dozen calves that don't have prions - the infectious proteins that cause mad cow disease. The research project is reported in the online journal Nature Biotechnology. Preliminary tests suggest that the brains of the genetically engineered calves are immune to Bovine Spongiform Encephalopathy (BSE, or mad cow disease). The scientists verified this by trying to infect post mortem brain tissue from two of the 20-month old calves with prions, but the tissue remained healthy. This follows a long process using donor cattle cells in which the gene known to trigger the production of prions was "switched off". The cells were...
