Applications of genetic engineering to the pharmaceutical industry

A frequent motive for genetic engineering is to transfer the gene for the desired protein from a cell that is difficult or impossible to grow into a cell which is easy and inexpensive to handle. In the pharmaceutical field this usually means isolation of a gene coding for a protein secreted by human cells, the protein often being glycosylated. While bacterial cells are an inexpensive host in which to express genes, they do not produce proteins which are glycosylated, nor necessarily properly processed. Thus while there are examples of successful bacterial systems, there is also an intense interest in expression in animal cells. The situation is often complicated by our lack of knowledge of the function, or even the necessity, of glycosylation. Examples of successes and problems in production of insulin and interferons in several hosts have been presented.