Scientists trying to develop

cattle resistant to mad cow

BLACKSBURG, Va. (AP) – Scientists looking for a surefire way to stop mad cow disease are trying to clone cattle that are genetically engineered to resist the deadly brain-wasting illness.

The Biotechnology Industry Organization, a Washington trade group, says at least three research teams are trying to produce clones. One of those, a team in Korea, announced last month the birth of four “mad cow-proof” calves.

At Virginia Tech University, Will Eyestone and William Huckle say they are hoping for success soon, too.

“If all goes well, we’re looking to have a cloned cow born later this year or early next year,” Eyestone said.

Using such a tricky and expensive method to protect the beef of the future doesn’t seem very practical, beef industry and consumer advocates say. Still, there is interest in the effort.

“We’re not in support of cloning cattle,” said James “Bo” Reagan, of the National Cattlemen’s Beef Association in Denver. “But the more knowledge we have on any subject, the better off we’ll be on making decisions.”

The Food and Drug Administration has not approved beef from cloned cattle or their offspring for food. Even if it does get FDA approval someday, Reagan said ranchers probably wouldn’t rush to buy genetically engineered cows. Mad cow disease remains a small threat for American beef, he said, and a herd of genetically engineered animals would cost a fortune.

But if mad cow disease became a serious threat “and we felt like there was a high risk, then yeah – there would be a lot of people interested,” he said.

Jean Halloran, director of the Consumer Policy Institute in New York, said some consumers would be open to the idea of buying cloned meat that’s being promoted as “mad cow-proof.” But she said doing so seems like overkill.

“This is a profoundly wrongheaded approach to the problem,” she said of the cloning research. “Especially when there’s a much easier solution, which is that you stop feeding contaminated feed to animals that they weren’t meant to have in the first place. Cows are vegetarians.”

Eyestone and Huckle said they started working on cloning calves about two years ago in hopes of learning more about prions, the twisted proteins blamed for several types of brain-wasting disease in people and animals.

The rogue prions that cause mad cow disease, formally known as bovine spongiform encephalopathy (BSE), can withstand ultraviolet light, ionizing radiation, sterilizing temperatures and chemical disinfectants.

As they work through the body, the prions infect normal prion proteins, causing them to misfold and infect other proteins, eventually creating tiny sponge-like holes in the brain. Infected animals wobble and slobber; people with the human form of the disease also lose muscle control and suffer from dementia before dying.

Cattle are thought to get BSE from eating feed that contains prion-contaminated meal made from other cows. Such feed was banned in 1997. Scientists believe people can get the human form of the disease by eating processed beef products containing spinal or nervous system tissue from a BSE-infected cow.

The Korean researchers who reported success at cloning BSE-resistant calves reported in the journal Nature that their animals were genetically engineered to produce prion proteins that resist being converted into the pathogenic form.

The Virginia Tech researchers are taking a different approach – attempting to remove the DNA in cow cells that code for prion proteins. The remaining DNA will be used to clone calves that will be unable to produce the proteins, cutting them off from the disease altogether.

The researchers say they’re not sure how their calves will function without these proteins. Mice already have been cloned without the prion proteins, Huckle said, and they had side effects, including insomnia.

The two men, who have a $300,000 National Institutes of Health grant, say they hope to clone one male and one female calf.

“We hope this will serve as an example of how genetic modification and cloning might be used for disease resistance in livestock,” Eyestone said. “It may provide an alternative way to dealing with diseases over and above the classical vaccinations.”

AP-ES-01-21-04 0146EST

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