Scientists crack designer eggs

The egg whites will be used for new medication

By BBC science correspondent David Concar

The scientists who made history by producing Dolly the Sheep clone say they are now attempting to create designer chickens whose eggs may help to produce drugs to fight cancer.

By altering the hens' genetic make-up, they want to transform the birds into living pharmaceutical factories.

The drugs in question are complex proteins that may prove effective in treating lung and skin cancer. They have been identified as potential cancer therapies by an American drugs company called Viragen.

At present, though, the company's research is stymied by the fact that it can only make the proteins in tiny quantities and at huge expense. So it has struck a deal with the Roslin Institute in Edinburgh, UK, to develop genetically modified chickens capable of mass-producing the substances in the whites of their eggs.

"This collaborative effort is being undertaken to enable the production of a wide variety of drugs in greater volume and at a fraction of the cost when compared to conventional manufacturing methods," said Viragen's chairman Gerald Smith.

'Valuable proteins'

Modifying the genes of birds is technically challenging. But two years ago, the Edinburgh team discovered how to insert new genes into the embryos of chickens to create GM hens.

The birds they have created so far do not produce anything useful. But the next generation will carry the genes needed to make the anti-cancer proteins, insists Dr Helen Sang of the Roslin Institute. And the ultimate aim, she says, is to create designer birds using the cloning technique used to make Dolly the sheep.

"Technology used to create Dolly has allowed the production of valuable proteins needed for drug development in the milk of mammals," said Dr Sang.

"We now intend to take this technology a step further and develop transgenic chickens to produce eggs rich in protein-based drugs to treat cancer and other serious diseases."

The Roslin team faces stiff commercial competition from rivals in the US. AviGenics of Athens, Georgia, says it already has chickens capable of manufacturing an anti-cancer protein called interferon, while GeneWorks of Ann Arbor, Michigan, claims it has a flock of between 50 and 60 genetically engineered hens. Some carry a gene that enables them to make a human growth factor in their eggs.

Pharmaceutical powerhouse

If things go well for the rival teams, the humble hen's egg will be transformed into a pharmaceutical powerhouse manufacturing life-saving drugs to order.

But already there are concerns about the same technology being used to create GM chickens for the dinner table.

The announcement was given a cautious welcome by the Church of Scotland. Dr Donald Bruce, director of its Society, Religion and Technology Project, warned animals should not be mistreated.

"We support the general aim of Roslin's research into antibody production using chicken eggs," said Dr Bruce.

"Care must be taken, however, that it does not pose undue animal welfare problems and that human safety implications are fully addressed."