Streptococcal virulence factors in extra-oral disease

描述：感染性心内膜炎是一种严重的疾病，需要长期的内科或外科治疗，会导致严重的并发症，包括充血性心力衰竭和中风，即使接受治疗，也往往是致命的。绿色链球菌是引起这种疾病的主要原因，尤其是血链球菌。识别链球菌毒力决定因素将有助于更好地了解链球菌性心内膜炎的发病机制，并确定预防和治疗的靶点。我们已经应用签名标记突变(STM)来鉴定心内膜炎的血链球菌毒力因子。这种方法依赖于动物模型中的感染过程来确定疾病原因所需的细菌基因。我们最初的三年项目导致了一种用于血链球菌的体外转座STM技术的适应，并创建和筛选了800个标记突变体。目前的应用建议使用STM和非STM方法来检查细胞壁锚定蛋白和脂蛋白对心内膜炎毒力的贡献。用于这些分析的血链球菌菌株也正在由我们和我们的合作者进行测序，并即将完成。该序列的可获得性将允许使用涉及体外转座到定义的扩增片段的靶向方法来执行剩余的诱变。这种方法在技术上将比我们以前的STM分析更简单，也将提供更多的信息，允许将这些基因归类为对培养正常生长至关重要的、对心内膜炎毒力必不可少的或对这两个特征都是必不可少的。这一方法将全面分析两类表面蛋白在心内膜炎毒力中的作用。我们还希望这项研究将检查几乎所有可能的血吸虫候选疫苗，并确定最有希望的候选疫苗。

DESCRIPTION: Infective endocarditis is a serious illness that requires lengthy medical or surgical treatment, causes severe complications including congestive heart failure and stroke, and is often fatal, even when treated. The viridans streptococci as a group and Streptococcus sanguis in particular are a leading cause of this disease. Identification of streptococcal virulence determinants would lead to a better understanding of the pathogenesis of streptococcal endocarditis and to the identification of targets for prevention and therapy. We have applied signature-tagged mutagenesis (STM) to identify Streptococcus sanguis virulence factors for endocarditis. This approach relies on the infection process in an animal model to identify bacterial genes needed for disease causation. Our initial three-year project resulted in adaptation of an in vitro transposition STM technique for use with S. sanguis and the creation and screening of 800 tagged mutants. The current application proposes to use STM and non-STM approaches to examine the contribution of cell wall-anchored proteins and lipoproteins to endocarditis virulence. The S. sanguis strain being used for these analyses is also being sequenced by us and our collaborators and is near completion. The availability of the sequence will allow for the remainder of the mutagenesis to be performed using a targeted approach involving in vitro transposition into defined amplicons. This approach will be technically simpler than our previous STM analysis and will also be more informative, allowing for categorization of these genes as essential for normal growth in culture, essential for endocarditis virulence, or dispensable for both traits. This approach will provide a comprehensive analysis of the role of two classes of surface proteins in endocarditis virulence. We also expect the study to examine virtually all potential vaccine candidates in S. sanguis and to identify those that are most promising.