Eastern Equine Encephalitis Emergence in Panama

 描述(申请人提供)：东部马脑炎病毒(EEEV)，一种新出现的蚊媒病毒，导致美国最致命的虫媒病毒疾病，病死率高达75%。然而，EEEV也在南美洲和中美洲(SA)传播，那里的许多人接触到受感染的蚊子，但几乎没有疾病的证据。流行病学和发病机制研究表明，SA菌株对人的传染性较差，可能与对I型干扰素(干扰素)较高的敏感性和较强的干扰素诱导有关 在髓系细胞感染后。2010年，北美和南美的EEE发病率的主要对比发生了戏剧性的变化，当时拉丁美洲有记录的第一次人类疫情发生在巴拿马(PA)。临床疾病与NA相似，我们的遗传和流行病学数据表明，自1986年以来，地方性PA EEEV毒株增加了其传染性和/或毒力。由于金黄色葡萄球菌EEEV媒介比NA媒介更频繁地叮咬人，如果2010年PA毒株传播到拉丁美洲其他地区，或者如果该地区发生类似的病毒变化，EEEV毒力的这种变化可能会对公共卫生产生重大影响。因此，了解2010年PA株的遗传和表型变化对于我们减少虫媒病毒病的长期目标至关重要。最近，我们的反向遗传方法与动物和体外模型的实验感染相结合，在理解虫媒病毒疾病出现方面取得了重大进展，包括委内瑞拉马脑炎和基孔肯雅热。然而，为了应用这些方法来从机制上理解2010年PA EEE的出现，需要更好的体外和小动物EEE模型。目前，缺乏这样的模型是更好地理解人类EEE和开发改进的干预措施的主要瓶颈。在这个探索性项目中，我们将利用最近在了解EEE分子致病机理方面的重大进展来建立模型，使用两个特定目标来预测1984和2010年PA EEEV毒株的人类毒力差异：1.测试棉花鼠，如果需要，测试各种小鼠和仓鼠复制类似人类疾病的能力，并反映NA和以前分离的SA EEEV毒株之间的典型感染力/毒力差异，并在这些模型中比较1984和2010年PA毒株。2.对PA和代表性的NA和SA EEEV毒株进行体外分子致病比较研究，以确定人类毒力的标志。这些模型将使我们能够检验这一假设，即1986-2010年间PA EEEV毒株的基因变化，包括3‘未翻译基因组区域的基因变化，改变了病毒对树突状细胞的感染力和干扰素反应的诱导，从而导致更强的毒力和传染性 人类。这一开发项目不仅将促进对EEEV出现的机理的理解，而且将促进对甲型病毒致病机制的理解，这将导致改进监测、诊断、治疗和疫苗开发。

 DESCRIPTION (provided by applicant): Eastern equine encephalitis virus (EEEV), an emerging mosquito-borne virus, causes the deadliest arboviral disease in the U.S., with case-fatality rates up to 75%. However, EEEV also circulates throughout South and Central America (SA), where many people are exposed to infected mosquitoes yet with little evidence of disease. Epidemiologic and pathogenesis studies suggest that SA strains are poorly infectious for people, possibly related to higher sensitivity to type I interferon (IFN) and greater IFN induction following infection of myeloid cells. The major contrast in EEE incidence in NA vs. SA changed dramatically in 2010, when the first human outbreak ever documented in Latin America occurred in Panama (PA). Clinical disease was similar to that seen in NA, and our genetic and epidemiologic data indicate that an enzootic PA EEEV strain increased its infectivity and/or virulence since 1986. Because SA EEEV vectors bite people more frequently than NA vectors, this change in EEEV virulence could have major public health implications if the 2010 PA strain spreads to other parts of Latin America, or if similar viral changes occur in the region. Understanding the genetic and phenotypic changes in the 2010 PA strain is therefore critical to our long-term goal of reducing arboviral disease. Recently, our reverse genetic approaches combined with experimental infections of animal and in vitro models led to major advances in understanding arboviral disease emergence, including Venezuelan equine encephalitis and chikungunya. However, to apply these approaches to gain a mechanistic understanding the 2010 PA EEE emergence, better in vitro and small animal EEE models are needed. The lack of such models currently represents the major bottleneck to a better understanding of human EEE and developing improved interventions. In this exploratory project, we will exploit recent, major advances in the understanding of EEE molecular pathogenesis to develop models that predict differential human virulence of 1984 vs. 2010 PA EEEV strains using 2 specific aims: 1. Test cotton rats, and if needed, a variety of mouse strains and hamsters for their ability to reproduce human-like disease and to mirror the typical differences in infectivity/virulence between NA and previously isolated SA EEEV strains, and to compare 1984 and 2010 PA strains in these models. 2. Perform comparative in vitro molecular pathogenesis studies of PA and representative NA and SA EEEV strains to identify markers of human virulence. These models will allow us to test the hypothesis that genetic changes in PA EEEV strains between 1986-2010, including in the 3' untranslated genome region, altered the virus' infectivity for dendritic cells and the induction of interferon responses, resulting in greater virulence and infectivity for humans. This developmental project will advance the mechanistic understanding not only of EEEV emergence, but also of alphavirus pathogenesis, which will lead to improved surveillance, diagnostics, treatment and vaccine development.