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Anti-cancer chicken eggs produced Anti-cancer chicken eggs produced
(30 minutes later)
UK scientists have developed genetically modified chickens capable of laying eggs containing proteins needed to make cancer-fighting drugs.UK scientists have developed genetically modified chickens capable of laying eggs containing proteins needed to make cancer-fighting drugs.
The breakthrough has been announced by the same research centre that created the cloned sheep, Dolly.The breakthrough has been announced by the same research centre that created the cloned sheep, Dolly.
The Roslin Institute, near Edinburgh, says it has produced five generations of birds that can produce useful levels of life-saving proteins in their eggs.The Roslin Institute, near Edinburgh, says it has produced five generations of birds that can produce useful levels of life-saving proteins in their eggs.
The work could lead to a range of drugs that are cheaper and easier to make.The work could lead to a range of drugs that are cheaper and easier to make.
Professor Harry Griffin, director of the institute, said: "One of the characteristics of lots of medical treatments these days is that they're very expensive. Professor Harry Griffin, director of the institute, told the BBC: "One of the characteristics of lots of medical treatments these days is that they're very expensive.
"The idea of producing the proteins involved in treatments of flocks of laying hens means they can produce in bulk, they can produce cheaply and indeed the raw material for this production system is quite literally chicken feed.""The idea of producing the proteins involved in treatments of flocks of laying hens means they can produce in bulk, they can produce cheaply and indeed the raw material for this production system is quite literally chicken feed."
BBC medical correspondent Fergus Walsh told BBC News 24 that the scientists, who have bred 500 birds, had been working on the project for seven years. Roslin has bred some 500 modified birds. Their existence is the result of more than 15 years' work by the lead scientist on the project, Dr Helen Sang.
But it could be another five years before patient trials get the go-ahead and 10 years until a medicine is fully developed, the Roslin Institute said.
'10-year wait''10-year wait'
But it could be another five years before patient trials get the go-ahead and 10 years until a medicine is fully developed, he said. Therapeutic proteins such as insulin have long been produced in bacteria; but there are some complex proteins that can only be made in the more sophisticated cells of larger organisms.
Although proteins have been developed in the egg whites, researchers do not yet know whether the resulting drugs would work in practice. Scientists have successfully made these in the milk of genetically modified sheep, goats, cows and rabbits.
In June 2005 the scientists announced that designer chickens whose eggs contain large amounts of cancer-fighting proteins could become a commercial reality. The work at Roslin shows it is now possible to use chickens as "biofactories", too.
At the time, researchers at Roslin - where Dolly the Sheep - the first mammal cloned from an adult cell was created - said they had produced a version of an antibody designed to treat malignant skin cancer. Some of the birds have been engineered to lay eggs that contain miR24, a type of antibody with potential for treating malignant melanoma, or skin cancer. Others produce human interferon b-1a, which can be used to stop viruses replicating in cells.
Egg production of three other protein drugs had also been studied. The proteins are secreted into the whites of the eggs. It is a fairly straightforward process then to extract and purify them.
During the process, human genes are added to the chickens' DNA enabling them to produce complex proteins. Dr Sang said the team was highly encouraged by the level of the birds' productivity, but further improvements were required.
These are then secreted into the whites of the eggs and can be used to create medicines. "We're probably getting a high enough productivity if you want to make a very active protein like interferon, but not enough yet if you want to make an antibody because 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 told BBC News.
The Avian Transgenic Manufacturing project is a joint venture between the Roslin Institute, biotechnology firm Viragen and the British biotech company Oxford BioMedica.The Avian Transgenic Manufacturing project is a joint venture between the Roslin Institute, biotechnology firm Viragen and the British biotech company Oxford BioMedica.
The latest research work is to be published this week in the US journal Proceedings of the National Academy of Sciences.