Fig 1: Identification and Epitope Mapping of Neutralizing Antibodies(A) Summary of the indicated characteristics of all authentic viral neutralizing antibodies. Column 1, IC50 of authentic SARS-CoV-2 neutralization; column 2, epitope-mapping results (note that although 553-60 showed an identical pattern to 553-49 in the mutagenesis assay, it partially completed with 414-1, and therefore was classified as epitope C/A); column 3, IC50 of pseudoviral neutralizing results; column 4, cocktail IC50 of pseudoviral neutralizing results of the indicated antibodies together with 553-15 (note that 505-3 was used as representative for 515-1 and 505-5); columns 5 and 6, binding ELISA and blocking ELISA results; columns 7 and 8, FCA results of the binding and ACE2 competition to freshly expressed membrane-bound S protein (color shading in the heatmaps represents magnitude of intensities—light green, weak; darker green, strong); and columns 9 and 10, results of ELISA binding to RBD or S-ECD. Red highlights the antibodies with similar CDR3 sequences.(B) Left, neutralization results of 414-1 against authentic virus (SARS-CoV-2-SH01) using Vero-E6 (n = 2). Right, BLI examination of 414-1 and RBD binding affinity.(C) Left, positions of the 15 designed single amino acid replacements in the non-ACE2 binding surface of RBD, purple; middle-left, ACE2 binding surface, yellow; middle-right, amino acid replacements that affected epitope-B antibody 553-15 binding to RBD, green; right, amino acid replacements that affected the RBD bindings of 553-49 and 553-60, blue. Proposed epitopes A, B, and C were circled.