Closing In On Goat Scrapie

Toward that end, Agricultural Research Service (ARS) scientists and their collaborators have developed a live-animal test to detect scrapie in goats. Called the rectal mucosa biopsy test (RMBT) or rectal biopsy, the new method involves snipping a tiny piece of lymphoid tissue from the lining of an afflicted animal's rectum. A dab of local anesthetic eases the animal's discomfort, notes microbiologist Katherine O'Rourke with the ARS Animal Diseases Research Unit in Pullman, Wash.

Lymphoid tissue is used because it collects malformed proteins called prions, which are thought to cause scrapie, adds O'Rourke. She's a member of a scrapie research team that includes Washington State University, Colorado State University, the Animal and Plant Health Inspection Service (APHIS), the National Park Service and the Canadian Food Inspection Agency.

Advantages of using the rectal biopsy test method include speed, easier methodology and its generation of a high number of repeat samples from individual animals.

On a related front, ARS Pullman geneticist Stephen White is leading studies to characterize the prion protein gene of goats and identify differences between individual animals and breeds harboring the gene. His team has so far examined the sequences and distribution of alleles—alternative forms of genes—from 446 goats representing 10 breeds, including Alpine, Angora, Boer and Nubian.

The ARS Pullman lab also is collaborating with APHIS to formulate a strategy aimed at helping the U.S. goat industry eliminate scrapie from its herd, which numbers four million head. Hardships imposed by scrapie on America's goat and sheep producers include the physical loss of animals, costs of disposal of carcasses and offal, trade restrictions and diminished domestic and international markets for breeding stock, semen and embryos.