Table 1 PB2 proposed mammalian adaptation markers among human and avian H5N1, H9N2, H7N9 and seasonal H3N2 isolates*.

PB2 genotype		All H5N1				Indonesia H5N1				H9N2				H7N9				H3N2 ^†
		Human^‡ ( n =261)		Avian^§ ( n =1,290)		Human ( n =70)		Avian ( n =48)		Human^\|\| ( n =8)		Avian^¶ ( n =620)		Human^# ( n =96)		Avian ( n =47)		1968–71 ( n =90)		1972–2014 ( n =4,872)
Proposed human adaptation marker	526R	47	194 (74%)	20	342 (27%)	47	56 (80%)	13	13 (27%)	1	7 (88%)	9	207 (33%)	4	81 (84%)	0	3 (6%)	0	90 (100%)	8	4,858 (99.7%)
	590S	8		38		0		0		5		192		1		0		0		0
	591K	3		0		2		0		0		2		5		0		0		0
	627K	114		279		1		0		0		4		61		3		66		17
	701N	14		2		0		0		1		0		8		0		0		2
	526R/627K	8		3		6		0		0		0		2		0		24		4,831
Avian genotype**		67 (26%)		948 (73%)		14 (20%)		35 (73%)		1 (12%)		413 (67%)		15 (16%)		44 (94%)		0		14 (0.3%)

^*Full-length PB2 sequences of seasonal H3N2, human and avian H5N1, H9N2 and H7N9 influenza A viruses from NCBI Influenza Virus Resource Database, and human HPAI H5N1 from Influenza Sequence Database were analysed. Right column under each Human/Avian represents total number and percentage of isolates containing adaptation marker.
^†Five human H3N2 isolates contains 526R/590S and one has 591K/701N.
^‡Two human H5N1 isolates from Indonesia contain 526R/591K; two contain 590S/627K; two are 590S/701N and one contains both 627K and 701N markers.
^§Two avian H5N1 isolates have 627K/701N and five contain 590S/627K.
^||One human H9N2 isolate has triple adaptation markers, 526R/590S/701N.
^¶Three avian H9N2 isolates contain dual 590S/591K signatures and one has 590S/627K.
^#Three human H7N9 isolates contain 526R/701N genotypes.
^**Avian genotype indicates isolates that lack any proposed human adaptation markers in the PB2.

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