An SPR Biacore biosensor S200 (Cytiva, Sweden) was used to measure the kinetics and affinity of lectins' interactions with SARS-CoV spike recombinant S1.The experiments were conducted at 25°C in 1x PBS running and sample buffer with 0.05% Tween 20. The CM5 sensor chip (Cytiva) was derivatized using an EDC/NHS mediated standard amine coupling reaction . Spike S1 was diluted in 10mM Sodium Acetate (pH 4.0 to 5.5 established in preconcentration tests) to 25 and 50 μg/m and two S1 surfaces were covalently bound to the sensor matrix at 2970RU and 4200RU, respectively, which is equivalent to a surface density of ~40 and 50RU/kDa respectively . Flow cells were then blocked with 1 M ethanolamine. Soluble ACE2 8.23-2000nM was used as a positive control to confirm the functionality of coupled SARS-CoV S1 subunit. Lectin proteins CV-N, CV-N [P51G], and GRFT were injected over the immobilized proteins at concentrations spanning 8.23 to 2000 nM of a 3-fold dilution series, in duplicate. Multiple buffer injections were included to correct the signal noise. The surfaces were regenerated with two 20s pulses of 10 mM glycine, pH 2.5. The sensorgrams generated from the direct binding assays were processed by double referencing using Scrubber 2.0c software. Exported data were fit to a simple 1:1 and alternative kinetic models were fit using CLAMP® (BioLogic Software) which allowed defining additional kinetic parameters. Sensorgrams demonstrating the binding of Spike subunit S1 to CV-N, [P51G]-CV-N, GRFT, and the sACE2 control are given in Supplemental Figure .