HEADLINES:
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R/£ Breeding breakthroughproducesmad cowresistant cattle
January 02, 2007 Edition 1
WASHINGTON: US and Japanese scientists reported on Sunday that they had used genetic engineering to produce cattle that resist mad cow disease.
They hope the cattle can be the source of herds that can provide dairy products, gelatin and other products free of the brain-destroying disease, also known as bovine spongiform encephalopathy or BSE.
Writing in the journal Nature Biotechnology, the researchers said their cattle were healthy at the age of 20 months, and sperm from the males made normal embryos that were used to impregnate cows, although it is not certain yet that they could breed normally.
The cattle lack the nervous system prions, a type of protein, that cause BSE and other related diseases such as scrapie in sheep and Creutzfeldt-Jakob disease, known as CJD, in humans, the researchers said.
"(Prion-protein-negative) cattle could be a preferred source of a wide variety of bovine-derived products that have been extensively used in biotechnology, such as milk, gelatin, collagen, serum and plasma," they wrote.
Yoshimi Kuroiwa, of Kirin Brewery Company in Tokyo, and colleagues made the cattle, known as "knockouts" because a specific gene has been "knocked" out of them, using a method they call gene targeting.
"By knocking out the prion protein gene and producing healthy calves, our team has successfully demonstrated that normal cellular prion protein is not necessary for the normal development and survival of cattle. The cows are now nearly two years old and are completely healthy," said James Robl, of Hematech, a South Dakota subsidiary of Kirin.
BSE swept through British beef herds in the 1980s and people began developing an odd, early-onset form of CJD called variant CJD, or vCJD, a few years later. CJD normally affects one in a million people globally, usually the elderly.
There is no cure and it is always fatal. - Reuters
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