Vibrio harveyi is an opportunistic Gram-negative pathogen that threatens future development of global aquaculture as well as human health. In this study, to gain insight into virulence regulation of cqsA in V. harveyi, a ΔcqsA mutant strain and complementation of the ΔcqsA mutant (C-cqsA) were constructed and phenotypically characterized. Deletion of cqsA led to enhanced mobility, iron absorption, resistance to H₂O₂, and biofilm formation ability, and reduced the ability to secrete extracellular proteases. In addition, pearl gentian grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatu) challege experiment was conducted to observe the changes in virulence at the absence of cqsA in V. harveyi. The results showed that the cumulative mortalities of the pearl gentian grouper challenged with the ΔcqsA⁺ mutant by intraperitoneal injection reached 91.67%, which was significantly higher than that of wild-type (WT⁺) (41.67%) and C-cqsA (41.67%) strains. Deletion of cqsA also resulted in a significant increase in the ability of V. harveyi to colonize the spleen and liver of the pearl gentian grouper simultaneously. Meanwhile, the early expression levels of immune-related genes of the pearl gentian grouper in the ΔcqsA⁺ mutant group, including TNF-α, IL-1β, MHC-Iα, IL-16, and IgM were up-regulated post-challenge, indicating that the ΔcqsA⁺ mutant may hijack the immune signaling pathway and cause early overexpression of some host immune-related genes. The expression levels of the V. harveyi virulence-associated genes flaA, flaC, fliA, fliS, cheR, lafA, aphA, and fur were up-regulated, while vhh and hapR were down-regulated. Collectively, these findings point to broad regulatory functions of cqsA in V. harveyi cells, which likely underlie an important role in pathogenicity.

哈维氏弧菌是机会性革兰氏阴性菌，威胁全球水产养殖的未来发展以及人类健康。在这项研究中，以深入了解的毒力调节cqsA在哈氏弧菌，一个Δ cqsA的Δ的突变菌株和互补cqsA突变体（C- cqsA）构建和表型表征。cqsA的删除导致增加的迁移率，铁吸收，对H ₂ O _2的抵抗力和生物膜形成能力，并降低了分泌细胞外蛋白酶的能力。此外，珍珠龙胆石斑鱼（♀Epinephelus fuscoguttatus ×♂石斑鱼lanceolatu）的质疑进行实验在没有观察的毒力的变化cqsA在哈氏弧菌。结果表明，经腹腔注射ΔcqsA ⁺突变体攻击的珍珠龙胆石斑鱼的累积死亡率达到91.67％，显着高于野生型（WT ⁺）（41.67％）和C- cqsA（41.67）。 ％）株。删除cqsA还导致哈氏弧菌的能力大大提高同时定居珍珠龙胆石斑鱼的脾脏和肝脏。同时，在攻击后，ΔcqsA ⁺突变组的珍珠龙胆石斑鱼免疫相关基因的早期表达水平被上调，包括TNF-α，IL-1β，MHC-Iα，IL-16和IgM。 ，表明ΔcqsA ⁺突变体可能劫持了免疫信号通路，并导致某些宿主免疫相关基因的早期过表达。哈氏弧菌毒力相关基因flaA，flaC，fliA，fliS，cheR，lafA，aphA和fur的表达水平被上调，而vhh和hapR被下调。总的来说，这些发现表明cqsA在哈维螺旋藻细胞中具有广泛的调控功能，这可能是在致病性中起重要作用的基础。