Titration curves of SARS-CoV-2 Variant B.1.351 S polyclonal antibody (Cat # PAB31801) with EC50 of 0.000046. 96-well corning ELISA plate was coated with S (SARS-CoV-2 Variant B.1.351) RBD Recombinant Protein (Cat # P6703) at a concentration of 2 ug/mL.