Fig. 3

Assessment of the binding affinity of Bi-Nab to the SARS-CoV-2 S protein. A HEK293T cells separately transfected with plasmids encoding WT SARS-CoV-2 S, Alpha S, Beta S, or Delta S proteins were incubated with Bi-Nab, 32C7 or 35B5, respectively, followed by a FITC-conjugated anti-human IgG antibody or FITC-conjugated anti-His antibody. As a positive control, hACE2 with a His-tag was used. The binding affinity was quantified using flow cytometry. Mean fluorescence intensity (MFI) was normalized to the mock (empty vector) group. B The fluorescence mobility of Bi-Nab binding to Delta S was significantly improved. The experiments were performed three times, and one representative is shown