Suffering of the lambs

摘要

The flock of sheep grazing in a field on a farm outside Edinburgh in Scotland looks and behaves just like any other flock of sheep. But these animals are highly, unusual. They belong to PPL Therapeutics, a fledgling biotechnology company, and they have been genetically engineered to secrete in their milk a protein called alpha-1-antitrypsin, which helps to treat cystic fibrosis.