Researchers create, evaluate prion-free cattle

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The Department of Agriculture's Agricultural Research Service has announced initial results of research involving prion-deficient cattle.

Animals naturally produce the prion protein, but an abnormal form of prion causes transmissible spongiform encephalopathies in many species. Prion-deficient cattle might be a useful model for research and could provide industrial bovine products free of the protein.

Hematech Inc., a pharmaceutical research company in Sioux Falls, S.D., genetically engineered eight Holstein males in which prion production is disrupted. Dr. Jürgen Richt of the ARS National Animal Disease Center in Ames, Iowa, led an evaluation of the cattle that revealed no apparent developmental abnormalities by 20 months of age.

Scientists at ARS, Hematech, and the University of Texas evaluated the cattle via careful observation, necropsies of two animals, and assessment for abnormal proteins. Further tests will take at least three years to complete.

The evaluation appeared in the January issue of the journal Nature Biotechnology, online at

In early 2006, a group of scientists from Texas A&M University College of Veterinary Medicine and Biomedical Sciences and Howard Hughes Medical Institute reported genetically engineering a prion-deficient goat fetus. Other studies have focused on the disruption of prion production in mice, a species that does not naturally contract prion diseases.