Soto Esteban, Yun Susan, Lewis Jainee, Kearney Michael T, Hansen John
University of California-Davis, Department of Medicine and Epidemiology, School of Veterinary Medicine, Davis, CA 95616, USA.
University of California-Davis, Department of Medicine and Epidemiology, School of Veterinary Medicine, Davis, CA 95616, USA.
Microb Pathog. 2017 Apr;105:326-333. doi: 10.1016/j.micpath.2017.03.003. Epub 2017 Mar 7.
Francisella noatunensis subsp. orientalis (Fno) (syn. F. asiatica) is an emergent warmwater fish pathogen and the causative agent of piscine francisellosis. Although Fno causes septicemia and can live extracellularly in infected tilapia (Oreochromis spp.), the early interaction of Fno with vasculature endothelium is unknown. In the present study, we examined the interaction of wild-type Fno (WT) and two Fno knockout [intracellular growth loci C (ΔiglC) and pathogenicity determinant protein A (ΔpdpA)] strains with the endothelial O. mossambicus bulbus arteriosus cell line (TmB) at 25 °C and 30 °C. Similar amounts of WT, ΔiglC, and ΔpdpA attached and were detected intracellularly after 5 h of incubation at both temperatures; however temperature affected attachment and uptake. While significantly greater amounts of Fno (WT, ΔiglC, and ΔpdpA) were detected intracellularly when TmB cells were incubated at 30 °C, bacteria attached to TmBs at greater levels at 25 °C. Only WT Fno was able to replicate intracellularly at 25 °C, which resulted in Fno mediated cytotoxicity and apoptosis at 24 and 72 h post-infection. WT Fno incubated at 30 °C as well as ΔiglC, and ΔpdpA incubated at 25 °C and 30 °C were all defective for survival, replication, and the ability to cause cytotoxicity in TmB. Taken together, these results demonstrate that temperature plays a vital role for Fno intracellular survival, persistence and cytotoxicity.
东方诺卡氏弗朗西斯菌亚种（Fno）（同义词：亚洲弗朗西斯菌）是一种新出现的温水鱼类病原体，也是鱼类弗朗西斯菌病的病原体。尽管Fno可引起败血症，并且能够在受感染的罗非鱼（尼罗罗非鱼属）细胞外存活，但Fno与血管内皮的早期相互作用尚不清楚。在本研究中，我们检测了野生型Fno（WT）以及两个Fno基因敲除株[细胞内生长位点C（ΔiglC）和致病性决定蛋白A（ΔpdpA）]在25℃和30℃下与莫桑比克罗非鱼动脉球内皮细胞系（TmB）的相互作用。在这两个温度下孵育5小时后，检测到WT、ΔiglC和ΔpdpA的附着量和细胞内含量相似；然而，温度会影响附着和摄取。当TmB细胞在30℃下孵育时，细胞内检测到的Fno（WT、ΔiglC和ΔpdpA）量显著更多，但在25℃下，细菌与TmB的附着水平更高。只有野生型Fno能够在25℃下在细胞内复制，这导致在感染后24小时和72小时出现Fno介导的细胞毒性和细胞凋亡。在30℃下孵育的野生型Fno以及在25℃和30℃下孵育的ΔiglC和ΔpdpA在TmB中的存活、复制和引起细胞毒性的能力均存在缺陷。综上所述，这些结果表明温度对Fno在细胞内的存活、持续存在和细胞毒性起着至关重要的作用。
