胰淀素Fab抗体的筛选及初步鉴定

目的:从人天然Fab噬菌体抗体库中筛选胰淀素(amylin又称为胰岛淀粉样多肽)Fab抗体,测定其特异性及抗原结合活性.方法:以胰淀素为抗原,对抗体库进行5轮"吸附-洗脱-扩增"的富集筛选;将从人源噬菌体抗体库中筛选出的阳性克隆,提取其质粒、切除gⅢ、自身环化并转入大肠杆菌中,以IPTG诱导表达可溶性抗体,最后用SDS-PAGE鉴定抗体表达情况、ELISA鉴定抗原结合活性和特异性.结果:成功筛选并表达了抗胰淀素的可溶性Fab抗体,经SDS-PAGE蛋白电泳,在相对分子质量约为47 kD处可见一蛋白条带.ELISA和Western blot证实了该Fab片段与胰淀素抗原的结合活性和特异性.结论:利用噬菌体抗体库技术获得了人源性的特异抗胰淀素Fab抗体,为临床进行下一步研究奠定了基础.

Selection and preliminary identification of human Fab fragement antibody against amylin from phage antibody library

Objective:To obtain antibodies against amylin from a 'naive' human Fab fragment antibody phage diasplay library and to analyze the specificity of antigen binding activity.Methods:Panning and screening Fab antibody from the antibody library,the positive clones with well reactivity to amylin were selected after five times selection of 'adsorption-elution-enrichment'.Then the plasmid DNA which was extracted from the clones,was digested with Spe Ⅰ and Nhe Ⅰ to delete gⅢ (about 660 bp).The digested 47 000 bp DNA which was purified after separation of bands from agarose gel was ligated with T4-DNA ligase.The constructed expressing phagemids were transformed to the BL21(DE3)pLysS,soluble Fab was expressed in it by the induction of IPTG and its characteristics and specificity were determined by ELISA and Western blot.Results:Soluble Fab antibodies were expressed in E.coli.According with molecular weight of IgG Fab,protein band of about 47 kD was shown by SDS-PAGE.Western blot using the goat anti human IgG-HRP showed their binding activities.ELISA showed their specificity with amylin antigens and they did not react with bovine serum albumin.Conclusion:The high level expression and identification of the soluble human anti- amylin Fab fragment antibodies has been obtained successfully,which lays a solid foundation for further researching about the biological and pathological activities of amylin.