Legionella pneumophila Pathogenesis in the Galleria mellonella Infection Model
Legionella pneumophila Pathogenesis in the Galleria mellonella Infection Model
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DOI：
10.1128/iai.00510-12
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发表时间：
2012-08-01
影响因子：
3.1
通讯作者：
Frankel, Gad
中科院分区：
文献类型：
--
作者：
Harding, Clare R.;Schroeder, Gunnar N.;Frankel, Gad
嗜肺军团菌是一种兼性细胞内人类病原体，是称为军团病的严重肺炎的病原体。其毒力取决于蛋白质分泌系统，特别是Dot/Icm IV型分泌系统（T4 SS），其对于在巨噬细胞中建立允许复制的空泡至关重要。分析这些系统的作用和它们的发病机制的底物需要易于使用的模型，近似人类感染。我们研究了蜡螟Galleria mellonella幼虫作为L.嗜肺菌感染我们发现L. pneumophila菌株130 b、巴黎和JR 32引起G.对大蜡螟幼虫的感染具有菌株、感染剂量、生长阶段和T4 SS依赖性。野生型L pneumophila持续存在，并在幼虫内复制，而T4 SS突变体迅速清除。L.在缺乏胸苷的情况下减毒但具有功能性T4 SS的嗜肺菌菌株Lp 02在G.感染后18 h内无死亡。免疫荧光和透射电镜观察表明，L.嗜肺军团菌存在于昆虫血细胞内的空泡中，其超微结构类似于在巨噬细胞中观察到的含军团菌的空泡（LCV）。空泡用T4 SS效应子和LCV标记物SidC装饰。感染对昆虫器官造成严重损害并引发免疫反应，包括激活酚氧化酶级联反应，导致黑化、结节形成和抗菌肽上调。这些结果表明，G.大蜡螟为研究L.嗜肺菌和宿主。
Legionella pneumophila is a facultative intracellular human pathogen and the etiological agent of severe pneumonia known as Legionnaires' disease. Its virulence depends on protein secretion systems, in particular, the Dot/Icm type IV secretion system (T4SS), which is essential to establish a replication-permissive vacuole in macrophages. The analysis of the role of these systems and their substrates for pathogenesis requires easy-to-use models which approximate human infection. We examined the effectiveness of the larvae of the wax moth Galleria mellonella as a new model for L. pneumophila infection. We found that the L. pneumophila strains 130b, Paris, and JR32 caused mortality of the G. mellonella larvae that was strain, infectious dose, growth phase, and T4SS dependent. Wild-type L. pneumophila persisted and replicated within the larvae, whereas T4SS mutants were rapidly cleared. L. pneumophila strain Lp02, which is attenuated in the absence of thymidine but has a functional T4SS, resisted clearance in G. mellonella up to 18 h postinfection without inducing mortality. Immunofluorescence and transmission electron microscopy revealed that L. pneumophila resided within insect hemocytes in a vacuole that ultrastructurally resembled the Legionella-containing vacuole (LCV) observed in macrophages. The vacuole was decorated with the T4SS effector and LCV marker SidC. Infection caused severe damage to the insect organs and triggered immune responses, including activation of the phenoloxidase cascade leading to melanization, nodule formation, and upregulation of antimicrobial peptides. Taken together, these results suggest that G. mellonella provides an effective model to investigate the interaction between L. pneumophila and the host.