Persistent chikungunya virus infection and disease

描述(申请人提供)：基孔肯雅病毒(CHIKV)是NIAID C类优先病原体，可导致人类丧失行动能力的肌肉骨骼疾病，其特征是行走能力受损，周围关节剧烈疼痛，持续数周至数月。在2004-2007年涉及数百万患者的CHIKV爆炸性流行期间，受感染的旅行者直接导致CHIKV在非流行国家的引入。基孔肯雅热翻译为“弯曲关节的症状”，反映了大多数感染者所经历的令人衰弱的风湿病症状。高达的患者在首次诊断后一年多仍有持续的风湿症状，12%的患者在3-5年后仍有症状。有趣的是，与CHIKV感染相关的慢性关节症状可以周期性地发生，这表明疾病症状的死灰复燃是由未知的机制发生的。我们已经建立了一种CHIKV感染的小鼠模型，在该模型中，主要的病理结果，关节炎，肌炎和腱鞘炎，与大多数CHIKV感染的人类经历的临床体征一致。值得注意的是，我们发现CHIKV接种后的小鼠关节组织中的组织病理学改变和CHIKV RNA都持续了至少三周，这表明病毒或病毒RNA的持续存在可能是慢性炎症的原因。我们从接种后3周的小鼠关节组织中提取出CHIKV RNA，并将其导入细胞中，表明感染CHIKV的基因组在组织中持续存在。基于这些研究，我们假设CHIKV诱导的风湿性疾病的持续性与CHIKV的持续性感染有关。为了验证这一假设，在目标1中，我们将定义CHIKV感染的持续时间和性质以及关节组织的组织病理学变化。此外，我们将使用454测序来确定持续感染的关节组织中存在的病毒基因类型，以测试CHIKV在关节中的持久性与选择独特的病毒变种有关的假设。我们的初步研究表明，CHIKV在关节组织中持续存在，但可有效地从非关节组织中清除。在目标2中，我们将使用一组适应性免疫反应成分中存在遗传定义缺陷的小鼠来确定导致CHIKV从非关节组织中清除的免疫学机制。此外，我们将确定感染后免疫抑制的程度与CHIKV复制和风湿病症状的重新出现有关。这些研究直接解决了该领域的一个悬而未决的问题，即持续的CHIKV诱导的风湿病症状是否与持续感染有关。确定这种联系和调节CHIKV清除以及感染部位和持续时间的免疫学机制具有重要的治疗和公共卫生意义，包括为CHIKV引起的慢性风湿病症状的治疗战略提供信息，以及关于CHIKV活动地区的血液和组织捐赠的政策。 与公共卫生相关：基孔肯雅病毒引起爆炸性流行，并已蔓延到世界许多地区，使其成为新出现的主要疾病威胁。人类感染基孔肯雅病毒会导致肌肉骨骼系统的衰弱疼痛和炎症，这通常会变成慢性的。申请中提出的研究将有助于理解基孔肯雅病毒感染如何导致慢性肌肉骨骼疾病，以及调节这些过程的免疫学机制。

DESCRIPTION (provided by applicant): Chikungunya virus (CHIKV), an NIAID category C priority pathogen, causes incapacitating musculoskeletal disease in humans characterized by an impaired ability to ambulate and intense pain in the peripheral joints that lasts for weeks to months. During the explosive 2004-2007 epidemic of CHIKV that involved millions of patients, infected travelers led directly to the introduction of CHIKV in nonendemic countries. Chikungunya translates as "that which bends up the joints," and reflects the debilitating rheumatic symptoms that are experienced by most infected individuals. Up to 64% of patients reported persistent rheumatic symptoms more than one year after initial diagnosis, and 12% still reported symptoms 3-5 years later. Interestingly, chronic joint symptoms associated with CHIKV infection can occur in a cyclic manner, suggesting resurgence of disease symptoms occurs by unknown mechanisms. We have developed a mouse model of CHIKV infection in which the major pathological outcomes, arthritis, myositis, and tenosynovitis, are consistent with the clinical signs experienced by the majority of CHIKV-infected humans. Strikingly, we found that both histopathological changes and CHIKV RNA persisted in joint tissues of CHIKV-inoculated mice for at least three weeks post- inoculation, suggesting that the persistence of virus or viral RNA may drive chronic inflammation. We isolated CHIKV RNA from murine joint tissues at 3 weeks post-inoculation and showed that it was infectious when transfected into cells, indicating that infectious CHIKV genomes persisted in tissues. Based on these studies, we hypothesize that persistence of CHIKV-induced rheumatic disease is associated with persistent CHIKV infection. To test this hypothesis, in Aim 1 we will define the duration and the nature of CHIKV infection and histopathological changes in joint tissues. In addition, we will use 454 sequencing to define the viral genotypes present in persistently infected joint tissue to test the hypothesis that CHIKV persistence in joints is associated with the selection of unique viral variants. Our preliminary studies indicate that CHIKV persists in joint tissue yet is efficiently cleared from non-joint tissues. In Aim 2, we will use a panel of mice with genetically-defined deficiencies in components of the adaptive immune response to define the immunological mechanisms responsible for CHIKV clearance from non-joint tissues. In addition, we will define the extent to which immunosuppression after infection is established is associated with a resurgence of CHIKV replication and rheumatic disease signs. These studies directly address an outstanding question in the field of whether persistent CHIKV-induced rheumatic disease signs are associated with persistent infection. Defining this association and the immunological mechanisms that regulate CHIKV clearance and the sites and duration of infection has important treatment and public health implications, including informing therapeutic strategies for the treatment of chronic CHIKV-induced rheumatic disease symptoms and policies regarding blood and tissue donation in regions with CHIKV activity. PUBLIC HEALTH RELEVANCE: Chikungunya virus causes explosive epidemics and has spread to many regions of the world, making it a major emerging disease threat. Infection of humans with chikungunya virus leads to debilitating pain and inflammation of the musculoskeletal system that often becomes chronic. The studies proposed in this application will help understand how chikungunya virus infection causes chronic musculoskeletal disease and the immunological mechanisms that regulate these processes.