Genetic determinants of WN virus pathogenicity

描述（由申请人提供）：黄病毒属包含60多种密切相关的病毒，包括几种具有全球和地方流行病学重要性的人类病原体，其中大多数通过节肢动物媒介传播。西尼罗河病毒（WN）是最广泛的黄病毒，地理分布现在包括五大洲中的四个。鉴于其适应性和多样化的传播周期，这种病毒在美洲大陆出现后，很可能会融入现有的生态系统，从而在国家一级造成长期和重大的流行病问题。西尼罗河病毒广泛的地理分布导致形成两种不同WN病毒谱系的毒株之间存在相当大的异质性，其致病特性在很大程度上仍未得到表征。虽然谱系I病毒株通常与人或马的爆发有关，但第二谱系的病毒株更经常被鉴定为野外分离株。在美国出现的WN病毒也属于谱系I，与鸟类和人类的神经系统疾病有关。该菌株在细胞培养物中也表现出高度致细胞病变性。我们已经确定了几个高度致细胞病变和非致细胞病变WN菌株，分别属于谱系I和II。我们打算在细胞培养和小鼠模型中比较这些菌株的细胞和致病特性。使用385-99分离株作为代表，我们将组装谱系I西尼罗河病毒的感染性克隆。使用这种感染性克隆和谱系II WN感染性克隆，我们已经报道过，我们将制备嵌合病毒，以确定是否包膜蛋白基因携带的决定因素负责观察到的小鼠的致病性和细胞培养和体内的细胞病理学。在这项研究中获得的数据将有助于表征最近在美国出现的传染性病原体，并将有助于抗WN疫苗和抗病毒药的合理设计。

DESCRIPTION (provided by applicant): The Flavivirus genus incorporates over 60 closely related viruses including several human pathogens of global and local epidemiological importance, with most of them being transmitted by arthropod vectors. West Nile (WN) virus is the most widespread of the flaviviruses, with geographic distribution now including four out of five continents. Given its adaptability and diversified transmission cycles, this virus, having been appeared on the American continent, very likely will integrate into the existing ecosystems resulting in establishment of a permanent and substantial epidemiological concern at the national level. The broad geographic distribution of West Nile virus has resulted in considerable heterogeneity among strains forming two distinct WN virus lineages, pathogenic properties of which remain largely uncharacterized. While lineage I virus strains were often identified in connection with human or equine outbreaks, strains of the second lineage more often were identified by occasion as field isolates. The WN virus emerged in the U.S. also belongs to lineage I and has been associated with neurological disease both in birds and humans. This strain also appeared highly cytopathic in cell culture. We have identified several highly cytopathic and non-cytopathic WN strains, which belong to lineage I and II, respectively. We intend to compare cyto- and pathogenic properties of these strains in cell culture and in the mouse model. Using a 385-99 isolate as a representative, we will assemble an infectious clone of lineage I West Nile virus. Using this infectious clone and the lineage II WN infectious clone that we have reported earlier, we will prepare chimeric viruses to determine if the envelope protein genes carry determinants responsible for the observed pathogenicity in mice and cytopathology in cell culture and in vivo. Data obtained in the study will contribute to characterization of the infectious agent recently emerged in the U.S. and will aid in rational design of anti-WN vaccines and antivirals.