具有中和活性的抗人IL-1β单链抗体的构建

目的构建抗人IL-1β单链抗体(anti-hIL-1βscFv)的原核表达载体,并对其表达的蛋白进行生物学活性检测。方法使用PCR的方法从含有抗人IL-1β抗体基因的质粒中获得抗人IL-1β的单链抗体基因,将其插入原核表达载体pET-27b中,构建重组表达载体pET-27b-hIL-1βscFv。将该载体转化大肠杆菌Rosetta(DE3)后诱导表达,经凝胶过滤色谱柱上复性得到可溶的抗人IL-1β的scFv蛋白。使用ELISA方法鉴定scFv抗体的特异性结合活性,使用Real time-PCR的方法检测scFv抗体的中和活性。结果成功地对抗人IL-1β单链抗体进行诱导、表达和复性,蛋白相对分子质量约为28 000。ELISA结果证实scFv蛋白对hIL-1β具有特异性结合能力。Real time-PCR实验结果证实该scFv抗体可以有效阻断人IL-1β刺激人T细胞表达细胞因子IL-18及IL-1β的作用。结论通过原核表达系统得到的抗人IL-1β单链抗体经复性后,与人IL-1β蛋白有特异性结合能力,并且表现出中和活性,为进一步研究人IL-1β相关疾病及其治疗性抗体奠定了基础。     

新型抗IL-1β和IL-17A双特异抗体的构建及特性鉴定

目的 双特异性抗体(bispecific antibody,BsAb)具有双重的生物学功能.本实验旨在设计并原核表达抗人IL-1β和抗人IL-17A的双特异性抗体(BsAbl/17),获得具有生物活性的BsAb1/17,为深入研究和利用双特异性抗体奠定基础.方法 利用重叠PCR方法构建VH1VL17-CL和VL1VH17-CH1基因片段,并且在所用引物的5'和3'端附加Nco Ⅰ和BamH Ⅰ的酶切位点.将重叠PCR产物进行胶回收后用Nco Ⅰ/BamH Ⅰ进行双酶切,酶切产物再次胶回收,将其连接到用Nco I/BamH I消化的pET-27b载体上.将重组质粒pET-27b-VH1VL17-CL(petA)和pET-27b-VL1VH17-CH1(petB)转化到E. coli Rosetta中.SDS-PAGE和Western blot进行鉴定,用real-time PCR检测其阻断IL-1 β刺激人T细胞表达细胞因子IL-18的活性,人IL-6定量酶联检测试剂盒检测其阻断IL-17A刺激HeLa细胞表达人IL-6的活性.结果 DNA测序结果证明成功构建了pET-27b-VH1VL17-CL(petA)和pET-27b-VL1VH17-CH1(petB)表达质粒.petA、petB诱导产物主要以包涵体形式存在,成熟蛋白纯化产物纯度超过90%以上,经SDS-PAGE分析表明表达产物的相对分子质量约为38×103,与理论值相符.Western blot和ELISA结果证实双特异抗体BsAb1/17对IL-1 β和IL-17A均具有很好的亲和力.通过RT-PCR检测证明其具有阻断IL-1 β刺激人T细胞大量表达细胞因子IL-18的活性,并且具有阻断IL-17A刺激HeLa细胞产生IL-6的活性.结论 成功构建了同时抗IL-1β和IL-17A的双特异抗体,并利用大肠杆菌表达系统高效表达较高纯度的具有生物活性的双特异抗体.

Abstract：

Objective To construct bispecific antibody BsAb1/17 against both IL-1β and IL-17A,express and purify the biologically active BsAbl/17 protein in prokaryotic system for further studies and applications. Methods VH1VL17-CL and VL1VH17-CH1 gene segments were constructed by overlap-PCR.Restriction enzyme sites Nco Ⅰ and BamH Ⅰ were designed at the 5'and 3' end primers respectively. The products of overlap-PCR were ligated to the Nco Ⅰ/BamH Ⅰ -prepared pET-27b vector. The recombinant plasmids pET-27b-VH1 VL17-CL(petA) and pET-27b-VL1 VH17-CH1 ( petB ) were transformed into E. coliRosetta separately. The expressing products were analyzed by SDS-PAGE and Western blot. Neutralization activity of the bispecific antibody for blocking the induction of IL-18 expression by IL-1β in human T cells was determined by real-time PCR. Neutralization activity of the bispecific antibody for blocking the induction of IL-6 expression by IL-17A in HeLa cells was determined by ELISA assay. Results The structure of the plasmids pET-27b-VH1 VL17-CL(petA) and pET-27b-VL1 VH17-CH1 (petB)was confirmed by DNA sequencing. After induction, the fusion proteins were expressed mainly as inclusion bodies. The purity of the both proteins exceeded 90%. SDS-PAGE analysis suggests the relative molecular mass of both products expressed by petA and petB were approximately 38× 103, which is in accordance with the theoretical value. The results of Western blot and ELISA test demonstrated that BsAb1/17 molecule had binding ability to both IL-1β and IL-17A. The BsAb1/17 could block IL-1β to stimulate human T cell to express IL-18 and block IL-17A to stimulate HeLa cell to express IL-6. Conclusion We successfully constructed a novel bispecific antibody BsAb1/17 against both IL-1 β and IL-17A, and expressed biologically active BsAb1/17 protein in prokaryotic system.     

筛选Fab抗体库的细菌展示技术的建立

目的:利用NlpA蛋白的前六个氨基酸(CDQSSS)将抗体锚定在细菌内膜建立筛选Fabs抗体库的展示技术,为今后抗体的研发工作奠定基础.方法:从pNAD质粒中克隆出NlpA leader(含有CDQSSS序列)基因序列,利用相应的酶切位点将该序列插入pComb3表达载体中构建成用于展示Fab的重组质粒pBFD.将从pEAI质粒克隆得到的anti-human IL-1β抗体的重链Fab和全长轻链分别插入到NlpA leader和pelB leader( pComb3载体自带的果胶酶基因前导肽)的下游.将pBFD-Fab转入到E.coli DH5α中诱导表达,原生质球制备后,采用梯度浓度的抗原进行孵育,最后经流式细胞术(FCM)检测抗体展示情况并且分选阳性群体,利用质粒提取的方法来替代PCR方法拯救阳性基因,转化E.coli DH5α,利用FCM再次检测该群体展示的抗体与抗原结合情况.结果:所展示的anti-hlL-1β Fab抗体依次与抗原和FITC标记的抗原特异性抗体孵育后,用FCM实时检测,结果显示出很强的荧光信号并且表现出抗原浓度依赖性.拯救出的pBFD-Fab-原生质球的FCM检测结果与首次展示的FCM结果一致,该系统能够稳定的展示抗体.结论:经过该细菌展示系统展示的Fab抗体能够有效的折叠,与相应的抗原具有很好的特异性结合能力.成功改进该展示技术的基因拯救方法,避免了基因突变和链置换的发生.此外还证明了该展示技术具有很好的稳定性.本实验成功构建了筛选Fab抗体库的细菌展技术.     

抗新城疫中药复方口服液的急性毒性和蓄积性毒性

目的 评价抗新城疫中药复方口服液的急性毒性和蓄积性毒性。