Fragment Size-Based Pathogen Enrichment in cfDNA

项目摘要 无细胞DNA片段大小选择对病原菌的致病作用 血浆和无菌体液的无细胞DNA测序是一种有吸引力的方法 基础广泛的病原体检测。血浆cfDNA可以采集各种身体部位的样本 允许对未知病原体检测进行可预测的快速(24小时)结果，而 现有的筛查方案，如血液培养，需要5天或更长时间才能恢复 不是。传染病的鸟枪式测序方法的一个主要问题 诊断是宿主背景较高引起的炎症可明显 降低了分析的灵敏度。人类cfDNA形成一种刻板印象 片段大小分布模式为167个碱基对，片段少于~5% 测量在120个BP以下。病原体cfDNA通常在这些 更短的片段，因为它们很少用核小体保护自己的DNA。在这里，我们建议 优化选择性测序短cfDNA片段的方法，以增加 Cfdna测序用于病原体检测的分析灵敏度。具体来说，我们将 优化血浆提取、文库制备和大小选择参数以回收 短片段和枯竭片段&gt；120bp。然后，我们将验证此方法 在一系列已知的覆盖DNA的病原体阳性的150份血浆样本上 病毒、细菌、真菌/霉菌以及100份阴性血浆标本。使用这个 我们的目标是将cfDNA测序的分析灵敏度扩展到超过 具体的定量聚合酶链式反应方法。

Project Summary Pathogen enrichment by fragment size selection of cell-free DNA Cell-free DNA sequencing of plasma and sterile body fluids is an attractive approach for broad-based pathogen detection. Plasma cfDNA can sample a variety of body sites and allows for predictable and rapid (24-hour) results for agnostic pathogen detection, while existing screening regimens such as blood culture require 5 days or more to return negative. A major issue with shotgun sequencing approaches to infectious disease diagnostics is the high host background induced by inflammation can significantly compromise the analytical sensitivity of the assay. Human cfDNA forms a stereotyped fragment size distribution with a mode of 167 bp with fewer than ~5% of fragments measuring under 120 bp. Pathogen cfDNA is often overwhelmingly found in these shorter fragments as they rarely protect their DNA with nucleosomes. Here, we propose to optimize methods to selectively sequence short cfDNA fragments to increase the analytical sensitivity of cfDNA sequencing for pathogen detection. Specifically, we will optimize plasma extraction, library preparation, and size selection parameters to recover shorter fragments and deplete fragments > 120bp. We will then validate this approach on a series of 150 plasma specimens known to be positive for pathogens covering DNA viruses, bacteria, fungi/molds as well as 100 negative plasma specimens. Using this approach, our aim is to extend the analytical sensitivity of cfDNA sequencing to surpass that of specific qPCR approaches.