Investigations of the impact of different determinants on the virulence and fitness of EHEC O104:H4

不同决定因素对EHEC O104:H4毒力和适合度影响的研究

• 批准号: 276606594
• 负责人: Dr. Petya Berger
• 金额: --
• 依托单位: Department of Biological Sciences
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/276606594?language=en
• 关键词: Investigations; impact; different; determinants; virulence

Enterohemorrhagic Escherichia coli (EHEC) can cause severe foodborne illness in humans, which is typically characterized by bloody diarrhea and progresses to hemolytic uremic syndrome (HUS) in circa 10% of the cases. EHEC O104:H4 was identified as the causative agent of the largest German outbreak (May-July 2011) during which nearly 4000 people were infected, and of them 22% developed HUS. Besides having a chromosomally integrated Shiga toxin 2 (Stx2) encoding phage, the highly virulent EHEC O104:H4 expresses pAA plasmid-encoded aggregative adherence fimbriae I (AAF/I; a characteristic virulence feature of enteroaggregative E. coli), which are mediating its tight adherence to cultured human epithelial cells. In addition, EHEC O104:H4 displays an extended spectrum beta-lactamase (ESBL) phenotype mediated by the conjugative pESBL plasmid.Our research exploits state of the art transcriptomic approaches to gain further insight into the virulence and fitness determinants of EHEC O104:H4. In the first funding period, we analyzed the primary transcriptomes of the pAA and pESBL plasmids and gained further insights into their gene expression using differential RNA seq, which is a powerful method for mapping of transcription start sites and non-coding RNAs. In addition, using comparative RNA-seq we identified features which are shared between EHEC O104:H4 and other less pathogenic and commensal strains, but are differentially expressed under identical conditions. We hypothesized that such cases of differential gene expression may significantly contribute to EHEC O104:H4 virulence and fitness. Our transcriptome analysis revealed that under conditions simulating the gut central metabolic genes are downregulated in EHEC O104:H4 in comparison to the control strains included in our analysis. Further investigations revealed that lysogenizing E. coli K-12 MG1655 with the Stx2 phage of EHEC O104:H4 resulted in analogous changes in the transcriptome and phenotype. Therefore, in the second funding period we will analyze the impact of Stx2 phage carriage on EHEC O104:H4 host gene expression. Moreover, we will investigate the impact of Stx2 phage-dependent transcriptome on EHEC O104:H4 virulence and fitness and identify the phage-encoded factors mediating it. Last but not least, we will evaluate the biological function of several genes, which were found upregulated in EHEC O104:H4 in our analysis and were previously linked to E. coli virulence and fitness. We anticipate that our results will significantly contribute to our general understanding of EHEC pathogenicity and in particular be beneficial for risk assessment of emerging Stx hybrid strains. Moreover, the identification of common but differentially regulated E. coli determinants associated with EHEC virulence will be of relevance to public health by facilitating phenotypic characterization and surveillance of pathogenic strains and eventually therapy and/or prevention of the disease.

肠出血性大肠杆菌（EHEC）可引起人类严重的食源性疾病，其典型特征是出血性腹泻，并在约10%的病例中发展为溶血性尿毒综合征（HUS）。O 104：H4型肠出血性大肠杆菌被确定为德国最大规模疫情（2011年5月至7月）的病原体，在此期间，近4000人感染，其中22%发展为溶血尿毒综合征。除了具有染色体整合的滋贺毒素2（Stx 2）编码噬菌体外，高毒力EHEC O 104：H4表达pAA质粒编码的聚集粘附菌毛I（AAF/I;肠聚集性E. coli），其介导其与培养的人上皮细胞的紧密粘附。此外，EHEC O 104：H4具有由接合型pESBL质粒介导的超广谱β-内酰胺酶（ESBL）表型，本研究利用最先进的转录组学方法进一步了解EHEC O 104：H4的毒力和适应性决定因素。在第一个资助期内，我们分析了pAA和pESBL质粒的初级转录组，并使用差异RNA seq进一步了解了它们的基因表达，这是一种强大的转录起始位点和非编码RNA作图方法。此外，使用比较RNA-seq，我们确定了EHEC O 104：H4与其他致病性较低和易感染菌株之间共享的特征，但在相同条件下差异表达。我们推测，这种情况下的差异基因表达可能显着有助于肠出血性大肠杆菌O 104：H4毒力和健身。我们的转录组分析显示，在模拟肠道的条件下，与我们分析中包括的对照菌株相比，EHEC O 104：H4中的中心代谢基因下调。进一步的研究表明，溶原性E。coli K-12 MG 1655与EHEC O 104：H4的Stx 2噬菌体在转录组和表型上产生了类似的变化。因此，在第二个资助期，我们将分析Stx 2噬菌体携带对EHEC O 104：H4宿主基因表达的影响。此外，我们还将研究Stx 2噬菌体依赖性转录组对EHEC O 104：H4毒力和适应性的影响，并鉴定介导其毒力和适应性的噬菌体编码因子。大肠杆菌毒力和适应性。我们预计，我们的研究结果将显着有助于我们的一般理解肠出血性大肠杆菌的致病性，特别是有利于新兴的Stx杂交菌株的风险评估。此外，鉴定常见但差异调节的E.与肠出血性大肠杆菌毒力相关的大肠杆菌决定簇将通过促进致病菌株的表型表征和监测以及最终治疗和/或预防疾病而与公共卫生相关。