Does Dengue Virus Suppress RNA Interference in its Mosquito Vector?

描述(申请人提供)：节肢动物传播的病毒(虫媒病毒)在对抗脊椎动物宿主和节肢动物媒介的抗病毒防御方面面临双重挑战。在脊椎动物中，对抗病毒的前线防御是干扰素(IFN)反应，而在许多节肢动物中，它是RNA干扰(RNAi)，即有针对性地破坏信使-正义RNA，与双链RNA触发具有同源性。虽然虫媒病毒诱导和逃避干扰素反应的能力一直是一个密集的研究领域，但对虫媒病毒和节肢动物RNAi反应之间的相互作用知之甚少。特别重要的是调查蚊媒黄病毒中的这种相互作用，这种病毒包括一些重要的新兴病原体，如登革热、黄热病和西尼罗河病毒。目前，利用合成的短干扰RNA(siRNA‘s)利用RNAi来控制黄病毒的感染和传播的潜力是相当令人兴奋的，但关于黄病毒抑制RNAi的能力还不清楚，也没有研究RNAi在控制自然媒介感染中的作用。此外，目前还没有抗病毒药物可用于治疗任何黄病毒，而作为RNAi(VSR)病毒抑制因子的蛋白质可能为药物开发提供新的靶点。许多黄病毒，特别是登革热病毒都需要疫苗，而使VSR失效的突变可能会导致候选疫苗的减毒。最后，需要对媒介用来控制黄病毒的途径以及虫媒病毒用来对抗它们的机制有一个基本的了解，以解释黄病毒的进化模式和媒介的特异性。这项拟议的研究将通过以下三个方面来研究登革热病毒与其蚊媒中的RNAi之间的相互作用：(I)确定哪些DENV蛋白(如果有)作为RNAi的病毒抑制因子；(Ii)测量RNAi对DENV复制的影响；以及(Iii)监测RNAi对DENV基因组进化的影响。与公共卫生相关的登革热病毒是一种蚊子传播的病原体，每年在全球范围内导致数百万例严重疾病，因为没有预防登革热感染的疫苗，也没有治疗登革热疾病的抗病毒药物。一种新发现的阻断病毒感染的途径，称为RNA干扰，有望在新的抗病毒疗法的开发中发挥作用。这项拟议的研究将调查登革热病毒是否具有对抗RNA干扰的机制。

DESCRIPTION (provided by applicant): Arthropod-borne viruses (arboviruses) face a two-fold challenge in countering the antiviral defenses of both vertebrate hosts and arthropod vectors. In vertebrates, the front-line defense against viruses is the interferon (IFN) response, whereas in many arthropods, it is RNA interference (RNAi), the targeted destruction of messenger-sense RNA with homology to a double-stranded RNA trigger. While the ability of arboviruses to induce and elude the IFN response has been an area of intense study, much less is known about the interactions between arboviruses and the arthropod RNAi response. It is particularly important to investigate this interaction in the mosquito-borne flaviviruses, which include a number of important emerging pathogens such as dengue, yellow fever and West Nile virus. Currently there is considerable excitement about the potential for harnessing RNAi using synthetic short interfering RNA's (siRNA's) to control flavivirus infection and transmission, but nothing is known about the ability of flaviviruses to inhibit RNAi, nor has the role of RNAi in control of natural vector infections been studied. Additionally, there are currently no antivirals available to treat any flavivirus, and proteins that act as viral suppressors of RNAi (VSR's) may offer novel targets for drug development. Vaccines are needed for many flaviviruses, particularly dengue virus, and mutations that disable VSR's may contribute to attenuation of vaccine candidates. Finally, a fundamental understanding of the pathways that vectors use to control flaviviruses, and the mechanisms arboviruses use to counter them, are needed to interpret patterns of flavivirus evolution and vector specificity. The proposed research will investigate three aspects of the interaction between dengue virus and RNAi in its mosquito vector by: (i) identifying which, if any, DENV proteins act as a viral suppressor of RNAi, (ii) measuring the impact of RNAi on DENV replication various mosquito systems, and (iii) monitoring the impact of RNAi on DENV genomic evolution. PUBLIC HEALTH RELEVANCE Dengue virus is a mosquito-transmitted pathogen that causes millions of cases of severe disease worldwide every year because there are no vaccines to prevent dengue infection and no antiviral medications to treat dengue disease. A newly-discovered pathway that blocks viral infection, called RNA interference, holds promise in the development of new antiviral therapies. The proposed research will investigate whether dengue virus possesses mechanisms to counteract RNA interference.