Identification and characterization of novel genetic factors contributing to the significance of Listeria monocytogenes as a foodborne pathogen

有助于单核细胞增生李斯特氏菌作为食源性病原体的重要性的新遗传因素的鉴定和表征

• 批准号: 402573-2013
• 负责人: Allen, Kevin
• 金额: $ 1.82万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=550963
• 关键词: Identification; characterization; novel; genetic; factors

The perils of pathogen-contaminated food are fresh in the minds of many Canadians, and stem from the recent outbreak linked to widespread distribution of E. coli O157:H7 contaminated beef products across North America. Correspondingly, consequences of food safety failures are of considerable interest to Canadians. Regarding Listeria monocytogenes (Lm), 99% of listeriosis cases are estimated to derive from contaminated food. Therefore, improved mitigation strategies aimed at more effective control of Lm are required to reduce recalls and rates of listeriosis. To this end, my research program aims to identify factors contributing to food chain survival that enable more effective Lm mitigation. At this time, we are focusing on a recently discovered genomic island (LGI1) reported in deli meat and BC seafood. This islet encodes putative stress response, quaternary ammonium compound resistance, and virulence genes. Notably, strains carrying LGI1 were recently shown to form a new epidemic clone (ECV), and have caused human disease in Canada since 1988. To elucidate whether LGI1 genes contribute to food chain survival and/or virulence, my research program will use traditional and molecular approaches to address hypotheses. In short, we will compare Lm 1/2a serotype strains lacking LGI1 to 1/2a strains possessing LGI1 to see if differences exist in the ability to tolerate food-related stress (acidic pH, high salt) and sanitizers. Similarly, we will determine if Lm having LGI1 adhere to food surfaces and enterocytes more effectively. To complement these traditional food microbiology approaches, my program will also use qPCR and targeted gene deletion/complementation to confirm LGI1 contributions. As well, since LGI1 encodes an alternate sigma factor and a two-component regulator, RNA sequencing will be employed to investigate possible stress response/regulatory differences in strains encoding LGI1. This research program will contribute new knowledge regarding the role of LGI1. Considering its association with clinical listeriosis in Canada, such insight is critical, and will provide a foundation from which new and/or improved control strategies will evolve.

许多加拿大人对受病原体污染的食品的危险还记忆犹新，这源于最近与受大肠杆菌 O157:H7 污染的牛肉产品在北美广泛分布有关的疫情。相应地，加拿大人对食品安全失败的后果非常感兴趣。关于单核细胞增生李斯特菌 (Lm)，估计 99% 的李斯特菌病病例源自受污染的食物。因此，需要改进缓解策略，旨在更有效地控制 Lm，以减少李斯特菌病的召回和发生率。为此，我的研究项目旨在确定有助于食物链生存的因素，从而更有效地缓解 Lm。目前，我们关注的是最近在熟食肉类和不列颠哥伦比亚省海鲜中发现的基因组岛 (LGI1)。该胰岛编码假定的应激反应、季铵化合物抗性和毒力基因。值得注意的是，最近显示携带 LGI1 的菌株形成了一种新的流行性克隆 (ECV)，并自 1988 年以来在加拿大引起了人类疾病。为了阐明 LGI1 基因是否有助于食物链生存和/或毒力，我的研究计划将使用传统和解决假设的分子方法。简而言之，我们将比较缺乏 LGI1 的 Lm 1/2a 血清型菌株与具有 LGI1 的 1/2a 菌株，看看在耐受食物相关压力（酸性 pH 值、高盐）和消毒剂的能力上是否存在差异。同样，我们将确定具有 LGI1 的 Lm 是否更有效地粘附在食物表面和肠细胞上。为了补充这些传统的食品微生物学方法，我的计划还将使用 qPCR 和靶向基因删除/互补来确认 LGI1 的贡献。此外，由于 LGI1 编码替代 sigma 因子和双组分调节因子，因此将采用 RNA 测序来研究编码 LGI1 的菌株中可能的应激反应/调节差异。该研究计划将贡献有关 LGI1 作用的新知识。考虑到其与加拿大临床李斯特菌病的关联，这种见解至关重要，并将为新的和/或改进的控制策略的发展提供基础。