Fig. 1: S2-binding VHHs that potently neutralize a broad range of SARS-CoV-2 variants.
From: Ultrapotent SARS coronavirus-neutralizing single-domain antibodies that clamp the spike at its base
a Screen of E. coli periplasmic extracts (PE) of VHH clones isolated after 3 (R3) or 4 (R4) rounds of bio-panning on SARS-CoV-2 spike protein for binding to the indicated recombinant proteins (blue heat map) and for neutralization of VSV particles pseudotyped with SARS-CoV-2 spikes (red heat map). b Amino acid sequences alignment of S2 binding, neutralizing VHHs. Numbering according to Kabat. The boxes indicate CDR1, CDR2 and CDR3 as defined by IMGT. The amino acids indicated in red are part of the paratope. c Binding of VHHs to HEK293T cells expressing the spike protein of SARS-CoV-2 D614G, BA.1, BA.2, BA.5, BQ.1.1, MERS or transfected with empty vector (EV). S309 was used as a positive control and GBP, a GFP-binding VHH, as a negative control. d Neutralization of VSV pseudotyped with spike protein of the indicated SARS-CoV-2 variants and SARS-CoV-1 (SC-1) by R3DC23. The graph shows the mean (line) and individual (dots) IC50 values calculated from at least 2 independent neutralization assays. e Neutralization of authentic SARS-CoV-2 D614G and BA.1 virus by S2-binding VHHs. The graphs show the mean ± S.D. (N = 2) number of counted plaques for each VHH dilution. S309 was used as positive control. f Binding kinetics of R3DC23 to S-2P trimer immobilized on a BLI biosensor. *Due to the poor fitting for the association phase, the calculated KD, app and kon, app might not be accurate. Source data are provided as a source data file.
