The Binding Activity of SARS-CoV-2-S Antibody, Biotin conjugated with SARS-CoV-2-S1-RBD. Activity: Measured by its binding ability in a functional ELISA. Immobilized SARS-CoV-2-S1-RBD (CSB-MP3324GMY1) at 2 μg/ml can bind SARS-CoV-2-S Antibody, Biotin conjugated, the EC50 is 118.7 ng/ml.