灿烂弧菌是海水养殖动物的重要病原菌，其致病性依赖密度感应，干扰密度感应致使菌体致病力降低60%。密度感应调控sRNA-Qrr是关键调控因子，其对LuxR的精细调控是密度感应的关键过程。因此解析灿烂弧菌3个Qrr介导的致病通路是揭示灿烂弧菌致病的关键所在，也是解决由该菌引起的水产病害的迫切需求。基于此，本项目在不同菌体密度和铁离子浓度下，分析Qrr在野生型、突变株∆fur和∆luxO中的差异表达，解析Fur或Fur-Fe2+分别对Qrr和LuxO启动子的调控及Fur与LuxO对Qrr启动子的竞争调控，阐明菌体密度和铁复合调控Qrr的机制；通过对Qrr单、双和三突变体中luxR的差异表达分析，剖析Qrr调控LuxR的模式，以金属蛋白酶和LD50为指标评价Qrr调控LuxR介导的致病力。研究将揭示灿烂弧菌中Qrr介导密度感应的致病机制，并为将来设计特异高效的灿烂弧菌抑制剂提供潜在的靶位点。

Vibrio splendidus is an important pathogen to many aquaculture animals, and its virulence relay on quorum sensing, and disturbance of quorum sensing regulatory could reduce 60% of its virulence. The quorum regulatory sRNA Qrr is the key factor of the quorum sensing, and its regulation on LuxR is also an important process. So the virulence pathway mediated by the three Qrrs in V. splendidus is the key to illustrate the virulence of V. splendidus, and can also meet the urgent need for the solution to the aquaculture disease caused by V. splendidus. .Based on this bacground, we intend to fix the high and low iron condition at different cell densities, and measure the expressions of each qrr in the wild type, and the mutant strains ∆fur and ∆luxO; to illustrate the mechanism on the Qrr expression regulated by cell density and iron, binding of Fur or Fur-Fe2+ on the promoter regions of Qrr and LuxO, and the competition between Fur and LuxO on the Qrr promoter will be determined; the expressions of luxR in the single, double and triple mutants will be measured to illustrate the modulate mode of Qrr on LuxR, and the virulence factor metalloprotease Vsm and LD50 will be used as indicators to reflect the virulence mediated by Qrr and LuxR. The result of the study is expected to reveal the virulence mediated by Qrr, and also to offer the potential targets for the development of specific and efficient inhibition regents for V. splendidus.