Dissertation Research: A mechanistic approach to quantifying the costs of parasite communities

大多数动物，包括人类，同时感染多种寄生虫，但直到最近，大多数感染主要是在孤立的情况下研究的。来自人类和野生动物疾病的新证据表明，共同感染（即同居）同一宿主的寄生虫之间的相互作用可以影响对个体宿主健康和疾病传播的总体影响。该研究项目将研究共同感染的寄生虫在宿主内相互作用的方式，并调查不同寄生虫组合感染对宿主健康的影响。自由生活（非寄生）物种通常通过竞争食物或空间直接相互作用，或通过共同的敌人间接相互作用；同样，共同感染的寄生虫群落可能会在宿主内争夺有限的资源，或试图逃避由共同感染的寄生虫引发的宿主免疫防御。研究人员将在小鼠中使用实验室实验来操纵宿主资源（通过营养）和寄生虫群落组成（感染寄生虫的数量和身份），以验证资源竞争和/或免疫系统的捕食驱动共同感染寄生虫之间相互作用的变化，从而影响寄生虫繁殖、宿主状况和对新寄生虫的易感性的假设。丰富的免疫学和单种寄生虫感染实验小鼠数据为建立这一复杂的共感染实验提供了坚实的基础。此外，脊椎动物免疫系统的保守性使研究结果具有广泛的适用性。总的来说，本研究的结果将回答有关多种感染对宿主的潜在协同作用的基本问题。该项目将为两名本科生提供研究经验，并加强一名研究生的博士研究。主要研究人员还将参加一个项目，将实践生态学习带到佐治亚州的K-12教室。具体来说，这个项目的方法和结果将用于开发一个教学模块，介绍在外部环境（如自由生活群落中物种之间的竞争和捕食）和内部环境（如单个宿主个体内寄生虫之间的竞争和免疫逃避）中发生的生态过程的相似性。

Most animals, including humans, are infected with multiple parasites simultaneously, but until recently, most infections have primarily been studied in isolation. Emerging evidence from human and wildlife diseases suggests that interactions among parasites co-infecting (i.e., cohabiting) the same host can influence the overall impact on individual host health and disease spread. This research project will examine ways in which co-infecting parasites interact within a host, and investigate the consequences of infection with different combinations of parasites for host health. Free-living (non-parasitic) species often interact directly by competing for food or space, or indirectly via a shared enemy; similarly, communities of co-infecting parasites may compete for limited resources within the host, or attempt to evade host immune defenses triggered by co-occurring parasites. The investigators will use laboratory experiments in mice to manipulate host resources (via nutrition) and parasite community composition (the number and identity of infecting parasites), to test the hypothesis that resource competition and/or predation by the immune system drive changes in interactions between co-infecting parasites with consequences for parasite reproduction, host condition and susceptibility to new parasites. The wealth of immunological and singe-species parasite infection data in laboratory mice provide a strong foundation upon which to build this complex co-infection experiment. Furthermore, the conserved nature of the vertebrate immune system enables broad applicability of study results. Overall, the results of this study will answer fundamental questions about the potential synergistic effects of multiple infections on hosts. This project will provide research experiences for two undergraduate students in addition to enhancing the doctoral research of a graduate student. The principal investigators will also participate in a program that brings hands-on ecological learning to K-12 classrooms in Georgia. Specifically, methods and results from this project will be used to develop a teaching module on the similarity of ecological processes taking place in the external (e.g. competition and predation between species in free-living communities) and internal environments (e.g. competition and immune evasion between parasites within a single host individual).