Genetic dissection of the RNAi-mediated antiviral immunity in C. elegans

描述（由申请人提供）：具有RNA基因组的病毒通过与DNA基因组不同的机制复制和进化，是重要的人类、动物和植物病原体。哺乳动物的免疫机制，抵御RNA病毒的特点很差。这项拟议的研究将从遗传学上剖析由最具特征的RNA病毒之一--鸡群屋病毒（FHV）引发的秀丽隐杆线虫动物的免疫途径。我们最近的研究表明，FHV复制是由整合在C.线虫基因组触发病毒衍生的siRNA的产生，其通过RNA沉默或RNA干扰（RNAi）指导病毒RNA清除。进一步的遗传分析为C.线虫对FHV或另一种不同的RNA病毒的反应。我们利用C. elegans/FHV系统。我们的饲养RNAi筛选已经鉴定了RSI所需的35个基因，包括drh-1，其与外源dsRNA诱导的RNAi无关，并且与最近鉴定的RNA病毒的哺乳动物免疫受体高度同源。从化学筛选中回收的有活力的RSI缺陷型蠕虫突变体包括RNAi缺陷型和RNAi敏感型突变体，并且没有一个与drh-1或另一种常见的RNAi缺陷型等位基因等位。因此，我们的结果表明，C。秀丽线虫RSI需要与外源RNAi共享和互补的组分，以及与哺乳动物病毒免疫组分同源的组分。我们计划进一步表征病毒siRNA引导的病毒RNA清除机制、次级病毒siRNA的特征和作用以及RSI组分对蠕虫中外源性RNAi的特异性机制。此外，我们将使用实验室已经建立的方法，通过全基因组喂养RNAi和化学诱变筛选分离动物RSI途径的其他组分。拟议的实验将提供整个动物中病毒免疫途径的第一个基因组视图，鉴定在先前使用非病毒RNAi触发剂的筛选中无法获得的新型RNAi组分，并揭示针对RNA病毒的免疫机制，以促进理解哺乳动物病毒免疫。

DESCRIPTION (provided by applicant): Viruses with an RNA genome replicate and evolve via mechanisms distinct from DNA genomes and are important human, animal and plant pathogens. The mammalian immune mechanisms that defend against RNA viruses are poorly characterized. The proposed research will genetically dissect the immune pathway of Caenorhabditis elegans animals triggered by Flock house virus (FHV), one of the best characterized RNA viruses. We have shown recently that FHV replication launched from an inducible transgene integrated in the C. elegans genome triggers production of virus-derived siRNAs, which guide viral RNA clearance by RNA silencing or RNA interference (RNAi). Further genetic analyses have provided evidence for a conserved RNA silencing virus immunity (RSI) pathway in C. elegans in response to either FHV or another distinct RNA virus. We have carried out pilot feeding RNAi and chemical mutagenesis screens using the C. elegans/FHV system. Our feeding RNAi screen has identified 35 genes required for RSI including drh-1, which is dispensable for RNAi induced by exogenous dsRNA and highly homologous to the recently identified mammalian immune receptor for RNA viruses. Viable RSI-defective worm mutants recovered from the chemical screen include both RNAi-defective and RNAi-sensitive mutants and none are allelic with drh-1 or another frequent occurring RNAi-defective allele. Hence, our results have shown that C. elegans RSI requires components that are shared with, and dispensable for, exogenous RNAi, as well as those homologous to mammalian viral immunity components. We plan to further characterize the mechanism of viral RNA clearance guided by viral siRNAs, the features and roles of secondary viral siRNAs, and the specificity mechanism of RSI components dispensable for exogenous RNAi in worms. Further, we will isolate additional components of the animal RSI pathway through genome-wide feeding RNAi and chemical mutagenesis screens using the methodology already established in the lab. The proposed experiments will provide the first genome-view of the viral immunity pathway in whole animals, identify novel RNAi components that cannot be obtained in previous screens using non-viral RNAi triggers, and reveal immune mechanisms against RNA viruses that facilitate understanding mammalian viral immunity.