Figure 2

Construction of A7 Fab expression plasmid (A) and SDS-PAGE of the purified A7 Fab fragment (B). Cys-tag1, Cys-tag2: peptides containing cysteine residues for dye-labeling; M: Color Mixed Protein Marker (11–180 kDa; Solarbio). Original gel image is presented in Supplementary Fig. S3. The binding activity of A7 Fab to SARS-CoV-2 RBD (C), the full-length spike proteins isolated from Wuhan (WT) and the variants (D-E) were investigated by ELISA (n = 3). Data have been expressed as mean ± standard deviation.