Global assignment of the function of salmonella genes in livestock

家畜沙门氏菌基因功能的全球分配

• 批准号: BB/D018080/1
• 负责人: Ian Charles
• 金额: $ 9.13万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FD018080%2F1
• 关键词: Global; assignment; function; salmonella; genes

Bacteria of the species Salmonella enterica are a threat to public health and sustainable agriculture. Over 2460 distinct variants of the organism have been described and these can be divided into two groups; serovars restricted or adapted to a given host that cause systemic illness (e.g. S. Typhi, which causes Typhoid fever in humans) and serovars causing gastroenteritis in a wide range of hosts (e.g. S. Typhimurium). Typhoid fever is a largely water-borne disease perpetuated by unsanitary conditions and 21 million human illnesses and 216,510 deaths are estimated to occur each year worldwide. Gastroenteritis caused by non-typhoidal Salmonella strains is also common, with an estimated 1.4 million cases and 600 deaths per annum in the United States alone. These infections are often associated with the consumption of foods derived from chickens, pigs and cattle owing to the ability of the bacteria to colonise the intestines of such animals. Strategies to reduce the carriage of S. enterica in food-producing animals are expected to lower the incidence of human infections and improve animal health. Whilst vaccines exist for the control of Salmonella in poultry, they confer weak and variable protection against different serovars and it is widely agreed that effective vaccines or treatments are needed for use in other livestock species. Furthermore, not all S. enterica serovars found in animals pose a threat to humans and tools are needed to predict the epidemic potential of such strains. The development of novel vaccines, treatments and diagnostics for Salmonella requires an understanding of the molecular events underlying intestinal colonisation. Our laboratories have identified some S. Typhimurium factors needed for colonisation of chickens, pigs and calves, but the function of less than one fifth of all Salmonella genes has so far been examined. S. Typhimurium infections in calves and pigs result in acute gastroenteritis whilst carriage in chickens tends to be asymptomatic. The reasons why Salmonella causes disease in one host but not another are not understood. Furthermore, it is not known why some S. enterica serovars cause systemic disease in a given host whereas others are restricted to the alimentary tract. We have invented a new method that permits the simultaneous screening of thousands of individual Salmonella mutants, each lacking a particular character, during infection of animals. The method (transposon-mediated differential hybridisation, TMDH) can rapidly describe the role of virtually all Salmonella genes during infection and relies on detecting signals from each mutant on a chip on which all the bacterial genes are arrayed. Bacterial genes are mutated at random then the mutants are assembled into large pools that can be inoculated into animals. The use of large pools dramatically reduces the number of animals that are needed. If a mutant is represented in the inoculum, but not in a pool recovered after the bacteria have passed through the animal, it can be inferred that the character disrupted in that mutant is important for colonisation. TMDH has been validated in mice, but it now needs to be used in food-producing animals. The method supersedes existing approaches, since it can inform the researcher when a gene is, or is not, required during infection without the need to isolate and examine the mutated gene. We propose to screen 10,000 S. Typhimurium mutants by this method for their ability to colonise the intestines of chickens, pigs and cattle. This will provide insights that cannot be obtained using surrogate rodent or cell-based assays and relies on the unique expertise and facilities at the applicants' laboratories. TMDH will greatly accelerate the identification of factors needed for Salmonella pathogenesis, some of which may be suitable as targets for drugs or included in a vaccine. Treatments developed for use in livestock may also be suitable for use in humans against typhoid fever.

肠道沙门氏菌对公共卫生和可持续农业构成威胁。已描述了超过 2460 种不同的生物体变体，这些变体可分为两类：限制或适应特定宿主的血清型会引起全身性疾病（例如伤寒沙门氏菌，会导致人类伤寒），而血清型则会在广泛的宿主中引起胃肠炎（例如鼠伤寒沙门氏菌）。伤寒是一种主要由水传播的疾病，由于不卫生的条件而长期存在，估计全世界每年有 2100 万人患病，216,510 人死亡。由非伤寒沙门氏菌菌株引起的胃肠炎也很常见，仅在美国每年估计就有 140 万例病例和 600 人死亡。这些感染通常与食用鸡、猪和牛的食物有关，因为细菌能够在这些动物的肠道中定殖。减少食品动物肠沙门氏菌携带的策略预计将降低人类感染的发生率并改善动物健康。虽然存在用于控制家禽沙门氏菌的疫苗，但它们对不同血清型的保护作用较弱且可变，并且人们普遍认为需要有效的疫苗或治疗方法用于其他牲畜物种。此外，并非所有在动物中发现的肠沙门氏菌血清型都对人类构成威胁，因此需要工具来预测此类菌株的流行潜力。沙门氏菌新型疫苗、治疗方法和诊断方法的开发需要了解肠道定植的分子事件。我们的实验室已经鉴定出鸡、猪和牛犊定植所需的一些鼠伤寒沙门氏菌因子，但迄今为止，只有不到五分之一的沙门氏菌基因的功能得到了检验。牛犊和猪的鼠伤寒沙门氏菌感染会导致急性胃肠炎，而鸡的感染往往无症状。沙门氏菌在一种宿主中引起疾病​​而不是在另一种宿主中引起疾病​​的原因尚不清楚。此外，尚不清楚为什么某些肠沙门氏菌血清型会在特定宿主中引起全身性疾病，而另一些则仅限于消化道。我们发明了一种新方法，可以在动物感染期间同时筛选数千个单独的沙门氏菌突变体，每个突变体都缺乏特定的特征。该方法（转座子介导的差异杂交，TMDH）可以快速描述感染过程中几乎所有沙门氏菌基因的作用，并依赖于检测排列有所有细菌基因的芯片上每个突变体的信号。细菌基因随机突变，然后将突变体组装成可以接种到动物体内的大库。大型水池的使用大大减少了所需动物的数量。如果在接种物中出现突变体，但在细菌穿过动物后回收的库中没有出现突变体，则可以推断该突变体中被破坏的特征对于定殖很重要。 TMDH 已在小鼠身上得到验证，但现在需要用于食用动物。该方法取代了现有方法，因为它可以告知研究人员在感染过程中何时需要或不需要某个基因，而无需分离和检查突变基因。我们建议通过这种方法筛选 10,000 个鼠伤寒沙门氏菌突变体，以确定它们在鸡、猪和牛肠道中定殖的能力。这将提供使用替代啮齿动物或基于细胞的测定无法获得的见解，并且依赖于申请人实验室的独特专业知识和设施。 TMDH 将极大地加速沙门氏菌发病机制所需因素的鉴定，其中一些因素可能适合作为药物靶标或包含在疫苗中。为牲畜开发的治疗方法也可能适用于人类治疗伤寒。

项目成果

Comprehensive assignment of roles for Salmonella typhimurium genes in intestinal colonization of food-producing animals.

• DOI: 10.1371/journal.pgen.1003456
• 发表时间: 2013-04
• 期刊: PLoS genetics
• 影响因子: 4.5
• 作者: Chaudhuri RR;Morgan E;Peters SE;Pleasance SJ;Hudson DL;Davies HM;Wang J;van Diemen PM;Buckley AM;Bowen AJ;Pullinger GD;Turner DJ;Langridge GC;Turner AK;Parkhill J;Charles IG;Maskell DJ;Stevens MP
• 通讯作者: Stevens MP