Determining Molecular Mechanisms of Chikungunya Virulence and Attenuation

描述(申请人提供)：甲型病毒属，Togaviridae科，包括作为人类重要病原体的病毒。基孔肯雅病毒(CHIKV)是一种虫媒病毒，通过受感染的蚊子媒介在人类和非人类灵长类动物之间传播。CHIKV在非洲、亚洲和美洲热带地区的幼稚人口中周期性地引起爆炸性流行。自2005年初以来，CHIKV疫情已导致印度和印度洋的留尼汪岛、毛里求斯、马达加斯加和塞舌尔的150多万例赤热病病例。此外，从这些地区返回欧洲、加拿大和美国的旅行者已被诊断出患有这种疾病，这增加了在世界其他地区爆发疫情的可能性。赤热病很少是致命的，尽管目前的疫情造成的死亡人数高于典型的死亡人数。在成年人中，这种感染类似于登革热，伴有剧烈的肌肉和关节疼痛的急性发热性疾病。关节痛/关节炎的症状常常持续数周或数月，直到最初的疾病消失。然而，疾病的严重程度与年龄密切相关：受感染的儿童很少出现关节炎，但通常会出现发热性惊厥，并可能伴随神经后遗症和出血表现。虽然CHIKV在流行/大流行规模上导致严重的人类疾病，但该病毒的发病机制在很大程度上仍未确定，没有获得许可的疫苗，人类感染的治疗仅限于支持性护理。 拟议研究的目的是了解病毒/宿主相互作用的机制，从而促进随后用于治疗急性疾病的疗法和用于保护的疫苗的设计。这些研究将通过建立CHIK的基因定义的致病模型来促进，其中包括两个天然CHIKV分离株的cDNA克隆：1983年塞内加尔一次疫情期间分离的CHIKV-37997株和本次疫情早期在里乌尼奥岛分离的拉鲁尼翁(CHIKV-LR)株。我们建议通过探索病毒毒力和宿主反应，建立准确复制人类CHIKV感染的病因的小鼠致病模型，包括出血性和关节致病性。该应用的具体目的是：1)确定乳鼠致死性感染与成人自限性疾病相比的发热反应和出血表现；2)研究CHIKV感染在老年小鼠非致死性疾病中的关节致病表现；3)通过CHIKV的小鼠适应来改进小鼠的发病模型。我们假设，致命性感染和非致命性感染的比较将确定宿主和病毒编码的疾病严重性决定因素。这些决定因素将为急性感染期间的治疗干预提供靶标，无论是通过自然节肢动物传播还是通过生物武器/生物恐怖主义攻击获得。

DESCRIPTION (provided by applicant): The Alphavirus genus, family Togaviridae, includes viruses that are significant human pathogens. Chikungunya virus (CHIKV) is an arbovirus, transmitted between human and non-human primates by the bite of an infected mosquito vector. CHIKV periodically causes explosive epidemics in naive human populations in the African, Asian and American tropics. Since early 2005, a CHIKV epidemic has been responsible for over 1.5 million cases of CHIK fever in India and the Indian Ocean islands of Riunion, Mauritius, Madagascar and Seychelles. Furthermore, travelers returning to Europe, Canada and the United States from these areas have been diagnosed with the disease raising the possibility for outbreaks in other parts of the world. CHIK fever is rarely fatal, although the current epidemic is causing a higher than typical death toll. In adults, the infection resembles dengue fever, with acute febrile illness associated with excruciating muscle and joint pain. The symptoms of arthralgia/arthritis frequently persist for weeks or months later the initial illness has disappeared. However, the severity of disease is strongly age-dependent: infected children rarely develop arthritis, but commonly suffer febrile convulsions with possible associated neurologic sequelae and hemorrhagic manifestations. Although CHIKV causes severe human disease on an epidemic/pandemic scale, the pathogenesis of the virus remains largely uncharacterized, no licensed vaccine is available and the treatment of human infections is limited to supportive care. The objective of the proposed research is to provide an understanding of the mechanisms of virus/host interaction and thereby facilitate the subsequent design of therapeutics for the treatment of acute disease and vaccines for protection. These studies will be facilitated by the development of a genetically-defined pathogenesis model for CHIK, including a cDNA clone of two natural CHIKV isolates: the CHIKV-37997 strain isolated during an epidemic in Senegal, 1983 and the La Rhunion (CHIKV-LR) strain isolated on Riunion Island early in the current epidemic. We propose to develop murine pathogenesis models that accurately reproduce the etiologies of human CHIKV infection, both hemorrhagic and arthritogenic, by exploring virus virulence and host response. The specific aims of the application are: 1) To characterize the febrile response and hemorrhagic manifestations in fatal infection of suckling mice versus self-limiting disease in adults; 2) To characterize arthritogenic manifestations of CHIKV infection in non-fatal disease of older mice; and 3) To improve murine pathogenesis models by mouse-adaptation of CHIKV. We hypothesize that comparison of fatal to non-fatal infections will identify host- and virus-encoded determinants of disease severity. These determinants will provide targets for therapeutic intervention during acute infection, whether acquired from natural arthropod transmission or a biowarfare/bioterrorism attack.