基于醚脂质囊泡的抗原赋予针对实验性李斯特菌病的保护作用。

BACKGROUND: Incidence of food-borne infections from Listeria monocytogenes, a parasite that has adapted intracellular residence to avoid antibody onslaught, has increased dramatically in the past few years. The apparent lack of an effective vaccine that is capable of evoking the desired cytotoxic T cell response to obliterate this intracellular pathogen has encouraged the investigation of alternate prophylactic strategies. It should also be noted that Archaebacteria (Archae) lipid-based adjuvants enhance the efficacy of subunit vaccines. In the present study, the adjuvant properties of archaeosomes (liposomes prepared from total polar lipids of archaebacteria, Halobacterium salinarum) combined with immunogenic culture supernatant antigens of L. monocytogenes have been exploited in designing a vaccine candidate against experimental listeriosis in murine model. METHODS: Archaeosome-entrapped secretory protein antigens (SAgs) of L. monocytogenes were evaluated for their immunological responses and tendency to deplete bacterial burden in BALB/c mice challenged with sublethal listerial infection. Various immunological studies involving cytokine profiling, lymphocyte proliferation assay, detection of various surface markers (by flowcytometric analysis), and antibody isotypes (by enzyme-linked immunosorbent assay) were used for establishing the vaccine potential of archaeosome-entrapped secretory proteins. RESULTS: Immunization schedule involving archaeosome-encapsulated SAgs resulted in upregulation of Th1 cytokine production along with boosted memory in BALB/c mice. It also showed protective effect by reducing listerial burden in various vital organs (liver and spleen) of the infected mice. However, the soluble form of the antigens (SAgs) and their physical mixture with sham (empty) archaeosomes, besides showing feeble Th1 response, were unable to protect the animals against virulent listerial infection. CONCLUSION: On the basis of the evidence provided by the current data, it is inferred that archaeosome-entrapped SAgs formulation not only enhances cytotoxic T cell response but also helps in the clearance of pathogens and thereby increases the survival of the immunized animals.

背景：过去几年中，寄生虫李斯特菌引起的食源性感染发病率急剧上升，这种寄生虫已经适应了细胞内居住，以避免抗体的攻击。显然，缺乏一种能够引起理想的细胞毒性 T 细胞反应来消灭这种细胞内病原体的有效疫苗，这促使人们探索替代的预防策略。还应该注意的是，古细菌（Archae）脂类佐剂增强了亚单位疫苗的功效。在本研究中，利用古生菌（嗜盐菌 Halobacterium salinarum 的总极性脂质制备的脂质体） archaeosomes 的佐剂特性，结合李斯特菌的免疫原性培养上清抗原，设计了一种针对实验性李斯特菌病的候选疫苗。

方法：评估了李斯特菌 secretory 蛋白抗原（SAgs）的 archaeosome 包封物的免疫反应性和减少用亚致死性李斯特菌感染挑战的 BALB/c 小鼠的细菌负荷的能力。涉及细胞因子谱分析、淋巴细胞增殖测定、各种表面标记物（流式细胞分析）检测和抗体同种型（酶联免疫吸附测定）的各种免疫学研究用于确定 archaeosome 包封 secretory 蛋白的疫苗潜力。

结果：涉及 archaeosome 包封 SAg 的免疫方案导致 Th1 细胞因子产生的上调以及 BALB/c 小鼠的记忆增强。它还通过降低感染小鼠各种重要器官（肝脏和脾脏）中的李斯特菌负荷来显示保护作用。然而，可溶性形式的抗原（SAgs）及其与 sham（空） archaeosomes 的物理混合物，除了显示出微弱的 Th1 反应外，也不能保护动物免受强毒李斯特菌感染。

结论：根据当前数据提供的证据，可以推断出 archaeosome 包封的 SAg 制剂不仅增强了细胞毒性 T 细胞反应，而且有助于清除病原体，从而提高了免疫动物的存活率。