Identification of Gal-α-1,3-Gal peptide mimetic by phage display

The obstacle for pig-to-human transplantation is hyperacute rejection (HAR) triggered by the interaction between human natural antibodies and the antigenic epitope Gal-alpha-1, 3 -Gal. The alpha-Gal structure is considered to be the major xenoantigenic epitopes present on porcine tissues. A phage-displayed peptide library is used to identify a 17-amino-acid peptide CCWLLRQPVPFVRSIRS that binds to the mAb anti-B (anti-B monoclonal antibody which binds the carbohydrate Gal alpha-1, 3 Gal). The melibiose competes with the binding of mAB anti-B to the peptide, suggesting that they may bind the same site. Using a pig RBC agglutination assay, it is shown that this peptide can inhibit the agglutination of pig RBCs by human serum or GS-I-B4.