抗呼吸道合胞病毒高中和活性抗体的保护机制研究

RSV是全球范围导致5 岁以下儿童下呼吸道感染住院的首要病原，至今缺乏疫苗。仅有一种抗RSV-F 蛋白的单抗药物palivizumab获准上市，但其效价不足、成本高昂，仅用于预防高危新生儿的感染，并限制了其在发展中国家的应用。本课题组在前期研究中发现了一类高中和活性抗体（5C4），其识别位点为RSV F蛋白的瞬时构象上的全新表位。此类抗体在体内、外实验中均优于上市抗体10-100倍，表明这类抗体是可用于RSV预防的新一代抗体药物候选。但是对这类抗体的前期研究主要集中于蛋白表位解构与抗体活性鉴定，其高中和活性的分子机制尚不完全清楚。本课题将主要利用电镜系列技术平台，对高中和活性抗体与天然病毒表面F蛋白的相互作用方式进行深入研究。揭示高中和活性抗体如何影响天然状态下F蛋白的功能从而达到高效抑制感染的效果，阐明其保护机制。为这类抗体的临床转化奠定理论基础，也为RSV疫苗设计提供理论支撑。

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections, which resulted in hospitalization globally in children less than 5 years old. Although there is currently no effective vaccine available for RSV, a monoclonal antibody, palivizumab (Synagis®) was approved as prophylaxis against RSV in the children with prematurity, bronchopulmonary dysplasia, and congenital heart disease. However Palivizumab was administered via intramuscular at high does with high cost, is related to the relatively low neutralization titer. Meanwhile the high cost also limit the application of palivizumab worldwide, especially in developing countries and regions, in which there is not efficient medicine to be used to treat RSV infection in the newborn. Our group have isolated a novel RSV F antigenic site (site Ø) specific murine monoclonal antibody, 5C4, with 50-100 fold improved neutralizing activity over palivizumab in vitro and vivo. It supports that 5C4 is available as candidate prophylaxis antibody for improving passive immunization against RSV infection, reducing the RSV prophylaxis cost greatly. The mechanism of these high neutralizing antibodies is unclear as previous studies still focused on the characteristics (reactivity with F protein and neutralize activity for RSV) and epitope identification. In this project, we will investigate the interaction between 5C4 and natural F protein on the virus surface through using series electron microscope technology platforms, to elucidate the higher neutralizing mechanism, which helps the clinical transformation of 5C4, and provide a potential pathway for anti-RSV vaccine design.