Evolution of Virulence in Streptococcus pneumoniae

肺炎链球菌毒力的演变

• 批准号: 6831589
• 负责人: Susan K. Hollingshead
• 金额: $ 42.17万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-12-01 至 2007-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6831589
• 关键词: Evolution; Virulence; Streptococcus; pneumoniae

EXCEED THE SPACE PROVIDED. Transformation has been of key importance in the history of bacterial genetics in general and streptococcal genetics in particular and it is currently still the most important technique for genetic analysis of Streptococcus pneumoniae. Transformation is the major means of spread of antibiotic resistance in this species and the factors governing transformation in natural environments will be a key factor in the success of future vaccines and interventions. The goal of this grant is to address a simple question: What is the proportion of genomic information typically exchanged during transformation in the pneumococcus? Estimates based on experiments from the 60's and 70's are that this proportion is as high as 10% of the genome but those studies were based on a small number of marker genes and the results were not representative of the whole. The readout for Igenomic exchange in our experimental approach will be the proportion of strain-specific genes exchanged las measured by microarray. In Aim 1, some of the parameters that determine this proportion during in I vitro transformation will be explored, including the length of donor DNA fragment and the concentration of donor DNA. In Aim 2, gene exchange from in vivo transformation will be followed retrospectively by looking at its extent following clonal divergence. For this purpose, the clonal complex (CC14) that includes serogroup 6 isolates in five world-wide multi drug-resistant lineages from 23 countries, will be studied. CC14 is associated with invasiveness in humans and mouse virulence vary across the lineage. Keeping in mind that virulence is multi factorial, this allows the detection of virulence-associated genes in the strain-specific gene sets. In Aim 3, in vivo transformation that has occurred during nasopharyngeal carriage in a mouse model will be examined. Isolates with recombinant genotypes will be detected by FACS sorting using markers to detect exchange in genes for two of the major virulence factors, capsule and pspA (pneumococcal surface protein A). By comparing the virulence of isolates within CC14 with their genes detected using a special microarray of strain-specific genes, we hope to also identify new virulence genes of pneumococci. PERFORMANCE SITE ========================================Section End===========================================

超过提供的空间。 转化在一般和链球菌遗传学的历史上至关重要，目前仍然是肺炎链球菌遗传分析的最重要技术。转化是抗生素耐药性在该物种中传播的主要手段，而自然环境中控制转化的因素将是未来疫苗和干预措施成功的关键因素。 这笔赠款的目的是解决一个简单的问题：在肺炎球菌转化期间，基因组信息的比例是多少？基于60年代和70年代的实验的估计值是该比例高达基因组的10％，但这些研究基于少量标记基因，结果并不代表整体。在我们的实验方法中，依基因组交换的读数将是通过微阵列测量的LAS交换的应变特异性基因的比例。在AIM 1中，将探讨确定IT体外转化中此比例的某些参数，包括供体DNA片段的长度和供体DNA的浓度。在AIM 2中，通过在克隆差异之后查看其范围，从体内转化的基因交换将进行回顾性。为此，将研究来自23个国家 /地区的五个世界范围内抗药性谱系中血清群6分离株的克隆综合体（CC14）。 CC14与人类的侵入性有关，小鼠毒力在整个谱系中各不相同。 请记住，毒力是多阶乘，这允许在菌株特异性基因集中检测与毒力相关的基因。在AIM 3中，将检查在小鼠模型中鼻咽运输过程中发生的体内转化。通过使用标记物检测两个主要毒力因子胶囊和PSPA（肺炎球菌表面蛋白A）的FACS分类，将检测具有重组基因型的分离株。通过比较CC14中分离株的毒力与使用特殊菌株特异性基因的特殊微阵列检测到的基因，我们希望还可以鉴定出肺炎球菌的新毒力基因。表演站点=============================================================================================