By Jonathan Amos
BBC News Online science staff
European scientists have launched a project to make pharmaceutically useful products in genetically modified crops.
The plants to be used have yet to be chosen
The consortium, called Pharma-Planta, wants to produce vaccines and other treatments for major diseases, such as HIV/Aids, rabies and TB.
The EU has put 12 million euros (£8m) into the project, which hopes to start clinical trials by 2009.
The first product, possibly grown in maize, is likely to be an antibody that can be used to block HIV transmission.
It would be incorporated into a microbicidal cream that could be used in the vagina.
The second product will probably to be a post-bite vaccine for rabies, which is still a significant killer in Africa and southeast Asia. The viral disease is responsible for 40-70,000 deaths per year, mostly in children.
The project's aim is to focus on areas that will be of greatest benefit to developing nations - and any plant "platforms" that are found to work particularly well will be freely licensed in those countries.
Cultivation of the GM plants and the processing necessary to remove the useful molecules from the plant tissues would all be done locally.
"We are addressing what we consider to be serious issue of global inequity of health," said Professor Julian Ma, from St George's Hospital Medical School, London, UK, who is Pharma-Planta's scientific coordinator.
"The major burden of disease is in developing nations where access to many vaccines is very poor."
The EU Framework 6 project is led by academia - not industry. Thirty-nine labs in 11 European countries will work together, with input from researchers in South Africa, where HIV/Aids is a major public health issue.
Similar projects are underway in other parts of the world. One such approach is already being used successfully in Cuba to create human proteins in tobacco plants which allow the purification of Hepatitis B vaccine.
But in general, many commercial companies have withdrawn from vaccine development and production because of what are regarded as low economic returns.
Pharma-Planta hopes the technology it will develop over the course of its initial five years of funding will eventually boost the global supply of treatments.
"Plants are inexpensive to grow, and if we were to engineer them to contain a gene for a pharmaceutical product, they could produce large quantities of drugs or vaccines at low cost," Professor Ma said.
"The current methods used to generate these types of treatments include genetic modification of human cells and microorganisms such as bacteria. These techniques are labour intensive, expensive and often only produce relatively small amounts of pharmaceuticals."
He said it was difficult to make comparisons but the costs of developing plant-derived products could be 10-100-times lower than conventional production.
The production of GM crops for food consumption has been viewed with deep suspicion in Europe, but the scientists hope the public will view this project differently.
"I was involved in the GM debate in the UK - I was on the steering board. And one interesting observation from that was that there was support for medicinal uses of GM plants, especially for applications in developing countries," said Pharma-Planta's biosafety co-ordinator, Professor Philip Dale, from the John Innes Centre in Norwich, UK.
The project has yet to decide which plants to use but candidates could include tobacco, maize, potatoes and tomatoes.
The preference would be to go with plants in which the desired protein products are expressed in high quantities in the seeds, which are easily harvestable.
"The plants would be grown in pharmaceutical production units on dedicated land, isolated from food crops," said Professor Dale.
"They would be genetically isolated, too - new male sterile lines that don't produce pollen. The crops would be harvested using dedicated equipment - combine harvesters and storage. Even the initial phases of the processing would be done on site."
Professors Dale and Ma thought it unlikely, though not impossible, that the "pharming" would be done in the UK.
Anti-GM group Friends Of The Earth said the project's aims were laudable but warned its research could have widespread negative impacts.
"Food crops in the United States have already been destroyed because of contamination by experimental 'pharm' crops," said campaigner Clare Oxborrow.
"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."