Researchers Find Better TSE Test

Agricultural Research Service scientists have added a new tool they can use to study the development and spread of transmissible spongiform encephalopathies or TSE. This deadly group of diseases can develop in a range of mammals, including humans. A TSE can only be definitely diagnosed after an animal has died.

During the diagnosis, researchers typically check tissues for abnormal proteins called prions. But the present procedure has its challenges. The new procedure, developed at the ARS National Animal Disease Center in Ames, Iowa, lets researchers extract and identify abnormal prions in formalin-fixed tissue using a combination of mild detergent, a series of freeze-boil cycles, and enzyme digestion.

Initial results indicate the accuracy of this method begins to decline two years after the tissue is first preserved, and is completely lost at the end of six years. So, the researchers looked again at the Western blotting test already in use. They found that if they fix the tissues in formalin and then preserve it in paraffin, their results equaled—and at times even exceeded--the effectiveness of Western blotting analysis for tissues that had only been fixed in formalin.