`Scientists said yesterday that they have used genetic engineering techniques to produce the first cattle that may be biologically incapable of getting mad cow disease.
The animals, which lack a gene that is crucial to the disease’s progression, were not designed for use as food. They were created so that human pharmaceuticals can be made in their blood without the danger that those products might get contaminated with the infectious agent that causes mad cow.
[..] In one experiment, tissues from one of the animals’ brains were grown in a culture dish and exposed to two different strains of infectious, mad cow prions. As expected, the bad prions did not propagate, according to a report in yesterday’s online issue of the journal Nature Biotechnology.’