Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention & Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Taian, 271018, PR China.
Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention & Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Shandong Agricultural University, Taian, 271018, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 272000, PR China; Shandong Key Laboratory of Disease Control in Mariculture, Marine Biology Institute of Shandong Province, Qingdao, 266104, PR China.
Fish Shellfish Immunol. 2020 Sep;104:587-591. doi: 10.1016/j.fsi.2020.05.065. Epub 2020 May 26.
Edwardsiella piscicida (E. piscicida) is a significant bacterial pathogen of cultured fish, which infected fish meanly through the intestine. Glucose 6-phosphate (Glu6P) in the intestine is nutritious to the pathogen, Meanwhile, Glu6P was found using as a virulent regulating signal for bacteria. The UhpA, one of the Glu6P transport system regulatory proteins could down-regulate the uhpC/uhpB/uhpA system and decrease its pathogenicity. However, the motility and the colonization of E. piscicida affected by UhpA were still unclear. In this study, the motility and the colonization of E. piscicida were monitored. The result demonstrated that the motility of EIB202 was significantly stronger than that of in ΔuhpA according to fractions 4, 8 and 9. However, the motility of ΔuhpA was significantly stronger than that of EIB202 according to the total number at the whole experiment. Although, there was no difference in the number of bacteria in the posterior intestine of tilapia after infected with E. piscicida EIB202 and ΔuhpA. The number of bacteria in the anterior and the middle intestine of fish infected with ΔuhpA were significantly higher than that of in fish infected with EIB202 at the whole experiment (P < 0.05). Interestingly, both E. piscicida strains colonized in the anterior intestine than that of in the middle and posterior intestines of tilapia. Besides, the gene expression of IL-1β and TNF-α in the head-kidney of fish infected with ΔuhpA showed significantly higher (p < 0.05) than fish infected with EIB202 during the whole experimental period. Most importantly, the survival rate of E. piscicida EIB202 and ΔuhpA were 57% and 37% respectively. All results indicate that the uhpA gene mutant in E. piscicida could enhance its motility and the colonization in the intestine of tilapia, this illustrates the mechanism of UhpA decreases the pathogenesis of E. piscicida in fish.
爱德华氏菌（E. piscicida）是一种重要的养殖鱼类细菌性病原体，主要通过肠道感染鱼类。肠道中的葡萄糖 6-磷酸（Glu6P）对病原体具有营养作用，同时，Glu6P 被发现作为细菌的毒力调节信号。UhpA 是 Glu6P 运输系统调节蛋白之一，可下调 uhpC/uhpB/uhpA 系统并降低其致病性。然而，UhpA 对爱德华氏菌的运动性和定植能力的影响尚不清楚。在本研究中，监测了爱德华氏菌的运动性和定植能力。结果表明，根据第 4、8 和 9 部分，EIB202 的运动性明显强于 ΔuhpA。然而，在整个实验中，ΔuhpA 的运动性明显强于 EIB202。尽管如此，感染 E. piscicida EIB202 和 ΔuhpA 后，罗非鱼后肠中的细菌数量没有差异。在整个实验过程中，感染 ΔuhpA 的鱼的前肠和中肠中的细菌数量明显高于感染 EIB202 的鱼（P < 0.05）。有趣的是，两种爱德华氏菌菌株在前肠中的定植能力均强于中肠和后肠。此外，在整个实验期间，感染 ΔuhpA 的鱼的头肾中 IL-1β 和 TNF-α 的基因表达明显更高（p < 0.05）。最重要的是，E. piscicida EIB202 和 ΔuhpA 的存活率分别为 57%和 37%。所有结果表明，爱德华氏菌中的 uhpA 基因突变可增强其在罗非鱼肠道中的运动性和定植能力，这说明了 UhpA 降低爱德华氏菌在鱼类中致病性的机制。
