ELISA: SARS-CoV-2 Spike RBD Antibody (RBD-2B9) - VHH [NBP3-12843] - A direct ELISA was performed using SARS-CoV-2 Spike recombinant proteins (RBD, S1, ECD) as coating antigen at 1 ug/mL and the anti-SARS-CoV-2 Spike RBD antibody (NBP3-12843) as the capture antibody, following by anti-cMyc-tag antibody at 1 ug/mL. Secondary: Goat anti-mouse IgG HRP conjugate at 1:5000 dilution. Detection range is from 0.3 ng/mL to 1000 ng/mL. SARS-CoV-2 Spike S1 RBD Antibody, NBP3-12843 can detect spike RBD, S1 and ECD proteins at 2 ng/mL.