Science: A spoonful of honey...

Bees could soon have an important role in delivering drugs.

HONEY MADE by bees from the nectar of genetically modified (GM) plants could be used to give people vaccines or new drugs, according to Dutch biologists. By using bees to concentrate the proteins produced in the GM nectar, the costs of purifying and delivering new drugs would be substantially reduced, say a team at the Centre for Plant Breeding and Reproduction Research in Wageningen in Holland.

"It's a production system that would require very little purification," says Tineke Creemers of the centre. "The protein is concentrated by the bees, so it's a very cheap production method."

Producing vaccines in honey might also be a means of making the therapeutic proteins last better, because the sugar in the solution could act as a preservative even in hot countries.

The thrust of research, described in New Scientist magazine, followed the discovery that plants naturally produce extra antifungal proteins which are secreted in their nectar. These are not damaged or filtered out when the bees concentrate it into honey: tests were able to find those proteins in commercially-produced brands. Clearly, they are not harmful to humans in such doses.

Bees have recently begun to look like a problem for GM production, because they can fly up to three miles from a hive. That means that standard varieties of plants six miles from GM sites could be cross-fertilised by bees travelling the maximum distance in either direction. Furthermore, the John Innes Centre reported last week that it was, in essence, impossible to guarantee that pollen from GM plants would not reach unmodified plants if they are both grown in the open.

The Dutch, however, decided to try to stop unwanted cross-fertilisation while still getting the benefits of GM. They discovered a genetic switch - a promoter - that turns on genes in the nectary, where the plant secretes nectar. By adding the extra genes for the new proteins at a point where they would be activated by the nectary promoter, the scientists believe that only the nectar, and not other parts of the plant, would produce the added proteins.

They are working with a genetically engineered petunia that should produce part of a protein that appears on the "coat" of the parvovirus, which causes disease in dogs. Exposing the dogs to that protein should lead to an immune response to the full virus. "Dogs would either eat the honey as an oral vaccine or the vaccine would be purified and injected," Dr Creemers suggests.

The team is using bumblebees, and keeping the plants in greenhouses so that the bees will concentrate the vaccine and both minimise the chance of introducing nectar from outside plants, and of cross-pollinating them if the petunia pollen is genetically modified.

They hope to have the first honey from their GM pentunias in a year's time. Because parvovirus is specific to dogs, the testing phase would be much shorter than if they were using a protein for a human vaccine or drug - though the potential commercial benefits of the latter would be huge and are a likely target for later work.

The pressure group Friends of the Earth says that the research is still in its early stages: "We would want to look at studies on the long-term effect on bees. Also, if they are using bumblebees, they produce less honey than honey bees, so can this be a commercial project in the long run?"

The plan to use GM to produce vaccines is not new: there are already research projects under way in Britain and the US to develop GM bananas and other fruit which would also produce vaccines and drugs as part of the fruit. Similarly, GM sheep are producing human proteins in their milk which could be used to treat people with cystic fibrosis. The problems in all three systems are the dual ones of purity - ensuring that the proteins are made in the right form - and ensuring that patients get the right amount of drugs. Even with GM bananas, people would not be allowed to eat unlimited amounts: it would be the equivalent of letting them eat medicines.