Bioengineered proteins are already being used to treat the following diseases:

• Hepatitis C: Pegylated (PEG) therapeutic protein. The PEG barrier obstructs the protein breakdown machinery in the body’s cells and thereby prolongs the drug’s duration of action.
• Renal anemia: A specially modified chemically synthesised protein that stimulates red blood cell production.

Therapeutic antibodies form a relatively new drug class that has only been made possible by modern biotechnology. Antibodies are components of the immune system. They identify foreign structures in the body – e.g. molecules on the surface of body cells, bacteria or viruses – and mark them out for elimination by the immune system. There are  several classes of antibodies, each of which has a different function. IgG antibodies are the most abundant. These Y-shaped proteins bear two identical regions on their two short arms that identify a specific foreign structure. The long stem of the molecule interacts with other components of the immune system, which ultimately initiate destruction of the intruders.