表达结核抗原的减毒重组李斯特菌的免疫生物学特性

Immunobiologic characteristics of a recombinant Listeria monocytogenes expressing Mycobacterium tuberculosis antigens

【目的】结核病是一种由结核分枝杆菌复合群引起的严重危害人类健康的慢性传染病,研制预防结核病的新型疫苗对于有效控制结核病具有重要的公共卫生意义。【方法】本研究对表达M.tb融合蛋白的重组李斯特菌LMΔhly::Ag85b-esat-6的免疫生物学特性进行了初步研究。【结果】实验结果显示,重组菌溶血活性丧失,对C57BL/6小鼠的半数致死剂量提高了4个log值,以0.1 LD50的剂量尾静脉注射C57BL/6小鼠,5天时被完全清除,病理切片结果未显示明显病理变化,表明重组菌具有良好的安全性。以尾静脉途径免疫C57BL/6小鼠,对其诱导的免疫应答测定结果表明,重组菌所运送的结核抗原能诱导小鼠Th1型免疫应答,激发较强的结核抗原特异性的CTL效应。【结论】上述实验结果表明,表达结核分枝杆菌融合蛋白的减毒重组李斯特菌是一种安全的结核病疫苗候选株,具有潜在的应用价值。

[Objective] Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis complex.Hence,novel vaccines against TB are urgently needed and important to the public health.[Methods]Immunobiologic characteristics of a recombinant attenuated Listeria monocytogenes strain LMΔhly：：Ag85b-esat-6 was evaluated.[Results]LMΔhly：：Ag85b-esat-6 had lost the hemolytic activity.It was completely cleared from the livers and spleens of mice 5 days after inoculation via intravenous route.Furthermore,the LD50 of the recombinant strain increased by 4 Logs comparing to that of the parent strain. Histopathology reveals no obvious pathological changes following administration of the recombinant strain to mice,indicating its safety.In addition,the potential protective immune response was evaluated on C57BL/6 mice via intravenous immunization route.The results indicate that the antigen delivered by the recombination LM could induce Th1 type immune response and elicit strong cytotoxic lymphocyte effect against Ag85B-ESAT-6.[Conclusion]Thus,LMΔhly：：Ag85b-esat-6 had high safety to mice,and could be used as a novel vaccines candidate for preventing tuberculosis.