Binding properties of GC-derived mAbs.
(A) Clonality, VH and VK mutations, binding to S RBDs of CoV-1, WIV1, SHC014, CoV-2, PaGX, AL-103, Rs4081, Rf1/2004, and BM48-31, neutralizing activity against CoV-1, WIV1, SHC014, CoV-2, and PaGX pseudoviruses of mAbs derived from CoV-1 and CoV-2 RBD cross-reactive GC B cells of mice immunized with GM9 (GM9-1 and GM9-2) or GM14 (GM14-1 and GM14-2). (B) Correlation between mAb binding to CoV-2 RBD and other sarbecovirus RBDs. Binding of mAbs with individual RBDs was measured by bead-based flow-cytometric assays. The binding signals to respective RBDs (gMFI) are plotted in the graph. Spearman’s rank correlation coefficients and P values are shown. (C) Binding affinity of human Fab fragments with RBD proteins determined by biolayer interferometry. The equilibrium dissociation constants (KD[M]) and IC50s (μg/ml) of individual clones are shown. (D) Neutralizing activity (IC50 [μg/ml]) of representative cross-reactive mAbs and mouse IgG2c recombinant antibodies carrying the variable regions of previously isolated S304 (class 3) and CR3022 (class 4) human anti-RBD antibodies. Results are representative of at least two independent experiments (A–D). Ab, antibody.