Fig. 2.

Affinity/avidity of ACE2 and commercial antibodies (S1-mAb and S1-pAb) for the wild-type SARS-CoV-2 antigens and its variants, as assessed by biolayer interferometry (BLI). a) Association and dissociation curves for the interaction between SARS-CoV-2 S1 antigens (wild-type and variants) and the ACE2 receptor (or commercial antibodies). Dotted lines represent the response curves. Solid lines represent the fitted curves. b) The kinetic constants for the interactions between ACE2 (or commercial antibodies) and SARS-CoV-2 spike antigens. Binding constants were calculated from the fitted curves using a 1:1 binding model.