Prophage contribution to the virulence of Staphylococcus aureus

描述（由申请人提供）：金黄色葡萄球菌是一种重要的革兰氏阳性人类病原体，在医院和社区环境中引起多种人类疾病。这种细菌与原噬菌体的关系非常密切，因此很少能在大肠杆菌中发现这种细菌。不含前噬菌体的金黄色葡萄球菌分离物。在葡萄球菌中，β-溶血素（hlb）转化噬菌体是最成功的噬菌体;它存在于90%以上的临床分离的葡萄球菌中。金黄色。噬菌体编码多种毒力因子，如外毒素和免疫调节分子，可抑制人类先天免疫反应。然而，几条证据表明，葡萄球菌原噬菌体通过提供毒力因子以外的其他机制增加细菌毒力：1）在原噬菌体调节基因中插入转座子，而不是在毒力因子基因中插入转座子，减少了S。金黄色葡萄球菌杀死秀丽隐杆线虫; 2）虽然删除个别毒力基因编码的hlb转化噬菌体？在小鼠模型中，NM 3对葡萄球菌的毒力没有影响，缺失整个？NM 3的缺失降低了葡萄球菌的毒力; NM 3不仅消除了由染色体编码的重要毒力因子α毒素的产生，而且改变了胞外蛋白质谱。在这项研究计划中，我们测试的假设，即原噬菌体可以增加葡萄球菌的毒力，不仅通过提供毒力因子，但也通过改变细菌的基因表达。为了检验这一假设，我们将进行以下具体目标：1）确定？NM 3对细菌基因表达的影响; 2）确定参与细菌基因表达的遗传决定因素？NM 3介导的毒力增加和α-毒素表达的激活。这些研究的结果有可能改变我们目前对噬菌体在细菌发病机制中作用的看法，并促进我们对葡萄球菌发病机制的了解以及针对重要人类病原体的治疗剂的开发。公共卫生相关性：这项建议将如何确定β-溶血素转化噬菌体？NM 3增加金黄色葡萄球菌的致病潜力。这些研究结果将使我们了解前噬菌体在由沙门氏菌引起的疾病中的作用。金黄色葡萄球菌，以及我们如何使S.金黄色葡萄球菌通过阻断噬菌体贡献机制而更容易受到免疫应答的影响。

DESCRIPTION (provided by applicant): Staphylococcus aureus is an important gram-positive human pathogen causing a variety of human diseases in both hospital and community settings. This bacterium is so closely associated with prophages that it is rare to find S. aureus isolates without prophages. Of the staphylococcal phages, the beta-hemolysin (hlb)-converting phage is the most successful phage; it is found in more than 90% of clinical isolates of S. aureus. The phage encodes multiple virulence factors such as exotoxins and immune modulatory molecules, which can inhibit human innate immune responses. Several lines of evidence, however, suggest that staphylococcal prophages increase bacterial virulence by additional mechanisms other than providing virulence factors:1) Transposon insertion in prophage regulatory genes, but not in the genes for virulence factors, reduces S. aureus killing of Caenorhabditis elegans; 2) Although deletion of individual virulence genes encoded by the hlb-converting phage ?NM3 had no effect on the staphylococcal virulence in murine model, deletion of the entire ?NM3 reduced the staphylococcal virulence; 3) The deletion of ?NM3 not only abolished the production of alpha-toxin, an important virulence factor encoded by the chromosome, but also altered the extracellular protein profile. In this research proposal, we test the hypothesis that prophages can increase staphylococcal virulence not only by providing virulence factors but also by altering bacterial gene expression. To test the hypothesis, we will conduct the following specific aims: 1) Determine the global effects of ?NM3 on bacterial gene expression; and 2) Identify genetic determinants involved in the ?NM3-mediated virulence increase and activation of alpha-toxin expression. The results from these studies have the potential to change our current view on the role of phages in bacterial pathogenesis and facilitate our understanding of staphylococcal pathogenesis and the development of therapeutic agents against the important human pathogen. PUBLIC HEALTH RELEVANCE: This proposal will determine how the beta-hemolysin converting phage ?NM3 increases the pathogenic potential of Staphylococcus aureus. The results from these studies will lead us to understand the role of prophages in diseases caused by S. aureus, and how we can make S. aureus more susceptible to immune responses by blocking the phage contribution mechanism.