Modulation of arboviruses in mosquitoes

描述（由申请人提供）：节肢动物传播的病毒（虫媒病毒）疾病仍然是全球公共卫生的重大负担。虫媒病毒在自然界的维持需要一个生物传播周期，其中包括在易感脊椎动物宿主和吸血节肢动物中交替进行病毒复制。虽然脊椎动物感染是急性的，并且通常与疾病有关，但病毒的持续传播取决于在节肢动物中建立持续的非致病性感染。病毒和节肢动物宿主显然都受益于这种非致病性感染。事实上，目前的媒介能力模型预测，当虫媒病毒感染对蚊子存活没有影响时，传播率将是最高的。存在内源性机制，定量地限制病毒产量，称为“调节”，已被提出作为蚊子细胞对虫媒病毒潜在细胞病变效应的明显抗性的解释。然而，这从未在实验中得到证实。虫媒病毒学家在30多年的时间里对这种调节的观察也没有直接与特定的免疫机制联系起来。我们的研究已经建立了虫媒病毒调节和最近证据表明RNA干扰（RNAi）作为节肢动物的先天抗病毒免疫反应之间的联系。完成本文概述的具体目标旨在全面评估影响基于rnai的调节与蚊子体内产生虫媒病毒感染之间关系的内在和外在因素。本研究的具体目标是：1)确定甲病毒在自然载体宿主中限制免疫调节的机制；2)确定温度对RNAi和基于RNAi的甲病毒调节的精确影响；3)确定基于RNAi的免疫应答在自然载体宿主中调节黄病毒感染中的作用。我们相信，了解虫媒病毒如何与基于RNAi的调控相互作用将解决我们对蚊子媒介能力的认识上的明显空白，并可能最终形成基于RNAi的转基因和疾病控制现场诊断方法的基础。公共卫生相关性：黄热病等节肢动物传播的病毒（虫媒病毒）疾病仍然是全球公共卫生的重大负担。本建议直接处理引起脑炎或出血热的选择剂和生物安全3级病毒。我们的目的是描述这些病原体成功感染蚊子载体的机制。这些知识对于理解和预测虫媒病毒流行是如何开始、传播和维持至关重要，并可能最终形成基于RNAi的转基因和疾病控制现场诊断方法的基础。

DESCRIPTION (provided by applicant): Arthropod-borne virus (arbovirus) diseases remain a significant burden on global public health. Maintenance of arboviruses in nature requires a biological transmission cycle that involves alternating virus replication in a susceptible vertebrate host and a blood feeding arthropod. While the vertebrate infection is acute and often associated with disease, continual transmission of virus depends on the establishment of a persistent, non-pathogenic infection in the arthropod. Both the virus and arthropod host clearly benefit from this non-pathogenic infection. Indeed, current models of vectorial capacity predict that transmission rates will be highest when arboviral infection has no effect on mosquito survival. The existence of endogenous mechanisms that quantitatively limit virus yields, termed "modulation", has been advanced as an explanation for the apparent resistance of mosquito cells to the potential cytopathic effects of arboviruses. However, this has never been demonstrated experimentally. Nor have previous observations of modulation, made by arbovirologists over a period of more than 30 years, been directly linked to a specific immune mechanism. Our studies have established a link between arbovirus modulation, and recent evidence indicating that RNA interference (RNAi) functions as an innate anti-viral immune response in arthropods. Accomplishing the specific aims outlined here is designed to provide a comprehensive assessment of intrinsic and extrinsic factors influencing the relationship between RNAi-based modulation and the establishment of productive arbovirus infections in the mosquito. The specific goals of the proposed research are to 1) characterize the mechanism by which alphaviruses limit immune modulation in natural vector hosts, 2) determine the precise effects of temperature on RNAi and RNAi-based modulation of alphaviruses, and 3) determine the role of an RNAi-based immune response in modulating flavivirus infections in natural vector hosts. We believe that understanding how arboviruses interact with RNAi- based modulation will address glaring gaps in our knowledge of mosquito vector competence, and may ultimately form the basis of RNAi-based transgenic and field diagnostic approaches for disease control. PUBLIC HEALTH RELEVANCE: Arthropod-borne virus (arbovirus) diseases such as yellow fever remain a significant burden on global public health. This proposal deals directly with select agent and biosafety level 3 viruses which cause encephalitis or hemorrhagic fever. We aim to describe mechanisms used by these pathogens to successfully infect mosquito vectors. This knowledge is vital to understanding and predicting how arboviral epidemics are initiated, spread, and maintained, and may ultimately form the basis of RNAi- based transgenic and field diagnostic approaches for disease control.