Evolutonary Mechanisms of RNA Virus Host Switching

7.项目摘要 广泛的长期目标：本文所述的研究目标以及未来的研究， 将在这些发现的基础上，寻求揭示机制中的一般科学原理， 驱动人畜共患RNA病毒的“溢出”和适应。 重要性：RNA病毒导致超过一半的人类传染病， 起源于人畜共患病野生动物研究，以形成一个完整的理解RNA病毒- 宿主相互作用，特别是那些直接测试生态压力对病毒的影响的宿主相互作用， 在接触过程中传播和病毒在溢出过程中的第一个适应步骤可以提供 重要的见解。具体来说，研究汉坦病毒的出现和适应， 提供关键数据：（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点;（3）基本了解 调节病毒-宿主相互作用和病毒遗传变异的选择压力。 具体目标：我们建议使用南美汉坦病毒作为 一个测试特定选择压力以揭示RNA进化机制的模型系统 病毒在宿主（HR）和溢出宿主（HS）宿主系统中的适应。提出的三个目标 将：（1）定义病毒出现在宿主水库和同域啮齿动物物种， 外在（环境）压力;（2）揭示外在（环境）压力与 生态）对野生啮齿动物种群中预先存在的宿主内遗传变异的压力;以及， (3)定义病毒适应性、毒力和体外适应新宿主物种的基因型。 研究设计和方法：目标1的拟议实地地点位于巴拉圭东部， 两种汉他病毒共同传播，汉他病毒的血清阳性率水平升高， 与人为改变土地利用有关。我们建议评估以下因素的影响：（1） 增加食物资源和（2）减少捕食病毒流行（目标1）和内部和 原生和干扰林区啮齿动物的宿主间遗传变异（目标2）。在目标3中， 我们专注于这些病毒的适应性和毒性，以及导致 适应使用原代内皮细胞培养为基础的方法，我们将定义影响 当新的宿主物种HS与病毒相互作用时， 当它复制的时候，适应一个新的宿主。

7. Project Summary 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 understanding 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.