肠毒素大肠杆菌定居因子CS3和肠毒素融合抗原基因在减毒鼠伤寒沙门氏菌中的共表达

不耐热肠毒素（LT）和耐热肠毒素（ST）是产肠毒素大肠杆菌的主要致病因素，CS3为该菌的优势定居因子，是定居因子CFA/Ⅱ菌毛抗原的共有抗原组分。采用基因操作技术将编码CS3和融合肠毒素蛋白基因转化到减毒鼠伤寒沙门氏菌疫苗侯选株X4072中进行表达。用重组菌株口服免疫小鼠后，免疫动物能产生抗CS3、LT和ST的血清抗体。特别有意义的是，所产生的抗ST抗体能中和天然ST的生物活性。这一结果为研究载体疫苗防治肠毒素大肠杆菌腹泻疾病奠定了基础。

Simultaneous Expression of CS3 Colonization Factor Antigen and LT-B/ST Fusion Enterotoxin Antigen of enterotoxigenic Escherichia coli by Attenuated Salmonella typhimurium

LT and ST are the main enterotoxins of enterotoxigenic Escherichia coli(ETEC)found in clinical isolates,and CS3(the common antigen in the CFA/Ⅲ family of fimbrial antigens )is one of the most prevalent antigens of colonization factors.The Genetic determinants encoding CS3 and LT-B/ST fusion toxin were manipulated so that these important antigens are expressed simultaneously in attenuated Salmonella typhimurium oral vaccine strain X4072.These antigens produced by X4072(pXZL88)could be recognized with monospecific CS3,LT to ST antibodies respectively.The specific antibodies against CS3,LT and ST could be detected.in the sera of immunized mice via oral route with the live bacteria.Significantly,the antibody to ST was able to neutralize the biological activity of native ST.This prototype construct may be proved bto be useful in investigating the live vector approach to immunoprophylaxis of ETEC diarrhea disease.