For centuries first nation peoples have known chewing on willow tree bark would ease pain. More recently a random deposit of a fungus spore on a bacterial culture started Sir Ian Flemming on the road to discovering penicillin. Plants have always been a source of medicines. It can be argued the first medical product of biotechnology is recombinant human insulin. “Humulin” was created by inserting the human insulin gene into a bacterium. It became a commercial product to treat people with diabetes in 1982. No longer did diabetics suffer from complications of using insulin isolated from pigs. Recombinant human insulin made life much better for diabetics. Today scientists are using recombinant DNA technologies and common agricultural plants to produce a wide range of pharmaceutical compounds. These medicine producing engineered plants are often called pharma-crops.
Scientists have been successful transforming barley, maize, carrots, tomatoes, alfalfa, bananas, rice and tobacco. The engineered genes vary from those that code for proteins found in milk and tears to potential vaccines.
There has been a large outcry about a recent biotech crop that was supposed to be grown in California and later in Missouri. The biotech crop is rice and the engineered proteins are lysozyme and lactoferrin. These two human proteins can be found in breast milk, saliva, or tears. These hardly representing a dire threat to our food supply as many media stories have stated. The fear stories even convinced a major beer producer to threaten not buy any rice grown in the vicinity of these engineered crops. Why? Because critics have spread fear stories that these engineered rice crops could contaminate other rice fields by cross pollination. The problem with that story is rice is a self pollinating crop so does not spread its pollen to the wind. There are also very conservative geographic isolation and harvesting procedures to reduce the chances of contamination to near zero. The production of these two proteins in large amounts may help substantially reduce the infant mortality in the developing world. Diarrhea disease caused by bacteria literally kill millions of children each year. Lactoferrin and lysozyme have been proven to help reduce bacterial diarrhea infections. It is important that we look at the whole risk benefit evaluation for this biotech crop and stop publishing only the hypothetical or potential risks. There are millions of children who could benefit from this engineered rice.
It may be that the demands of critics will slow the use of food crops for pharmaceutical production in the near future but that does not mean these technologies will stop. Non-food crops like tobacco are becoming a favorite of biotechnology researchers. There is something deliciously ironic about tobacco becoming a major medicine producing crop.
Research has shown promising results in the production of Insulin-like Growth Factor (IGF-1) in both rice and tobacco. This human protein is one of the few treatments that slow the progress of Lou Gehring disease. Similar success has been demonstrated for engineered protective monoclonal antibodies against rabies and colorectal cancer.
It has been estimated vaccines save 3 million live each year. For the past thirty years we have used chicken eggs to make vaccines. Unfortunately not all vaccines can be made that way. A good example involves the Human Papilloma Virus. This virus can only be grown in human cells and therefore we can not produce a papilloma vaccine in chicken eggs. There are over 140 different types of this virus and most do not cause any harm but a few are associated with cancer.
According to the World Health Organization there are 600 million people infected worldwide with over 20 million in North America. The pathogenic strains cause a half million cases of cervical cancer each year, mostly in the developing world. Poor access to PAP smears in developing countries, mean nearly half of those are fatal.
Researchers have engineered a tobacco plant to produce the VP16-L1 protein from the virus. Tests have shown it is very effective at generating an immune response against the virus. With this breakthrough it will be possible to make large amounts of the protein to manufacture a vaccine. In the developing world, where there are significant logistical problems with production and storage of purified vaccines, an oral version is being developed in tomatoes. It is hoped that soon young women will only have to eat a few specially supplied tomatoes to gain immunity to this killer virus.
The potential of pharma-crops is best exemplified with the anthrax story. At present there is only one form of vaccine that protects against anthrax. Along with being expensive to produce and store, it has significant side effects in some people. Researchers have engineered the protective antigen (PA) from anthrax into tobacco. This time, instead of inserting the gene into the nucleus of which there is one per cell, they inserted it into the chloroplast. With hundreds of chloroplasts per cell, this greatly increases the yield of the engineered protein. Couple this with 40 tonnes of leaf tissue per acre and 2-3 harvests per year means the ability to produce large amounts of the anthrax vaccine in tobacco is soon to be a reality. A mere one acre of genetically engineered tobacco will be able to produce 400 million doses of stable anthrax vaccine.
Today pharma-crops produce $19 billion of pharmaceuticals. It is estimated that by 2010 genetically engineered crops will generate $100 billion of medicinal products. Golden Rice, with its engineered beta carotene, will soon be available to help prevent 500,000 children from going blind from lack of vitamin A. Salt and drought tolerant crops will allow present lands to remain productive or even increase yields. Insect resistant crops will continue to generate large yields with reduced pesticide use. Bio-fuels will reduce our needs for foreign oil. Now pharma-crops will add to the benefits biotechnology is bringing the world.
Globe and Mail, Dec 01 2005