Abstract：
Pseudomonas plecoglossicida is a vital pathogen that poses a substantial risk to aquaculture. Small RNAs (sRNAs) are non-coding regulatory molecules capable of sensing environmental changes and modulating virulence-associated signaling pathways, such as the assembly of flagella. However, the relevant researches on P. plecoglossicida are an urgent need. Here, we report a novel sRNA, sRNA562, which has potential to regulate the post-transcriptional of fliP, a key component of the lateral flagellar type III secretion system. In this study, the effects of sRNA562 on the virulence of P. plecoglossicida and its role in regulating the pathogenic process were investigated through the use of a constructed sRNA562 deletion strain. The deletion of sRNA562 resulted in an up-regulation of fliP in P. plecoglossicida, and leading to increased swarming motility and enhanced the ability of biofilm formation, adhesion and chemotaxis. Subsequent artificial infection experiment demonstrated that the deletion of sRNA562 increased the virulence of P. plecoglossicida towards hybrid grouper, as evidenced by a reduction in survival rate, elevation of tissue bacterial load, and the exacerbation of histopathological damage. Further studies have found that the deletion of sRNA562 lead to an up-regulation of fliP expression during hybrid grouper infection, thereby enhancing bacterial swarming ability and ultimately heightening pathogenicity, leading to a dysregulated host response to infection, tissue damage and eventually death. Our work revealed a sRNA that exerts negative regulation on the expression of lateral flagella in P. plecoglossicida, thereby impacting its virulence. These findings provide a new perspective on the virulence regulation mechanism of P. plecoglossicida, contributing to a more comprehensive understanding in the field of pathogenicity research.
摘要：
斑纹假单胞菌是一种重要的病原体，对水产养殖构成重大风险。小RNA(sRNAs)是能够感知环境变化和调节毒力相关信号通路的非编码调节分子,如鞭毛的组装。然而,迫切需要对P.plecoglossicida的相关研究。这里,我们报告了一种新的sRNA,sRNA562，它有可能调节FLIP的转录后，外鞭毛III型分泌系统的关键组成部分。在这项研究中,通过构建的sRNA562缺失株，研究了sRNA562对P.plecoglossicida毒力的影响及其在调节致病过程中的作用。sRNA562的缺失导致P.plecoglossicida中fliP的上调，并导致蜂群运动增加并增强生物膜形成的能力，粘附和趋化性。随后的人工感染实验表明，sRNA562的缺失增加了P.plecoglossicida对杂种石斑鱼的毒力，存活率下降证明了这一点，组织细菌负荷的升高，以及组织病理学损害的恶化。进一步的研究发现，在杂交石斑鱼感染过程中，sRNA562的缺失导致fliP表达上调，从而增强细菌聚集能力，最终提高致病性，导致宿主对感染的反应失调，组织损伤并最终死亡。我们的工作揭示了一种sRNA，该sRNA对P.plecoglossicida中外侧鞭毛的表达具有负调控作用，从而影响其毒力。这些发现为P.plecoglossicida的毒力调控机制提供了新的视角，有助于更全面地了解致病性研究领域。
