Table 1.

Effect of NA substitutions at residues 148 and 150 on NA-mediated hemagglutination of recombinant A(H3N2) viruses.

Source of NA	NA amino acid at residue		Infectivity (log10 IU/ml)	Hemagglutination titer (HAU/50 μl)				NA-mediated binding
				Turkey RBCsc		Guinea pig RBCs
	148	150		− Osed	+ Ose	− Ose	+ Ose
A/Wyoming/3/2003a	T	H	7.4 ± 0.1	<2	<2	<2	<2	No
	T	R	7.8 ± 0.1	<2	<2	<2	<2	No
	I	H	7.7 ± 0.1	16	<2	32	<2	Yes
A/New York/07/2010b	T	R	8.1 ± 0.4	<2	<2	<2	<2	No
	I	R	7.4 ± 0.4	128	<2	256	<2	Yes

Recombinant A(H3N2) viruses containing the HA from A/Alaska/140/2015 (H3N2) and NA from designated viruses were generated in the background of A/Puerto Rico/8/34 (H1N1) through reverse genetics. Boldface amino acid indicates substitution.

^aNA amino acid sequence is identical to A/Netherlands/109/2003.

^bNA amino acid sequence is identical to A/Netherlands/761/2009.

^cRBCs, red blood cells.

^dOseltamivir, 20 nM.