DNA vaccine encoding the enterohemorragic Escherichia coli (EHEC) Shiga-like toxin 2 (Stx2) A2 and B subunits confers protective immunity to Stx challenge in the murine model .

BENTANCOR L; BILEN M; FERNANDEZ BRANDO R,; RAMOS MV; FERREIRA LCS; GHIRINGHELLI D; PALERMO MS

CLINICAL AND VACCINE IMMUNOLOGY

AMER SOC MICROBIOLOGY

Año: 2009 vol. 16 p. 712 - 718

1556-6811

Production of verocytotoxin or shiga-like toxin (Stx) particularly Stx2 is the basis of hemolytic uremic syndrome (HUS) pathogenesis, as the frequently lethal outcome of enterohemorrhagic Escherichia coli (EHEC) infected patients. The toxin is formed by a single A subunit that promotes protein synthesis inhibition in eukaryotic cells, and five B subunits, which bind to globotriaosylceramide (Gb3) at the surface of host cells. The A subunit is enzimatically cut in eukaryotic cells into two peptides leading to the A1 peptide, which possesses N-glycosidase activity to the 28S rRNA, and the A2 peptide that confers stability to the B pentamer. In the present manuscript we report the construction of a DNA vaccine that expresses a non-toxic Stx2 mutated form consisting of the first A1 N-terminal amino acid genetically fused to complete A2 sequence as well as the B subunit, as a separate polypeptide. Immunization trials carried out with this new DNA vaccine in BALB/c mice resulted in systemic Stx-specific antibody responses with enhanced toxin neutralization activity both in vitro and, more importantly, upon in vivo Stx2 challenge in mice. The present vector represents the second DNA vaccine reported by our group conferring protective immunity to Stx2 and may be used, either alone or combined with other therapeutic procedures, to prophylatically or therapeutically decrease sequels associated with EHEC infection.