新型Aβ42寡聚体模拟表位疫苗的制备

Preparation of a Novel Aβ42 Oligomer Mimotope Vaccine

旨在获得一株特异靶向致病性Aβ42寡聚体的模拟表位疫苗。在前期工作中,应用亲和层析的方法从人静脉用免疫球蛋白(Intravenous immune globulin,IVIG)中纯化获得特异性识别Aβ42寡聚体的抗体组分IVIG-AOB。以IVIG-AOB为靶蛋白,应用噬菌体展示技术淘选出一系列Aβ42寡聚体的特异性环状模拟表位多肽,随后将表位多肽融合表达至乙肝病毒核心蛋白(HBcVLP)构建成表位载体疫苗,进而将免疫小鼠,从中筛选出能有效免疫产生抗Aβ42寡聚体抗体的模拟表位疫苗。从噬菌体环形七肽库中筛选出5条特异性结合IVIG-AOB的模拟表位多肽,将其克隆至HBc载体,并在大肠杆菌中成功表达和组装成嵌合表位的HBc-VLP,通过免疫小鼠优选出一株效果最好的Aβ42寡聚体构象表位疫苗HBc-C4。Aβ寡聚体是AD发生发展的主要致病因素。基于Aβ42寡聚体独特的构象表位研制的表位HBc-VLP疫苗诱导机体产生的抗体将能够特异靶向并中和毒性Aβ42寡聚体,而不影响Aβ42的正常生理功能,从而起到从根本上治疗AD的作用。

The objective of this study is to obtain a mimotope vaccine specifically targeting to pathogenic Aβ42 oligomer. In previous studies,we purified an antibody IVIG-AOB,which specifically recognizes Aβ42 oligomers,from intravenous immunoglobulin（IVIG）by affinity chromatography. Using phage display technique,a series of ring-shape mimotope polypeptides were screened for specific binding to IVIG-AOB. These oligomer epitope peptide genes were then cloned to HBc-VLP vector and the recombinant proteins were expressed in Escherichia coli. After that,the recombinant Aβ42 oligomer conformational epitope HBc-VLP vaccine were applied to Balb/c mice. The antibody responses induced by the Aβ42 oligomer-targeted VLP vaccine were determined. Five mimotope polypeptides specifically-bound with IVIG-AOB were successfully screened from phage cyclic peptide library and cloned into HBc-VLP vector. The recombinant proteins were successfully expressed in E. coli. HBc-C4 elicited the highest antibody titer after vaccination to Balb/c mice. Conclusively,Aβ oligomer is the major factor in the pathological processes of Alzheimer＇s disease（AD）. The mimotope HPc-VLP vaccine based on the unique structure of Aβ42 oligomer induced body to generate the antibody targeting and neutralizing the toxic Aβ42 oligomers,while not affecting its normal physiological function, thus it plays a fundamental role in the treatment of AD.