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

The diphtheria toxoid antigen is a major component in pediatric and booster combination vaccines and is known to raise a protective humoral immune response upon vaccination. Although antibodies are considered critical for diphtheria protection, little is known about the antigenic determinants that m...

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Bibliographic Details
Published in:	Vaccines (Basel) Vol. 9; no. 4; p. 313
Main Authors:	De-Simone, Salvatore Giovanni, Gomes, Larissa Rodrigues, Napoleão-Pêgo, Paloma, Lechuga, Guilherme Curty, de Pina, Jorge Soares, da Silva, Flavio Rocha
Format:	Journal Article
Language:	English
Published:	Switzerland MDPI AG 26-03-2021 MDPI
Subjects:	Amino acids Antibodies Antigenic determinants Antigens Assaying B epitopes bi-specific peptides Binding sites Cellulose Continuity (mathematics) diagnostic performance Diagnostic systems Diphtheria Diphtheria toxin Domains ELISA Enzyme-linked immunosorbent assay Epitope mapping Humoral immunity Immune response Immune response (humoral) Immune system Immunization Immunoglobulin G Immunoreactivity Lymphocytes B Mass spectrometry Membranes Peptide mapping Peptides Phosphatase Proteins Scientific imaging Synthesis Tetanus Toxins Vaccines Whooping cough Brazil United States > US Europe Germany diphtheria toxin bi-specific peptides B epitopes diagnostic performance epitope mapping ELISA
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Summary:	The diphtheria toxoid antigen is a major component in pediatric and booster combination vaccines and is known to raise a protective humoral immune response upon vaccination. Although antibodies are considered critical for diphtheria protection, little is known about the antigenic determinants that maintain humoral immunity. One-hundred and twelve 15 mer peptides covering the entire sequence of diphtheria toxin (DTx) protein were prepared by SPOT synthesis. The immunoreactivity of membrane-bound peptides with sera from mice immunized with a triple DTP vaccine allowed mapping of continuous B-cell epitopes, topological studies, multiantigen peptide (MAP) synthesis, and Enzyme-Linked Immunosorbent Assay (ELISA) development. Twenty epitopes were identified, with two being in the signal peptide, five in the catalytic domain (CD), seven in the HBFT domain, and five in the receptor-binding domain (RBD). Two 17 mer (CB/Tx-2/12 and CB/DTx-4-13) derived biepitope peptides linked by a Gly-Gly spacer were chemically synthesized. The peptides were used as antigens to coat ELISA plates and assayed with human (huVS) and mice vaccinated sera (miVS) for in vitro diagnosis of diphtheria. The assay proved to be highly sensitive (99.96%) and specific (100%) for huVS and miVS and, when compared with a commercial ELISA test, demonstrated a high performance. Our work displayed the complete picture of the linear B cell IgG response epitope of the DTx responsible for the protective effect and demonstrated sufficient specificity and eligibility for phase IIB studies of some epitopes to develop new and fast diagnostic assays.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	2076-393X 2076-393X
DOI:	10.3390/vaccines9040313