Epitope Mapping of the Diphtheria Toxin and Development of an ELISA-Specific Diagnostic Assay

Background: The diphtheria toxoid antigen is a major component in pediatric and booster combination vaccines known to raise protective humoral immune response upon vaccination. Although antibodies are considered critical for protection, little about the antigenic determinants that maintain immunity. Methods: One-hundred twelve 15 mer peptides covering entire sequence of toxin (DTx) protein were prepared by SPOT synthesis. immunoreactivity membrane-bound with sera from mice immunized triple DTP vaccine allowed mapping continuous B-cell epitopes, topological studies, multiantigen peptide (MAP) synthesis, Enzyme-Linked Immunosorbent Assay (ELISA) development. Results: Twenty epitopes identified, two being signal peptide, five catalytic domain (CD), seven HBFT domain, receptor-binding (RBD). Two 17 (CB/Tx-2/12 CB/DTx-4–13) derived biepitope linked Gly-Gly spacer chemically synthesized. used as antigens coat ELISA plates assayed human (huVS) vaccinated (miVS) vitro diagnosis diphtheria. assay proved be highly sensitive (99.96%) specific (100%) huVS miVS and, when compared commercial test, demonstrated high performance. Conclusions: Our work displayed complete picture linear B cell IgG epitope DTx responsible effect sufficient specificity eligibility phase IIB studies some develop new fast diagnostic assays.