消除ADE表位兼具良好免疫原性的寨卡疫苗研究

The 2015 outbreak of Zika epidemic has explosively spilled over 80 countries and regions worldwide. China has imported cases and also has ZIKV isolation in local vector. Zika virus (ZIKV) infection can cause adult Guillain–Barré syndrome and microcephaly in fetuses and newborns. Zika now is the worldwide threat to the public health. Although progresses have been made in vaccine development against ZIKV, the potential antibody-dependent enhancement (ADE) of infection of dengue virus (DENV) caused by ZIKV vaccine has become a widespread safety concern, especially considering the fact of the high degree of overlap between their epidemic areas. Some scholars eliminated ADE effect by mutating fusion loop (FL) of ZIKV, but immunogenicity was also significantly reduced. Based on analysis of structural biology, this project intends to select FL mutation which is beneficial to structural stability of ZIKV capsule protein and introduce disulfide bond to further stabilize the natural conformation of antigen in aim to screen ZIKV vaccine which can eliminate ADE effect and also has good immunogenicity. DNA vaccine platform was used to evaluate vaccine efficacy against ZIKV and ADE potential on DENV by ex vivo and in vivo experiments. This project will lay the foundation for the development of a safer ZIKV vaccine and have promising application potential. Moreover, this project will also provide new evidence for the immunological interplay between ZIKV and DENV.

2015年寨卡疫情爆发，蔓延至全球80多个国家和地区，我国既有输入病例也在本土蚊虫中分离到寨卡病毒。寨卡病毒可导致成人格林-巴利综合征和新生儿小头症，严重威胁全球公共卫生安全。尽管寨卡疫苗研发已取得一定进展，但寨卡对登革的抗体依赖感染增强效应（ADE）是大家普遍担忧的疫苗安全性问题，特别是考虑到这两种病毒流行地域高度重叠的现实。有学者通过将寨卡病毒疏水融合环（FL）表位进行突变消除了ADE效应，但疫苗免疫原性也显著降低。基于结构生物学分析，本项目拟选用利于寨卡囊膜蛋白结构稳定的FL突变并引入二硫键进一步稳固抗原天然构象的方法，筛选可消除ADE效应兼具良好免疫原性的寨卡疫苗。使用DNA疫苗平台在细胞和动物水平评价疫苗对寨卡病毒的免疫保护效果和对登革病毒感染的ADE效应。该项目将为研制更安全的寨卡疫苗奠定基础并具有较高的应用潜力，也为寨卡和登革病毒之间的免疫互作规律提供新依据。

寨卡病毒可导致成人格林-巴利综合征和新生儿小头症，严重威胁全球公共卫生安全。寨卡病毒和登革病毒同属黄病毒科，亲缘关系近，并且两种病毒流行区域高度重叠，寨卡病毒感染可导致对登革的抗体依赖的感染增强效应（ADE）。本项目通过把寨卡病毒E蛋白的FL区域与黄病毒属中进化关系最远的昆虫特异性黄病毒的FL区域进行同源替换获得了MutB和MutC突变体，并开发了相应的腺病毒载体疫苗，两种突变体疫苗可在小鼠中诱导针对寨卡病毒的清除性免疫，同时消除了针对登革感染的ADE效应，该疫苗具有巨大的应用潜力，并为其余黄病毒疫苗的开发提供了重要借鉴。.此外，在本项目的资助下，我们基于新冠病毒RBD开发了mRNA疫苗，该疫苗一针免疫即可在小鼠中诱导高水平的持久的免疫应答，具有重要的应用前景；研究了新冠RBD和S免疫原所诱导的抗体库差异，发现S抗原诱导的抗体多样化且NTD中和抗体和RBD中和抗体具有很好的协同效应，中和活性高，RBD抗原可诱导大量非阻断的中和抗体，由于在新冠病毒进行中，NTD中和抗体易失活，RBD和NTD中和抗体协同效应丧失，RBD免疫原显示出比S更好的抗病毒突变能力；针对I类囊膜病毒提出了非标签化的受体结合结构域三聚化策略，开发了可抵抗新冠和流感病毒共感染的新冠和流感联合疫苗。