Figure 2.

Screening of neutralizing antibodies

(A) The binding ability of the antibodies against Spike-expressing cells, as indicated by mean fluorescence intensity (MFI), and the inhibiting ability of ACE2 to bind to Spike-expressing cells, as indicated by ACE2-binding rate, are shown. Antibodies that have binding ability without neutralization ability are encircled by a dotted line, and antibodies that have a correlation between binding and neutralization ability are encircled by a solid line. Color indicates the individual and shape indicates the cell type from which the antibodies were derived. Spearman’s rank correlation coefficient was calculated from all samples.

(B) The percentage of antibodies having high binding ability to Spike and high ability to inhibit ACE2 binding to Spike is shown by the source cell. Chi-squared test.

(C) The neutralization ability of recombinant monoclonal antibody was measured by fusion inhibition assay. The quantity of cell fusion without the antibody is defined as 100%, and the quantity of cell fusion after incubation with antibodies is shown as the fusion rate. The correlation between the ACE2-binding rate and the fusion rate for antibodies with the ACE2-binding rate of 50% or less is shown. Spearman’s rank correlation coefficient.

(D) The correlation between the end-point micro-neutralization titer and the ACE2-binding rate is shown. Spearman’s rank correlation coefficient.