Neutralization of shiga toxins Stx1, Stx2c, and Stx2e by recombinant bacteria expressing mimics of globotriose and globotetraose

Strains of Escherichia coli producing Shiga toxins Stx1, Stx2, Stx2c, and S tx2d cause gastrointestinal disease and the hemolytic-uremic syndrome in hu mans. We have recently constructed a recombinant bacterium which displays g lobotriose (the receptor for these toxins) on its surface and adsorbs and n eutralizes these Shiga toxins with very high efficiency. This agent has gre at potential for the treatment of humans with such infections. E. coli stra ins which cause edema disease in pigs produce a variant toxin, Stx2e, which has a different receptor specificity from that for the other members of th e Stx family. We have now modified the globotriose-expressing bacterium suc h that it expresses globotetraose (the preferred receptor for Stx2e) by int roducing additional genes encoding a N-acetylgalactosamine transferase and a UDP-N-acetylgalactosamine-4-epimerase. This bacterium had a reduced capac ity to neutralize Stx1 and Stx2e in vitro, but remarkably, its capacity to bind Stx2e was similar to that of the globotriose-expressing construct; bot h constructs neutralized 98.4% of the cytotoxicity in lysates off. coli JM1 09 expressing cloned stx(2e). These data suggest that either globotriose- o r globotetraose-expressing constructs may be suitable for treatment and/or prevention of edema disease in pigs.