Figure 1.

Identification and characterization of SARS-CoV-2 S-targeting neutralizing antibodies. (A) Characteristics of antibodies binding to SARS-CoV-2 RBD, NTD or S2 by ELISA. SARS-CoV-2 RBD-, NTD- and S2-specific mAbs are colored in pink, wheat and pale cyan dots, respectively. A number of mAbs that exhibit non-specific bindings to both SARS-CoV-2 RBD and NTD are presented in wheat dots with pink outlines. (B) Proportion of SARS-CoV-2 S-specific antibodies targeting each of the indicated domains. (C) Bar graph depicting the binding of 10 representative mAbs (FC01, FC05, FC06, FC07, FC08, FC11, FC118, FC120, FC122 and FC124; positive control antibody-P17 and negative control antibody-D6 were used in the assay) to S proteins of SARS-CoV-2, SARS-CoV and MERS-CoV using ELISA assays (shown as mean ± SD of values derived from experiments conducted in triplicate). (D) Summary of the performance of the representative 10 mAbs in the indicated assays. All listed antibodies in Fig. 1D were tested for their ability to compete with hACE2 and the ‘-’ means ‘no competition’. In vitro neutralization activities of (E) 10 individual mAbs or (F) the cocktail of antibodies against SARS-CoV-2 in Vero-E6 cells. Positive (P17) [22] and negative (D6, EV71 antibody) [38] controls were used in the neutralization assay. Neutralizing activities are represented as mean ± SD. Experiments were performed in triplicates. The lower dotted lines indicate the IC₅₀ values, and the upper ones indicate the IC₉₀ values.