RAPID: Investigation of Natural Selection and Host-microbiome-virome Interactions in an Unprecedented and Ongoing Marine Epidemic

大规模传染病暴发允许宿主、感染病原体和宿主内的微生物群落(微生物组)相对较快地发生进化变化。虽然人们对这些相互作用知之甚少，但它们对预测和控制未来的疫情非常重要。有记录以来最大的海洋流行病目前正在北美西海岸的潮间带生态系统中发生。海星衰减症(SSWD)正在影响从阿拉斯加东南部到墨西哥下加利福尼亚州的海星种群，当地的灭绝是一个严重的问题。随着全球环境和物种种群分布的变化，预计像这样的大规模流行病将变得更加常见。当前的这一疾病事件提供了一个独特的机会，可以更好地了解宿主、宿主的微生物群和疾病如何在整个流行病中引起病原体的变化。这项研究将从进化和生态学的角度对这些疾病事件进行更深入的了解，通过表征流行后自然选择导致的宿主和病原体的变化。本项目旨在了解微生物群和病毒体在个体、群体和社区水平对宿主疾病状态和进展的影响。这项工作将有助于将有机体理解为其居民的总和，并将剖析微生物群落在对疾病的生理和进化反应中的作用。疾病通常是由于生物体复杂的微生物群落的平衡被破坏所致。因此，疾病的进化不是两个参与者(宿主和病原体)的共同进化，而是宿主群落中所有成员的共同进化。正在进行的海星衰减症事件提供了一个独特的机会来研究这种进化是如何在大范围流行中发挥作用的。具体地说，这项研究的目的是(1)确定宿主和病毒群体中自然选择的靶标，(2)研究宿主、病毒和微生物组中强调宿主抗性和病毒毒力的分子机制，以确定无症状宿主和有症状宿主之间的临界点。这将使用一种新的测序技术来完成，该技术同时从真核宿主、细菌群落和病毒群落的转录本中收集序列数据。这种方法允许确定互动中的主要参与者以及他们的职能角色。对这种复杂的共同进化的理解将影响疾病生态和进化领域，并影响理解野生动物和人类疾病的方式，并有望预防或控制这些疾病。

Large infectious disease outbreaks allow for relatively faster evolutionary changes in the host, the infectious pathogen, and the community of microorganisms living within the host (the microbiome). While these interactions are poorly understood, they're extremely important in predicting and controlling future outbreaks. The largest recorded marine epidemic ever recorded is currently ongoing in intertidal ecosystems along the west coast of North America. Sea star wasting disease (SSWD) is effecting sea star populations from South Eastern Alaska to Baja California, Mexico and local extinctions are a serious concern. Large-scale epidemics such as these are expected to become more common as the global environment and species' population distributions change. This current disease event provides a unique opportunity to better understand how hosts, the hosts' microbiome, and the disease causing pathogen change throughout an epidemic. The research proposed here will lead to a deeper understanding of these disease events from an evolutionary and ecological perspective by characterizing changes in host and pathogen due to natural selection following epidemics.This project aims to understand the impact of the microbiome and virome on host disease status and progression at the individual, population, and community levels. The work will contribute to the understanding of an organism as a sum of its inhabitants and will dissect the role of the microbial community in physiological and evolutionary responses to disease. Disease may often be due to a disruption in the balance of an organisms' complex community of microorganisms. Thus, the evolution of disease is not the coevolution of two players (host and pathogen), but rather the coevolution of all members of the host's community. The ongoing Sea Star Wasting Disease event provides a unique opportunity to investigate how this evolution plays out in a widespread epidemic. Specifically, the proposed research aims to (1) identify the targets of natural selection in host and virus populations and (2) investigate molecular mechanisms in the host, virus, and microbiome that underline resistance in hosts and virulence in virus in order to identify the tipping point between asymptomatic and symptomatic hosts. This will be accomplished using a novel sequencing technique that simultaneously collects sequence data from the transcripts of the eukaryotic host, bacterial community, and viral community. This approach allows for identification of the major players in the interaction as well as their functional roles. The understanding of this complicated coevolution will impact the fields of disease ecology and evolution as well as affect the way wildlife and human diseases are understood and, hopefully, prevented or controlled.