Mechanism of VEE Attenuation

描述：(改编自《调查者摘要》)：委内瑞拉马 脑炎病毒(VEE)是马和人类的重要病原体。它 在由高毒力的流行性疾病株引起的流行病中定期出现。 天然VEE菌株的毒力决定因素在 分子水平。在疫苗株和实验室减毒株中， 小鼠的毒力决定因素已被映射到EL和E2糖蛋白和 5‘非翻译区(UTR)。该基因第3位核苷酸(NT3)的单一变化 将VEE基因组的5‘非编码区(G到A替换)引入分子中 野生型强毒VEE的克隆会导致一种完全 在小鼠身上减弱。长期目标是确定通过什么机制 VEE基因组5‘端非编码区的特定突变可使病毒减毒，并 利用VEE系统阐明lFNAB在甲型病毒致病中的作用。 我们假设nt3A突变导致一种病毒 由于病毒水平增加，对lFNaB的抗病毒作用的敏感性 DsRNA复制中间体，因此(A)增加对 干扰素刺激的抗病毒基因，(B)增强干扰素诱导的激活 需要dsRNA作为辅因子的抗病毒蛋白，或者(C) Nt3A突变病毒抑制宿主蛋白质合成的速度可能较慢，从而允许 继续合成关键的抗病毒活性。我们将检验这些假设 在以下具体问题的背景下：1)什么是相对的 异烟肼诱导的抗病毒通路PKR和2‘-5’OAS/核糖核酸酶L的作用 野生型与nt3A突变型VEE体外复制抑制作用的比较 在体内呢？2)nt3A突变是否影响诱导和/或 激活下游的IFNaB效应机制，如PKR，2‘-5’OAS， 核糖核酸L，和阿达尔？3)nt3A突变对人类免疫功能有何影响 病毒诱导的宿主蛋白合成抑制？

DESCRIPTION: (Adapted from the Investigator's abstract): Venezuelan equine encephalitis virus (VEE) is an important equine and human pathogen. It periodically emerges in epidemics caused by highly virulent epizootic strains. Virulence determinants of the natural VEE strains are not well understood at the molecular level. In vaccine strains and laboratory attenuated strains, virulence determinants for mice have been mapped to El and E2 glycoproteins and the 5' untranslated region (utr). A single change at nucleotide 3 (nt3) of the 5' utr of the VEE genome (G to A substitution) introduced into a molecular clone of wild-type virulent VEE results in a virus that is completely attenuated in mice. The long-term goal is to determine the mechanisms by which specific mutations in the 5' utr of the VEE genome attenuates the virus, and to use the VEE system to elucidate the role of lFNAB in alphaviruses pathogenesis. We hypothesize that the nt3A mutation results in a virus with increased sensitivity to the antiviral actions of lFNaB due to increased levels of viral dsRNA replication intermediates, consequently (a) increasing induction of IFN-stimulated antiviral genes, (b) enhancing activation of IFN-induced antiviral proteins that require dsRNA as cofactor, or alternatively, (C) the nt3A mutant virus may be slower in inhibiting host protein synthesis, allowing continued synthesis of key antiviral activities. We will test these hypotheses in the context of the following specific questions: 1) What is the relative contribution of INFaB-induced antiviral pathways PKR and 2'-5' OAS/RNase L in the inhibition of replication of wild type compared to nt3A mutant VEE in vitro and in vivo? 2) Does the nt3A mutation affect the induction and/or the activation of downstream IFNaB effector mechanisms such as PKR, 2'-5' OAS, RNase L, and ADAR? and 3) What is the effectof the nt3A mutation on virus-induced host protein synthesis inhibition?