Puerperal sepsis and group A Streptococcus heterogeneity

产后败血症和 A 族链球菌异质性

• 批准号: 9222500
• 负责人: Paul Sumby
• 金额: $ 7.18万
• 依托单位: UNIVERSITY OF NEVADA RENO
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-11-25 至 2018-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9222500
• 关键词: Adherence; Applications Grants; Bacterial Infections; Biological Assay; Blood; Cell Line; Cell surface; Cessation of life; Childbirth; Clinical; Communicable Diseases; Communities; Complement; Data; Development; Disease; Elements; Epidemiology; Epithelial Cells; Female; Frequencies; Future; Genes; Genomic Islands; Goals; Growth; Heterogeneity; Human; Individual; Infection; Infertility; Knowledge; Life; Link; Measures; Modeling; Molecular; Morbidity - disease rate; Neonatal; Pathogenicity Island; Phenotype; Postpartum Women; Pregnant Women; Public Health; Puerperal Infection; Regulation; Research; Reverse Transcriptase Polymerase Chain Reaction; Sepsis; Sequence Analysis; Serotyping; Streptococcal Infections; Streptococcus; Streptococcus Group B; Streptococcus pyogenes; Testing; Transcript; United States; Vagina; Virulence Factors; Western Europe; base; epidemiologic data; insight; interest; mouse model; mutant; novel therapeutics; pathogen; prophylactic; reproductive tract; tissue culture; transcription factor; transcriptome; transcriptome sequencing

PROJECT SUMMARY Bacterial infections following childbirth, so-called puerperal infections, cause morbidity in 5 to 10% of all pregnant women globally. In most instances the infection is limited to the reproductive tract but at low frequency the infection spreads to the blood resulting in life-threatening sepsis, puerperal sepsis. Pathogens causing puerperal sepsis include the group A Streptococcus (GAS, S. pyogenes), which is the most common cause of severe maternal puerperal infections and death worldwide. GAS epidemiological data gained over the course of the last fifty years identifies a serotype-specific variability in the ability of GAS to cause disease. Of relevance to this proposal, serotype M28 GAS isolates are non-randomly associated with cases of puerperal sepsis. The molecular basis of why serotype M28 isolates cause puerperal sepsis at a significantly higher rate relative to those of other serotypes is to be investigated in this proposal. More specifically, the goal of the proposed research is to characterize whether the presence of a genomic island, termed `region of difference 2' (RD2), is key to the enhanced ability of serotype M28 GAS to cause puerperal sepsis. Sequence analysis of RD2 is consistent with this element being horizontally transferred into M28 GAS from group B Streptococci (GBS, S. agalactiae), an important finding given that GBS are a common constituent of the normal vaginal microflora and are also a major cause of neonatal invasive infections. Specific Aim 1: Test the hypothesis that RD2 enhances the ability of serotype M28 GAS isolates to both colonize the female reproductive tract and cause sepsis. To facilitate testing our hypothesis we recently constructed RD2 deletion mutant and complemented mutant derivatives of a representative M28 isolate. The parental, mutant, and complemented strains will be compared in tissue culture adherence assays, in growth assays using whole human blood (as a model of sepsis), and in a mouse model of vaginal colonization. Specific Aim 2: Test the hypothesis that the RD2 element alters the abundance of transcripts of core chromosomally-encoded virulence factors. Five putative transcription factors and two putative small regulatory RNAs are encoded within RD2. To test whether these putative regulators have targets outside of the RD2 region we will perform transcriptome comparisons between our parental and RD2 deletion mutant strains (via RNAseq). Comparisons will be performed following GAS growth in an ex vivo model of invasive infection. RNAseq data will be verified by targeted quantitative RT-PCR and Western analyses. Completion of the proposed research will advance our understanding of strain emergence and phenotypic heterogeneity in a prevalent Gram-positive pathogen. Specifically, the data would inform on the importance of RD2 with respect to the association of M28 GAS isolates with puerperal sepsis, and thereby provide a link between GAS gene content and clinical observations.

项目摘要 分娩后的细菌感染，即所谓的产褥感染，在所有产妇中占5%至10%， 全球孕妇在大多数情况下，感染仅限于生殖道，但在低 感染扩散到血液中的频率导致危及生命的败血症、产褥期败血症。病原体 引起产褥败血症的链球菌包括A组链球菌（GAS，S.化脓性），这是最常见的 严重的产妇产褥感染和死亡的原因。获得的GAS流行病学数据 过去50年的过程确定了GAS引起疾病的能力的特定类型的可变性。 与此提议相关的是，血清型M28 GAS分离株与以下病例非随机相关： 产后败血症血清型M28分离株引起产褥败血症的分子基础， 本提案中将调查相对于其他血清型的较高比率。更具体地说，目标 拟议的研究的一个特点是，是否存在一个基因组岛，称为“区域， 差异2'（RD 2）是血清型M28 GAS引起产褥期脓毒症的能力增强的关键。 RD 2的序列分析与该元素水平转移到M28 GAS中一致， B群链球菌（GBS，S.无乳），这是一个重要的发现，因为GBS是一种常见的成分， 正常阴道微生物群落，也是新生儿侵入性感染的主要原因。 具体目的1：检验RD 2增强血清型M28 GAS分离株 都能在女性生殖道内定植并导致败血症为了检验我们的假设， 最近构建的RD 2缺失突变体和代表性M28的互补突变体衍生物 孤立。将在组织培养粘附试验中比较亲本、突变体和补充菌株， 在使用人全血的生长测定中（作为脓毒症模型），以及在阴道感染的小鼠模型中， 殖民化 具体目标2：检验RD 2元件改变核心转录本丰度的假设 染色体编码的毒力因子。五个假定的转录因子和两个假定的小 调节RNA在RD 2内编码。为了测试这些假定的调节器是否有目标以外的 我们将在亲本和RD 2缺失突变体之间进行RD 2区域转录组比较 菌株（通过RNAseq）。将在侵袭性肿瘤的离体模型中GAS生长后进行比较。 感染RNAseq数据将通过靶向定量RT-PCR和Western分析进行验证。 完成拟议的研究将推进我们对菌株出现和表型的理解。 一种流行的革兰氏阳性病原体的异质性。具体而言，这些数据将说明以下方面的重要性： RD 2关于M28 GAS分离株与产褥期脓毒症的关联，从而提供了一种联系 GAS基因含量和临床观察之间的关系。