Fig. 1. Characterization of SARS-CoV-2 targeting monoclonal antibody 8-9D.

a Schematic for the neutralizing monoclonal antibody selection and evaluation. b Binding affinity of 8-9D to RBDs of WT, Omicron BA.1, Omicron BA.2 and Omicron BA.4/BA.5 by biolayer interferometry (BLI). The association and dissociation of the response curves of 8-9D are shown. The gray lines represent the fitted curves based on the experimental data. Equilibrium dissociation constants (KD) are shown above each plot. c Antibody 8-9D and hACE2 competition for binding to SARS-CoV-2 RBD determined by BLI. The traces show the binding of the hACE2 to preformed 8-9D-RBD complexes. The level of reduction in shift of 8-9D + hACE2 compared to the hACE2-only control indicates the blocking capacity of the antibody. d Epitope competition measured by BLI. The antibody 8-9D was assayed for epitope specificity with 4 structurally defined monoclonal antibodies, CB6 (class 1), C121 (class 2), COV2-2130 (class 3), and COVA1-16 (class 4). The traces represent the binding of the second antibody (2nd Ab) to preformed first antibody (1st Ab)-RBD complexes in an in-tandem binning assay. e–g Neutralization of monoclonal antibody 8-9D against pseudotyped SARS-CoV-2 wild type, previously circulating variants of concern (VOCs) (e), previously circulating variants of interest (VOIs) (f), and Omicron subvariants (g). The 50% inhibitory concentration (IC₅₀) values are shown. The dashed line indicates a 50% reduction in viral infectivity. The curves were fitted by nonlinear regression (log [inhibitor] vs. normalized response, variable slope), n = 2 biologically independent samples, and the results are representative of 2 or more independent experiments with similar results. Data are mean ± SEM of the experiments. h Neutralizing activity of 8-9D against authentic SARS-CoV-2 wild type, Beta, Delta, Omicron BA.1, and Omicron BA.2 variants as in (e–g). Source data are provided as a Source data file.