Fig. 2: Neutralizing activity, epitope characterization and gene family analysis of the top 40 RBD-specific antibodies.

Neutralization activity against a panel of 17 pseudoviruses carrying the S proteins of wild-type and various VOCs and VOIs, indicated by antibody concentration required to achieve 50% reduction in viral infectivity (IC₅₀, ng ml⁻¹). The neutralizing activity is colored from red, orange, yellow, green to gray, with red being the strongest, while gray failed to reach IC₅₀ at the highest concentration tested (10,000 ng ml⁻¹). A few representative mutations that potentially facilitate viral escape from antibodies are indicated below each of the VOCs and VOIs. The complete set of mutations for each of the VOCs and VOIs can be found in the Methods. Epitope specificity was determined by competition with typical class 1 (P2C-1F11 and REGN10933), class 2 (P2B-2F6) and class 3 (REGN10987 and S309) antibodies measured by surface plasmon resonance (SPR). All results were calculated from at least two independent experiments. The germline gene usage (IGHV, IGKV, IGLV), the length of complementarity determining region (CDR) 3 and the proportion of somatic hypermutation (SHM) were estimated using the IMGT program. Antibodies highlighted in red text are those competed with typical class 1 antibody P2C-1F11 and which preferentially used germline IGHV3-53/66. For clarity, the five antibodies that had their crystal or cryo-EM structures resolved in complex with RBD or S trimer are labeled with either red (class 1) or black (other classes) background. G1 to G5, group 1 to group 5; VOIs, variants of interest.