Molecular Basis of Flavivirus Neurovirulence

描述（由申请方提供）：本提案的目的是促进对控制人类宿主中黄病毒复制和毒力的病毒分子决定因素的理解。从这些研究中获得的信息可用于设计和改进具有公共卫生重要性的病毒的减毒活病毒疫苗，以及深入了解病毒发病机制。黄病毒属是一组不同的蚊子和蜱传播的RNA病毒，其在人类中引起一系列疾病综合征，包括出血热和急性脑炎。由于它们在全球范围内的持续出现和重新出现，对于针对这些黄病毒感染的疫苗的可用性的需求不断增长，这些黄病毒感染对人类群体构成不可预测的严重威胁。由于缺乏任何有效的抗黄病毒疗法，疫苗接种结合蚊虫控制措施仍然是预防疾病的主要策略。然而，需要提高某些黄病毒疫苗的效力，并且在某些情况下需要提高其安全性。在这项提议中，黄热病（YFV）和日本脑炎（JEV）病毒的分子克隆将用于确定小鼠模型中神经毒力的分子基础，并测试减毒突变对实验性YFV和JEV疫苗特性的影响。在目的1中，目标是确定在神经适应性YF 17 D疫苗以及高神经毒性法国亲神经性疫苗（FNV）的情况下，YFV的神经毒力是否主要由病毒包膜（E）蛋白内编码的决定簇控制。 在目标2中，将通过在E蛋白中引入新的减毒突变来修饰YF 17 D分子克隆，并将它们对神经毒力特性和免疫原性的影响与17 D疫苗进行比较。在目标3中，将通过在中国目前用于人类疫苗接种的减毒JE SA 14 -14-2疫苗和高神经毒力JE-Nakayama毒株之间构建型间病毒，并测试其毒力来研究JE病毒神经毒力的分子基础小鼠的毒力特性。这些研究的结果预计将产生与使用分子克隆技术作为疫苗开发方法相关的数据，因此对减少与黄病毒感染相关的全球疾病负担具有长期意义。

DESCRIPTION (provided by applicant): The objectives of this proposal are to advance understanding of the viral molecular determinants governing replication and virulence of flaviviruses in human hosts. Information from these studies may be used to design and improve live-attenuated viral vaccines for viruses of public health importance, as well as to gain insight into the mechanisms of viral pathogenesis. Flaviviruses are a diverse group of mosquito- and tick-transmitted RNA viruses which cause a range of disease syndromes in humans including hemorrhagic fever and acute encephalitis. Due to their continuing emergence and re-emergence on a global scale, there is growing demand for the availability of vaccines against those flavivirus infections which present unpredictable and serious threats to human populations. Because of the lack of any effective antiviral therapies against flaviviruses, vaccination in conjunction with mosquito control measures, remains the principal strategy for the prevention of disease. However there is a need to improve the efficacy and in some cases the safety of certain flavivirus vaccines. In this proposal molecular clones of yellow fever (YFV) and Japanese encephalitis (JEV) viruses will be used to define the molecular basis of neurovirulence in a mouse model, and to test the effects of attenuating mutations on the properties of experimental YFV and JEV vaccines. In Aim 1 the goal is to determine if the neurovirulence of YFV is mainly controlled by determinants encoded within the viral envelope (E) protein, both in the context of neuroadapted YF 17D vaccine, as well as the highly neurovirulent French neurotropic vaccine (FNV). In Aim 2, the YF 17D molecular clone will be modified by introduction of novel attenuating mutations in the E protein and their effects on neurovirulence properties and immunogenicity will be compared to 17D vaccine. In Aim 3 the molecular basis of JE virus neurovirulence will be investigated by constructing intertypic viruses between the attenuated JE SA14-14-2 vaccine currently used for human vaccination in China, and a highly neurovirulent JE-Nakayama strain, and testing their virulence properties in mice. The results of these studies are expected to yield data relevant to the use of molecular clone technology as an approach to vaccine development, and therefore have long-term implications for reducing the worldwide disease burden asssociated with flavivirus infections.