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

项目概要 波瓦桑病毒 (POWV) 是一种神经侵袭性蜱传黄病毒，在自然界中由蜱蜱维持。 在过去的十年中，人类感染病例的数量增加了四倍，野生动物研究表明 地方性动物传播的强度也在增加。 POWV 的特点是传输周期多样， 疾病结果。该病毒由两个不同的系统发育分支组成，感染证据已被证实 在几种蜱和脊椎动物中观察到。 POWV之间关系的实验研究 目前缺乏遗传多样性、蜱传播和疾病结果。这项研究的目标是 确定 POWV 体外表型多样性，识别具有潜在医学重要性的相关基因型， 并确定病毒在蜱中传播的效率。为了促进这项研究，我们收集了 47 北美广泛地理范围内的环境隔离物，来自多种蜱虫和 脊椎动物来源，跨越 6 个十年。我们假设 POWV 是一种表型多样化的病毒 疾病潜力和传播能力可能不同的病毒。为了检验这个假设，我们确定复制 和人类和蜱细胞培养物中的细胞病变效应表型。我们与布罗德研究所合作 使用 POWV 全基因组序列来识别与细胞中病毒表型相关的遗传变异 文化。我们的第二个目标是使用一种创新的病毒条形码方法来研究病毒传播 蜱传播有 4 种途径：口腔、垂直、跨空间和共同进食。此信息对于 了解 POWV 如何在刻度向量中持续存在。这项拟议研究的结果有助于我们 目前缺乏对这种新兴黄病毒的了解。建议实现以下目标： 目标 1：量化细胞培养物中的 POWV 表型多样性并识别感兴趣的遗传变异。 目标 2：评估传播途径对肩胛硬蜱中 Powassan 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.