Identifying Variation in the U.S. Bovine Prion Gene

Do genes affect bovine spongiform encephalopathy—also known as BSE, or "mad cow" disease? Are some cattle more susceptible than others?

To address these and other questions, Agricultural Research Service (ARS) scientists at the U.S. Meat Animal Research Center in Clay Center, Neb., have sequenced the bovine prion gene (PRNP) in 192 cattle that represent 16 beef and five dairy breeds common in the United States.

This work, partially funded by a grant from the U.S. Department of Agriculture's Cooperative State Research, Education and Extension Service, is expanding the understanding of how the disease works.

BSE is a fatal neurological disorder characterized by prions—proteins that occur naturally in mammals—that fold irregularly. Molecular biologist Mike Clawson and his Clay Center colleagues are examining PRNP variation in order to learn if and how prions correlate with BSE susceptibility.

From the 192 PRNP sequences, Clawson and his colleagues have identified 388 variations, or polymorphisms, 287 of which were previously unknown. Some of these polymorphisms may influence BSE susceptibility in cattle.

Comparing PRNP sequences from infected and healthy cattle may enable researchers to identify genetic markers in the prion gene that predict BSE susceptibility. In addition to PRNP, the team is currently sequencing several closely related genes, which will also be tested for their association with BSE.

The prevalence of BSE in the United States is extremely low, but this research could improve understanding of the disease and prepare the cattle industry to respond if another prion disease should arise in the future.

Read more about this research in the January 2007 issue of Agricultural Research magazine.

ARS is the USDA's chief scientific research agency.