Fig. 1. Isolation of SARS-CoV-2 neutralizing antibodies from a convalescent donor.

a, Plasma neutralization against SARS-CoV-2 and from convalescent (C) and healthy (H) donors. Convalescent Donor 3, highlighted in red, was selected for B cell sorting based on high plasma neutralization against IL1/2020 and high-magnitude binding antibodies to the NTD, RBD and S trimer, as measured in a multiplex bead-based assay. Bars indicate the median value. MFI, mean fluorescence intensity. b, The percentage of isolated mAbs binding to the subdomains of S protein. c, Neutralization potency of isolated WRAIR mAbs segregated by subdomain binding specificity. Shown are the mean IC₅₀ values (µg ml⁻¹) from the SARS-CoV-2 (IL1/2020) pseudotyped assay, calculated from three independent experiments. d, Correlation between neutralization potency (IC₅₀) for NTD-directed (right, n = 14 xy pairs) and RBD-directed (left, n = 18 xy pairs) mAbs and their respective binding magnitude to the SARS-CoV-2 stabilized S trimer, obtained from a single experiment. A significant (inverse) correlation was only observed for the WRAIR RBD-directed mAbs. Spearman r values are indicated above each graph with P values (two-tailed). e,f, Neutralization curves of the most potent NTD-directed and RBD-directed neutralizing antibodies as measured in the pseudotyped (e) and authentic (f) SARS-CoV-2 assays, using strains IL1/2020 and INMI1/2020, respectively, which share an identical S sequence. Plotted are the mean ± s.e.m. from three (e) or two (f) independent experiments. The IC₅₀ value (µg ml⁻¹) for each mAb is indicated in parentheses and calculated using a five-parameter regression analysis. g, Correlation between the pSV and authentic virus assays, n = 24 xy pairs. The Spearman r value and P value (two-tailed) are indicated above the graph. h, NTD and RBD WRAIR mAb binding to cell-surface-expressed S protein using 293F cells as measured by flow cytometry. Black lines indicate the mean value and asterisks represent significance by two-tailed Mann–Whitney t-test; P = 0.0009. The dotted line indicates the positivity threshold. i,j, Assessment of NTD and RBD mAbs recruitment of Fc-mediated complement (ADCD; i) and phagocytic activities (ADCP and ADNP; j). ADCD was measured using an S-expressing 293F cell line, whereas phagocytic activities were determined using the stabilized S trimer. Black horizontal lines indicate the mean value and asterisks represent significance by two-tailed Mann–Whitney t-test; P < 0.0001. The dotted line indicates the positivity threshold. h–j, Shown are representative data (n = 2) from a single experiment. In c, d and h–j, neutralizing and non-neutralizing mAbs are in closed and open circles, respectively, while the control RBD mAb CR3022 is shown as a gray closed circle in h–j.

Source data