London - Something to crow about - chickens could soon be at the forefront of the fight against cancer.
British scientists have developed genetically modified chickens capable of laying highly specialised eggs which contain proteins needed to make cancer-fighting drugs.
The breakthrough was announced by the same research centre that gave the world Dolly, the famous cloned sheep.
According to the BBC, scientists at Roslin Institute near Edinburgh, Scotland, have produced five generations of birds able to provide high levels of life-saving proteins in egg whites.
Roslin director Professor Harry Griffin believes flocks of hens will be able to bulk-produce the proteins cheaply, paving the way to huge savings on life-saving drugs.
"The raw material for this production system is quite literally chicken feed," he said.
About 500 modified birds have been bred after 15 years of work by the project's lead scientist, Dr Helen Sang. It could, however, take five years before patient trials get the nod and 10 years until a medicine is fully developed.
Therapeutic proteins such as insulin have long been produced in bacteria. Some complex proteins can, however, only be made in the more sophisticated cells of larger organisms and scientists have successfully made a range of these molecules in the milk of genetically modified sheep, goats, cows and rabbits.
Now chickens are getting their chance. Some have been engineered to lay eggs that contain miR24, a type of antibody with potential for treating malignant melanoma. Yet others produce human interferon b-1a, which can be used to stop viruses replicating in cells.
Interferon is the subject of ongoing research by other scientists (not based at Roslin) in treating relapsing/remitting multiple sclerosis and rheumatoid arthritis.
The National Multiple Sclerosis Society in Britain has shown interest in the research.
Meanwhile, Roslin scientists say the proteins secreted into the whites of the eggs can be easily extracted and purified.
Sang told the BBC that to make a very active protein like interferon, extra-high productivity was required.
"People need large doses of these over long periods. So one of our next challenges is to try to increase the yield in egg white," she said.
Explaining the advantages of chickens for "pharming", Sang said hundreds of birds could be bred from a single cockerel once the correct gene was in place.
Dolly was the first mammal to be cloned from an adult cell. She was euthanased in 2003 after contracting a common lung disease.