表达大肠杆菌 LT-B/pro-ST融合抗原的减毒鼠伤寒沙门菌株的构建

目的：构建表达 Ｌ Ｔ Ｂ／ Ｓ Ｔ 融合蛋白的产肠毒素大肠杆菌口服活菌疫苗候选株。方法：编码 Ｌ Ｔ Ｂ／ Ｓ Ｔ 融合蛋白的基因插入ｐ Ｙ Ａ２４８ 载体中，构建了重组质粒 ｐ Ｘ Ｚ Ｌ６６。该重组质粒转入减毒鼠伤寒沙门菌 Ｓ Ｒ１１，Δ Ｃｙａ， Δ Ｃｒｐ， Δ Ａｓｄ 菌株 Ｘ４０７２。结果：此无抗药性的杂合菌株 Ｘ４０７２（ｐ Ｘ Ｚ Ｌ６６） 表达的 Ｌ Ｔ Ｂ／ Ｓ Ｔ 融合蛋白具有耐热及不耐热肠毒素的免疫原性而没有可检出的生物毒性。结论：为研究预防产肠毒素大肠杆菌腹泻提供了口服活菌疫苗候选株。

Construction of the attenuated Salmonella typhimurium strain expressing Escherichia coli LT B/ST fusion antigens

Objective: To construct a live oral vaccine expressing E.coli LT B/ST fusion antigens. Methods: The fusion gene encoding LT B and ST antigens was inserted into the vector plasmid pYA248. The resulting recombinant plasmid pXZL66 was constructed and transformed into the delta Cya, delta Crp, delta Asd attenuated S.typhimurium vaccine strain X4072 and the live vaccine strain X4072 (pXZL66). Results: The LT B/ST fusion protein expressed by X4072(pXZL66) had good immunogenicity and no biological toxicity. Conclusion: This live vaccine strain X4072(pXZL66) is worthy to be considered as a new live oral vaccine candidate against enterotoxic E.coli diarrhea.