Fisheries College, Jimei University, Xiamen, Fujian, 361021, China.
Key Laboratory of Aquatic Functional Feed and Environmental Regulation of Fujian Province, Fujian Dabeinong Aquatic Sci. & Tech. Co., Ltd., Zhangzhou, Fujian, 363503, China.
Fish Shellfish Immunol. 2023 Jan;132:108512. doi: 10.1016/j.fsi.2022.108512. Epub 2022 Dec 30.
As a pathogen of cultured teleosts, Pseudomonas plecoglossicida has caused significant economic losses. flgC plays an important role in encoding flagellar basal-body rod proteins. Our previous studies revealed the high expression of P. plecoglossicida flgC in infected Epinephelus coioides. To explore the role of flgC in the virulence of P. plecoglossicida and the immune response of E. coioides to the infection of P. plecoglossicida, flgC gene of P. plecoglossicida was knocked down by RNA interference (RNAi). The results showed that the flgC gene in all four mutants of P. plecoglossicida was significantly knocked down, and the mutant with the best knockdown efficiency of 94.3% was selected for subsequent studies. Compared with the NZBD9 strain of P. plecoglossicida, the flgC-RNAi strain showed a significantly decrease in chemotaxis, motility, adhesion, and biofilm formation. Furthermore, compared with the E. coioides infected with the NZBD9 strain, the infection of flgC-RNAi strain resulted in the infected E. coioides a 1.5-day delay in the time of first death and an 80% increase in survival rate, far fewer white nodules upon the spleen surfaces, and lower pathogen load in the spleens. RNAi of flgC significantly influenced the metabolome and transcriptome of the spleen in infected E. coioides. KEGG enrichment analysis exhibited that the Toll-like receptor signaling pathway was the most enriched immune pathway; the most significantly enriched metabolic pathways were associated with Linoleic acid metabolism, Choline metabolism in cancer, and Glycerophospholipid metabolism. Further combined analysis of transcriptome and metabolome indicated significant correlations among pantothenate and CoA biosynthesis, beta-alanine metabolism, lysosome metabolites, and related genes. These results suggested that flgC was a pathogenic gene of P. plecoglossicida; flgC was associated with the regulation of chemotaxis, motility, biofilm formation, and adhesion; flgC influenced the immune response of E. coioides to the infection of P. plecoglossicida.
作为养殖鱼类的病原体，鮰爱德华氏菌已造成重大经济损失。flgC 在编码鞭毛基体杆状蛋白中发挥重要作用。我们之前的研究表明，在感染的杂交石斑鱼中，鮰爱德华氏菌 flgC 高度表达。为了探讨 flgC 在鮰爱德华氏菌毒力和石斑鱼对鮰爱德华氏菌感染的免疫反应中的作用，我们通过 RNA 干扰（RNAi）敲低了鮰爱德华氏菌 flgC 基因。结果表明，所有 4 株鮰爱德华氏菌突变株的 flgC 基因均显著敲低，敲低效率最高达 94.3%的突变株被选为后续研究。与鮰爱德华氏菌 NZBD9 株相比，flgC-RNAi 株的趋化性、运动性、黏附性和生物膜形成能力显著降低。此外，与感染 NZBD9 株的石斑鱼相比，感染 flgC-RNAi 株的石斑鱼首次死亡时间延迟 1.5 天，存活率提高 80%，脾脏表面白色结节更少，脾脏中的病原体载量更低。flgC 的 RNAi 显著影响了感染石斑鱼脾脏的代谢组和转录组。KEGG 富集分析显示，Toll 样受体信号通路是最富集的免疫通路；最显著富集的代谢途径与亚油酸代谢、癌症中的胆碱代谢和甘油磷脂代谢有关。转录组和代谢组的进一步联合分析表明，泛酸和辅酶 A 生物合成、β-丙氨酸代谢、溶酶体代谢物和相关基因之间存在显著相关性。这些结果表明，flgC 是鮰爱德华氏菌的致病基因；flgC 与趋化性、运动性、生物膜形成和黏附的调节有关；flgC 影响了石斑鱼对鮰爱德华氏菌感染的免疫反应。
