EV71病毒VP2抗原细胞免疫原性及其与其他肠病毒的交叉反应机制研究

EV71 virus correlated hand foot mouth disease (HFMD) has become a major threat to public health among children in China. Though previous studies indicated that T-cell immune responses had played critical roles in immunoprotection against EV71 infection, our understanding of immunoprotection mechanisms against EV71 was still limited. Furthermore, prevalence of other enteroviruses that caused HFMD, emergence of novel enteroviruses and programmed poliovirus immunization had made the situations more complicated. Whether T-cell responses against VP2 antigens from different enteroviruses would cross-react with each other and to what extent the cross-reactive immune responses would provide immune protection remains unclear. In our previous research work, we found that VP2 antigen dominated the T-cell immune responses against EV71. In the present study, immunogenicity mechanisms of VP2 antigen would be determined through the identification and characterization of major HLA-A allele molecule restricted epitopes. VP2 specific T-cell responses and Tfh cell frequency, phenotype and functional characteristics would also be determined to elucidate the immunogenicity mechanisms of VP2 antigen. Furthermore, correlation of VP2 antigen specific T-cell immune responses with humoral responsive magnitudes specific to EV71 or VP1 antigen would be analyzed to elucidate the roles of VP2 specific T cell immunity in humoral immune responses. Taken together, all these aspects would benefit our understanding of host immune protection mechanisms and shed light to vaccine development.

EV71病毒感染引起的手足口病已成为影响我国儿童健康的重要传染病。尽管现有研究提示细胞免疫对EV71感染后疾病控制具有重要作用，但对其免疫保护机制的理解仍不完善。不仅如此，引起手足口病的其他肠病毒同样广泛流行并不断出现新型肠病毒，脊灰疫苗长期计划接种，这些肠病毒间是否存在交叉细胞免疫反应及交叉保护？通过前期研究，我们发现VP2抗原介导了EV71病毒主要的细胞免疫反应。本研究进一步以VP2抗原为基础，通过生物信息学分析其在其他肠病毒中的保守性，对不同病毒来源的免疫原性多肽在人体中的交叉反应水平及交叉免疫细胞表型和功能特征等进行鉴定分析，以阐明人群对不同手足口病相关肠病毒的交叉免疫保护机制；通过对VP2抗原中国人群主要HLA-A位点分子限制性表位的鉴定以及特异性T细胞表型及功能等的分析，阐明VP2抗原的免疫原性机制。为理解EV71病毒的免疫保护机制及疫苗设计提供理论基础。

T细胞免疫在抗肿瘤和抗病原感染过程中发挥了重要作用，特别是近年来利用单克隆抗体阻断抑制性免疫检查点分子在临床肿瘤免疫治疗中取得了重大突破。本项目阐明了PD-1/PD-L1及CTLA-4等T细胞关键免疫检查点抗体药物作用机制，发现nivolumab主要结合PD-1的N端loop区，且其结合并不受PD-1糖基化修饰的影响; 发现avelumab和durvalumab结合PD-L1模式完全不同，但其结合区域均与PD-1的结合区域存在重叠，这些研究为理解免疫调控机制及新型药物开发提供了重要参考；研究发现结核分枝杆菌Rv3615c抗原具有丰富的CTL表位，能够显著提高结核感染，尤其是菌阴结核检出率，为提高结核感染检测效率提供了重要基础；发现2009甲型H1N1流感病毒疫苗接种后，HA特异性T细胞响应水平与抗体水平具有显著相关性，为疫苗改造和疫苗评价提供了重要参考。.本项目在基础研究的基础上开展了应用性研究。在对现有PD-1和PD-L1抗体药物作用和结合机制的研究基础上，建立了肿瘤免疫治疗抗体药物筛选技术平台和抗体人源化改造平台，筛选获得了多个PD-1及PD-L1抗体，所获得的PD-1抗体目前正在进行中试生产及临床前研究。本项目在对结核分枝杆菌抗原Rv3615c的免疫原性的研究基础上，研制了“结核感染T细胞免疫检测试剂盒（免疫斑点法）”，并通过了临床研究，取得了医疗器械注册证书，对于提高我国结核感染的诊断水平具有重要意义。