Construction of Eukaryotic Expression Plasmids Encoding Chicken IL-18 Gene and Its Immunoenhancement on Newcastle Disease Inactivated Vaccine

The whole sequence of chicken IL-18(ChIL-18) gene was amplified by PCR from plasmid pGEM-ChIL-18 and inserted into eukaryotic expression plasmid pcDNA3.1(+)to construct recombinant eukaryotic expression plasmid pcDNA3.1/ChIL-18(pChIL-18).The results of identification of PCR and enzyme digestion and sequencing for recombinant plasmid showed the sequence of the eukaryotic expression plasmid pChIL-18 in the reading frame and the ligation part were correct.After the transfection of pChIL-18 into Cos7 cells,ChIL-18 mRNA expression was found in Cos7 cel1s.The results of MTT assay showed that the expression of ChIL-18 protein in Cos7 cell could induce significantly transformation of chicken T lymphocytes.Immunoenhancement effect of the pChIL-18 plasmid on Newcastle disease vaccine was observed by proliferation response of T lymphocytes from spleen.It can obviously enhance the cell-mediated immune response.