Effect of Powassan virus genetic variation on replication in human cell culture and transmission by ticks

项目总结 鲍瓦桑病毒(POWV)是一种由硬蜱传播的神经侵袭性黄病毒，在自然界中由硬蜱维持。 在过去的十年里，人类感染病例的数量翻了两番，野生动物研究表明 地方性疾病传播的强度也在增加。POWV的特点是不同的传播周期和 疾病后果。该病毒由两个不同的系统发育分支组成，感染的证据一直是 在几种扁虱和脊椎动物中观察到。功率随时间变化关系的实验研究 目前缺乏遗传多样性、壁虱传播和疾病结局。这项研究的目标是 测定POWV的体外表型多样性，鉴定具有潜在医学意义的相关基因型别， 并确定病毒在扁虱体内的传播效率。为了促进这项研究，我们收集了47 在北美广泛的地理范围内的环境分离株，来自许多扁虱和 脊椎动物来源，跨越60多年。我们假设POWV是一种表型多样化的 疾病潜在性和传播能力可能不同的病毒。为了检验这一假设，我们确定了重复 以及在人类和扁虱细胞培养中的细胞病变效应表型。在与布罗德研究所的合作下，我们 利用POWV全基因组序列识别与细胞内病毒表型相关的遗传变异 文化。在我们的第二个目标中，我们使用一种创新的条形码病毒方法来调查病毒传播 在4种传播途径中：口腔、垂直、经腹和共喂。这一信息对于 了解POWV如何在滴答向量中持续存在。这项拟议研究的结果有助于我们的 目前对这种新出现的黄病毒缺乏了解。建议的目标如下： 目的1：量化POWV在细胞培养中的表型多样性，并鉴定感兴趣的遗传变异。 目的2：评价不同传播途径对肩部硬蜱鲍瓦桑病毒种群的影响。

PROJECT SUMMARY Powassan virus (POWV) is a neuroinvasive tick-borne flavivirus that is maintained in nature by Ixodid ticks. Over the past decade, the number of human cases has quadrupled, and wildlife studies suggest that the intensity of enzootic transmission is also increasing. POWV is marked by diverse transmission cycles and disease outcomes. The virus consists of two distinct phylogenetic clades, and evidence of infection has been observed in several tick and vertebrate species. Experimental studies of the relationships between POWV genetic diversity, tick transmission, and disease outcome are currently lacking. The goal of this study is to determine phenotypic diversity of POWV in vitro, identify relevant genotypes of potential medical importance, and determine efficiency of virus dissemination in ticks. To facilitate this study, we have collected 47 environmental isolates spanning a wide geographic range in North America, from a number of tick and vertebrate sources, and spanning over 6 decades. We hypothesize that POWV is a phenotypically diverse virus that can differ in disease potential and ability to transmit. To test this hypothesis, we determine replication and cytopathic effect phenotypes in human and tick cell culture. In collaboration with the Broad Institute, we use POWV whole genome sequences to identify genetic variants that correlate with virus phenotype in cell culture. In our second aim, we use an innovative method of barcoding virus to investigate virus dissemination in 4 tick transmission routes: oral, vertical, transstadial, and co-feeding. This information is critical to understanding how POWV persists in the tick vector. The results of this proposed study contribute to our currently lacking knowledge of this emerging flavivirus. The following aims are proposed: Aim 1: Quantify POWV phenotypic diversity in cell culture and identify genetic variants of interest. Aim 2: Assess the effects of transmission route on Powassan virus population in Ixodes scapularis ticks.