Antiviral Mechanisms of the Yeast RNA Decay Machinery And Viral Countermeasures

智力优势：宿主细胞已经开发出各种方法来检测病毒感染和降低病毒载量。产生针对病毒抗体的适应性免疫系统是抗病毒防御的一个很好的特征部分，但这种防御机制只在有颌骨的脊椎动物中活跃。免疫系统的第二个分支，称为先天免疫系统，也可以对抗病毒感染。天然免疫系统存在于许多不同的真核生物中，在脊椎动物、无脊椎动物和植物中已有研究，但在真菌中的研究相对较少。该项目将重点研究细胞用来对抗病毒的机制，以及病毒反过来用来逃避宿主防御的策略。宿主防御中的一个关键挑战是区分正常的细胞RNA和由病毒入侵者编码的RNA。宿主信使RNA通常含有单链RNA，在其5‘端以帽结构修饰，在其3’端以聚(A)尾修饰。来自病毒的RNA可能是双链的、无帽的和/或缺少聚(A)尾巴。先天免疫系统的几个分支识别病毒RNA的这些一般特征。这项研究的目的是通过使用贝克氏酵母和酵母杀手病毒来证明真核细胞对病毒感染有一种额外的先天免疫。酵母含有Ski蛋白，这种蛋白在RNA腐烂过程中起作用，并具有抗病毒功能。假设酵母Ski蛋白识别缺少聚(A)尾巴的RNA，如病毒RNA，并将其作为降解的目标。已经证明L-A病毒有一个产生无上限细胞基因的过程，这一过程有助于病毒复制的机制也将被研究。这项研究将为病毒逃避宿主先天免疫系统的机制提供新的见解。更广泛的影响：这项研究包括为研究生和本科生提供重要的教育机会。这项研究将在一个实验室进行，该实验室有为本科生提供做基础生物学研究的机会的既定记录。在实验室工作了一个夏天的本科生现在都在一流的研究生院学习。这项研究使用酵母遗传学方法，特别适合于教授学生产生假说的过程，设计实验来检验这一假说，并在夏季研究项目中解释产生的数据。已经与当地三所为少数民族服务的大学建立了联系，以帮助招收本科生参与拟议的研究。

Intellectual Merit: Host cells have developed a variety of methods to detect viral infection and reduce viral load. The adaptive immune system that generates antibodies against viruses is a well-characterized part of the antiviral defense, but this defense mechanism is only active in jawed-vertebrates. A second branch of the immune system, called the innate immune system, can also battle virus infection. The innate immune system is found in many different eukaryotic species and has been studied in vertebrates, invertebrates and plants, but remains relatively poorly studied in fungi. This project will focus on studying the mechanisms that cells use to combat viruses and the tactics that viruses, in return, use to evade host defenses. A key challenge in the host defense is to distinguish normal cellular RNAs from RNAs encoded by viral invaders. Host messenger RNA generally contains a single strand of RNA that is modified at its 5' start with a cap structure and at its 3' end with a poly(A) tail. RNA from viruses may be double stranded, uncapped, and/or lack a poly(A) tail. Several branches of the innate immune system recognize these general features of viral RNA. This research aims to demonstrate through the use of Baker's yeast and Yeast killer viruses that eukaryotic cells have an additional type of innate immunity against viral infection. Yeast contains Ski proteins, which function in RNA decay, and have an antiviral function. The hypothesis is that the yeast Ski proteins recognize RNA that lacks a poly(A) tail, such as viral RNA, and target it for degradation. It has been shown that the L-A virus has a process to produce uncapped cellular mRNA, and the mechanism by which this aids virus replication will also be investigated. The research will provide new insights into the mechanisms by which viruses evade the host innate immune system. Broader Impacts: The research includes significant educational opportunities for graduate and undergraduate students. The research will be carried out in a lab with an established track record of giving undergraduate students an opportunity to do basic biological research. Undergraduate students who have worked in the lab for a summer are now in top-tier graduate schools. This research uses yeast genetic methods, which are especially well suited to teach students the process of generating a hypothesis, designing experiments to test this hypothesis and interpreting the resulting data within a summer research program. Contacts with three local minority-serving universities have been established to help recruit undergraduate students to participate in the proposed research.