Immunogenicity of a novel Stx2B–Stx1B fusion protein in a mice model of Enterohemorrhagic Escherichia coli O157:H7 infection

Shiga toxin type 1 and 2 produced by Enterohemorrhagic Escherichia coli (EHEC) O157:H7 are responsible for hemolytic uremic syndrome, a life-threatening sequela. We constructed a novel fusion protein carrying both of the immunogenic B subunits derived from the two toxins, designated Stx2B–Stx1B (2S for short), expressed in the E. coli BL21 and harvested the purified protein by a simple anion-exchange chromatography method. The fusion protein induced high level humoral IgG in mice, subclass analysis showed IgG1 dominate the IgG increase trend, which indicated that a partial to Th2 response contributed to this humoral reactivity. High level neutralizing antibodies elicited by this fusion protein inhibited cytotoxicity of toxins and protected mice from lethal dose challenge of lysed EHEC O157:H7.