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Mol Immunol. 2015 Feb;63(2):235-44. doi: 10.1016/j.molimm.2014.07.008. Epub 2014 Jul 23.

Structural and antigenic features of the synthetic SF23 peptide corresponding to the receptor binding fragment of diphtheria toxin.

Author information

1
Regulatory Proteins and Peptides Laboratory, Institute of Physiology of the National Academy of Sciences of Belarus, Academicheskaya 28, Minsk, Belarus.
2
Department of General Chemistry, Belarusian State Medical University, Dzerzinskogo 83, Minsk, Belarus. Electronic address: vvkhrustalev@mail.ru.
3
Department of General Chemistry, Belarusian State Medical University, Dzerzinskogo 83, Minsk, Belarus.
4
Laboratory of Vaccine Preventable Diseases, Republican Research and Practical Centre for Epidemiology and Microbiology, Filimonova 23, Minsk, Belarus.
5
Department of Child Infectious Diseases, Belarusian State Medical University, Dzerzinskogo 83, Minsk, Belarus.

Abstract

The SF23 peptide corresponding to the receptor binding fragment of diphtheria toxin (residues 508-530) has been synthesized. This fragment forming a protruding beta hairpin has been chosen because it is the less mutable B-cell epitope. Affine chromatography and ELISA show that antibodies from the sera of persons infected by toxigenic Corynebacterium diphtheriae and those immunized by diphtheria toxoid are able to bind the synthetic SF23 peptide. There are antibodies recognizing the SF23 peptide in the serum of horses hyperimmunized with diphtheria toxoid. Analysis of circular dichroism spectra show formation of beta hairpin by the peptide. Taken together, the results showed that the structure of the less mutable epitope of C. diphtheriae toxin was reproduced by the short SF23 peptide. Since antibodies against that epitope should block its interactions with cellular receptor (heparin-binding epidermal growth factor), the SF23 peptide can be considered as a promising candidate for synthetic vaccine development. Fluorescence quenching studies showed the existence of chloride and phosphate binding sites on the SF23 molecule. Phosphate containing adjuvants (aluminum hydroxyphosphate or aluminum hydroxyphosphate sulfate) are recommended to increase the SF23 immunogenic properties.

KEYWORDS:

Affine chromatography; Circular dichroism; Diphtheria toxin; Diphtheria toxoid; Fluorescence quenching; Synthetic vaccine

PMID:
25062832
DOI:
10.1016/j.molimm.2014.07.008
[Indexed for MEDLINE]

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