TABLE 1.

Comparison of the TY165, LS1349, and QT517 PA protein sequences with those of the VD5 and VD18 viruses and with the consensus sequence of avian H5N1 PA proteins^a

Amino acid position	Amino acid
	LS1349	TY165	QT517	VD5	VD18	Consensus amino acid of avian H5N1 influenza viruses
20	T	T	A	A	A	A
27	S	S	D	D	D	D
44	V	V	I	V	V	V
63	A	A	V	V	V	V
85b	T	T	A	T	T	T
142	R	R	K	K	K	K
185	R	K	R	R	R	R
231	A	A	T	A	A	A
241b	C	C	Y	C	C	C
263	T	T	K	T	T	T
272	E	E	D	D	D	D
305	Y	Y	F	Y	Y	Y
352	D	D	E	E	E	E
372	D	E	E	E	E	E
379	I	V	V	V	V	V
401	R	R	K	R	R	R
538	V	E	E	E	E	E
573	I	I	V	I	I	I
614	T	T	N	N	N	N
631	S	S	G	G	G	G

^aShown are positions at which the TY165, LS1349, and/or QT517 PA proteins differ from the VD5 and VD18 PA proteins, and at which avian H5N1 viruses encode a highly conserved amino acid (shared by > 85% of isolates). Strain-specific amino acid differences are underlined.

^bNot tested in this study because our unpublished data suggest that the PA gene of an H5N1 virus carrying these two residues does not confer attenuating properties in mammalian cells.