摘要
Salmonella remains a leading cause of foodborne illnesses in the U.S. and worldwide. Though numerous strategies are implemented to control foodborne Salmonella, many come with limitations that reduce their efficacy or restrict which foods can be treated. An alternative control strategy that addresses these limitations is the application of bacteriophage cocktails, consisting of numerous bacterial viruses which kill the target pathogen. However, the use of phages also comes with two significant drawbacks: phage resistance and manufacturing hurdles. Resistance to phages may reduce the efficacy of phage cocktails, while concerns with at-scale phage production include handling of pathogenic host bacteria and optimization of numerous, complex biological variables. In the first part of this work, I show that ToxIN, a resistance system which aborts phage infection, is present in outbreak strains of Salmonella; confers resistance to the broad host range phage FelixO1 and other phage isolates; and is found in the whole-genome sequences of numerous Salmonella serovars and in other human pathogens. The second half of this work describes the in vitro synthesis of FelixO1 using an Escherichia coli-based cell-free expression system, demonstrating for the first time that a Salmonella phage can be produced in this manner. Taken together, this work illustrates that ToxIN may be of concern for food applications of phages while also establishing an important milestone in advancing Salmonella biocontrol using phages.
摘要译文
在美国和全球，沙门氏菌仍然是食源性疾病的主要原因。尽管采取了许多控制食源沙门氏菌的策略，但许多策略都具有限制，以降低其功效或限制可以治疗哪些食物。解决这些局限性的替代控制策略是应用噬菌体鸡尾酒，该鸡尾酒由许多杀死靶病原体的细菌病毒组成。但是，噬菌体的使用也带有两个重要的缺点：抗噬菌体性和制造障碍。对噬菌体的耐药性可能会降低噬菌体鸡尾酒的疗效，而对噬菌体产生的关注包括处理致病宿主细菌以及优化众多复杂的生物学变量。在这项工作的第一部分中，我表明毒素是一种流产噬菌体感染的抗药性系统，存在于沙门氏菌的爆发株中。赋予对广泛的宿主范围噬菌体Felixo1和其他噬菌体分离株的抵抗力；并在许多沙门氏菌血清射手和其他人类病原体的全基因组序列中发现。这项工作的后半部分描述了使用基于大肠杆菌的无细胞表达系统的Felixo1体外合成，这是首次以这种方式产生沙门氏菌噬菌体。综上所述，这项工作表明，毒素可能关注噬菌体的食物应用，同时还建立了使用噬菌体推进沙门氏菌生物防治的重要里程碑。
McFarlane, John Arthur. ToxIN-Mediated Resistance to and Cell-Free Production of Salmonella Bacteriophages[D]. US: University of Minnesota, 2023