Disease resistant bull cloned at Texas A&M

IN A GROUNDBREAKING procedure, researchers at Texas A&M University have successfully cloned what is believed to be the first animal specifically cloned for disease resistance.

The month-old calf was cloned using cells that were frozen for 15 years, representing the longest time ever that genetic material has been maintained by cryopreservation, thawed and then successfully used in cloning.

The calf, named 862 (86 Squared) due to his exponential genetic potential, was born three years after the death of Bull 86, his genetic donor.

After testing hundreds of cattle, Bull 86, was found to be naturally disease-resistant to brucellosis and, under laboratory conditions, resistant to tuberculosis and salmonellosis - all serious diseases in veterinary and human health. Until Bull 86 was no longer able to breed, he was extensively studied as part of a breeding research program conducted by Drs. Garry Adams and Joe Templeton from the Texas Agricultural Experiment Station and College of Veterinary Medicine at Texas A&M University.

In 1985, cells from the tip of Bull 86's ear were frozen for future genetic study. Fifteen years later, Drs. Taeyoung Shin and Mark Westhusin, also from the Experiment Station and the College of Veterinary Medicine, were able to clone Bull 86. A DNA analysis showed that Bull 862 is a genetic clone of Bull 86.

Brucellosis, tuberculosis and salmonellosis are infectious bacterial diseases that can be transmitted from one herd to another and even to humans. Although nearly eradicated in the United States and Canada, brucellosis and tuberculosis are widespread elsewhere in the world and could find their way back into U.S. herds.

"The impact of cloning disease-resistant cattle is potentially monumental," Adams said. "For example, in countries where they are unable to pasteurize milk to kill the bacteria or process meat appropriately, breeding disease-resistant cows could greatly contribute to a safer food supply, especially pre-harvest. The potential to combine natural disease resistance with the outstanding production traits of U.S. cattle increases the market value of our cattle in the world market."

"Brucellosis and tuberculosis are prevalent in Mexico and could easily be brought into the United States by stray cattle that swim across the Rio Grand River, or by any of the approximately 1 million cattle that are imported annually from our neighbors under the NAFTA treaty," said Templeton. "That's why the potential to purposefully breed this natural resistance into cattle will be an important addition to current disease control methods which have not been 100 perfect effective in the United States and abroad."

Vaccinations, testing, quarantine, and even destroying infected herds has not resulted in the worldwide eradication of these diseases.

"This research will benefit ranchers in many countries who cannot afford to vaccinate or test their herds for these diseases. Unprotected cattle are a potential reservoir for re-infection in the United States and specifically in Texas since most imports pass through Texas," said Templeton.

Once a single infected cow is imported, the disease will be re-introduced and will spread.

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