Construction,expression and identification of human B7-H1-Fc chimeric molecule in mammalian CHO cell

Objective To construct eukaryotic expression plasmid of human B7-H1 extracellular region-hIgG1Fc-pCI-neo eukaryotic expression vector,and express the functional fusion protein in mammalian CHO cell.Methods Full-length human B7-H1 encoding sequence was amplified from human activated T cell cDNA library by PCR,fused with hIgG1Fc,then transformed into pCI-neo expression vector and verified by sequencing.The validated recombinant was transfected into mammalian CHO cell by lipofectamine reagent.The supernatant of the cultured cell was collected and analyzed by the sandwhich ELISA to detect if there was the fusion protein,and the fusion protein was purified by HiTrap recombination protein Protein A affinity chromatography.The concentrated supernatant or purified fusion protein were used for Western blotting after SDS-PAGE to identify the molecular weight and immune activity of the fusion protein of B7-H1.Results The extracellular region of hB7-H1 about 727 bp was cloned from human T cell cDNA library and was inserted with hIgG1Fc into the eukaryotic expression vector pCI-neo.After the transfection of recombinant into mammalian CHO cell by lipofectamine reagent,the expression of B7-H1 fusion protein was detected in the cultured CHO cell supernatant by the sandwhich ELISA.The immune activity of the fusion protein was verified by Western blotting,and its molecular weight was about 51.76×10~(3),very close to the expected value.Conclusion The hB7-H1-Fc chimeric molecule was successfully constructed and the expression of its functional fusion protein in mammalian CHO cells lays a foundation for further research on the role of B7-H1 in immune tolerance,autoimmune diseases.