Use of peptide synthesis to probe viral antigens for epitopes to a resolution of a single amino acid.

TLDR

The authors developed a rapid solid‑phase peptide synthesis workflow that produces hundreds of high‑purity peptides, allows direct ELISA detection on the support, and enables systematic amino‑acid substitution to map antibody‑binding residues. Using the workflow, the authors mapped a seven‑residue epitope (146‑152) on the foot‑and‑mouth disease virus coat protein, revealing that leucines at positions 148 and 151 are essential for antibody binding while glutamine and alanine at 149 and 152 contribute less, thereby enhancing epitope resolution and understanding of antigen‑antibody specificity.

Abstract

A procedure is described for rapid concurrent synthesis on solid supports of hundreds of peptides, of sufficient purity to react in an enzyme-linked immunosorbent assay. Interaction of synthesized peptides with antibodies is then easily detected without removing them from the support. In this manner an immunogenic epitope of the immunologically important coat protein of foot-and-mouth disease virus (type O1) is located with a resolution of seven amino acids, corresponding to amino acids 146-152 of that protein. Then, a complete replacement set of peptides in which all 20 amino acids were substituted in turn at every position within the epitope was synthesized, and the particular amino acids conferring specificity for the reaction with antibody were determined. It was found that the leucine residues at positions 148 and 151 were essential for reaction with antisera raised against intact virus. A lesser contribution was derived from the glutamine and alanine residues at positions 149 and 152, respectively. Aside from the practical significance for locating and examining epitopes at high resolution, these findings may lead to better understanding of the basis of antigen-antibody interaction and antibody specificity.