By Patricia Reaney

LONDON, Sep 08 (Reuters) - An apple a day may keep more than just the doctor away if British scientists have their way. They are working on ways to inject a peptide--a fragment of a protein--into the fruit. The peptide blocks the bacterium Streptococcus mutans, which causes tooth decay, so that cavities and painful visits to the dentist could become a thing of the past.

Researchers at Guys Hospital in London have already isolated a gene and the peptide that prevents the bacterium from sticking to the teeth.

Professor David James, a plant biotechnologist at the Horticulture Research International in southern England, is trying to find ways to deliver the peptide into the mouth through apples or strawberries.

Although they are still some years away, he and his colleagues hope that by incorporating it into fruit it can be delivered into the mouth where it will cover the receptor sites that accept the bacteria and block its action to stop tooth decay.

"It's very novel strategy and it has much wider implications in other diseases besides tooth decay," James told a news conference.

"Instead of killing bacteria, as you would with antibiotics, you identify receptors on the bacteria you are targeting, and then produce a peptide or protein to prevent the bacteria sticking to the sites it normally sticks to," he said.

The technique, if it is successful, will not only help to fight tooth decay but will encourage people to eat more fruit in line with government recommendations for a healthy diet.

Another possibility is to derive commercial products from the peptide, such as a mouthwash, but they would probably be regarded as pharmaceutical products, which need appropriate regulation and testing.

Scientists know that if the compound is applied as an extract and painted on teeth it can last up to 80 days. James and his team still do not know how much of the peptide is needed for it to be effective or how much will be delivered in the fruit.

"To get the right amounts we need (in the fruit) is one of our big targets for the future," he explained.

"We hope that in the future we will be able to get fruit tissues to produce specific 'magic bullets' like this to counteract human diseases by the relatively simple process of eating controlled amounts of them," he said.

(From Reuters Health)