肠毒素大肠杆菌LT—B基因转基因马铃薯口服免疫原性研究

Study on Immune Responses by Oral Immunization with B Subunit of Escherichia coli Heat-labile Enterotoxin Expressed in Transgenic Potatoes

探讨马铃薯表达的产肠毒素大肠杆菌热敏肠毒素B亚基口服免疫原性,选择4周龄的昆明白小鼠。转基因马铃薯块茎经冷冻干燥后,研磨成粉状,以灌胃给药的方式对小鼠进行免疫。分0.2 g、0.4 g和0.6 g三个剂量组,免疫三次,每周一次。对照组用5μg细菌中表达的抗原蛋白腹腔注射免疫小鼠,空白组小鼠饲喂普通鼠粮。利用ELISA方法对小鼠血清、粪便特异性抗体表达进行分析。结果有45%小鼠经转基因马铃薯口服免疫后可诱导特异性的免疫应答。与细菌表达的抗原免疫反应相比,血清IgG反应和黏膜sIgA反应略强或相当。说明产肠毒素大肠杆菌转基因植物疫苗免疫动物可诱导特异的系统免疫应答和黏膜免疫应答。为利用植物生产预防大肠杆菌性腹泻可食用的口服疫苗,保护儿童免受细菌性腹泻的侵染奠定了基础。

To determine the oral immunogenicity of B subunit of Escherichia coli Heat-labile enterotoxin expressed in transgenic potatoes,transgenic potatoes were made into dry-freezed powder.Mice were administrated weekly with three doses 0.2 g,0.4 g and 0.6 g powder containing about（30—50）μg LT—B for three time,comparing with the mice injected with 5 μg of LT—B from recombinant E.coli.After feeding the test animals,specific antibody in serum and fecal extract of the tested animals were detected by ELISA.It is resulted that experimental results demonstrated that 45% mices gavaged with transgenic plant had higher or equivalent levels of serum IgG response and fecal extracts IgA than those injected with bacterial LT—B.Systemic immune response and mucosal immune response have increased to approximately the highest values on 56 d and declined on 70 d after the last immunization.It is conclused this findings show that oral immunization with transgenic plant could induce LT—B specific mucosal and systemic immune responses.An edible plant vaccine against ETEC could provide a potential means to protect children from ever acute diarrhea.