In order to investigate the immune effect of SLT- Ⅱ e coding gene mutant strain of Escherichia coli as oral vaccines against porcine edema disease, the weaned piglets were immunized via oral with the SLT- Ⅱ e gene mutant strain of E. coli (O139/SLT- Ⅱ e*/07) constructed in our laboratory, then the colonization of the mutant strains in intestinal tract and immune responses to the mutant E. coli were detected by indirect ELISA. The results showed that the mutant E. coli were found in faeces from group 1 (microcapsule group) and group 2 (gavaged group) on 21st day post immune (pi); In group 1, the IgG antibodies (P/N＞2), anti-SLT- Ⅱ eA , anti-F18ab and anti-O139, were detected in serum from 7th, 14th and 28th day pi, respectively, and the anti-SLT- Ⅱ eB antibody had no significant rise; the sIgA antibodies (P/N＞2) anti-SLT- Ⅱ eA, anti-SLT- Ⅱ eB, anti-O139 and anti-F18ab, were detected in faeces from 7th and 14th day pi, respectively; INF- γ level in serum rised. The levels of antibodies of group 2 were lower than these of group 1. Oral immunized piglets was protected completely against challenge of SLT- Ⅱ e. The results of study indicated that the SLT- Ⅱ e gene mutant strain of E. coli could be a candidate strain of oral vaccine against porcine edema disease.%为研究猪水肿病大肠杆菌SLT-Ⅱe编码基因突变菌株作为口服疫苗的免疫效果,本实验用构建的突变菌株(O139/SLT-Ⅱ e/07)口服免疫断奶仔猪后,检测突变菌株在仔猪肠道的定植情况,仔猪血清及粪便中的特异性抗体和细胞因子水平,并进行了免疫保护效力评价.结果显示,免疫后21 d仍能在实验1组(微胶囊口服免疫)和2组(直接口服免疫)的仔猪粪便中检出突变菌株;从免疫后第7 d、14 d和21 d开始,在实验1组血清样品中可分别检测到抗SLT-Ⅱ eA蛋白、F18ab菌毛蛋白和O139抗原的IgG抗体(P/N＞2);从免疫后第7 d、14 d开始,在粪便中可分别检测到抗SLT-Ⅱ eA蛋白、SLT-Ⅱ eB蛋白、O139抗原、F18ab菌毛蛋白的slgA抗体(P/N＞2);免疫仔猪血清中的INF-γ的含量升高;实验2组的血清特异性IgG水平和粪便中sIgA抗体水平比实验1组低;该突变菌株对仔猪具有免疫保护作用.研究结果表明该大肠杆菌基因突变株可作为仔猪水肿病口服疫苗的候选菌株.
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