Identification of conditionally essential genes for <i>Streptococcus suis</i> infection in pigs

is a Gram-positive bacterium and zoonotic pathogen that causes meningitis and sepsis in pigs and humans. The aim of this study was to identify genes required for <i>S. suis</i> infection. We created Tn-Seq libraries in a virulent <i>S. suis</i> strain 10, which was used to inoculate pigs in an intrathecal experimental infection. Comparative analysis of the relative abundance of mutants recovered from different sites of infection (blood, cerebrospinal fluid, and meninges of the brain) identified 361 conditionally essential genes, i.e. required for infection, which is about 18% of the genome. The conditionally essential genes were primarily involved in metabolic and transport processes, regulation, ribosomal structure and biogenesis, transcription, and cell wall membrane and envelope biogenesis, stress defenses, and immune evasion. Directed mutants were created in a set of 10 genes of different genetic ontologies and their role was determined in <i>ex vivo</i> models. Mutants showed different levels of sensitivity to survival in whole blood, serum, cerebrospinal fluid, thermic shock, and stress conditions, as compared to the wild type. Additionally, the role of three selected mutants was validated in co-infection experiments in which pigs were infected with both wild type and isogenic mutant strains. The genetic determinants of infection identified in this work contribute to novel insights in <i>S. suis</i> pathogenesis and could serve as targets for novel vaccines or antimicrobial drugs.本研究涉及的病原菌为革兰氏阳性（Gram-positive）人畜共患病原体，可引发猪与人类的脑膜炎及败血症。本研究旨在鉴定猪链球菌（*S. suis*）感染所需的功能基因。我们在强毒力猪链球菌菌株10中构建了转座子测序（Tn-Seq）文库，并将该文库用于颅内注射感染猪的实验模型。通过对从不同感染部位（血液、脑脊液及脑膜）回收的突变体相对丰度开展比较分析，共鉴定出361个感染必需的条件必需基因（conditionally essential genes），约占其基因组的18%。此类条件必需基因主要参与代谢与转运过程、基因调控、核糖体结构与生物发生、转录过程、细胞壁膜及包膜生物发生、应激防御以及免疫逃逸。我们针对10个隶属于不同基因本体（genetic ontologies）类别的基因构建了定向突变体，并通过体外（ex vivo）模型验证了其功能。相较于野生型（wild type）菌株，各突变体在全血、血清、脑脊液、热休克及多种应激条件下的存活能力呈现出不同程度的敏感性变化。此外，我们选取3株突变体开展共感染实验验证：将野生型菌株与同基因（isogenic）突变株共同感染仔猪，进一步确认了其致病相关功能。本研究鉴定的感染相关遗传决定因子，为猪链球菌致病机制研究提供了全新视角，同时可作为新型疫苗或抗菌药物的开发靶点。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于猪链球菌感染猪的过程中条件必需基因的识别研究，通过Tn-Seq方法在猪体内实验感染中，比较不同感染部位的突变体，确定了361个条件必需基因（约占基因组的18%），这些基因主要参与代谢、运输、调控和免疫逃逸等过程。研究还包括体外模型和猪体内共感染实验验证基因功能，数据集支持对猪链球菌发病机制的新见解，并为疫苗或药物开发提供潜在靶点。