β-Netrin抗原表位的分析及其抗体的制备与鉴定

The epitope analysis of β-Netrin and preparation and characterization of its antibodies

目的:制备抗神经细胞突起生长诱向因子(β-Netrin)的多克隆抗体(pAb)和单克隆抗体(mAb),并对其特异性进行鉴定。方法:应用GoldKey软件分析人βNetrinC末端结构域氨基酸的序列(共114个氨基酸),确定抗原表位并人工合成多肽。然后采用碳化二亚胺法,将合成肽与载体蛋白牛血清白蛋白(BSA)偶联作为抗原,免疫BALB/c小鼠。取免疫小鼠脾细胞与Sp2/0骨髓瘤细胞常规融合,依次进行HAT选择培养,间接ELISA法筛选阳性的杂交瘤细胞并克隆化。对分泌的mAb的效价、Ig亚类(型)及特异性,分别用间接ELISA和Westernblot进行鉴定。同时,通过免疫细胞化学染色鉴定抗体的特异性。另外,以偶联的分子免疫新西兰白兔,制备抗β-Netrin的pAb,用Westernblot鉴定其特异性。结果:以确定的此16个氨基酸的序列NH2-FRGKRT-LYPESWTDRG-COOH作为抗原表位,以人工合成多肽与BSA偶联作为免疫原,获得3株可稳定分泌特异性抗β-Netrin mAb的杂交瘤细胞。免疫细胞化学染色结果表明,这3株抗体均能特异性地识别细胞中的抗原。另外,制备了高效价的抗β-Netrin的pAb,并能特异性地识别原核表达的β-Netrin蛋白。结论:采用人工合成多肽作为半抗原成功地制备出抗β-Netrin的pAb和mAb。

AIM: To prepare and characterize anti-human β-Netrin antibodies. METHODS: B cell dominant epitopes of human β-Netrin C-terminal 114 amino acid sequences were predicated by the GoldKey software. One of the epitopes was synthesized and coupled with bovine serum album (BSA) by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). The BALB/c mice were immunized with the coupled protein. The splenocytes of immunized mice were fused with Sp2/0 cells by routine method and the hybridomas were selected in HAT medium. The hybridoma cells secreting specific antibody were detected by ELISA and cloned by limiting dilution. The titer specificity, and Ig subclass of anti-β-Netrin mAbs were characterized by ELISA, Western blot and immunocytochemical staining. In addition, New Zealand rabbits were immunized with the coupled protein to prepare polyclonal antibody against β-Netrin. The specificity of the antiserum was verified by Western blot. RESULTS: A 16-mer peptide NH_2-FRGKRTLYPES-WTDRG-COOH was the dominant epitope of the B cells. Synthesized peptide coupled with BSA was used as the immunogen to immunize BALB/c mice. Three hybridoma cell lines that stably secrete specific mAbs were obtained. The result of immunocytochemical staining showed that prepared mAb specifically recognize the antigen in the neuronal cells. The polyclonal antibody against β-Netrin had high specificity. Western blot analysis showed that the antiserum bind with the prokaryotically expressed β-Netrin specifically. CONCLUSION: Using the synthesized peptides as hapten, we have prepared epitope-specific mAbs and pAb against β-Netrin successfully.