Fig. 3From: Identifying novel amino acid substitutions of hemagglutinin involved in virulence enhancement in H7N9 virus strainsInteraction assessment between HA7 protein and its receptors. (a) Expression levels of the HA7 protein in 293 T cells, detected by Western blot; (b) Quantitative detection of HA binding to 3′SL- (b-1) or 6′SL-labeled receptors (b-2) by measuring KD values. (c) Quantification of NA activity was determined by measuring optical density generated in the chromogenic reactionBack to article page