Indirect ELISA analysis performed by coating plate with recombinant Spike ECD protein(s) derived from different strains of SARS-CoV-2 virus (ie., Wild type; B1.617.2 delta variant) (29.71-0.46 nM). Coated protein was probed with SARS-CoV-2 (COVID-19) Spike RBD antibody [HL1003-HU] (GTX635866) (1 μg/mL). Human IgG antibody (HRP) (1:200000) was used to detect bound primary antibody.

Inhibition analysis of immobilized recombinant SARS-CoV-2 (COVID-19) Spike RBD protein, His tag (active) (GTX136090-pro) (coated at 2 μg/mL) binding to soluble recombinant Human ACE2 (ECD) protein, mouse IgG Fc tag (active) (GTX135683-pro) (1000 ng/mL). ACE2 binding was inhibited by increasing concentrations of SARS-CoV-2 (COVID-19) Spike RBD antibody [HL1003-HU] (GTX635866) (0.09-66.67 nM). Bound ACE2 was detected by Goat Anti-Mouse IgG antibody (HRP) (GTX213111-01) (1:10000).