Characterizing Diverse Phage Roles in a Defensive Symbiosis

昆虫和其他动物经常感染母体遗传的共生细菌，这些细菌可以通过提供营养或宿主保护而使它们的动物宿主受益。许多有益的共生体本身被称为噬菌体的病毒感染，这种病毒具有以关键方式影响宿主生物学的能力，但它们在动物-细菌共生体中的作用却知之甚少。在豌豆蚜虫Acyrthosiphon pisum中，细菌共生体Hamiltonella防御系统可以保护其免受寄生蜂的攻击，但只有在称为APSEs的噬菌体也存在的情况下。除了这种保护作用外，APSEs对H. defensa和蚜虫生物学的影响知之甚少，特别是APSEs如何促进寄生虫的死亡以及在共生体丰度调节中的潜在作用。该项目将使用多种方法，包括基因组学和分子生物学，来描述APSEs在调节和维持保护性共生关系中的作用，并确定导致黄蜂死亡的具体因素。破译噬菌体-共生体的相互作用对于研究动物-微生物的相互作用以及了解许多具有重要经济意义的昆虫（如蚜虫）的生物学是非常重要的。这项工作将为害虫种群的管理和噬菌体在建立和维持细菌-节肢动物关系中的作用提供具有实际意义的信息，这种关系在自然界中广泛存在。该研究的跨学科性质也非常适合作为培养共生，细胞生物学，寄生虫学和分子过程界面的年轻科学家的平台。该项目将培养高中生、本科生和研究生以及博士后研究人员。

Insects and other animals are frequently infected with maternally inherited symbiotic bacteria, which can benefit their animal hosts by providing nutrition or host protection. Many beneficial symbionts are themselves infected with viruses called bacteriophages, which have the capacity to impact host biology in critical ways, yet their roles in animal-bacterial symbioses are poorly understood. In the pea aphid, Acyrthosiphon pisum, the bacterial symbiont Hamiltonella defensa confers protection from attack by parasitic wasps, but only when bacteriophages called APSEs are also present. Aside from this role in protection, little is known about the influence of APSEs on H. defensa and aphid biology, including specifically how APSEs contribute to the demise of parasites and the potential role in the regulation of symbiont abundance. This project will use a combination of approaches, including genomics and molecular biology, to characterize the roles of APSEs in the regulation and maintenance of the protective symbiosis and to identify specific factors responsible for wasp mortality. Deciphering phage-symbiont interactions is important to the study of animal-microbial interactions generally and to understanding the biology of many economically important insects like aphids. The proposed work will yield information of practical importance for the management of pest insect populations and on the role of phages in the establishment and maintenance of bacterial-arthropod associations, which are widespread in the natural world. The interdisciplinary nature of this research is also well suited as a platform to train young scientists at the interface of symbiosis, cell biology, parasitology, and molecular processes. This project will train high school students, undergraduate and graduate students, and post-doctoral researchers.