Table 1.

Analysis of genetic markers associated with virulence in the viral PB2, PB1-F2, PB1, PA, NP, M1, M2, NS1, and N S2 proteins of the 173 Egyptian H9N2 viruses isolated from poultry in Egypt from 2017 to 2021.

Protein	Site	Avirulent	Virulent	Subtypes Tested	Total Egyptian H9N2 (2017–2021) = 173	References
PB2	627	E	K	H9N2	E (172), K (1)	[37,39]
	147	M	L	H9N2	I (155), N/A (18)	[37]
	250	V	G	H9N2	V (155), N/A (18)	[37]
	292	I	V	H7N9	I (101), V (57), N/A (15)	[40]
	504	I	V	H1N1	V (170), N/A (3)	[31]
	588	A	V	H5N1 H7N9	A (169), V (4)	[41,42]
	701	D	N	H1N1, H5N1	D (173)	[38,43]
	404	F	L	H9N2	F (163), N/A (10)	[44]
	591	Q	K	H7N9	Q (171), L (2)	[45]
PB1	317	M/V	I	(H5N1, H9N2, H7N2, H7N7), H5N1	M (165), I (5), N/A (3)	[34,46]
	622	D	G	H5N1	G (171), S (1), N/A (1)	[47]
PB1-F2	66	N	S	H5N1	N (120), K (33), N/A (13) 166	[48]
PA	127	I	V	H5N1	V (155), N/A (18)	[49]
	383	N	D	H5N1	D(173)	[50]
	224	S	P	H5N1	S (156), N/A (17)	[50]
	550	I	L	H1N1	L (173)	[31]
HA	Cleavage site	Monobasic	Multibasic	H5N1	KSSR*GLF (4), VSDR*GLF (1), RSSR*GLF (168)	[51]
NP	286	A	V	H7N9	A (173)	[52]
	437	T	M	H7N9	T (173)
M2	64	P	S/A/F	H5N1	S (173)	[49]
	69	L	P	H5N1	P (173)	[49]
NS1	42	A/P	S	H5N1	S (172), N/A (1)	[53]
	92	D	E	H5N1	D (170), E (3)	[46]
	103	F	L	H3N2	F (173)	[54]
	106	M	I	H3N2	M (173)	[54]
	149	V	A	H5N1	A (173)	[55]
	189	D/G	N	H5N1	D (173)	[56]
NS2	31	M	I	H5N1	M (173)	[56]
	56	H/L	Y	H5N1	H (173)	[56]

N/A: not applicable due to partial sequencing.