1N1