Fisheries College, Jimei University, Xiamen, Fujian, 361021, China.
College of Environment and Public Health, Xiamen Huaxia University, Xiamen, Fujian, 361024, China.
Fish Shellfish Immunol. 2023 Sep;140:108971. doi: 10.1016/j.fsi.2023.108971. Epub 2023 Jul 20.
Pseudomonas plecoglossicida is a pathogen that causes visceral white spot disease in a variety of teleosts. The protein encoded by fliP gene is involved in the assembly of bacterial flagella, which plays a vital role in bacterial pathogenicity. However, the roles of the fliP gene on the host immune response remain unclear. Here, we compared the pathogenicity of fliP gene-deleted (ΔfliP) strain, fliP gene-complemented (C-ΔfliP) strain and wild-type (NZBD9) strain of P. plecoglossicida to hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂), and explored the impacts of fliP gene on the immune response of hybrid grouper to P. plecoglossicida infection by using RNA-seq. In this study, the grouper in the ΔfliP strain-infected group had a 30% higher survival rate than those in the NZBD9 strain-infected group. In addition, the deletion of fliP gene decreased bacterial load in the spleen, intestine, liver as well as head kidney of hybrid grouper and the tissues damage were weakened. Moreover, the infection of hybrid grouper spleen by the ΔfliP strain induced 1,189 differential expression genes compared with the counterpart infected by NZBD9 strain. KEGG enrichment analysis showed that 9 immune-related pathways, 5 signal transduction pathways, and 3 signaling molecules and interaction pathways were significantly enriched. qRT-PCR analysis revealed that the ΔfliP strain mainly up-regulated the expression of inflammation related genes (IL-6, IL-12, IL-1β, IL-10, CXCL8, CXCL10) and immune regulation related genes (TLR2, P65, MyD88, P85, AKT), but down-regulated the expression of cell death related genes (FoxO1, Bim, PLK2 and LDHA) during infection. Based on the above results, fliP gene contributed to the pathogenicity of P. plecoglossicida to hybrid grouper (E. fuscoguttatus ♀ × E. lanceolatus ♂), deletion of fliP gene promoted the inflammation and immune response of hybrid grouper to P. plecoglossicida infection, which accelerating host clearance of pathogen and reducing tissue damages.
杀鲑气单胞菌是一种引起多种鱼类内脏白点病的病原体。 fliP 基因编码的蛋白参与细菌鞭毛的组装，在细菌致病性中起着至关重要的作用。然而， fliP 基因对宿主免疫反应的作用尚不清楚。在这里，我们比较了杀鲑气单胞菌 fliP 基因缺失（Δ fliP）株、 fliP 基因互补（C-Δ fliP）株和野生型（NZBD9）株对杂交石斑鱼（♀♀ × ♀♂）的致病性，并通过 RNA-seq 探讨了 fliP 基因对杂交石斑鱼对杀鲑气单胞菌感染的免疫反应的影响。在本研究中，感染 Δ fliP 株的石斑鱼存活率比感染 NZBD9 株的石斑鱼高 30%。此外， fliP 基因缺失降低了杂交石斑鱼脾脏、肠道、肝脏和头肾的细菌载量，减轻了组织损伤。此外，与感染 NZBD9 株相比，Δ fliP 株感染杂交石斑鱼脾脏诱导了 1189 个差异表达基因。KEGG 富集分析表明，有 9 条免疫相关途径、5 条信号转导途径和 3 条信号分子和相互作用途径显著富集。qRT-PCR 分析显示，Δ fliP 株主要上调炎症相关基因（IL-6、IL-12、IL-1β、IL-10、CXCL8、CXCL10）和免疫调节相关基因（TLR2、P65、MyD88、P85、AKT）的表达，但下调细胞死亡相关基因（FoxO1、Bim、PLK2 和 LDHA）的表达。基于上述结果， fliP 基因有助于杀鲑气单胞菌对杂交石斑鱼（♀♀ × ♀♂）的致病性， fliP 基因缺失促进了杂交石斑鱼对杀鲑气单胞菌感染的炎症和免疫反应，加速了宿主清除病原体并减少组织损伤。
