Human trials for GM vaccines
By Ian Sample
HUMAN TRIALS of vaccines produced by genetically modified plants could begin within five years, scientists claimed recently. The researchers outlined proposals to grow fields of crops that have been genetically modified to produce vaccines and other pharmaceuticals to treat HIV, rabies, diabetes and TB. They said field trials of medicine-producing crops were likely to begin in 2006, with safety trials in humans beginning three years later at St. George's hospital in London.
Although the team will consider carrying out trials on plots of a hectare in Britain, the unfavourable climate and risk of sabotage mean that field studies, and ultimately full-scale growing of the plants, is most likely to happen in South Africa or southern Europe. Scientists have long known that GM technology can be used to trick a plant's molecular machinery into making a range of medically useful compounds.
Instead of using expensive pharmaceutical factories, advocates envisage fields of GM crops being harvested to reap new medicines cheaply, a process known as `pharming'. According to Julian Ma of St George's Hospital Medical School in London and the leader of the Pounds Sterling 8m project, the primary aim is to provide medicines for the developing world.
``The major burden of disease is in the developing world, but these are the countries that do not have access to vaccines,'' Ma said.
The number of people dying each year from the six major diseases for which vaccines exist is around 3.3 million. The scientists have already identified genes that can be put into plants to make them produce antibodies or other compounds that can help treat rabies, TB and diabetes.
While no vaccine yet exists for HIV, genes that produce antibodies capable of destroying the virus have been discovered. A cream containing the antibodies could help reduce the risk of HIV being transmitted during sexual intercourse, but the production technology cannot easily be scaled up. ``Using traditional techniques, you just cannot produce enough,'' said Ma.
Ma believes GM plants probably tobacco or maize offer a cheap way to make vast quantities of vaccines and other drugs. ``It looks like the cost of plant-derived products will be 10 to 100-fold less than conventionally derived products,'' he said. If the technique is proved, it may be adopted by developing countries, helping to breaking their reliance upon pharmaceutical multinationals. ``Growing and harvesting plants is low tech,'' Ma said. ``We see this as being transferred to countries where they can start up their own industry at a low start-up cost and produce the amounts they need.''
Philip Dale, an expert in GM safety issues at the John Innes Centre in Norwich, eastern England, is advising on possible risks of contamination, where genes from the GM plants get into others. ``The ability to be able to isolate these from other crops is a crucial factor,'' he said. ``There's a possibility of mixing with other crops and that's the basic challenge we have to wrestle with.''
Land used to grow the crops will need to be remote from other crops and dedicated machinery will be needed to process them, so that the medicine cannot enter the food chain. Sue Mayer of the lobby group GeneWatch said the researchers should pledge to make their technology free to all, to prevent it being claimed by pharmaceutical companies.
Friends of the Earth's GM campaigner, Clare Oxborrow, said: ``A clear set of criteria must be established to ensure that human health and the environment are protected. Any benefits must genuinely reach those that need them, rather than simply lining the pockets of the biotech and pharmaceutical industry.'' Guardian Newspapers Limited 2004
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