Deletion of the Major Facilitator Superfamily Transporter fptB Alters Host Cell Interactions and Attenuates Virulence of Type A Francisella tularensis.
Deletion of the Major Facilitator Superfamily Transporter fptB Alters Host Cell Interactions and Attenuates Virulence of Type A Francisella tularensis.
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DOI：
10.1128/iai.00832-17
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发表时间：
2018-03
影响因子：
3.1
通讯作者：
Barry EM
中科院分区：
文献类型：
--
作者：
Balzano PM;Cunningham AL;Grassel C;Barry EM
土拉弗朗西斯菌是一种革兰氏阴性、兼性、细胞内球杆菌，可以感染多种宿主。在人类中，土拉菌 F. tularensis 通过昆虫叮咬、摄入、吸入和处理受感染的动物而引起人畜共患土拉菌病。事实上，通过气溶胶途径输送的非常小的接种物就可以引起严重的疾病，再加上其用作气雾化生物武器的可能性，导致土拉弗朗西斯菌被分类为 A 类选择剂，并重新引起了人们对疫苗配制的兴趣。为此，我们设计了 A 型菌株 SchuS4 衍生物，其中包含主要易化子超家族 (MFS) 转运蛋白 fptB 的定向删除。基于该缺失在土拉弗朗西斯 LVS 背景中的减毒能力，我们假设该转运蛋白的缺失将改变 A 型菌株的细胞内复制和细胞因子诱导，并减弱严格的 C57BL/6J 小鼠模型中的毒力。在这里，我们证明 fptB 的缺失显着改变了 F. tularensis 的细胞内生命周期，减弱了细胞系来源的巨噬细胞和原代巨噬细胞的细胞内复制，并诱导了一种新的胞质逃逸延迟。此外，我们观察到人巨噬细胞样细胞的体外细胞因子谱存在显着差异。该突变体在 C57BL/6J 小鼠模型中高度减毒，并针对 A 型土拉热镰刀菌的强毒力攻击提供部分保护。这些结果表明，这种营养转运蛋白对于土拉弗拉菌的复制周期和发病机制的及时进展至关重要。
Francisella tularensis is a Gram-negative, facultative, intracellular coccobacillus that can infect a wide variety of hosts. In humans, F. tularensis causes the zoonosis tularemia following insect bites, ingestion, inhalation, and the handling of infected animals. The fact that a very small inoculum delivered by the aerosol route can cause severe disease, coupled with the possibility of its use as an aerosolized bioweapon, has led to the classification of Francisella tularensis as a category A select agent and has renewed interest in the formulation of a vaccine. To this end, we engineered a type A strain SchuS4 derivative containing a targeted deletion of the major facilitator superfamily (MFS) transporter fptB. Based on the attenuating capacity of this deletion in the F. tularensis LVS background, we hypothesized that the deletion of this transporter would alter the intracellular replication and cytokine induction of the type A strain and attenuate virulence in the stringent C57BL/6J mouse model. Here we demonstrate that the deletion of fptB significantly alters the intracellular life cycle of F. tularensis, attenuating intracellular replication in both cell line-derived and primary macrophages and inducing a novel cytosolic escape delay. Additionally, we observed prominent differences in the in vitro cytokine profiles in human macrophage-like cells. The mutant was highly attenuated in the C57BL/6J mouse model and provided partial protection against virulent type A F. tularensis challenge. These results indicate a fundamental necessity for this nutrient transporter in the timely progression of F. tularensis through its replication cycle and in pathogenesis.