title: A DNA vaccine encoding the enterohemorragic Escherichia coli Shiga-like toxin 2 A2 and B subunits confers protective immunity to Shiga toxin challenge in the murine model.
abstract: Production of verocytotoxin or Shiga-like toxin (Stx), particularly Stx2, is the basis of hemolytic uremic syndrome, a frequently lethal outcome for subjects infected with Stx2-producing enterohemorrhagic Escherichia coli (EHEC) strains. The toxin is formed by a single A subunit, which promotes protein synthesis inhibition in eukaryotic cells, and five B subunits, which bind to globotriaosylceramide at the surface of host cells. Host enzymes cleave the A subunit into the A(1) peptide, endowed with N-glycosidase activity to the 28S rRNA, and the A(2) peptide, which confers stability to the B pentamer. We report the construction of a DNA vaccine (pStx2DeltaAB) that expresses a nontoxic Stx2 mutated form consisting of the last 32 amino acids of the A(2) sequence and the complete B subunit as two nonfused polypeptides. Immunization trials carried out with the DNA vaccine in BALB/c mice, alone or in combination with another DNA vaccine encoding granulocyte-macrophage colony-stimulating factor, resulted in systemic Stx-specific antibody responses targeting both A and B subunits of the native Stx2. Moreover, anti-Stx2 antibodies raised in mice immunized with pStx2DeltaAB showed toxin neutralization activity in vitro and, more importantly, conferred partial protection to Stx2 challenge in vivo. The present vector represents the second DNA vaccine so far reported to induce protective immunity to Stx2 and may contribute, either alone or in combination with other procedures, to the development of prophylactic or therapeutic interventions aiming to ameliorate EHEC infection-associated sequelae.
authors.affiliation: División Inmunología, Instituto de Leucemia Experimental, Instituto de Investigationes Hematológicas, Academia Nacional de Medicina, Buenos Aires, Argentina.
authors.forename: Leticia V
authors.initials: LV
authors.lastname: Bentancor
authors.forename: Marcos
authors.initials: M
authors.lastname: Bilen
authors.forename: Romina J Fernández
authors.initials: RJ
authors.lastname: Brando
authors.forename: María Victoria
authors.initials: MV
authors.lastname: Ramos
authors.forename: Luis C S
authors.initials: LC
authors.lastname: Ferreira
authors.forename: Pablo D
authors.initials: PD
authors.lastname: Ghiringhelli
authors.forename: Marina S
authors.initials: MS
authors.lastname: Palermo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000992:Antitoxins / Q000097:blood; D001483:Base Sequence; D002522:Chlorocebus aethiops; D054324:Enterohemorrhagic Escherichia coli / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D011041:Poisoning / Q000517:prevention & control*; D021122:Protein Subunits / Q000235:genetics / Q000276:immunology; D022603:Shiga Toxins / Q000235:genetics / Q000276:immunology*; D016019:Survival Analysis; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*; D014709:Vero Cells
chemical_list: D000907:Antibodies, Bacterial; D000992:Antitoxins; D021122:Protein Subunits; D022603:Shiga Toxins; D019444:Vaccines, DNA