Expression of recombinant human IFN-#beta#1a cDNA in CHO cells

Objective To express recombinant human IFN-β1a cDNA in CHO cells.Methods Mix recombinant plasmids pRC/CMV-IFNβ DNA and pSV2dhfr-DNA (used as a selective marker) at a ratio of (3∶1) and transfect into CHO-kldhfr cells by liposome technique. Screen the single clones grown in thymine-free selective medium for the pressure amplification of IFN-β gene. Subject the screened clones to large-scale culture, and collect the culture liquid for the purification by a series of procedures.Results The daily yield of IFN-β secreted by the cells resistant to 0.6 μmol/L MTX was 10~5 unit/10~6 cells.The specific activity of human IFN-β expressed in CHO cells reached 2.2×10~8 IU/mg after purification.Conclusion A CHO cell strain suitable for the expression of human IFN-β was established.