Table 4.

Important amino acid sequence changes found between the US 2020 H7N3 LPAIVs and HPAIV used as inoculum for the animal experiments. na: not applicable.

LPAIV-1	LPAIV-2	HPAIV	Position	Amino Acid Change	Protein	References	Remarks
na	na	DRKSRHRRI	339–347	Insertion: DRKSRHRRI	Hemagglutinin		Multibasic cleavage site
R	R	K	98	R98K	Nucleoprotein	[33]	Change found in samples from bobwhite quail infected with a 2014 H5N2 HPAIV virus from the US 2014–2015 H5 outbreak. Also found in later 2015 virus isolates from turkeys in Minnesota.
na	LNCSDTIITYNNTVINNITTTI	na	56–77	Deletion: LNCSDTIITYNNTVINNITTTI	Neuraminidase	[16,17,34,35,36,37,38,39]	Associated with adaptation to gallinaceous species
G	R	G	345	G345R	Neuraminidase	[26]	Found in a 2016 H7N3 virus from Mexico, when compared to an earlier 2012 H7N3 virus.