Development of a novel multipurpose model to propagate and study the tick transmission cycle of relapsing fever spirochetes from Eurasia.

开发一种新型多用途模型，用于繁殖和研究欧亚大陆回归热螺旋体的蜱传播周期。

• 批准号: 10651550
• 负责人: Job E Lopez
• 金额: $ 20.06万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-05 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10651550
• 关键词: Address; Asia; Bacteria; Bacterial Genome; Blood; Borrelia; Child; Chromosomes; Climate; Comparative Genomic Analysis; Complex; Country; Data; Development; Disease; Gene Rearrangement; Genes; Genetic Recombination; Genome; Genome Stability; Genomics; Goals; Growth; Health; In Vitro; Knowledge; Life Cycle Stages; Literature; Longevity; Maintenance; Mammals; Middle East; Modeling; Molecular; Molecular Probes; Morbidity - disease rate; Natural Source; Order Spirochaetales; Ornithodoros; Pathogenesis; Phylogenetic Analysis; Plasmids; Politics; Positioning Attribute; Public Health; Publications; Publishing; Relapsing Fever; Replicon; Reporting; Research; Resource-limited setting; Resources; Southern Blotting; System; Testing; Ticks; Time; Ukraine; chicken egg; cost effective; egg; epidemiology study; genome annotation; genome resource; genomic tools; improved; low income country; model development; mortality; neglect; novel; pathogen; pathogen genomics; poor communities; relapsing fever borrelia; tick bite; tick transmission; transmission process; vector; vector competence; vector tick; vector-borne pathogen

Project Summary Relapsing fever (RF) spirochetes are a group of neglected vector-borne pathogens that are a significant cause of child morbidity and mortality. The current approaches to grow and assess tick transmission of RF spirochetes are impractical in resource limited settings where they are prevalent. For example, propagating spirochetes in culture medium is expensive and labor intensive. Moreover, prolonged in vitro propagation in medium causes DNA rearrangements of their already exceedingly complex genomes, and this results in diminished vector colonization and pathogenesis. There is a critical need for cost effective practical approaches to grow and study RF spirochetes from neglected regions of the globe. This project builds on our prior our publication reporting the first isolation of Borrelia caucasica, which is part of the Persica species complex and is distributed through Eurasia and the Middle East. Moreover, our recent advances RF spirochete genomics addressed a major limitation in the field and resulted in complete chromosome and plasmid assembled and annotated genomes. The genomics tools we developed can now be utilized to characterize a model for the Persica complex species. Interestingly, historical literature suggested that embryonated chicken eggs (ECEs) could be infected with RF spirochetes by tick bite and the bacteria grew in this system. However, at the time molecular and genomics resources were not available to characterize this model and knowledge gaps remain about the pathogens genomic stability in ECEs. Leveraging recent advances in RF spirochete genomics, the ECE model can now be fully developed to study Persica complex species. In this study, two aims are proposed. The first aim is to utilize genomics resources for RF spirochetes and evaluate plasmid diversity and identify unique plasmid markers of B. caucasica isolates through a comparative genomic analysis. The first objective is to complete reference quality genomes assemblies of B. caucasica isolates and perform a comparative genomics analysis to identify plasmid markers. The second objective is to develop a panel of specific probes needed to evaluate plasmid retention and rearrangements during the B. caucasica life cycle. In the second aim, we will assess genomic changes of B. caucasica using the tick – ECE model. The first objective is to develop the B. caucasica model in ECEs and evaluate spirochete growth, tick acquisition, and subsequent tick transmission of spirochetes to naïve eggs. The second objective is to assess plasmid stability and the ability of B. caucasica to remain infectious after passage through ECEs. The establishment of the ECE model will result in a cost-effective approach to amplify RF spirochetes in the absence of culture medium. Moreover, the development of this model offers a practical system to study the transmission cycle and vector competence of RF spirochetes in resource limited settings. With the emergence and health burden of RF spirochetes in low-income countries, it is important to develop systems to propagate and study these neglected pathogens.

项目概要 回归热 (RF) 螺旋体是一组被忽视的媒介传播病原体，是导致回归热的重要原因。 儿童发病率和死亡率。目前生长和评估 RF 螺旋体蜱传播的方法 在它们盛行的资源有限的环境中是不切实际的。例如，螺旋体的繁殖 培养基昂贵且劳动密集。此外，在培养基中延长体外繁殖会导致 对已经极其复杂的基因组进行 DNA 重排，这导致载体减少 定植和发病机制。迫切需要具有成本效益的实用方法来成长和学习 来自全球被忽视地区的 RF 螺旋体。该项目建立在我们之前的出版物报告的基础上 首次分离出高加索疏螺旋体 (Borrelia caucasica)，它是 Persica 物种复合体的一部分，分布于 欧亚大陆和中东。此外，我们最近的进展 RF 螺旋体基因组学解决了一个主要问题 克服了该领域的限制，并产生了完整的染色体和质粒组装和注释的基因组。 我们开发的基因组学工具现在可用于表征 Persica 复杂物种的模型。 有趣的是，历史文献表明含胚鸡蛋 (ECE) 可能会感染 RF 蜱虫叮咬产生螺旋体，细菌在该系统中生长。然而，当时的分子和基因组学 没有资源来描述该模型，并且关于病原体的知识差距仍然存在 ECE 中的基因组稳定性。利用 RF 螺旋体基因组学的最新进展，ECE 模型现在可以 完全开发用于研究 Persica 复杂物种。在这项研究中，提出了两个目标。第一个目标是利用 RF 螺旋体的基因组学资源，评估质粒多样性并识别独特的质粒标记 通过比较基因组分析分离出高加索芽孢杆菌。第一个目标是完成参考质量 高加索菌株的基因组组装并进行比较基因组分析以鉴定质粒 标记。第二个目标是开发一组评估质粒保留和检测所需的特定探针。 B. caucasica 生命周期中的重排。在第二个目标中，我们将评估 B. 高加索使用蜱 - ECE 模型。第一个目标是在 ECE 中开发 B. caucasica 模型， 评估螺旋体的生长、蜱的获取以及随后蜱将螺旋体传播到幼稚卵。这 第二个目标是评估质粒稳定性以及高加索伯氏杆菌传代后保持感染性的能力 通过欧洲经委会。 ECE模型的建立将带来一种经济高效的射频放大方法 螺旋体在没有培养基的情况下。此外，该模型的开发提供了一个实用的系统 研究资源有限环境中射频螺旋体的传输周期和矢量能力。随着 鉴于低收入国家 RF 螺旋体的出现和健康负担，开发系统以 传播和研究这些被忽视的病原体。