Effect Of Inactivated Shiga-like Toxin From Escherichia Coli Against Edema Disease In Swine

Edema disease (ED) of pigs is an enterotoxaemic disease caused by enterotoxaemic Escherichia coli (ETEC) infection. Antimicrobial therapy for pigs with ED is controversial because it may induce death of sickish piglets. Associated with inhibition of cell wall synthesis, the exposure to ampicillin or fosfomycin increased the release of Stx 2e. Preventive agents may serve as important measures in the control of the diseases. Shiga-like toxin(SLT) is the most important pathogenic factor for ETEC. SLT is also named Verotoxin(VT) and Stx, including a class of toxins with silimar structure and function. In this study ,12 strains of Escherichia coli were isolated from the faeces of piglets with edema disease in Jilin province.Genes of Shiga-like toxin were detected by polymerase chain reaction,PCR products were sequenced.SLT from E.coli in swine with ED were extracted ,purified and inactivated.Then mixture of inactivated E.coli and SLT were prepared and vaccinated into mice. Protection of this preparation against pathogenic E.coli strains is better then that of inactivated E.coli body or SLT alone. And the live rate of mice immunited to E.coli strains including gene code SLT is 83.3%,and that of E.coli and SLT are 44.25% and 37.5%,respectively.The polyvalent inactity vaccine including E.coli body and SLT was developed for precaution ED in swine.The result show that incidence of the disease immuned by the vaccine is 3.3%,and mortality is 28.6%; on the contrary,that of control group are 7.32% and 78.0%,respectively。 So the mixtural vaccine is an effective method to prevent swine from ED.