Antiviral activity of leflunomide against respiratory syncytial virus

呼吸道合胞病毒（RSV）是婴儿中经常严重的、危及生命的肺部疾病的主要原因， 幼儿、免疫抑制的器官移植接受者、患有囊性纤维化的患者， 先天性心脏病和老年人。目前没有有效的疫苗可用于预防RSV 疾病利巴韦林，唯一批准的抗病毒治疗，必须通过气雾剂给药12至18 小时/天，持续3至7天，仅略微有效，且未显示出显著降低死亡率 与RSV疾病有关。而被动免疫预防用超免疫球蛋白或单克隆抗体 尽管已经显示抗体在某些情况下可以减轻疾病的严重程度，但令人满意的抗病毒治疗还没有被证实。 办妥了一批来氟米特是嘧啶合成和蛋白激酶活性的抑制剂， 批准用于治疗类风湿性关节炎的药物，目前正作为免疫抑制剂进行临床试验 在移植接受者中。该药物已被证明对巨细胞病毒具有强大的抗病毒活性 在体外和体内，以及在针对RSV的初步体外和体内研究中。具体目标是 研究旨在检验来氟米特降低RSV病毒载量和相关细支气管炎的假设， 并从分子水平阐明其抗病毒机制。接种RSV的棉鼠， 接受来氟米特、利巴韦林、帕利珠单抗或这些药物组合治疗的受试者将在 各种间隔。将通过肺匀浆的空斑试验和组织损伤和 肺部炎症将通过肺组织的组织学和免疫组织化学分析来评估。 RSV感染动物的免疫状态将通过脾细胞应答的增殖测定来评估， RSV抗原。分子抗病毒机制将通过病毒的定量真实的时间rtPCR分析来阐明。 病毒蛋白的基因组RNA合成和转录、免疫沉淀和western blot分析 合成和磷酸化，以及免疫金电子显微术。这些研究产生的数据是 预期将证明来氟米特在降低病毒载量和减少病毒感染方面的双功能效用。 主要导致RSV疾病的严重炎症反应的同时减弱 表现。此外，阐明这种药物的分子抗病毒机制可能会发现新的抗病毒药物。 未来抗病毒药物开发的目标。

Respiratory synctial virus (RSV) is a major cause of often serious, life-threatening lung disease in infants and young children, immunosuppressed organ transplant recipients, patients suffering from cystic fibrosis, congenital heart disease, and the elderly. No effective vaccine is currently available for prevention of RSV disease. Ribavirin, the only approved antiviral therapy, which must be administered by aerosol for 12 to 18 hours/day for 3 to 7 days, is only marginally effective and has not been shown to significantly reduce mortality associated with RSV disease. While passive immunoprophylaxis with hyperimmune globulin or monoclonal antibody has been shown to reduce disease severity in some cases, satisfactory antiviral therapy has yet to be achieved. Leflunomide, an inhibitor of pyrimidine synthesis and protein kinase activity, is an anti-inflammatory agent approved for treatment of rheumatoid arthritis and is currently in clinical trials as an immunosuppressant in transplant recipients. This agent has been shown to exert powerful antiviral activity against cytomegalovirus in vitro and in vivo, and in preliminary in vitro and in vivo studies against RSV. The specific aims of this investigation are to test the hypothesis that leflunomide reduces RSV viral load and associated bronchiolitis in vivo, and to elucidate its antiviral mechanisms at the moleclular level. Cotton rats inoculated with RSV and treated with leflunomide, ribavirin, Palivizumab, or combinations of theses agents will be euthanized at various intervals. Viral loads will be quantitated by plaque assay of lung homogenates, and tissue injury and pulmonary inflammation will be assessed by histologic and immunohistochemical analysis of lung tissue. Immune status of RSV-infected animals will be assessed by proliferation assays of splenocyte responses to RSV antigen. Molecular antiviral mechanisms will be elucidated by quantitative real time rtPCR assays of viral genomic RNA synthesis and transcription, immunoprecipitation and western blot analysis of viral protein synthesis and phosphorylation, and immunogold electron microscopy. Data generated by these studies are anticipated to demonstrate the bifunctional utility of leflunomide in both the reduction in viral load and the concurrent attenuation of the severe inflammatory reaction primarily responsible for RSV disease manifestations. Furthermore, elucidation of the molecular antiviral mechanisms of this agent may identify novel targets for future antiviral drug development.