Scientists in Cambridge believe they may be able to grow vegetables which can vaccinate against serious diseases within four years.

The first vaccine vegetable to go on trial is expected to be a potato that protects against Norwalk virus. The stomach virus caused several US warships to be put out of action during the Gulf War due to outbreaks among the crew.

Other vaccines which could be grown in genetically modified fruit and veg could include hepatitis B. Patient trials have already been carried out on a potato E. Coli vaccine. E.Coli was at the centre of the1996 food poisoning outbreak in Scotland.

Dried tomatoes

Fresh fruit is unlikely to be used because it rots too quickly. But scientists are investigating the possibility of marketing the medicinal fruit and veg in dried tomatoes, mashed potatoes and banana chips.

Cambridge-based Axis Genetics, one of the companies involved in vaccine research, has announced that it has reached an agreement to work on the project with the Boyce Thompson Institute in New York.

It could make a fortune if it is successful.

Fortune

Dr Iain Cubbitt, Axis' chief executive, said: "We haven't done the sums, but you don't need a very big area to grow these plants.

Needles could be replaced by veg

"You can get 50 tons of potatoes per hectare, and a piece of potato the size of a golfball is what you would need for a dose. How many doses can you get out of one acre? Millions."

Researchers have found that mice fed potatoes containing the hepatitis protein produce antibodies to the disease.

They believe edible vaccines could also prove effective because they allow the vaccine to be absorbed into the saliva and not just the bloodstream as injections do.