抗克伦特罗单链抗体表达载体的构建与鉴定

Construction and Expression of Anti-clenbuterol Single Chain Fv Recombinant Vector

为构建克伦特罗(Clenbuterol,CBL)单链抗体(scFv)表达载体,实现其在大肠杆菌中的表达。以pCANTAB5E-CBL质粒为模板,扩增CBL的scFv基因,与pPICZαA载体重组,然后以重组质粒pPICZαA-scFv为模板扩增scFv及其相连的6个组氨酸(6×His)片段,再与载体pBV220连接,转化大肠杆菌DH5α,阳性克隆质粒经酶切和PCR鉴定后进行目的片段的序列测定。重组菌经温度诱导表达重组单链抗体,并通过SDS-PAGE和Western blotting对其鉴定。采用竞争ELISA检测重组单链抗体的抗原结合活性。结果表明重组质粒pBV220-scFv含有插入片段,与原序列的同源性达99.8%。重组蛋白的分子量接近37kD,能够被抗His标签单克隆抗体特异性识别且可被游离的CBL竞争性抑制,IC50值为4.55ng/mL。这说明我们成功构建了重组质粒pBV220-scFv并实现了其在大肠杆菌中的表达,为进一步进行CBL免疫法快速检测奠定了一定的基础。

To construct the recombinant vector pBV220-scFv and express anti-clenbuterol （CBL） scFv antibody in Escherichia coli, we amplified the scFv gene using plasmid pCANTAB5E-CBL as a template, recombined it with pPICZαA, then amplified the scFv-His-tag gene from plasmid pPICZαA-scFv and linked it with expression plasmid pBV220. We identified the recombinant plasmid by restrictive enzyme digestion, PCR amplification and sequence analysis. Finally, we transformed the recombinant vector into E. coli DH5α that was temperature-induced and expressed recombinant protein. We identified the recombinant protein by SDS-PAGE, Western blotting and indirect competitive ELISA .The results show that recombinant plasmid pBV220-scFv contained the inserted fragment with highest homology about 99.8%. The expression of scFv induced by temperature show 37 kD Mw and anti-His-tag mAb recognized-activity by SDS-PAGE and Western blotting respectively, and could competitively combine with CBL, the IC50 is 4.55 ng/mL. The recombinant plasmid pBV220-scFv is constructed and expresses the scFv gene of CBL in E. coli successfully. This study suggests the corresponding immunoassay methods could be set up by the recombinant scFv.