BACKGROUND Legionella pneumophila (L.pneumophila), a Gram-negative small microorganism, causes hospital-acquired pneumonia especially in immunocompromised patients. Vaccination may be an effective method for preventing L.pneumophila infection. Therefore, it is necessary to develop a better vaccine against this disease. In this study, we developed a recombinant peptidoglycan-associated lipoprotein (PAL)/type IV pilin (PilE)/lagellin (FlaA) DNA vaccine and evaluated its immunogenicity and efficacy to protect against L.pneumophila infection. RESULTS According to the results, the expression of PAL, PilE, FlaA proteins and PAL/PilE/FlaA fusion protein in 293 cells was confirmed. Immunization with PAL/PilE/FlaA DNA vaccine resulted in highest IgG titer and strongest cytotoxic T-lymphocyte (CTL) response. Furthermore, the histopathological changes in lung tissues of mice challenged with a lethal dose of L.pneumophila were alleviated by PAL/PilE/FlaA DNA vaccine immunization. The production of T-helper-1 (Th1) cytokines (IFNγ, TGF-α, and IL-12), and Th2 cytokines (IL-4 and IL-10) were promoted in PAL/PilE/FlaA DNA vaccine group. Finally, immunization with PAL/PilE/FlaA vaccine raised the survival rate of mice to 100% after challenging with a lethal dose of L.pneumophila for 10 consecutive days. CONCLUSIONS Our study suggests that the newly developed PAL/PilE/FlaA DNA vaccine stimulates strong humoral and cellular immune responses and may be a potential intervention on L.pneumophila infection.

中文翻译：

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重组PAL / PilE / FlaA DNA疫苗可对BALB / c小鼠的肺炎军团菌提供保护性免疫。

背景技术革兰氏阴性小微生物嗜肺军团杆菌（L.pneumophila）引起医院获得性肺炎，特别是在免疫功能低下的患者中。接种疫苗可能是预防肺炎链球菌感染的有效方法。因此，有必要开发一种针对该疾病的更好的疫苗。在这项研究中，我们开发了一种重组肽聚糖相关的脂蛋白（PAL）/ IV型菌毛蛋白（PilE）/拉贝菌素（FlaA）DNA疫苗，并评估了其免疫原性和预防肺炎链球菌感染的功效。结果证实了PAL，PilE，FlaA蛋白和PAL / PilE / FlaA融合蛋白在293细胞中的表达。用PAL / PilE / FlaA DNA疫苗免疫可产生最高的IgG效价和最强的细胞毒性T淋巴细胞（CTL）反应。此外，PAL / PilE / FlaA DNA疫苗免疫减轻了致死剂量的肺炎链球菌攻击的小鼠肺组织的组织病理学变化。PAL / PilE / FlaA DNA疫苗组促进了T-helper-1（Th1）细胞因子（IFNγ，TGF-α和IL-12）和Th2细胞因子（IL-4和IL-10）的产生。最后，用PAL / PilE / FlaA疫苗免疫连续10天以致死剂量的嗜肺乳杆菌（L.pneumophila）攻击后，小鼠的存活率提高到100％。结论我们的研究表明，新开发的PAL / PilE / FlaA DNA疫苗可刺激强烈的体液和细胞免疫反应，并且可能是对肺炎链球菌感染的潜在干预措施。PAL / PilE / FlaA DNA疫苗组促进了T-helper-1（Th1）细胞因子（IFNγ，TGF-α和IL-12）和Th2细胞因子（IL-4和IL-10）的产生。最后，用PAL / PilE / FlaA疫苗免疫连续10天以致死剂量的嗜肺乳杆菌（L.pneumophila）攻击后，小鼠的存活率提高到100％。结论我们的研究表明，新开发的PAL / PilE / FlaA DNA疫苗可刺激强烈的体液和细胞免疫反应，并且可能是对肺炎链球菌感染的潜在干预措施。PAL / PilE / FlaA DNA疫苗组促进了T-helper-1（Th1）细胞因子（IFNγ，TGF-α和IL-12）和Th2细胞因子（IL-4和IL-10）的产生。最后，用PAL / PilE / FlaA疫苗免疫连续10天以致死剂量的嗜肺乳杆菌（L.pneumophila）攻击后，小鼠的存活率提高到100％。结论我们的研究表明，新开发的PAL / PilE / FlaA DNA疫苗可刺激强烈的体液和细胞免疫反应，并且可能是对肺炎链球菌感染的潜在干预措施。