Contribution of defined amino acid residues to the immunogenicity of recombinant Escherichia coli heat-stable enterotoxin fusion proteins.
We investigated whether the toxicity-associated receptor-binding domain of the non-immunogenic Escherichia coli heat-stable enterotoxin (STh) as a fusion with a carrier protein and the inclusion of an appropriate spacer are critical factors for eliciting antibody responses against the native toxin. The immunological properties of three toxic and one non-toxic fusion proteins, consisting of STh N-terminally joined to the C-terminus of the major subunit ClpG of E. coli CS31A fimbriae, were compared. In contrast to the non-toxic hybrid STh with glycine and leucine simultaneously substituted for the receptor-interacting Pro(13) and Ala(14) amino acids, the toxic chimeras responded by producing high serum levels of anti-STh antibodies in immunized animals. On the other hand, only the toxic ClpG-STh construct with the natural peptide 47KSGPESM(53) of Pro-STh as spacer stimulated STh-neutralizing responses against both native toxin and enterotoxigenic live E. coli cells. Altogether, these findings suggest a close relationship between conformational similarity to the native structure of STh and the ability to elicit specific antibody responses against STh.
Batisson
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Laboratoire de Microbiologie, Institut National de la Recherche Agronomique, Centre de Recherches de Clermont-Ferrand-Theix, 63122, Saint-Genès-Champanelle, France.
Der Vartanian
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D018830:Adhesins, Escherichia coli / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D001427:Bacterial Toxins / Q000235:genetics / Q000276:immunology*; D004768:Enterotoxins / Q000235:genetics / Q000276:immunology*; D004926:Escherichia coli / Q000276:immunology*; D029968:Escherichia coli Proteins; D010861:Fimbriae, Bacterial / Q000737:chemistry / Q000235:genetics; D005998:Glycine; D007125:Immunogenetics; D007930:Leucine; D051379:Mice; D008969:Molecular Sequence Data; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology
D018830:Adhesins, Escherichia coli; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; C034151:heat stable toxin (E coli); C071730:clpG protein, E coli; D007930:Leucine; D005998:Glycine