Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Ghent, Belgium.
PLoS One. 2012;7(7):e41788. doi: 10.1371/journal.pone.0041788. Epub 2012 Jul 25.
Vibrio harveyi is amongst the most important bacterial pathogens in aquaculture. Novel methods to control this pathogen are needed since many strains have acquired resistance to antibiotics. We previously showed that quorum sensing-disrupting furanones are able to protect brine shrimp larvae against vibriosis. However, a major problem of these compounds is that they are toxic toward higher organisms and therefore, they are not safe to be used in aquaculture. The synthesis of brominated thiophenones, sulphur analogues of the quorum sensing-disrupting furanones, has recently been reported. In the present study, we report that these compounds block quorum sensing in V. harveyi at concentrations in the low micromolar range. Bioluminescence experiments with V. harveyi quorum sensing mutants and a fluorescence anisotropy assay indicated that the compounds disrupt quorum sensing in this bacterium by decreasing the ability of the quorum sensing master regulator LuxR to bind to its target promoter DNA. In vivo challenge tests with gnotobiotic brine shrimp larvae showed that thiophenone compound TF310, (Z)-4-((5-(bromomethylene)-2-oxo-2,5-dihydrothiophen-3-yl)methoxy)-4-oxobutanoic acid, completely protected the larvae from V. harveyi BB120 when dosed to the culture water at 2.5 µM or more, whereas severe toxicity was only observed at 250 µM. This makes TF310 showing the highest therapeutic index of all quorum sensing-disrupting compounds tested thus far in our brine shrimp model system.
哈维弧菌是水产养殖中最重要的细菌性病原体之一。由于许多菌株已经对抗生素产生了耐药性，因此需要新的方法来控制这种病原体。我们之前曾表明，群体感应破坏呋喃酮能够保护卤虫幼虫免受弧菌病的侵害。然而，这些化合物的一个主要问题是它们对高等生物有毒，因此在水产养殖中不安全。最近已经报道了群体感应破坏呋喃酮的溴代噻吩酮的合成。在本研究中，我们报告这些化合物以低微摩尔浓度阻断哈维弧菌的群体感应。哈维弧菌群体感应突变体的生物发光实验和荧光各向异性测定表明，这些化合物通过降低群体感应主调节剂 LuxR 与靶启动子 DNA 结合的能力来破坏该细菌的群体感应。用无菌卤虫幼虫进行的体内挑战测试表明，噻吩酮化合物 TF310，（Z）-4-((5-(溴亚甲基)-2-氧代-2,5-二氢噻吩-3-基)甲氧基)-4-氧代丁酸，当以 2.5 µM 或更高的剂量添加到培养液中时，完全保护幼虫免受 BB120 哈维弧菌的侵害，而在 250 µM 时仅观察到严重毒性。这使得 TF310 在我们的卤虫模型系统中测试的所有群体感应破坏化合物中显示出最高的治疗指数。
