The molecular biology of production cell lines.

The emergence of a wide variety of biological expression systems for the large-scale production of therapeutic proteins has shifted the focus from vectors to host organisms. Although expression systems now span bacteria, fungi, plants, insects, and mammalian cells, the vast majority of recombinant-derived biopharmaceuticals at the present time have been produced in Escherichia coli and in mammalian cells. This promises to change as the economic benefits of the newer systems permit the development of a new generation of proteins heretofore considered unfeasible for commercial development. Despite the impressive results which have been observed for many of the newer systems, there are many commercial considerations which suggest that E. coli and CHO cell expression systems may continue to dominate the manufacture of biopharmaceuticals for a long time to come.