The effect of inter-species interactions on the virulence of Streptococcus mutans

描述（由申请人提供）：项目概述：变形链球菌是产生几种毒力因子的主要致龋菌。本研究的长期目标是确定S.口腔菌斑生物膜中的口腔细菌。我们推测这不仅仅是S.变形杆菌，决定最终的致龋性的斑块，但相互作用的病原体与其他生物膜细菌，影响毒力。存在于牙菌斑中的其他细菌可以调节生物体的毒力特性的群体感应依赖性表达。这一假说是基于以下观察结果：1）S。变形杆菌的能力刺激肽（CSP）和信号转导系统介导多种毒力特征：生物膜形成、细菌素产生、耐酸性、抗微生物敏感性和天然遗传转化。CSP或其信号转导系统的消除导致所有这些毒力活性的改变。2），其他口腔细菌，如口腔早期定植的牙菌斑物种戈登链球菌，可以传播。变形链球菌CSP从而干扰S.变形杆菌细菌素产生。因此，本实验的重点将是确定其他早期定殖菌如内氏放线菌和后来的厌氧定殖菌如牙龈卟啉单胞菌对S.变形链球菌，并确定这些生物体对S.变异人具体目标是：具体目标1。为了确定早期的殖民者，S。gordonii或A. naeslundii，拮抗S.变异人（1）S.变形链球菌WT及其comC突变体对S. gordonii查利斯或A.将通过放射性标记技术和共聚焦显微镜来评估内氏疟原虫。ii）S.变形链球菌及其与S. gordonii查利斯或A.将通过活细胞计数评估内氏疟原虫。具体目标2。为了确定是否晚期定植者如牙龈卟啉单胞菌、齿垢密螺旋体和嗜酸坦纳氏菌拮抗S.变异人i）S.变形链球菌细菌素的产生。变形链球菌和S.变形链球菌与牙龈卟啉单胞菌、T. denticola或T.将通过测定指示菌株的杀灭百分比来监测霍乱弧菌。ii）S.在单一培养物和与牙龈卟啉单胞菌、T. denticola或T.将对阿斯塔纳进行评估。iii）S.变形链球菌及其与牙龈卟啉单胞菌、T. denticola或T.将通过活细胞计数评估淋病。iv）我们将确定牙龈卟啉单胞菌的蛋白酶是否与S.变形菌CSP. 项目简介：龋齿是一种常见的慢性传染病，影响着全球大部分人口。色葡萄变形杆菌群体感应系统可能是一个适当的目标中断，以减少龋齿。CSP依赖性调节的破坏具有减弱细菌的潜力，使得其毒性较低。

DESCRIPTION (provided by applicant): Project summary: Streptococcus mutans is the primary cariogen that produces several virulence factors. The long-term goal of the proposed studies is to characterize specific interactions of S. mutans with oral bacteria in the dental plaque biofilm. We hypothesize that it is not merely colonization by S. mutans that determines the ultimate cariogenicity of plaque, but the interaction of the pathogen with other biofilm bacteria that affect virulence. Other bacteria present in dental plaque may modulate quorum sensing-dependent expression of virulence properties of the organism. This hypothesis is based on observations that: 1) S. mutans competence-stimulating peptide (CSP) and a signal transduction system mediate a variety of virulence characteristics: biofilm formation, bacteriocin production, acid tolerance, antimicrobial sensitivity, and natural genetic transformation. Elimination of CSP or its signal transduction system results in alterations in all of these virulence activities. 2), other oral bacteria, such as the commensal early-colonizing dental plaque species Streptococcus gordonii, can inactivate S. mutans CSP thereby interfering with S. mutans bacteriocin production. Therefore, the experimental focus of this proposal will be to determine the effects of other early colonizers such as Actinomyces naeslundii and later anaerobic colonizers such as Porphyromonas gingivalis on quorum-sensing in S. mutans and to determine the effects of these organisms on the virulence-associated properties of S. mutans. The Specific Aims are: Specific Aim 1. To determine if early colonizers, S. gordonii or A. naeslundii, antagonize colonization efficiency and the acid tolerance response in S. mutans. i) Colonization of S. mutans WT and its comC mutant on preformed biofilms of S. gordonii Challis or A. naeslundii will be assessed by both radioactive labeling techniques and confocal microscopy. ii) The acid tolerance response of S. mutans and mixtures with S. gordonii Challis or A. naeslundii will be assessed by viable cell counts. Specific Aim 2. To determine if late colonizers such as P. gingivalis, Treponema denticola, and Tannerella forsythia antagonize quorum-sensing properties in S. mutans. i) S. mutans bacteriocin production in broth monocultures of S. mutans and mixtures of S. mutans with P. gingivalis, T. denticola, or T. forsythia will be monitored by determining killing percentages of an indicator strain. ii) The transformation efficiencies of S. mutans in monocultures and in mixtures with P. gingivalis, T. denticola, or T. forsythia will be assessed. iii) The acid tolerance response of S. mutans and mixtures with P. gingivalis, T. denticola, or T. forsythia will be assessed by viable cell counts. iv) We will determine if the proteinases of P. gingivalis inactivate the S. mutans CSP. Project Narrative: Dental caries is a common chronic infectious disease affecting much of the worldwide population. The S. mutans quorum-sensing system may be an appropriate target for interruption to reduce dental caries. The disruption of CSP-dependent regulation has the potential to attenuate the bacterium so that it is less virulent.