B-Cell Epitope Mapping Using a Library of Overlapping Synthetic Peptides in an Enzyme-Linked Immunosorbent Assay

Area of Science:

• Immunology
• Bacteriology
• Protein Chemistry

Background:

• Rhodococcus equi is a significant cause of pneumonia in foals.
• Understanding bacterial virulence factors like VapA is crucial for developing effective vaccines and treatments.
• B-cell epitopes are key targets for antibody-based immune responses.

Purpose of the Study:

• To develop and validate a method for mapping linear B-cell epitopes on the VapA protein.
• To identify specific B-cell epitopes on VapA relevant to R. equi infections in foals.

Main Methods:

• Design and synthesis of overlapping biotinylated peptides representing the VapA protein sequence.
• Enzyme-Linked Immunosorbent Assay (ELISA) using NeutrAvidin™-coated plates to immobilize biotinylated peptides.
• Screening of sera from foals infected with R. equi against the peptide library.

Main Results:

• A linear B-cell epitope was successfully mapped to a 20-amino acid sequence within the VapA protein.
• The identified epitope is recognized by antibodies in sera from diseased foals, indicating its relevance during infection.

Conclusions:

• The described ELISA strategy using synthetic biotinylated peptides is effective for mapping linear B-cell epitopes.
• The identified VapA epitope represents a potential target for diagnostic or vaccine development against R. equi infections in foals.