Scientists at Hematech (Sioux Falls, SD) have genetically engineered a dozen "prion-protein-knockout" cows to be free from the proteins that cause bovine spongiform encephalopathy (BSE), or mad cow disease. Prion protein is a natural cellular protein that can become misfolded into infectious particles and cause BSE and a lethal variant of Creutzfeldt-Jakob disease (vCJD) in humans. Healthy prion-protein-free calves should be useful in investigating the function of normal cellular prion protein and the nature of prion diseases. Additionally, the cows should be useful as a source of prion-protein-free products.

Symptoms of BSE can take as long as two years to diagnose; the Hematech team expects key results later this year from calves injected with BSE. The experiment does not aim to produce new disease-resistant herds, rather, to develop medical procedures and medicines for people infected with brain-wasting conditions thought to be caused by misfolded prions.

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