Streptococcal virulence factors in extra-oral disease

口腔外疾病中的链球菌毒力因子

• 批准号: 6609685
• 负责人: TODD O. KITTEN
• 金额: $ 14.04万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2005-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6609685
• 关键词: Streptococcus sanguis; bacteria infection mechanism; bacterial endocarditis; bacterial genetics; disease /disorder model; genetic manipulation; genetic strain; genome; laboratory rabbit; laboratory rat; method development; mutant; nucleic acid sequence; oral bacteria; oral pharyngeal disorder; site directed mutagenesis; transposon /insertion element; virulence

Infective endocarditis affects about 22,000 people per year in the U.S. and kills over 2,000. This disease is caused primarily by viridans streptococci, and among viridans streptococci, primarily by Streptococcus sanguis. Previous studies concerning the virulence of streptococci for endocarditis have centered upon the examination of suspected virulence factors. The proposed research takes an entirely different approach, that of directly identifying new virulence factors. This will be done by adapting the technique of signature-tagged mutagenesis (STM) for use with S. sanguis. This approach requires no prior assumptions concerning the importance of any particular gene or activity in disease causation. Instead, it relies on the infection process to identify the bacterial genes needed for disease and their relative contributions. An S. sanguis strain that is also the subject of a separate ongoing genome sequencing project will be randomly mutagenized by STM using an in vitro transposition approach. The resulting mutants will be pooled and inoculated into rats serving as models for endocarditis. The STM approach will allow for the identification of mutants within the pool possessing increased or decreased virulence. The apparent altered virulence in these mutants will be verified by in vivo competition assays. Further characterization of mutants will include DNA sequence analysis to identify the mutated genes, further genetic manipulation to verify the contribution of the mutated genes, in vivo infectivity assays, and in vitro functional assays. It is anticipated that the characterization of mutants with altered virulence will result in a better understanding of the pathogenesis of endocarditis and will identify promising novel targets for vaccine or therapeutic development.

感染性心内膜炎在美国每年影响约22,000人，并杀死2,000多人。这种疾病主要由维里达人引起 链球菌，在Viridans链球菌中，主要由链球菌 Sanguis。先前关于链球菌毒力的研究 心内膜炎以检查可疑毒力因子的检查为中心。 拟议的研究采用了完全不同的方法，直接 识别新的毒力因素。这将通过调整技术来完成 与S. sanguis一起使用的标记标签诱变（STM）。这种方法 不需要关于任何特定基因的重要性的事先假设 或疾病因果关系的活性。相反，它依赖于感染过程 确定疾病及其相对所需的细菌基因 贡献。 S. sanguis菌株，也是独立的主题 正在进行的基因组测序项目将使用STM随机诱变 体外换位方法。由此产生的突变体将被汇总，并且 被接种成作为心内膜炎模型的大鼠。 STM方法将 允许识别池中的突变体增加或 毒力降低。这些突变体的毒力明显改变将是 通过体内竞争测定法验证。突变体的进一步表征 将包括DNA序列分析以鉴定突变基因，进一步 基因操纵以验证突变基因的贡献，体内 感染性测定和体外功能分析。预计 毒力改变的突变体的表征将导致更好 了解心内膜炎的发病机理，并将确定有希望的 疫苗或治疗发育的新靶标。