Gonococcal Mechanisms to Evade Host Defenses

描述（由申请人提供）： 项目摘要/摘要淋病奈瑟菌引起粘膜表面的局部无并发症感染和更具侵袭性的疾病，包括盆腔炎和血流感染。淋球菌逃避人血清抗体和补体（SAC）杀菌作用的能力在侵袭性血流感染中很重要，但这种耐药性的遗传和生化基础尚未完全了解。我们的长期目标是确定由淋球菌表达的SAC抗性的分子基础，以便可以开发新的策略来预防或治疗由革兰氏阴性病原体引起的血流感染。淋球菌感染仍然是退伍军人群体的一个主要临床问题，特别是女性退伍军人，她们经常患有由侵袭性疾病引起的严重妇科并发症。从我们的研究中获得的结果将有助于了解淋球菌和其他革兰氏阴性病原体如何逃避重要的先天宿主防御机制。更全面地了解革兰氏阴性菌如何抵抗SAC的杀菌作用对于成功开发新的治疗剂或疫苗至关重要，这些治疗剂或疫苗将降低血流感染的发生率和/或严重程度。我们推测，参与脂寡糖（LOS）生物合成的基因和编码膜蛋白的基因在决定淋球菌抵抗SAC杀菌作用的能力方面是重要的。我们有证据表明，淋球菌稳定抵抗正常人血清（NHS）杀死的一种机制是通过淋球菌LOS的核心寡糖和脂质A组分的结构改变遗传决定的。我们现在将确定决定SAC抗性的淋球菌基因库。我们也有证据表明，人血清通过依赖于活性补体系统的机制触发SAC耐药淋球菌的反应。我们现在将定义在NHS中细菌生长期间差异表达的淋球菌基因，并确定其基因产物在确定SAC抗性中的作用。我们将结合联合收割机技术的微生物遗传学，分子生物学和生物化学，以确定和表征的细胞被膜组件的淋球菌是重要的SAC耐药。在具体目标1中，我们将鉴定和表征从播散性淋球菌感染患者血流中分离的淋球菌菌株中决定SAC耐药性的基因。我们还将使用转座子诱变来鉴定SAC敏感和抗性菌株中的基因，这些基因决定了细菌对这种宿主防御系统的易感性水平。在特定目标2中，我们将使用微阵列来识别淋球菌在暴露于人血清和在人血清中生长期间差异表达的基因。将通过构建确定的突变来研究血清调节基因，以确定它们在SAC抗性中的作用。

DESCRIPTION (provided by applicant): 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.