LONDON, Ontario - The development of new biomedicines in today's changing environment of health-care spending cutbacks has caused biopharmaceutical companies to look for more efficient ways of producing therapeutics in order to reduce production costs.
This has generated a wave of interest in agricultural biotechnology. The use of plants, animals, insects and cell cultures as bioreactors for the commercial-scale production of recombinant proteins and peptides is one of the fastest-growing applications of biotechnology. The interest in the field is evidenced by the nearly 400 delegates who are attending an International Molecular Farming Conference being held here.
According to Ronald Meeson, vice president of research at Dow AgroSciences Inc. in Indianapolis, a keynote speaker at the conference, molecular farming is an emerging technology that will revolutionize how both agriculture and health care are viewed. The past decade and a half of research has brought forth a few initial transgenic crops aimed primarily at helping to solve agricultural production problems. However, the next decade should see an increasing number of transgenic crops producing novel products in the areas of pharmaceuticals, plastics, specialty foods and chemicals.
In addition, there is clear evidence the commercial activity is increasing with the emergence of a number of companies dedicated to producing products via plants and animals.
Raising the specter of edible plant vaccines, Meeson said they promise a number of advantages: no infectious agent is involved in the vaccination procedure of an immunizing event; plants are easily engineered and provide a low-cost, well managed production system; and there would be high consumer acceptance, providing an alternative to traditional injections.
There are a number of groups working in the area and research has intensified on demonstrating the feasibility of delivering vaccines through oral administration of transgenic plants.
For example, Hugh Mason, researcher at the Boyce Thompson Institute for Plant Research (BTI) at Cornell University, and colleagues are focused on production on candidate vaccines against diarrheal diseases, the Norwalk virus and hepatitis B.
Two such vaccines already have been tested in humans in the U.S. in National Institutes of Health-sponsored clinical trials. An oral vaccine directed against a form of bacteria-caused diarrhea (enterotoxigenic E. coli) was found to be safe and highly active in a Phase I trial. The trial used potatoes containing the heat-labile enterotoxin B subunit (LT-B), which itself is nontoxic but mediates the binding and delivery of the toxic LT-A subunit, and therefore is a good vaccine candidate. An oral vaccine against the Norwalk virus, which causes severe bouts of diarrhea, also has been completed. A plant-based vaccine, which would provide the world's first protection against the Norwalk virus, is currently under investigation.
Jim Brindle, genomics team leader at the Southern Crop Protection and Food Research Centre in London, is working with a team of scientists on field tests of three genetically enhanced low-nicotine tobacco strains. He said the plants are being tested for expression of human interleukin-10 and its oral administration in the treatment of Crohn's disease.
There is evidence that cytokines retain some of their biological activity following oral administration, which is why oral vaccines for the condition may be an effective therapy. The group is evaluating the biological activity of the plant IL-10 and intend to use it in an animal model of Crohn's disease.