【摘要】 目的 克隆金黄色葡萄球菌肠毒素A(SEA)全长基因并构建其表达载体。方法 采用PCR技术,从产SEA的葡萄球菌标准菌株ATCC13565基因组DNA中获得SEA全长序列共771 bp,克隆入pUC57载体中,进行酶切及测序鉴定。结果 克隆了SEA全长基因，经测序证实与Genbank中收录的SEA基因序列完全一致。结论 本研究成功地克隆了SEA全长基因,为进一步研究SEA基因的靶向抗肿瘤研究奠定了实验基础。
【关键词】 金黄色葡萄球菌;肠毒素;克隆;序列分析
Cloning and identification of the gene encoding the superantigen
staphylococcus enterotoxin A
HAO Lin1, HAN Conghui1*, WANG Yuemin2, GONG Zhen1, DONG Bingzheng1, HU Jianpeng1
(1.Department of Urology, Xuzhou Central Hospital, Xuzhou, Jiangsu 221009, China;
2.Department of Urology, Affiliated East Hospital, Tongji University, Shanghai 200120)
Abstract: Objective To clone the full-length gene of staphylococcal enterotoxin A (SEA) and construct its expression vector. Methods The technique of polymerase chain reaction (PCR) was employed to obtain 771bp full-length sequence of SEA from the gene group DNA of standard strain ATCC13565. The SEA gene was amplified and inserted into cloning vector pUC57. The structure of recombinant pUC57-SEA plasmid was confirmed by restriction endonuclease and sequence analysis. Results The 771 bp DNA sequencing showed that the DNA sequence of the cloned gene was identical to the data recorded in Genbank Database. Conclusion This study has successfully amplified and cloned the full-length gene encoding SEA toxin and established a basis for the SEA gene target for antitumor research.
Key words: staphylococcus aureus; enterotoxin; clone; sequence analysis
超抗原(superantigen，SAg)是一组细菌或病毒编码的蛋白质分子，可不需要抗原提呈细胞(antigen-presenting cell, APC)的提呈作用，以完整的蛋白质分子形式直接与APC膜的MHC-Ⅱ类分子抗原结合槽外侧结合并且提呈给T细胞[1]。SAg-MHC-Ⅱ类分子复合物仅与T细胞抗原受体(TCR)β链的V区相结合[2]，由于人类Vβ基因有20余种，故SAg激活的T细胞克隆数可达普通抗原的数千倍乃至数万倍。超抗原的抗肿瘤作用主要是由SAg依赖的细胞介导的细胞毒作用(superantigen-dependented cellular totoxicity, SDCC)来完成，这是超抗原抗肿瘤的主要作用。再者，SAg激活的CD4+T细胞还可以分泌多种足量的细胞因子，如：肿瘤坏死因子(TNF)-α、TNF-β和INF-γ、白细胞介素(IL)-2、IL-6等[3]，直接或间接地杀伤肿瘤细胞。本研究克隆超抗原金黄色葡萄球菌肠毒素A(SEA)全长基因，为进一步研究超抗原SEA基因片段在抗肿瘤中的作用提供实验基础。
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