Table 1.

Specificity of glycan recognition and efficacy of entry of wild-type and mutant HAs. H5 mutants KAN-1 from Thailand, or VN1203, and VN1194 from Vietnam were used as described in methods (18). The ability of indicated HAs to bind α2,3- and α2,6-SAs was determined by a resialylated hemagglutination assay (18) for (A) KAN-1 mutants with loss of α2,3 HA activity and relevant controls, (B) VN1203 and previously described VN1194 mutants (14), and (C) KAN-1 mutants with increased α2,6-SA binding. Viral entry of wild-type and mutant pseudotyped lentiviral vectors was measured as described (18). The degrees of entry were as follows: +, <25% of WT; ++, 25 to 50% of WT; +++, 50 to 75% of WT; ++++, >75% of WT. The H5 (KAN-1) here is identical to the GenBank sequence and differs at amino acids 186(N/K) from Yamada and colleagues (14), and the VN1194 mutants are identical to N182K and Q192R (14) according to alternative numbering conventions.

Mutation		HA titer			Entry
		CRBC	α2,3	α2,6
(A)	H5(KAN-1)	80	160	<2	++++
	E190D	<2	<2	<2	+
	G225D	40	<2	<2	++++
	E190,G225D	<2	<2	<2	+
	Q226L	40	<2	<2	+++
	Q226L,G228S	40	<2	<2	+++
	E190D,K193S	20	<2	<2	+++
	K193S,G225D	80	<2	<2	++++
	E190D,K193S,G225D	40	<2	<2	+++
	K193S,Q226L	20	<2	<2	+
	K193S,Q226L,G228S	40	<2	<2	+
	H1N1(1918/SC)	160	<2	160	++++
(B)	H5(VN1203)	20	20	<2	++++
	E190D,K193S,Q226L,G228S	40	<2	<2	+++
	A189K,K193N,Q226L,G228S	40	<2	<2	++++
	H5(VN1194)	320	320	<2	++++
	N186K	320	160	<2	++++
	Q196R	<2	<2	<2	++
(C)	S137A	80	80	80	++++
	T192I	80	160	80	++++
	S137A/T192I	40	40	80	+++