Survival and growth of Francisella tularensis in Acanthamoeba castellanii
Survival and growth of Francisella tularensis in Acanthamoeba castellanii
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土拉弗氏菌在蓖麻棘球蚴中的存活和生长
DOI：
10.1128/aem.69.1.600-606.2003
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发表时间：
2003-01-01
影响因子：
4.4
通讯作者：
Forsman, M
中科院分区：
文献类型：
--
作者：
Abd, H;Johansson, T;Forsman, M
土拉热弗朗西丝菌是一种高度传染性的兼性细胞内细菌，其在人类和哺乳动物中定期引起土拉菌病的流行。尽管推测可能存在于原生动物中，但这种细菌的自然宿主在很大程度上是未知的。土拉热菌工程化以在营养丰富的培养基中产生绿色荧光蛋白（GFP）。A.然后通过流式细胞术和荧光显微术监测Castellanii。此外，通过用单克隆抗体靶向细胞外细菌来区分细胞内细菌。电镜观察F. tularensis在A. Castellanii，并获得细胞外和细胞内细菌的活菌计数。结果表明，F. tularensis细胞位于A.卡氏细胞细菌在细胞内空泡内繁殖，最终杀死了许多宿主细胞。F.在完整的滋养体、排泄囊泡和包囊中发现土拉热病。此外，F. tularensis在与A. Castellanii比单独在相同培养基中生长时的效果更好。这种增长伴随着A数量的减少。卡氏细胞F.土拉原虫和阿米巴原虫的研究表明，普遍存在的原生动物可能是F.土拉热。
Francisella tularensis is a highly infectious, facultative intracellular bacterium which causes epidemics of tularemia in both humans and mammals at regular intervals. The natural reservoir of the bacterium is largely unknown, although it has been speculated that protozoa may harbor it. To test this hypothesis, Acanthamoeba castellanii was cocultured with a strain of F. tularensis engineered to produce green fluorescent protein (GFP) in a nutrient-rich medium. GFP fluorescence within A. castellanii was then monitored by flow cytometry and fluorescence microscopy. In addition, extracellular bacteria were distinguished from intracellular bacteria by targeting with monoclonal antibodies. Electron microscopy was used to determine the intracellular location of F. tularensis in A. castellanii, and viable counts were obtained for both extracellular and intracellular bacteria. The results showed that many F. tularensis cells were located intracellularly in A. castellanii cells. The bacteria multiplied within intracellular vacuoles and eventually killed many of the host cells. F. tularensis was found in intact trophozoites, excreted vesicles, and cysts. Furthermore, F. tularensis grew faster in cocultures with A. castellanii than it did when grown alone in the same medium. This increase in growth was accompanied by a decrease in the number of A. castellanii cells. The interaction between F. tularensis and amoebae demonstrated in this study indicates that ubiquitous protozoa might be an important environmental reservoir for F. tularensis.