HIGH-LEVEL PRODUCTION OF RECOMBINANT PROTEINS IN CHO CELLS USING A DICISTRONIC DHFR INTRON EXPRESSION VECTOR

We have constructed expression vectors for Chinese hamster ovary (CHO) cells that produce both selectable marker and recombinant cDNA from a single primary transcript via differential splicing. These vectors pr oduce stable CHO cell clones that, when pooled, produce abundant amoun ts of secreted recombinant proteins compared with the amounts produced by conventional expression approaches that have selectable marker and the cDNA of interest under control of separate transcription units. O ur vectors divert most of the transcript to product expression while l inking it, at a fixed ratio, to dihydrofolate reductase (DHFR) express ion to allow selection of stable transfectants. Pools of clones with i ncreased expression of the product gene can be efficiently generated b y selection in methotrexate. The high level of expression from pools a llows convenient and rapid production of milligram amounts of recombin ant proteins.