鸭白介素-18基因重组真核表达载体的构建及其表达产物的生物学活性

Construction of Eukaryotic Express Vector of Duck Interleukin 18 Gene and Identification of Bioactivity of Its Expressed Protein

从克隆质粒pGEM-DuIL-18扩增出鸭IL-18全基因片段,克隆到真核表达载体pcDNA3.1(+)中,构建重组质粒pcDNA3.1/DuIL-18(简称pDuIL-18)。将重组质粒pDuIL-18转染Cos7细胞,转染细胞中含鸭IL-18基因的mRNA。SDS-PAGE分析表明,表达产物是与鸭IL-18相符的约23000的蛋白条带。鸭淋巴细胞转化试验表明,表达产物对鸭淋巴细胞具有明显诱导转化作用。重组质粒pDuIL-18对H9亚型禽流感灭活疫苗免疫增强作用的研究表明重组质粒pDuIL-18能够提高禽流感灭活疫苗诱发的细胞免疫应答,为研究能够更好地防制禽流感的新型疫苗提供了新的思路。

Duck IL-18 gene was amplified from plasmid pGEM-DuIL-18 by PCR. The PCR product digested with Pst I and Xho I was inserted into eukaryotic express vector pcDNA3.1（＋） to generate an recombinant expression plasmid pcDNA3.1/DuIL-18 （pDuIL-18）, and transformed into Escherichia coli JM109. The recombinant colonies were identified by restriction enzyme digestion, PCR and sequencing. DNA sequence confirmed the correct sequence of the recombinant eukaryotic expression plasmid pDuIL-18 in the reading frame and the ligation part. After the transfection of pDuIL-18 into Cos7 cells, duck IL-18 mRNA was expressed in Cos7 cell. The SDS-PAGE analysis showed that the expressed duck IL-18 protein had molecular weight of 23 000 D. The results of methyl thiazolyl tetrazolium （MTT） assay showed that duck IL-18 protein expressed in Cos7 cell could induce significantly transformation of duck T lymphocytes. Immunoenhancement effect of recombinant expression plasmid pDuIL18 on avian influenza vaccine was observed by proliferation response of the T lymphocytes from spleen. It can obviously enhance the cell-mediated immune response.