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目的观察产肠毒素大肠杆菌(Enterotoxigenic E.coli,ETEC)基因工程疫苗在SD大鼠中的免疫原性。方法将含ETEC抗原成分热不稳定肠毒素B亚单位(Heat-labile enterotoxin Bsubunit,LTB)的双歧杆菌疫苗给SD大鼠灌胃4次,同时设对照组,以PBS平行灌胃。采用ELISA法检测大鼠粪便上清液IgA及血清IgG抗体水平;免疫组化法检测大鼠空肠中sIgA抗体的表达;肠绊试验检测肠毒素的活性。结果免疫疫苗的SD大鼠粪便上清液中产生了IgA抗体,血清中产生了特异性的IgG抗体,肠道内产生了特异性分泌型sIgA抗体;免疫组化结果显示,随着免疫次数的增加,抗体分泌量明显增加;双歧杆菌疫苗免疫的大鼠能够抵抗LT抗原的侵袭,而对照组大鼠则出现明显的肠道积液现象。结论构建的双歧杆菌疫苗具有良好的免疫效果,可保护SD大鼠免受ETEC的感染。
Objective To observe the immunogenicity of enterotoxigenic E. coli (ETEC) genetically engineered vaccine in SD rats. Methods Bifidobacterium vaccine containing heat-labile enterotoxin B subunit (ETB), an ETEC antigen component, was intragastrically administered to SD rats for 4 times. At the same time, rats in control group were given gavage in parallel with PBS. The levels of IgA and IgG in serum were detected by ELISA. The expression of sIgA antibody in jejunum of rats was detected by immunohistochemistry. The activity of enterotoxin was detected by intestinal trip test. Results IgA antibody was produced in the feces supernatant of SD rats of immunized vaccine, specific IgG antibodies were produced in the serum, and specific secreted sIgA antibodies were produced in the intestine. Immunohistochemical results showed that with the increase in the number of immunizations , Antibody secretion increased significantly; Bifidobacterium vaccine immunized rats can resist the invasion of LT antigen, while the control group rats showed significant intestinal fluid phenomenon. Conclusion The constructed Bifidobacterium vaccine has a good immune effect and can protect SD rats from ETEC infection.