Role of metal transport in Streptococcus sanguinis virulence and competitiveness

金属转运在血链球菌毒力和竞争力中的作用

• 批准号: 9089888
• 负责人: TODD O. KITTEN
• 金额: $ 37.54万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-06-15 至 2020-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9089888
• 关键词: Acids; Address; Aerobic; Animal Model; Antibiotic Prophylaxis; Antibiotic Resistance; Bacteremia; Bacteria; Biological; Biological Testing; Blood; Blood Circulation; Cell physiology; Cells; Communicable Diseases; Data; Defect; Dental; Dental Care; Dentistry; Disease; Divalent Cations; Drug Targeting; Ecology; Endocarditis; Environment; Family member; Goals; Growth; Health; Heart; Heart Valves; Human; In Vitro; Infection; Infective endocarditis; Lead; Life; Lipoprotein (a); Measures; Mediating; Metabolic; Metabolism; Metals; Microbe; Modeling; Mutation; Operon; Oral; Oral cavity; Oral health; Oryctolagus cuniculus; Oxidative Stress; Pathway interactions; Patient risk; Persons; Pharmaceutical Preparations; Play; Pneumococcal Pneumonia; Prevention; Process; Proteins; Publishing; Rattus; Reactive Oxygen Species; Regulation; Resistance; Ribonucleotide Reductase; Risk; Role; Streptococcus; Streptococcus Viridans Group; Streptococcus mutans; Superoxide Dismutase; System; Testing; Time; Tooth structure; Veillonella parvula; Virulence; Work; acid stress; base; in vitro Model; in vivo; in vivo Model; insight; metabolomics; mortality; mutant; novel; novel strategies; novel therapeutics; oral pathogen; oral streptococci; oxidation; prevent; prophylactic; targeted treatment; transcriptomics; uptake

 DESCRIPTION (provided by applicant): Infective endocarditis is a serious infection of the heart with mortality rates in excess of 20%. This disease is thought to occur when bacteria or other microbes gain access to the blood, attach to previously damaged heart valves, and multiply. The oral or viridans streptococci are a leading cause of this illness, and among this group, Streptococcus sanguinis is especially important. Prevention of endocarditis relies primarily on antibiotic prophylaxis for at-risk patients prior to dental procedures that are likelyto result in bacteremia. However, it is now recognized that most cases of endocarditis result from daily activities that lead to bacteremia, for which dental antibiotic prophylaxis provides no protection. The identification of virulence determinants could provide new targets for novel prophylactic measures capable of providing continuous protection for persons at risk without selecting for antibiotic resistance in the mouth. Toward this goal, we have performed multiple screens of S. sanguinis mutants for loss of endocarditis virulence in an animal model. These studies have identified a lipoprotein, SsaB, that is uniquely important for endocarditis virulence and is also a promising target for therapy or prevention. SsaB, like other members of the family to which it belongs, functions in Mn (and perhaps Fe) uptake, O2 tolerance, and virulence. There are a number of mechanisms by which Mn could contribute to O2 tolerance and virulence, but it is not clear exactly which mechanisms are employed or are most important in streptococci. We have made a number of recent advances in relation to SsaB's potential functions that are novel not just for S. sanguinis, but for any Streptococcus, including characterization of an Mn-dependent ribonucleotide reductase that is essential for aerobic growth, characterization of the biological relevance of superoxide dismutase activity remaining in an ssaB mutant, identifying physiologically relevant in vitro growth conditions that mimic findings from the rabbit endocarditis model, the observation of metal-dependent processing of the SsaB protein, and the finding of an important role for SsaB in acid tolerance. We propose to expand upon these novel findings by examining SsaB regulation and function. This will provide the first test in any Streptococcus of multiple hypotheses generated by our recent findings that are related to metal transport. Given that we know that the primary defect of an ssaB mutant is metabolic, an important part of our study will be an unprecedented metabolomic analysis of O 2 and acid-stressed cells grown under carefully controlled conditions. This will be followed by testing of selected strains in in vitro and in vivo models of oral colonization and endocarditis virulence to test the biological relevance of our findings. The results of this study promise to be directly applicable to a number of other important pathogens and oral colonizers that are known to require Mn. Moreover, this study promises to identify novel approaches to control oral health and prevent infective endocarditis.

 描述（由申请人提供）：感染性心内膜炎是一种严重的心脏感染，死亡率超过 20%。人们认为，当细菌或其他微生物进入血液，附着在先前受损的心脏瓣膜上并繁殖时，就会发生这种疾病。口腔链球菌或草绿色链球菌是导致这种疾病的主要原因，其中血链球菌尤其重要。心内膜炎的预防主要依赖于在可能导致菌血症的牙科手术之前对高危患者进行抗生素预防。然而，现在人们认识到，大多数心内膜炎病例是由导致菌血症的日常活动引起的，而牙科抗生素预防对此没有提供保护。毒力决定因素的鉴定可以为新型预防措施提供新的目标，这些措施能够为处于危险中的人提供持续的保护，而无需选择口腔中的抗生素耐药性。为了实现这一目标，我们对动物模型中心内膜炎毒力丧失的血链球菌突变体进行了多次筛选。这些研究发现了一种脂蛋白 SsaB，它对心内膜炎毒力特别重要，也是一个有希望的治疗或预防靶点。 SsaB 与其所属家族的其他成员一样，在 Mn（或许还有 Fe）吸收、O2 耐受性和毒力方面发挥作用。锰可以通过多种机制促进 O2 耐受性和毒力，但尚不清楚链球菌中到底采用了哪些机制或哪些机制最重要。我们在 SsaB 的潜在功能方面取得了许多最新进展，这些进展不仅对于血链球菌而且对于任何链球菌来说都是新颖的，包括对有氧生长至关重要的 Mn 依赖性核糖核苷酸还原酶的表征，对 ssaB 突变体中剩余的超氧化物歧化酶活性的生物相关性的表征，确定模拟研究结果的生理相关的体外生长条件。 兔心内膜炎模型，观察 SsaB 蛋白的金属依赖性加工，并发现 SsaB 在酸耐受性中的重要作用。我们建议通过检查 SsaB 的调控和功能来扩展这些新发现。这将首次对任何链球菌进行对我们最近与金属转运相关的发现所产生的多种假设的测试。鉴于我们知道 ssaB 突变体的主要缺陷是代谢，我们研究的一个重要部分将是对在严格控制的条件下生长的 O 2 和酸应激细胞进行前所未有的代谢组学分析。随后将在口腔定植和心内膜炎毒力的体外和体内模型中测试选定的菌株，以测试我们研究结果的生物学相关性。这项研究的结果有望成为 直接适用于已知需要锰的许多其他重要病原体和口腔定植菌。此外，这项研究有望找到控制口腔健康和预防感染性心内膜炎的新方法。