Quasispecies dynamics in arbovirus persistence emergence and fitness

描述(由申请人提供)：局部的、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)的传播动态。虫媒病毒反过来适应当地条件，最大限度地发挥其作为健康威胁长期存在和出现的潜力。虫媒病毒的适应潜力是由容易出错的复制驱动的，这在基因上创造了一个 每个宿主内存在不同的竞争病毒基因型池。这项应用调查了任何特定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与病毒的相互作用。我们之前的研究使我们能够对所检查的三个特征中的每一个做出非常明确的预测。蚊子和脊椎动物接触的频率在时间和空间上各不相同。目标1将利用实验室模型传播周期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。我们预测，在蚊子中孵化的时间较短，可以保持病毒的遗传多样性和高适应性。传播中心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)对西尼罗河病毒感染做出反应并从而推动病毒多样化的能力的不同程度。将对现场采集和定居的库蚊(主要)和伊蚊(次要)进行评估。我们预测，在蚊子内和蚊子之间，rNAi的激活将会有显著的差异，这种差异将与病毒遗传多样性和改变的媒介有关。 能力。西尼罗河病毒传播中心的第三个关键特征是参与病毒扩增的鸟类种类。因此，目标3将评估乌鸦、麻雀和知更鸟如何形成西尼罗河病毒的种群。病毒将在每一只禽类体内传递，并对遗传多样性和适合性进行评估。我们还将使用这些禽类来衡量不同现有西尼罗河病毒株和种群的复制适合度。我们预测，野生鸟类对西尼罗河病毒种群具有很强的净化选择能力，该病毒的遗传多样性对其在鸟类中的适合度影响不大，但鸟类感染可能会选择新的西尼罗河病毒基因型。这项工作的意义在于，它将为支持RNA病毒作为健康威胁出现的机制提供新的数据。这项拟议的研究在概念上是创新的，因为它将西尼罗河病毒传播中心的生态与病毒适应可塑性联系起来。它在技术上是创新的，因为它使用唯一的方法来测量体内相关宿主之间的病毒适合性，并通过使用深度测序。最终，我们寻求定义有利于出现新的病毒基因类型的条件。

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.