Quasispecies dynamics in arbovirus persistence emergence and fitness

描述（由申请方提供）：当地、特定地点的特征在很大程度上控制着节肢动物传播病毒（虫媒病毒）的传播动力学。虫媒病毒反过来适应当地条件，最大限度地发挥其永久存在的潜力，并成为健康威胁。虫媒病毒的适应性潜力是由易错复制驱动的，这在基因上创造了一个 在每个宿主内竞争病毒基因型的不同池。该应用程序检查了任何给定的传播焦点的三个重要特征对病毒遗传多样性的影响;以及遗传多样性如何影响宿主-病毒相互作用。我们之前的研究使我们能够对这三个特征中的每一个做出非常明确的预测。蚊子和脊椎动物之间的接触频率因时间和空间而异。目的1将确定这种接触的频率如何影响西尼罗河病毒（WNV）的遗传多样性，使用实验室模型传播周期。我们预测，在蚊子中较短的潜伏期可以维持病毒的遗传多样性和高适应性。传播焦点的第二个关键特征是参与病毒传播的蚊子种类。因此，目标2将评估媒介蚊子通过RNA干扰（RNAi）对WNV感染做出反应的能力有多重要，从而推动病毒多样化。将评估现场收集和定殖的库蚊（主要）和伊蚊（次要）。我们预测，在蚊子种内和种间将检测到RNAi激活的显著变化，并且这种变化将与病毒遗传多样性和改变的载体相关。 能力。西尼罗河病毒传播焦点的第三个关键特征是参与病毒扩增的鸟类。因此，目标3将评估乌鸦、麻雀和知更鸟如何塑造西尼罗河病毒种群。病毒将在这些鸟类中的每一只中传播，并评估遗传多样性和适应性。我们还将使用这些鸟类来测量不同的现有西尼罗河病毒株和种群的复制适应性。我们预测，野生鸟类对西尼罗河病毒种群施加强大的净化选择，病毒的遗传多样性对其在birs中的适应性贡献不大，但鸟类感染可能会选择新的西尼罗河病毒基因型。这项工作的重要性在于，它将为RNA病毒作为健康威胁的出现提供新的机制数据。这项研究在概念上是创新的，因为它将西尼罗河病毒传播疫源地的生态与病毒的适应性可塑性联系起来。它在技术上是创新的，因为它使用独特的方法来测量体内相关宿主之间的病毒适应性，并通过使用深度测序。最终，我们试图确定有利于新病毒基因型出现的条件。

DESCRIPTION (provided by applicant): Local, site-specific characteristics largely control the transmission dynamics of arthropod-borne viruses (arboviruses). Arboviruses, in turn, adapt to local conditions, maximizing their potential to perpetuate and emerge as health threats. The adaptive potential of arboviruses is driven by error-prone replication, which creates a genetically diverse pool of competing virus genotypes within each host. This application examines the influence of three important characteristics of any given transmission focus on viral genetic diversity; and how genetic diversity influences host-virus interactions. Our previous research has allowed us to make very clear predictions about each of the three examined characteristics. The frequency of contact between mosquitoes and vertebrates varies in time and space. Aim 1 will determine how the frequency of this contact influences the genetic diversity of West Nile virus (WNV) using a laboratory model transmission cycle. We predict that shorter incubation in mosquitoes allows maintenance of viral genetic diversity and high fitness. A second critical characteristic of a transmission focus is the mosquito species involved in virus transmission. Aim 2 will therefore assess how important vector mosquitoes differ in their ability to respond to WNV infection through RNA interference (RNAi) and thus drive virus diversification. Field-collected and colonized Culex (main) and Aedes (secondary) mosquitoes will be assessed. We predict that significant variation in RNAi activation will be detected within and between mosquito species, and that this variation will be associated with virus genetic diversity and altered vector competence. A third critical characteristic of a WNV transmission focus is the bird species involved in virus amplification. Aim 3, accordingly, will evaluate how crows, sparrows and robins shape WNV populations. Virus will be passed in each of these birds and genetic diversity and fitness assessed. We will also use these birds to measure the replicative fitness of different existing WNV strains and populations. We predict that wild birds exert strong purifying selection on WNV populations and that genetic diversity of the virus contributes little to its fitness in birs, but that bird infection may select for novel WNV genotypes. The significance of this work is that it will provide novel data the mechanisms that underpin the emergence of RNA viruses as health threats. The proposed research is conceptually innovative because it links the ecology of WNV transmission foci with virus adaptive plasticity. It is technically innovative because it uses uniqe methods for measuring virus fitness among relevant hosts in vivo and through its use of deep sequencing. Ultimately we seek to define the conditions that favor the emergence of novel virus genotypes.