Fig. 1: Identification of potential antibodies against a broader array of variants.

a RBD/ACE2 receptor blocking activity of the 177 ScFvs. RBD is from the original wild-type (WT) strain. Group 1: immunization with RBD protein and screening with RBD protein; Group 2: immunization with RBD protein and screening with Spike protein; Group 3: immunization with Spike protein and screening with RBD protein. OD₄₅₀ < 2.3 in the ELISA-based receptor-binding inhibition assay was defined as “positive” and OD₄₅₀ > 2.3 was defined as “negative”. b Blocking ACE2 receptor binding to RBDs of original WT strain, beta and delta strain by the 177 mAbs. mAbs were diluted as 0.25, 1, 4 μg/mL. These mAbs were grouped into seven families by heavy chain CDR3 sequence homology. c Neutralization activity of the 22 mAbs in 0.19 μg/mL using vesicular stomatitis virus (VSV) pseudotyped with Delta Spike protein was shown for preliminary screening. 8 mAbs were selected to test neutralization activities using VSV pseudotyped with Delta, Beta, or Kappa Spike protein for further screening, and IC₅₀ values were shown.