Modulation of arboviruses in mosquitoes

描述(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。自然界中虫媒病毒的维持需要一个生物传播周期，包括在敏感的脊椎动物宿主和食血节肢动物中交替复制病毒。虽然脊椎动物的感染是急性的，通常与疾病有关，但病毒的持续传播依赖于节肢动物中持续的、非致病性的感染。病毒和节肢动物宿主显然都从这种非致病性感染中受益。事实上，目前的媒介能力模型预测，当虫媒病毒感染对蚊子的生存没有影响时，传播率将最高。定量限制病毒产量的内源性机制的存在被称为“调节”，这是对蚊子细胞对虫媒病毒潜在细胞病变效应的明显抵抗力的解释。然而，这一点从未被实验证明。此前，树栖病毒学家在30多年的时间里观察到的调制也没有直接与特定的免疫机制有关。我们的研究已经建立了虫媒病毒的调节与最近的证据之间的联系，这些证据表明RNA干扰(RNAi)在节肢动物中作为一种先天的抗病毒免疫反应发挥作用。完成这里概述的具体目标是为了全面评估影响基于RNAi的调制与蚊子中产生性虫媒病毒感染之间关系的内在和外在因素。这项研究的具体目标是：1)确定甲型病毒限制自然载体宿主免疫调节的机制；2)确定温度对甲型病毒RNAi和基于RNAi的调控的精确影响；3)确定基于RNAi的免疫反应在调节自然载体宿主中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的调制相互作用将解决我们对蚊子媒介能力知识的明显空白，并最终可能形成基于RNAi的转基因和现场诊断疾病控制方法的基础。公共卫生相关性：节肢动物传播的病毒(虫媒病毒)疾病，如黄热病，仍然是全球公共卫生的重大负担。这项建议直接涉及导致脑炎或出血热的精选制剂和生物安全3级病毒。我们的目标是描述这些病原体成功感染蚊子媒介的机制。这一知识对于理解和预测虫媒病毒流行是如何发起、传播和维持至关重要的，并可能最终形成基于RNAi的转基因和现场诊断疾病控制方法的基础。

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.