Evolutonary Mechanisms of RNA Virus Host Switching

描述(由申请人提供)：广泛的、长期的目标：本文所述的研究目标以及在这些发现的基础上进行的未来研究，试图揭示推动人畜共患核糖核酸病毒“溢出”和适应的机制的一般科学原理。重要意义：在起源于人畜共患病的所有人类传染病中，有一半以上是由RNA病毒引起的。野生动物研究，以形成对RNA病毒与宿主相互作用的完整了解，特别是那些直接测试生态压力对 接触期间的病毒传播和溢出期间病毒的第一个适应步骤可以提供重要的见解。特别是，对汉坦病毒出现和适应的研究可以为：(1)预测RNA病毒出现和缓解的模型；(2)确定治疗干预的病毒和宿主靶标；以及(3)对调节病毒-宿主相互作用和病毒基因变异的选择压力有一个基本的了解。具体目的：我们建议使用南美汉坦病毒作为模型系统进行现场和实验室研究，以测试特定的选择压力，以揭示RNA病毒在水库(HR)和溢出宿主(HS)宿主系统中适应的进化机制。提出的三个目标将：(1)确定宿主宿主和共生啮齿动物物种在外部(环境)压力下的病毒出现；(2)揭示外部(环境和生态)压力对野生啮齿动物种群原有宿主内遗传变异的关系；(3)定义病毒适应、毒力和基因在体外适应新宿主物种的过程。研究设计和方法：AIM 1的拟议现场地点位于巴拉圭东部，那里有两种汉坦病毒共同传播，汉坦病毒血清阳性水平的升高与土地利用的人为变化有关。我们建议评估：(1)增加食物资源和(2)减少捕食对本地和受干扰林区内啮齿动物的病毒流行率(目标1)和宿主内和宿主间遗传变异(目标2)的影响。在目标3中，我们重点关注这些病毒的适合性和毒力以及导致适应的基因变化。使用基于原代内皮细胞培养的方法，我们将定义当新宿主物种HS在病毒复制、适应新宿主时与病毒相互作用时发生的内在(宿主)选择压力的影响。

DESCRIPTION (provided by applicant): Broad, long-term objectives: The research objectives stated herein, and in future studies that would build upon these findings, seek to reveal general scientific principles in the mechanisms that drive "spillover" and adaption of zoonotic RNA viruses. Significance: RNA viruses contribute to more than half of all human infectious diseases that have originated as zoonoses. Wildlife studies to form a complete understanding of RNA viral- host interactions, especially those that directly test the impact of ecological pressures on viral spread during contact and the first adaptive steps of the virus during spillover can provide important insights. Specifically, the study of the emergence and adaption of hantaviruses can provide critical data for: (1) models for prediction of RNA viral emergence and mitigation; (2) identification of viral and host targets for therapeutic intervention; and (3) a basic understandin of the selective pressures that modulate viral-host interactions and viral genetic variation. Specific aims: We propose field and laboratory studies using South American hantaviruses as a model system to test specific selective pressures to reveal evolutionary mechanisms of RNA virus adaption in reservoir (HR) and spillover host (HS) host systems. The three Aims proposed will: (1) define viral emergence within host reservoirs and sympatric rodent species during extrinsic (environmental) pressure; (2) reveal the relationship of extrinsic (environment & ecological) pressures on preexisting intrahost genetic variation in wild rodent populations; and, (3) define viral fitness, virulence, and genotype during adaptation to new host species in vitro. Research design and methods: The proposed field site for Aim 1 lies in eastern Paraguay, where two hantaviruses co-circulate, and where elevated seroprevalence levels of hantaviruses are associated with anthropogenic alteration of land use. We propose to assess effects of: (1) increased food resources and (2) reduced predation on virus prevalence (Aim 1) and intra- and interhost genetic variation in rodents within native and disturbed forest areas (Aim 2). In Aim 3, we focus on the fitness and virulence of these viruses and the genetic changes that lead to adaptation. Using primary endothelial cell culture-based approaches, we will define the impact of intrinsic (host) selective pressures occurring when a new host species, HS, interacts with virus as it replicates, adapts to a new host host.