抗阿尔茨海默病Aβ人源单链抗体基因的筛选和表达

目的 从人源噬菌体单链抗体库中筛选与阿尔茨海默病发病中起关键作用的β淀粉样多肽(Aβ)1-42特异性结合的单链可变区抗体(scFv)基因,利用原核生物大肠杆菌进行可溶性表达,以获得抗AB1-42人源抗体.方法 利用噬菌体展示技术对人源噬菌体单链抗体库进行多轮富集,以Aβ1-42为抗原经酶联免疫吸附(ELISA)检测,筛选与Aβ1-42特异性结合的阳性噬菌体克隆,再用阳性噬菌体感染E.coli HB2151进行可溶性表达,经SDS-PAGE、Western blot及ELISA法检测scFv单抗的可溶性表达水平及抗原结合活性.并对阳性scFv抗体基因进行基因测序鉴定.结果 获得了7个特异性的抗Aβ1-42 scFv阳性噬菌体克隆,其中4个克隆ELISA检测吸光度值(A值)高于阴性对照5倍以上;其中1株(A 10)获得可溶性单链抗体的成功表达,表达产物主要位于菌体中,ELISA效价显示在全菌蛋白中A值高于对照5倍以上.其相对分子质量约为33 000.DNA测序表明所获抗体的可变区基因属于scFv抗体基因,推导得到的氨基酸序列具有典型的抗体可变区结构.结论 用人源噬菌体单链抗体库筛选出抗Aβ1-42的人源抗体单链可变区基因,并成功表达了具有抗原结合活性的可溶性单链抗体,为进一步研究阿尔茨海默病的发病机制和治疗奠定了基础.

Cloning and expression of human single-chain Fv antibody against Aβ1-42 peptide involved in Alzheimer disease

Objective Screening of antibody clones specific for β amyloid peptide 1-42 from human phage-display single-chain Fv(scFv)antibody library,and to clone the antibody gene and to express it in a bacterial system,with an ultimate intention to obtain human anti-Aβ1-42 antibody for Alzheimer disease(AD) therapy.Methods β amyloid peptide 1-42 was bound on the solid surface of 96 wells plate as the antigen for the binding antibody clones from a human phage-display scFv antibody library.After four rounds of biopanning,random,well-separated colonies were identified by ELISA test.The specific positive phage clones were transfected into the host E.coli HB2151 to express soluble scFv antibodies.These antibodies were identified by SDS-PAGE and Western blot and their antigen-binding activities were determined by ELISA.Genes of the positive scFv antibodies were then sequenced.Results ELISA test showed that 7 clones could bind Aβ1-42.The soluble scFv antibody from clone A10 was expressed successfully to produce a 33 000 protein present mainly in the whole cell extract which was five folds in amount to that of the control as determined by A490 nm.DNA sequencing demonstrated that the gene of the positive antibody was the scFv gene and the deduced amino acids sequence confirmed its typical antibody V domain structure.Conclusions The specific antibody against Aβ1-42 was successfully identified from human phase-display scFv antibody library.The soluble scFv antibody specific to Aβ1-42 was expressed by E.coli HB2151 in a significant quantity.This cloned antibody promises to provide a solid basis for future studies of the pathogenesis and development of therapeutic agents for Alzheimer's disease.