A globotriaosylceramide (Gb3Cer) mimic peptide isolated from phage display library expressed strong neutralization to Shiga toxins

A Gb3-trisaccharide mimic peptide was selected with biopanning from a phage display library against anti-Gb3 antibody to neutralize Shiga toxins (Stxs). Biopanning was carried out on a microplate immobilized with a Fab fragment of anti-Gb3 antibody and a subtraction procedure screening was applied to enhance specificity. The selected phage clones showed strong affinity to anti-Gb3 antibody and to Stxs. Among these clones, a 9-mer sequence WHWTWLSEY was determined as the strongest Gb3 mimic peptide and chemically synthesized. The peptide bound strongly to Stx-1 and Stx-2, though the binding was inhibited with Gb3Cer. Surface plasmon resonance (SPR) and fluorescent spectroscopy determined that the affinity of the peptide to both Stxs was strong. Neutralization activity was confirmed by in vitro assay with HeLa cells. The Gb3 mimic peptide potentially has great promise for use against Stxs.