Regulation of Staphylococcus aureus biofilm by Rbf

描述(由申请人提供)：葡萄球菌是医院获得性感染的主要病原体。金黄色葡萄球菌可引起皮肤、骨骼、心脏瓣膜、血液和肺部感染，导致心内膜炎、骨髓炎和肺炎等严重疾病，而表皮葡萄球菌主要引起异物感染。长期以来，生物膜的形成一直被认为是表皮葡萄球菌的主要毒力因素，最近被认为在金黄色葡萄球菌引起的心内膜炎、骨髓炎和留置器械相关性感染中发挥了关键作用。生物膜是附着在固体表面的微生物群落，通常对抗生素和宿主免疫防御机制具有高度抵抗力，因此有助于疾病的持久性。葡萄球菌生物被膜的形成机制在很大程度上尚不清楚，仍有许多有待深入研究。最近，我们已经发现并初步鉴定了一种新的调节剂--RBF，它能积极地调节金黄色葡萄球菌生物膜的形成。我们证明了RBF在不同菌株中影响生物膜的形成，并影响到许多靶基因。我们还发现，RBF受AGR和SIGB两种调节因子的调节，在小鼠异物感染模型中是促进细菌持久性的重要毒力因子。在这项应用中，我们建议通过实现四个特定目标来继续我们的研究：(1)研究RBF基因座的分子结构并分析RBF在异物感染小鼠模型中的表达；(2)通过蛋白质组和微阵列方法确定RBF靶基因，并研究RBF对靶基因的调控机制；(3)研究已知调控因子agr和SIGB对RBF的调控作用，并找出其他影响RBF表达的基因；(4)利用小鼠败血症关节炎生物膜相关模型，研究RBF在天然组织感染中的作用。由于抗生素耐药菌株的出现，葡萄球菌感染变得更加难以治疗。此外，即使使用有效的抗生素，生物膜中形成生物膜的细菌也将受到保护，免受治疗。从分子水平上了解生物膜的形成及其调控机制将有助于对生物膜相关感染发病机制的新认识，从而为治疗生物膜相关葡萄球菌疾病提供新的治疗策略。

DESCRIPTION (provided by applicant): Staphylococcus is a leading causative agent for hospital-acquired infections. S. aureus can cause skin, bone, heart valve, blood, and lung infection resulting in severe diseases such as endocarditis, osteomyelitis and pneumonia, while S. epidermidis mainly causes foreign body infections. Biofilm formation has long been recognized as the major virulence factor for S. epidermidis and has been recently implicated to play a key role in endocarditis, osteomyelitis and indwelling device associated infections caused by S. aureus. Biofilm, a community of microorganisms attached to a solid surface, is generally highly resistant to antibiotics and host immune defense mechanisms and therefore contributes to persistence of diseases. The mechanism of biofilm formation in staphycococci is largely unknown and much remains to be explored. Recently, we have identified and initially characterized a novel regulator, Rbf, which positively regulates biofilm formation in S. aureus. We demonstrated that Rbf affected biofilm formation in various strains and it affected many target genes. We also showed that rbf was regulated by two regulators, agr and sigB, and was an important virulence factor in promoting bacterial persistence in a mouse foreign body infection model. In this application we propose to continue our studies by accomplishing four specific aims: (1) to study the molecular architecture of the rbf locus and to analyze rbf expression in the murine model of foreign body infection; (2) to identify the rbf target genes by proteomic and microarray approaches and to study the mechanism of target gene regulation by rbf; (3) to study regulation of rbf by known regulators, agr and sigB, and to identify additional genes affect Rbf expression; (4) to investigate the role of Rbf in native tissue infection using a biofilm relevant model of septic arthritis in mice. Staphylococcal infections have become more difficult to treat due to the emergence of antibiotic resistance strains. Moreover, bacteria that form biofilm will be protected in the biofilm from treatments even with effective antibiotics. Understanding biofilm formation and its regulation at the molecular level will contribute to new knowledge on the mechanisms of pathogenesis of biofilm-associated infecitons, which will lead to the development of novel therapeutic strategies for treating biofilm-related Staphylococcal diseases.