A CLONED goat fetus in a Texas lab is raising hopes of one day producing herds of genetically modified cattle that are immune to BSE. Researchers at Texas A&M University and Howard Hughes Medical Institute in New York genetically modified the fetus to be almost completely lacking in prions, the proteins which in their rogue form cause BSE in cattle and scrapie in sheep.
Animals that cannot produce normal prions are resistant to BSE-like diseases. 鈥淜nockout鈥� mice can be created with a non-functioning prion gene, but attempts to make knockout versions of larger animals have failed.
So Mark Westhusin and his colleagues turned to a technique called RNA interference. Using a virus, they introduced into a goat鈥檚 skin cell a double-stranded piece of RNA containing the instructions needed to make prions. The RNA targets the normal, single-stranded form of RNA, and destroys it. They then cloned the skin cell to create what they call a 鈥渒nockdown鈥� transgenic fetus incapable of making prions, which should therefore be resistant to BSE-like disease (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0600813103). The researchers say the method should also work for cows.
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