New Assay for Creutzfeldt-Jakob Disease

A highly sensitive post-mortem test can more accurately determine if a human death was caused by Creutzfeldt-Jakob disease (CJD), the human version of bovine spongiform encephalopathy (BSE), also known as mad cow disease. The test may be refined in the future to detect the prion disease in living people and animals.

The test, a conformation-dependent immunoassay (CDI), was originally developed to detect various forms of prions in cows, sheep, and other animals. In a new study, researchers found that CDI not only identifies prions in human brain tissue but is faster and far more precise than standard immunologic detection methods, which detect only a small fraction of the infectious prions that may be in the brain. The finding is reported in the March 1, 2005, issue of the Proceedings of the [U.S.] National Academy of Sciences.

In the study, scientists extracted brain tissue from 28 people who had died of CJD and tested these samples using CDI. CDI uses highly specific antibodies that bind to all disease-causing prions in the brain. The scientists also used immunohistochemistry (IHC) to measure only the prion proteins that are resistant to the protease enzyme, which are abnormal and usually infectious. They are exploring the possibility of using CDI in living tissue, such as blood or muscle, to detect and diagnose prion diseases while people or animals are still alive.

The study was conducted by scientists at the University of California, San Francisco (USA), including Stanley B. Prusiner, M.D., who received the 1997 Nobel Prize in physiology or medicine for his discovery of prions. Prions contain no DNA or RNA. These abnormal, misfolded proteins are believed to contribute to other age-related neurologic diseases such as Alzheimer's and Parkinson's diseases. Dr. Prusiner and his colleagues believe that CDI testing might eventually have a role in the diagnosis of these diseases.




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