Fig. 4

Epitope mapping of B-S2-mAb-2 with a phage-displayed peptide library. A The recovery ratios are shown for three rounds of biopanning. The input phage indicates the reacted titer of peptide-fused phages. The recovery phage indicates the eluted titer of peptide-fused phages interacting with B-S2-mAb-2. B Immunosorbent assay was performed to evaluate the binding of phage clones with B-S2-mAb-2. B-S2-mAb-2 (1 µg/ml) was coated on the ELISA plate. Normal mouse IgG (NMIgG) was used as a negative control. C The phage clones were analyzed. Red color indicates consensus amino acids. Tryptophan (W; purple) and phenylalanine (F) amino acids are structurally related aromatic amino acids. Illustration shows the domains of the S2 subunit (FP, fusion peptide; HR1, heptad repeats 1; HR2, heptad repeats; TM, transmembrane) and the occurrence of mutations in SARS-CoV-2 variants (Wuhan, Alpha, Beta, Gamma, Delta, Omicron BA.1, Omicron BA.2, Omicron BA.4/BA.5). Empty box indicates no mutation compared to the original Wuhan strain