抗TNF－α单克隆抗体是IBD治疗的有效生物制剂，但价格昂贵，多次使用甚至产生抗TNF－α镜像抗体影响疗效。在前一年短期国家自然基金研究的基础上，我们将以同源重组的方法，将假结核耶尔森菌的侵袭素(inv)和单核细胞增多性李斯特菌的溶血素(hly)基因，取代乳链菌基因组中的胸苷酸合成酶（thymidylate synthase，ThyA）基因，制备thyA基因缺陷型重组乳链菌。然后，构建含全长抗TNF-α单抗真核元件的乳链菌质粒，转化thyA基因缺陷型乳链菌。得到的重组乳链菌可侵袭肠黏膜上皮细胞，并在细胞内释放质粒。细胞通过转录质粒载体的真核表达元件，表达和分泌抗人TNF-α单克隆抗体。最后通过体内细胞培养和动物试验评价单抗表达效率。由于thyA缺陷型乳链菌在体外的环境不能生存，对环境将无生物污染。本研究细菌制备简便；单抗是由宿主产生的，将可有效避免抗抗体的产生。

Anti-TNF－α monoclonal antibodies is an effective biological agent in the treatment of inflammatory bowel disease,but the price of this agent is expensive .Using it frequently may produce anti-TNF-α mirror antibody .On the base of our experiments supported by a previous NSFC programme(NO.81250012), we have replaced the thymidylate synthase in Lactococcus lactis genome with the Yersinia pseudotuberculosis invasin (inv) and mononucleosis Lester bacteria hemolysin (hly) gene.And we make a thyA gene deficient recombinant Lactococcus lactis .We will electrotransform the thyA gene deficient recombinant Lactococcus lactis with the pladmid which has anti-TNF－αmonoclonal antibodies sequences , eukaryotic expression element,polyA sequences. Lactococcus lactis can invade the intestinal epithelial cells and release the plasmid into the cytosol .The intestinal epithelial cells will transcribe and translate the eukaryotic expression element sequences of the plasmid . Therefore ,the intestinal epithelial cells can express and secrete anti-TNF-α monoclonal antibody . The efficiency of monoclonal antibody expression will be evaluated by in vitro cell culture and in vivo animal experiments . The thyA deficient Lactococcus lactis has no biological pollution, because it could not survive in the environment.Moreover,the approach of experiment is convenient.Anti-TNF-α monoclonal antibody is produced by the host ,so it can effectively reduce the incidence of mirror antibody .