Vaccination with genetically modified Shiga-like toxin IIe prevents edema disease in swine

Escherichia coli strains producing Shiga-like toxin II variant (SLT-IIe, formerly called SLT-IIv) cause edema disease in weaned pigs, Vaccination of pigs with a genetically modified form of Shiga like toxin IIe, SLT-IIe(E167Q), has been previously shown to he nontoxic and to induce antibodies to SLT-IIe (V. M. Gordon, S. C. Whipp, H. W. Moon, A. D. O'Brien, and J. E. Samuel, Infect. Immun. 60:485-502, 1992), Fifty micrograms of SLT-IIe(E167Q) toxin was used to vaccinate suckling pigs at 1 and 2 weeks of age, Both vaccinated and nonvaccinated pigs were orally inoculated with an SLT-IIe-producing strain of E. coli after weaning (3 to 4 weeks of age). Pigs fed a low-protein diet that were not vaccinated with SLT-IIe(E167Q) developed subclinical edema disease, histologically evident as vascular necrosis, Pigs fed a high-protein diet that were not vaccinated with SLT-IIe(E167Q) developed clinical edema disease manifested as vascular necrosis, reduced weight gain, ataxia, palpebral edema, lateral recumbency, and death, Pigs vaccinated with SLT-IIe(E167Q) had a reduction in the incidence of subclinical edema disease and never developed clinical edema disease. These data demonstrate that vaccination with a genetically modified form of SLT-IIe prevents edema disease and are consistent with the notion that diet influences susceptibility to edema disease.