Figure 4.

Epitopes and neutralizing breadth. (A and B) Graphs show anti-SARS-CoV-2 neutralizing activity of mAbs, IC₅₀s value against WT, Omicron BA.1, and Omicron BA.4/5 SARS-CoV-2 pseudoviruses for all antibodies (n = 253). Ring plots show the fraction of neutralizing (IC₅₀ < 1,000 ng/ml, gray) and non-neutralizing (IC₅₀ > 1,000 ng/ml, black) antibodies against WT, Omicron BA.1, and Omicron BA.4/5 SARS-CoV-2 pseudoviruses. Number in inner circles indicates number of antibodies tested. (C) Results of epitope mapping performed by competition BLI, comparing mAbs cloned from vaccinated younger and elderly individuals. Pie charts show the distribution of the antibody classes among WT-neutralizing antibodies (upper panel), WT + Omicron BA.1-neutralizing antibodies (middle panel), or WT + Omicron BA.4/5-neutralizing antibodies (lower panel). (D) Graphs showing IC₅₀ neutralization activity of Class 1/2 antibodies among all antibodies in A. The deletions/substitutions corresponding to viral variants used in A, B, and D were incorporated into a spike protein that also includes the R683G substitution, which disrupts the furin cleavage site and increases particle infectivity. Neutralizing activity against mutant pseudoviruses was compared to a WT SARS-CoV-2 spike sequence (NC_045512), carrying R683G. All experiments were performed at least in duplicate and repeated twice. Each dot represents one antibody. Antibody sequences from elderly Vax4 are shown in blue. Red bars and values in A, B, and D, represent geometric mean values. Statistics were determined by two-tailed Kruskal–Wallis test with subsequent Dunn’s multiple comparisons (A, dot plot), two-sided Fisher’s exact test with subsequent Bonferroni–Dunn correction (A, ring plots), Mann–Whitney test (B and D), and two-tailed Chi-square test (C).