Chicken eggs could be source of drugs: First genetically engineered cockerel raises hopes for cheap medicine

HENS that lay eggs full of valuable drugs could soon be a reality now that scientists have created the world's first genetically engineered cockerel by gene injection.

The financial possibilities of Aesop's goose, which laid golden eggs, pale into insignificance compared with the prospect of hens that can lay eggs rich in the most expensive pharmaceutical proteins.

Scientists at the Roslin research institute near Edinburgh have successfully injected 'foreign' genes into a cockerel that has since fathered several transgenic chicks carrying the same genetic material.

They believe the results show that the genetic injection technique will work with genes for valuable human proteins used in medicine, such as the blood clotting factors needed by haemophiliacs or tissue plasminogen activator, an expensive drug used to unblock arteries.

The cockerel, known by the experimental code name of Lys8-1, was one of a batch of 128 fertilised eggs that were subjected to the gene injection technique. The others either died before hatching or were shown not to carry the foreign gene.

Margaret Perry and Helen Sang, researchers at the Agricultural and Food Research Council's animal physiology and genetics institute at Roslin, created transgenic poultry by using 'surrogate' egg shells.

They took the yolks of fertilised eggs before they were laid and inserted them into the shells of other yolk-less eggs in an incubator. The researchers were able to inject the foreign genes into the yolk cells before they divided for the first time, thereby increasing the chances of producing transgenic adults that will pass on the new genes to their offspring.

The scientists can mate the genetically engineered cockerel with many hens, producing transgenic chicks that can be cross-bred with each other to produce pure-breeding strains of transgenic animals.

The next stage is to attempt to insert a gene for a useful human protein needed in medicine. Scientists hope to create hens that can lay eggs loaded with sufficient quantities of valuable drugs for their recovery to be commercially viable.

Dr Sang said yesterday that such a prospect could become reality in a few years' time.

(Photograph omitted)