产肠毒素大肠杆菌基因工程疫苗在SD大鼠中的免疫原性

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。

Immunogenicity of Recombinant Enterotoxigenic E.coli Vaccine in SD Rats

Objective To observe the immunogenicity of recombinant ente rotoxigenic E.col(iETEC)vaccineinSDrats.Methods SD rats were immunized with the recombinant bifidobacterium strain containing heat-labile enterotoxin B subunit(LTB)of ETEC antigen for 4 times by oral route,using those immunized with PBS as control.The IgA in supernatant of feces and IgG in sera of rats were determined by ELISA,the expression of sIgA in jejunum by immunohistochemical assay,and the activity of enterotoxin by intestine hypodesmus test.Results Specific IgA was induced in the supernatant of feces of rats,and IgG in sera,while specific sIgA in enteric tract.Immunohistochemical assay proved that the antibody secretion level increased significantly with the increasing doses of vaccine.The rats immunized with the vaccine were protected against the challenge with LT antigen.However,obvious enteric hydrops were observed in the rats in control group.Conclusion The constructed recombinant ETEC vaccine showed good immune effect,which protected SD rats from ETEC infection.