Production of Recombinant Proteins in Plants

As of June 2011, scientists are working to find a way to use plants to produce recombinant proteins on an agricultural scale. If successful, it is possible that they will be able to produce any protein, whether naturally occurring or synthesized by humans, in a safe and affordable manner. Doing this on a large scale will provide scientists with the opportunity to produce plant-derived pharmaceuticals, recombinant antibodies, recombinant subunit vaccines and other medical products using only nutrients, water and sunlight.

Pharmaceuticals

• Several pharmaceutically-significant proteins that have their origin in mammals, such as humans, have been artificially synthesized in plants. For example, scientists have been able to derive blood products, such as human serum albumin, for which there is a yearly demand of more than 500 tonnes, from plants. They have also been able to produce signaling molecules, such as cytokines. These have been mostly produced using transgenic tobacco plants, although scientists are hopeful that they will be able to expand the plant base used for this process in the future.

Recombinant Antibodies

• Antibodies are complex glycoproteins that identify and bind to harmful antigens. They are used in the diagnosis, prevention and treatment of a wide range of diseases. Producing antibodies in plants is difficult, since they must fold and assemble in a very particular way in order to be effective. While these were also originally produced using tobacco plants, there has been a move toward using cereal seeds as an alternative. This allows for the long-term storage of the antibodies at ambient temperatures without risk of significant degradation.

Recombinant Subunit Vaccines

• Scientists are also looking into developing recombinant subunit vaccines, such as the hepatitis B vaccine, in plants on a large scale. While they were first developed in tobacco, they are increasingly being synthesized in edible plants, such as fruits and vegetables. Vaccines for the Norwalk virus and the E. Coli bacterium may also be derivable from potatoes.

Additional Proteins of Medical Import

• Plants have been used, and will continue to be used, to produce other proteins of use to medical science. For example, scientists have succeeded in synthesizing two different kinds of milk protein that can be used to improve child health. They have also produced protein polymers that could be used to replace tissue and in certain surgical contexts.