Figure 2. Redesigned cyclic peptides bind with high affinity to group 1 and 2 HAs.

Redesigned cyclic peptides C05 d1 (upper panels) and C05 truncated d4 (lower panels) bind to H1 (B, F) or H3 (C, G) HAs with high (<100 nM) affinity. The wild-type CDRH3 sequence does not bind to H1 HA in either full-length (A) or truncated (E) formats. To identify the peptide epitope, peptides were loaded onto a biosensor, which then was treated with recombinant HA from H1 A/Solomon Islands/03/2006 virus followed by baseline at 90 sec and either a receptor-binding site (C05), stem (CR6261), or irrelevant (MPXV-26) antibody at 120 sec (D, H).