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.
Fish Shellfish Immunol. 2020 Jun;101:192-197. doi: 10.1016/j.fsi.2020.03.028. Epub 2020 Mar 19.
Edwardsiella piscicida (E. piscicida) is an important zoonotic pathogen that infects fish by colonizing the intestines. The intestine provides nutrition including Glucose 6-phosphate (Glu6P) and a competitive environment for the microbiota. Although the transport system regulatory protein gene uhpA has been reported in E. piscicida genomes, whether the uhpA gene is involved in the pathogenicity of E. piscicida remains largely unknown. Therefore, the uhpA gene mutants strain E. piscicida ΔuhpA was constructed to elucidate the functions of Glu6P and the uhpA gene in E. piscicida. The results demonstrated that Glu6P significantly increased the gene expression of uhpC/uhpB/uhpA than without adding Glu6P in the culture. The gene expression of uhpC and uhpB was down regulated in the mutant strain than that of in the wild type strain. E. piscicida ΔuhpA exhibited an increase in virulence compared to that of E. piscicida EIB202 [LD value: (3.98 × 10 CFU/fish) and LD value: (1.45 × 10 CFU/fish) respectively]. Besides, although TNF-α did not show significant differences (p > 0.05) in the spleen of tilapia infected with ΔuhpA and EIB202 in the whole observed period, the gene expression of IL-1β and TGF-β in the spleen of tilapia infected with ΔuhpA showed significantly higher (p < 0.05) than that of in tilapia infected with EIB202. Meanwhile, the gene expression of IL-1β and TGF-β in spleen of tilapia infected with ΔuhpA showed significantly higher (p < 0.05) than that of in fish infected with EIB202 when zebrafish used as the control in the whole observed period. All these results suggested that Glu6P up-regulated the gene expression of uhpC/uhpB/uhpA; most important, the uhpA gene deletion in E. piscicida down-regulated the gene expression of uhpC and uhpB, enhanced its pathogenicity and its role in inducing the inflammatory cytokine responses in tilapia.
杀鲑爱德华菌（E. piscicida）是一种重要的人畜共患病病原体，通过定植于肠道感染鱼类。肠道为微生物群提供包括葡萄糖 6-磷酸（Glu6P）在内的营养物质和竞争环境。尽管已在杀鲑爱德华氏菌基因组中报道了运输系统调控蛋白基因 uhpA，但 uhpA 基因是否参与杀鲑爱德华氏菌的致病性在很大程度上仍不清楚。因此，构建了杀鲑爱德华氏菌 uhpA 基因缺失突变株 E. piscicida ΔuhpA，以阐明 Glu6P 和 uhpA 基因在杀鲑爱德华氏菌中的功能。结果表明，与不添加 Glu6P 相比，在培养物中 Glu6P 显著增加了 uhpC/uhpB/uhpA 的基因表达。与野生型菌株相比，突变株中 uhpC 和 uhpB 的基因表达下调。与杀鲑爱德华氏菌 EIB202 相比，E. piscicida ΔuhpA 的毒力增加[LD 值：（3.98×10 CFU/鱼）和 LD 值：（1.45×10 CFU/鱼）]。此外，尽管在整个观察期内，感染 ΔuhpA 和 EIB202 的罗非鱼脾脏中 TNF-α 没有显著差异（p>0.05），但感染 ΔuhpA 的罗非鱼脾脏中 IL-1β 和 TGF-β 的基因表达显著高于感染 EIB202 的罗非鱼（p<0.05）。同时，在整个观察期内，当使用斑马鱼作为对照时，感染 ΔuhpA 的罗非鱼脾脏中 IL-1β 和 TGF-β 的基因表达显著高于感染 EIB202 的鱼（p<0.05）。所有这些结果表明，Glu6P 上调了 uhpC/uhpB/uhpA 的基因表达；最重要的是，杀鲑爱德华氏菌中 uhpA 基因的缺失下调了 uhpC 和 uhpB 的基因表达，增强了其致病性及其在诱导罗非鱼炎症细胞因子反应中的作用。
