Table 1.

Amino acid changes in PA-X proteins from H5N1 IAV isolated in avian.

Position	Amino Acid	1996–1997	1998–2000	2001–2005	2006–2010	2011–2015	2016–2020
20	T	40.7	0	0.93	1.59	70.77	31.86
	A	59.3	100	98.75	97.97	29.09	68.13
	Other	0	0	0.31	0.42	0.13	0
85	A	40.74	0	0.61	0.62	1.85	1.44
	T	59.3	100	99.23	99.26	98.14	98.56
	Other	0	0	0.15	0.1	0	0
118	T	42.86	0	0.77	0	0	23.7
	I	57.14	100	99.22	99.68	93.84	70.19
	Other	0	0	0	0.31	6.15	6.73
127	I	25	0	0.46	0.42	0.26	0
	V	75	100	99.38	99.37	99.73	98.56
	Other	0	0	0.62	0.21	0	1.44
209	G	46.42	0	0.92	0.42	1.04	24.88
	E	53.57	100	98.92	99.48	98.29	75.11
	Other	0	0	0.15	0.1	0.66	0
212	V	39.28	0	1.4	2.6	1.44	0
	A	57.15	92	96.9	97.29	98.16	99.04
	Other	3.57	8	1.7	0.1	0.39	0.95
221	L	50	68	1.69	0.21	0.26	0.95
	R	50	32	97.69	99.58	99.6	98.08
	Other	0	0	0.62	0.21	0.13	0.95
250	R	46.43	4	6.33	0.52	1.7	1.91
	Q	46.43	96	92.73	98.84	97.37	95.21
	Other	7.14	0	0.93	0.63	0.92	2.87

Frequencies of identified mutations in H5N1 IAV PA-X proteins isolated from avian at the indicated time periods. Publicly available sequences in the Influenza Research Database (https://www.fludb.org/brc/home.spg?decorator=influenza (accessed on 23 June 2020)) were downloaded and the frequencies represented according to the year of isolation. The original amino acid present in 1996–1997 H5N1 IAV isolates is depicted first, whereas the amino acid most frequently found nowadays is depicted second. The numbers of sequences available at the Influenza Research Database are 27, 25, 644, 939, 739, and 204 sequences, for periods 1996–1997, 1998–2000, 2001–2005, 2006–-2010, 2011–2015, and 2016–2020, respectively.