Screening Of Mimic Epitopes Of GalNAc(α1-3)(Fucα1-2) Galβ Antigen From Phage 15-mer Peptide Library

ObjectiveTo find mimic epitopes of Blood group A antigen from phage 15-mer peptide library.Methods1. Four rounds biopanning from phage 15-mer peptide library using monoclonal blood group A antigen antibody.2. 37 Individual clones were picked up randomly from eluate of the fourth round selection, and analysis of the individual clones by ELISA.3. Refer to the result of ELISA, the positive clones were picked up to DNA purification and sequencing.4. Enriched clones were were diluted (1:10, 1:100, 1:500, 1:1000 ) for ELISA, Synchronously, original library used as negative control was diluted. Furthermore, erythrocyte hemagglutination test was involved to exam the recognition of the peptide to the blood group A antibody.5. Autodock Tools software was used to analysis molecule interaction between the peptide and blood group A antibody.Results1. After four rounds biopanning, the output/input rate enriched 1600 times, and the rate was increased with the number of biopanning. The result of ELISA suggested that 11 of 37 individual clones were positve clones. The positive rate was 27.5%.2. Refer to the result of the DNA sequencing, 9 of the positive clones shown the same sequence, which was TRWLVYFSRPYLVAT. 3. OD rate reduced with the decrease number of clone 8, and high concentration of clone 8 can more effectively inhibited RBC agglutination.4. Analysis of the peptide using Auto Dock, we found the peptide can model into the binding pocket on the surface of group A antibody which nature blood A antigen binds.ConclutionThe enriched peptide TRWLVYFSRPYLVAT can mimic the blood A antigen epitope.