Chickens are essentially little protein factories, producing a relatively large clump of pure protein in each egg they lay. Proteins are also the basis for many medicines, but synthesizing proteins commercially is difficult and expensive. That’s why researchers in Scotland have genetically modified chickens to produce therapeutic proteins in their eggs, reports Pallab Ghosh at the BBC.
In many human diseases, the main culprit is a protein that is either missing, not produced in sufficient quantities or is manufactured incorrectly by the body. By inserting a protein-producing gene into a chicken, the scientists essentially create a genetically-modified, or transgenic, animal. Armed with this new gene, the chicken’s body produces more of a type of protein it usually doesn’t make, which accumulates in large quantities in the eggs it lays. The egg whites can then be purified to recover the protein, a technique that’s 10 to 100 times cheaper than producing proteins in a factory, the team reports in the journal BMC Biotechnology.
So far, the researchers have used to the technique to produce two proteins, IFNalpha2a, which has strong cancer-fighting properties and macrophage-CSF, which stimulates tissues to repair themselves. Just three eggs are enough to produce a therapeutic dose of the proteins.
As for the chickens, they don’t seem to know they are being used as medical bioreactors and lead relatively cushy lives.
“They live in very large pens. They are fed and watered and looked after on a daily basis by highly trained technicians, and live quite a comfortable life,” lead author Lissa Herron of Roslin Technologies in Edinburgh tells Ghosh. “As far as the chicken knows, it's just laying a normal egg. It doesn't affect its health in any way, it's just chugging away, laying eggs as normal.”
This is not the first time animals have been used to produce drugs. In fact, there is a whole biotech industry called biopharming, in which transgenic plants and animals are used to produce proteins, enzymes and other biological products. Researchers have produced enzymes and proteins in tobacco plants and cow’s milk as well as a commercially available enzyme, Kanuma, that’s produced in chicken eggs. Overall, however, the commercialization process has had technical and regulatory setbacks and has yet to become a major force in medicine.
Study co-author Helen Sang, a molecular biologist at the Roslin Institute, tells CBS New York that this latest method could change that.
“In the past, making these transgenic animals has been very inefficient, very expensive, and difficult. What we’ve done is found a method that makes it a lot faster a lot more efficient,” she says.
But the chicken medicine won’t make into the doctor’s office for a while. It will take 10 to 20 years for the egg-based cures to make their way through the regulatory system and into the pharmacy. In the meantime, however, the research team hopes the technique can be used to make medication for animals, including immune-boosting proteins for farm animals that could help reduce the overuse of antibiotics.