The basis of strain-specific differences in virulence in the human pathogen Orientia tsutsugamushi

人类病原体恙虫病东方体毒力的菌株特异性差异的基础

• 批准号: 9891321
• 负责人: Jeanne Salje
• 金额: $ 23.4万
• 依托单位: RBHS-NEW JERSEY MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-01-14 至 2021-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9891321
• 关键词: Address; Affect; Africa; Animal Model; Animals; Ankyrin Repeat; Ankyrins; Antibiotic Therapy; Antibiotics; Asia; Bacteria; Bacterial Genes; Biological Assay; Biology; Clinical; Cultured Cells; Data; Data Analyses; Diagnostic; Disease; Doxycycline; Equilibrium; Exhibits; Expression Profiling; Future; Gene Expression; Genes; Genome; Human; Immune; Immune response; Immunologic Markers; In Vitro; Incidence; Infection; Inflammatory; Inflammatory Response; Integration Host Factors; Life; Measures; Membrane Proteins; Middle East; Modeling; Morbidity - disease rate; Mus; Nucleic Acids; Organism; Orientia tsutsugamushi; Outcome; Pathogenesis; Pathogenicity; Pathway interactions; Patients; Prevalence; Proteins; Proteomics; Proxy; Reporter; Reporting; Research; Role; Scrub Typhus; Serotyping; Severities; Source; South America; Southeastern Asia; Technology; Testing; Travel; Treatment Failure; Urbanization; Vaccine Therapy; Vaccines; Variant; Virulence; Virulence Factors; Virulent; Work; base; chemokine; climate change; cytokine; differential expression; functional genomics; genome sequencing; human disease; human pathogen; immunogenic; improved; in vivo; innovation; mortality; mouse model; neglect; neglected tropical diseases; novel diagnostics; pathogen; pathogenic bacteria; patient variability; resistant strain; response; tool; transcriptome sequencing; treatment risk; vector; vector-borne; whole genome

PROJECT SUMMARY Vector-borne obligate intracellular bacteria are an important cause of morbidity and mortality worldwide. One such pathogen, Orientia tsutsugamushi, causes the neglected tropical disease scrub typhus, which is estimated to cause infection in at least 1 million people each year, and is associated with high mortality if not treated promptly and with the appropriate antibiotics. The species O. tsutsugamushi is characterised by high strain diversity, where different strains exhibit different levels of virulence in patients and animal models. A major factor in the pathogenicity induced by O. tsutsugamushi is an over-activation of the inflammatory immune response. However, the detailed mechanisms describing how O. tsutsugamushi induces this response remain unknown. O. tsutsugamushi is genetically intractable and therefore functional genomics based approaches to identify virulence factors are not possible. Here we propose to take advantage of strain-specific natural variation to uncover key pathways important for virulence. In our preliminary work we have quantified the virulence of two clinical isolate strains of O. tsutsugamushi, Karp and UT176, and shown that they have significantly different outcomes in a mouse model. We have also used dual RNAseq to identify both bacterial and host genes that are differentially expressed between these two strains when grown in human cultured cells (HUVEC), and identified bacterial (surface proteins TSA22, TSA47, TSA56 and Ankyrins Ank6, Ank16, Ank17, Ank20) and host (SOCS2, IL33, other chemokines and cytokines) factors that strongly correlate with virulence. We have also recently generated complete genome sequences for 6 strains of O. tsutsugamushi, bringing the total number of completely sequenced strains up to 8. These strains will all be used in this study. Our preliminary work and previous reports led us to the hypothesis that strain specific differences in the virulence of O. tsutsugamushi are driven by differences in expression of bacterial virulence-related genes, resulting in either pathogen clearance or inflammatory induced pathogenesis. This hypothesis will be addressed in the following aims. In Aim 1, we will increase the power of our preliminary correlative analysis by quantifying the virulence and gene expression profiles of a total of 8 strains of O. tsutsugamushi, and will use this information to identify bacterial and host factors that robustly associate with virulence. In Aim 2, we will use an in vitro immune reporter assay to probe the role of specific bacterial genes in virulence, focusing on the factors identified in our preliminary studies and in Aim 1. Results of this study will guide future work on developing novel diagnostic tools and therapies against this pathogen.

项目概要 媒介传播的专性细胞内细菌是全世界发病和死亡的重要原因。一 这种病原体，恙虫病东方体，会导致被忽视的热带疾病丛林斑疹伤寒，这是 据估计每年至少导致 100 万人感染，如果不采取措施，死亡率将很高 及时治疗并使用适当的抗生素。恙虫病 O. tsutsugamushi 的特点是高 菌株多样性，不同菌株在患者和动物模型中表现出不同水平的毒力。一个 恙虫病引起的致病性的主要因素是炎症细胞的过度激活。 免疫反应。然而，描述恙虫病如何诱导这种反应的详细机制 仍然未知。恙虫病在遗传上很难处理，因此基于功能基因组学 确定毒力因子的方法是不可能的。在这里，我们建议利用菌株特异性 自然变异揭示对毒力重要的关键途径。在我们的前期工作中，我们量化了 研究了恙虫病两种临床分离菌株 Karp 和 UT176 的毒力，并表明它们具有 小鼠模型中的结果显着不同。我们还使用双 RNAseq 来鉴定这两种细菌 以及在人类培养细胞中生长时这两种菌株之间差异表达的宿主基因 (HUVEC)，并鉴定了细菌（表面蛋白 TSA22、TSA47、TSA56 和锚蛋白 Ank6、Ank16、Ank17、 Ank20）和宿主（SOCS2、IL33、其他趋化因子和细胞因子）因子与毒力密切相关。 我们最近还生成​​了 6 个恙虫病菌株的完整基因组序列，从而为 完全测序的菌株总数最多为 8 个。这些菌株将全部用于本研究。我们的 初步工作和之前的报告使我们得出了这样的假设： 恙虫病的毒力是由细菌毒力相关的表达差异驱动的 基因，导致病原体清除或炎症诱导的发病机制。这个假设 将在以下目标中予以解决。在目标 1 中，我们将增强初步相关性的力量 通过量化总共 8 种恙虫病 O. tsutsugamushi 菌株的毒力和基因表达谱进行分析， 并将利用这些信息来识别与毒力密切相关的细菌和宿主因素。瞄准 2、我们将使用体外免疫报告基因检测来探测特定细菌基因在毒力中的作用， 重点关注我们的初步研究和目标 1 中确定的因素。这项研究的结果将指导未来 致力于开发针对这种病原体的新型诊断工具和疗法。