The Molecular Basis of VEEV Pathogenesis

描述（由申请人提供）：托加病毒科的甲病毒属包括许多重要的人类和动物病原体，包括委内瑞拉（VEEV），东部（EEEV）和西部马脑炎（WEEV）病毒。后者在美国构成严重的公共卫生威胁，因为它们不断在自然界中传播，并有能力对人类和马匹造成致命疾病。此外，EEEV， WEEV，特别是VEEV具有被恐怖分子使用和作为生物战剂的潜力。尽管VEEV流行的持续威胁，但对VEEV的生物学，特别是其高毒力的分子基础的研究不如对其他甲型病毒的研究深入。认为Sindbis （SINV）和Semliki Forest （SFV）病毒致病性明显低于VEEV，为研究VEEV复制机制和病毒-宿主相互作用提供了良好的模型。然而，最近对VEEV和SINV的比较研究结果表明，VEEV的复制及其发病机制与先前描述的SINV有很大不同。因此，我们关于SINV生物学的大部分知识不能直接应用于VEEV。我们的初步研究强烈表明，VEEV衣壳在抑制核胞质运输和细胞转录方面起着关键作用，从而下调先天免疫反应。我们的研究结果还表明，VEEV基因组的5'UTR是病毒发病的重要决定因素之一。因此，本研究旨在进一步了解VEEV衣壳和5'UTR在病毒复制中的功能，并在不同水平上确定病毒的发病机制。提出的实验分为三个目的。在具体目标1中，我们打算确定VEEV衣壳在核胞浆运输抑制中的功能。在具体目标2中，我们将在分子和细胞水平上详细研究5'UTR序列中菌株特异性突变对VEEV复制和发病机制的影响；在具体目标3中，我们将利用在我们拟议的实验中产生的现有信息和新数据，开发用于疫苗应用的新的高度减毒的VEEV毒株。具体目标代表了三个独立的研究方向，但它们有望产生互补的数据。本研究结果也将适用于其他致脑性甲病毒，如eev和WEEV。

DESCRIPTION (provided by applicant): The Alphavirus genus in the Togaviridae family includes a number of important human and animal pathogens, including Venezuelan (VEEV), eastern (EEEV) and western equine encephalitis (WEEV) viruses. The latter constitute a serious public health threat in the US, because they continuously circulate in nature and have the ability to cause fatal disease in humans and horses. In addition, EEEV, WEEV and, in particular, VEEV have the potential for use by terrorists and as biological warfare agents. In spite of the continuous threat of VEEV epidemics, the biology of VEEV, in particular the molecular basis of its high virulence, has been studied less intensively than that of other alphaviruses. It was believed that Sindbis (SINV) and Semliki Forest (SFV) viruses, which are dramatically less pathogenic than VEEV, represent good models for studying the mechanism of VEEV replication and virus-host interactions. However, results from recent comparative studies with VEEV and SINV suggested that VEEV replication and its pathogenesis strongly differ from those previously described for SINV. Hence, a great part of our knowledge about SINV biology cannot be directly applied to VEEV. Our preliminary studies strongly suggested that the VEEV capsid plays critical roles in inhibiting both nucleocytoplasmic trafficking and cellular transcription and, thus, downregulation of the innate immune response. Our results also suggested the 5'UTR of the VEEV genome is one of the important determinants of viral pathogenesis. Therefore, the proposed research is aimed at further understanding the functions of VEEV capsid and 5'UTR in virus replication, and in determining virus pathogenesis at different levels. The proposed experiments are organized into three aims. In specific aim 1, we intend to define functioning of VEEV capsid in the nucleocytoplasmic transport inhibition. In specific aim 2, we will perform a detailed investigation of the effects of the strain-specific mutations in the 5'UTR sequence on VEEV replication and pathogenesis on molecular and cellular levels; and in specific aim 3, we will apply already available information and new data that will be generated in our proposed experiments to develop new, highly attenuated strains of VEEV for vaccine applications. The specific aims represent three independent lines of research, but they are expected to generate complementary data. The results of this study will also be applicable to other encephalitogenic alphaviruses, such as EEEV and WEEV. PUBLIC HEALTH RELEVANCE: Alphaviruses comprise a group of widely distributed human and animal pathogens; some of them induce highly debilitating diseases and represent a serious public health threat in the US. The goal of this application is to understand the role of viral proteins in modification of the intracellular environment during virus replication and development of new, highly attenuated, live vaccines against encephalitogenic alphaviruses.