Molecular characterization of Salmonella host specificity

沙门氏菌宿主特异性的分子特征

• 批准号: RGPIN-2020-05233
• 负责人: DAIGLE, France
• 金额: $ 3.06万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=760935
• 关键词: Molecular; characterization; Salmonella; host; specificity

The aim of this research program is to define the molecular and genetic basis of host tropism in related bacteria. Our bacterial model is Salmonella enterica, one of the leading foodborne bacterial pathogens in Canada. Salmonella strains are classified into serovars, some are specific to only one host, whereas others can colonize multiple host species. There are 2600 serovars and there is no way yet to predict their host range or virulence. We propose to compare and study a serovar that is specific only to humans, the host-specific S. Typhi and a broad-host range serovar, the generalist S. Typhimurium. We have already observed many phenotypic differences between these serovars and we will pursue by identifying genes involved in host adaptation. Biofilm is an adaptation mechanism in which the bacterium is embedded in an extracellular matrix to protect itself and persist. In Salmonella, the generalist produces biofilm in the environment while the host-specific serovar produces biofilm within the host. The major components of the biofilm matrix, cellulose and the curli adhesin, are not expressed by the host-specific serovar. We have demonstrated that the generalist produces less biofilm in the presence of bile, a substance found in the gut, whereas the host-specific serovar produce more biofilm in the presence of bile. Thus, we hypothesize that biofilm formation is critically linked to host specificity. We will investigate and compare biofilm produced by either the generalist or the host-specific serovar. First, we will characterize Salmonella biofilms in the presence of bile by determining the biomass, the matrix composition, organization and viability. Innovative, qualitative and quantitative approaches will be used to observed biofilm formation in real-time. We will then identify key factors involved in biofilm formation using a high-throughput robotic platform. We will also investigate the influence of microbiota on biofilm formation. Finally, we will investigate the influence of host cell type and origin on Salmonella biofilm formation. Comparison between these two distinctly adapted serovars will lead to the identification of key components that should shed light on specific mechanisms of host adaptation. It is anticipated that the research proposed in this application will contribute to our understanding of basic mechanisms of bacterial biofilm formation and species evolution. As some of the targeted systems are conserved among other bacteria, this may potentially lead to common strategies to potentially reduce the presence of such bacteria in different environments, both within the host and in environmental settings, such as in water and food sources.

本研究的目的是明确相关细菌中寄主嗜性的分子和遗传基础。我们的细菌模型是肠道沙门氏菌，它是加拿大主要的食源性细菌病原体之一。沙门氏菌分为不同的血清型，有些只针对一个宿主，而另一些则可以定植于多个宿主物种。有2600个血清型，目前还没有办法预测它们的寄主范围或毒力。我们建议比较和研究一个仅针对人类的血清型，即宿主特有的伤寒沙门氏菌和一个广泛宿主范围的血清型，即通用的鼠伤寒沙门氏菌。我们已经观察到这些血清型之间的许多表型差异，我们将通过识别参与宿主适应的基因来继续研究。生物膜是一种适应机制，在这种机制中，细菌被嵌入细胞外基质中以保护自己并持续存在。在沙门氏菌中，通才在环境中产生生物膜，而宿主特定的血清型在宿主内产生生物膜。生物膜基质的主要成分纤维素和卷曲粘附素不是由宿主特有的血清型表达的。我们已经证明，在胆汁存在的情况下，多面手产生的生物膜较少，而宿主特定的血清型在存在胆汁的情况下产生更多的生物膜。因此，我们假设生物膜的形成与宿主的特异性密切相关。我们将调查和比较由通用型或宿主特异性血清型产生的生物膜。首先，我们将通过测定生物量、基质组成、组织和活性来表征胆汁存在下的沙门氏菌生物膜。将使用创新、定性和定量的方法来实时观察生物膜的形成。然后，我们将使用高通量机器人平台确定生物膜形成的关键因素。我们还将调查微生物区系对生物膜形成的影响。最后，我们将研究宿主细胞类型和来源对沙门氏菌生物被膜形成的影响。对这两个不同适应的血清型的比较将导致对关键成分的识别，这应该有助于阐明宿主适应的具体机制。预计本申请中提出的研究将有助于我们理解细菌生物被膜形成和物种进化的基本机制。由于一些目标系统在其他细菌中是保守的，这可能会导致共同的战略，潜在地减少这些细菌在不同环境中的存在，无论是在宿主内部还是在环境设置中，如在水和食物来源中。