Gonococcal Mechanisms to Evade Host Defenses

项目摘要/摘要 淋病奈瑟菌可引起粘膜表面的局部无并发症感染和更多侵袭性感染 各种疾病，包括盆腔炎和血液感染。淋球菌感染的能力 避开人血清的杀菌作用--抗体和补体(SAC)在侵袭性疾病中的重要作用 血液感染，但这种耐药性的遗传和生化基础还不完全清楚。我们的 长期目标是确定淋球菌表达的SAC耐药性的分子基础，以便新的 可以制定策略来预防或治疗由革兰氏阴性病原体引起的血液感染。 淋球菌感染仍然是退伍军人，特别是女性的主要临床问题。 通常有严重的妇科并发症的退伍军人，这些并发症是由侵袭性疾病引起的。这个 我们的调查结果将有助于理解淋球菌和其他革兰氏阴性菌是如何 病原体可以逃避一种重要的、与生俱来的宿主防御机制。更全面地了解如何 革兰氏阴性菌抵抗SAC的杀菌作用是成功发展的关键 可降低血液感染发生率和/或严重程度的新疗法或疫苗。我们 假设参与脂寡糖(LOS)生物合成的基因和编码膜的基因 蛋白质在确定淋球菌抵抗SAC杀菌作用的能力方面是重要的。我们有 有证据表明淋球菌稳定抵抗正常人血清(NHS)杀死的一个机制是 通过核心低聚糖和脂类A组分的结构变化而决定的遗传 淋球菌LOS。我们现在将确定决定SAC耐药性的淋球菌基因谱系。 我们也有证据表明，人类血清通过一种 依赖于主动补体系统的机制。我们现在将定义淋球菌基因是 在NHS中细菌生长过程中的差异表达，并将决定它们的基因产物在 测定SAC阻力。我们将结合微生物遗传学、分子生物学和 生物化学，鉴定和表征淋球菌的细胞膜成分，这些成分对淋球菌的 SAC抵抗力。在特定的目标1中，我们将识别和表征决定SAC抗性的基因。 从播散性淋球菌感染患者的血液中分离的淋球菌菌株。我们会 也使用转座子突变来鉴定SAC敏感和耐药菌株中决定 细菌对这种宿主防御系统的敏感性水平。在具体目标2中，我们将使用微阵列来 确定淋球菌在接触人血清和在人血清中生长期间差异表达的基因。 将通过构建明确的突变来研究血清调节的基因，以确定它们在 SAC抵抗力。

Project Summary/ Abstract Neisseria gonorrhoeae causes both localized uncomplicated infections at mucosal surfaces and more invasive forms of disease including pelvic inflammatory disease and bloodstream infections. The ability of gonococci to evade the bactericidal action of human serum-antibody and complement (SAC) is important in invasive bloodstream infections, but the genetic and biochemical basis for this resistance is not fully understood. Our long-term goal is to define the molecular basis for SAC resistance expressed by gonococci so that novel strategies can be developed to prevent or treat bloodstream infections caused by Gram-negative pathogens. Gonococcal infections continue to be a major clinical problem for the veteran population, especially female veterans who often have severe gynecologic complications that result from invasive forms of disease. The results obtained from our investigations will help in understanding how gonococci and other Gram-negative pathogens can escape an important, innate host defense mechanism. A more complete understanding of how Gram-negative bacteria resist the bactericidal action of SAC is essential for the successful development of novel therapeutics or vaccines that would reduce the incidence and/or severity of bloodstream infections. We hypothesize that genes involved in lipooligosaccharide (LOS) biosynthesis and those that encode membrane proteins are important in determining the ability of gonococci to resist the bactericidal action of SAC. We have evidence that one mechanism by which gonococci stably resist killing by normal human serum (NHS) is genetically determined through structural alterations in the core oligosaccharide and lipid A components of the gonococcal LOS. We will now determine the repertoire of gonococcal genes that determine SAC resistance. We also have evidence that human serum triggers a response in SAC-resistant gonococci through a mechanism dependent on an active complement system. We will now define the gonococcal genes that are differentially expressed during bacterial growth in NHS and will determine the role of their gene products in determining SAC resistance. We will combine techniques of microbial genetics, molecular biology and biochemistry to identify and characterize the cell envelope components of gonococci that are important for SAC resistance. In Specific Aim 1, we will identify and characterize genes that determine SAC resistance in strains of gonococci isolated from the bloodstream of patients with disseminated gonococcal infection. We will also use transposon mutagenesis to identify genes in SAC-sensitive and -resistant strains that determine levels of bacterial susceptibility to this host defense system. In Specific Aim 2, we will use microarrays to identify genes in gonococci that are differentially expressed during exposure to and growth in human serum. Serum-regulated genes will be studied by constructing defined mutations in order to determine their role in SAC resistance.