December 14, 2010

US researchers develop faster testing methods for prion diseases

Researchers at NIH's National Institute of Allergy and Infectious Diseases (NIAID) in the US have developed a highly sensitive and rapid new method to detect and measure prions, which are responsible for causing brain conditions such as BSE in cattle and Creutzfeldt-Jakob disease in humans.

Prion diseases are primarily brain-damaging conditions also known as transmissible spongiform encephalopathies. They are difficult to diagnose, untreatable and ultimately fatal.

Currently available diagnostic tests lack the sensitivity, speed, or quantitative capabilities required for many important applications in medicine, agriculture, wildlife biology, and research. Because prion infections can be present for decades before disease symptoms appear, a better test might create the possibility for early treatment to stop the spread of disease and prevent death.

Through a blending of previous test concepts, the NIAID group has created the development of a new prion-detection method, called real-time quaking induced conversion assay, or RT-QuIC. Byron Caughey, Ph.D., led the study at NIAID's Rocky Mountain Laboratories in Hamilton, Montana, US.

The new assay can detect when miniscule amounts of infectious prions initiate the conversion of large amounts of normal prion protein into an abnormal form in test-tube reactions. By comparing the extent to which different samples can be diluted and still initiate conversion, scientists can estimate the relative infectious concentrations in the original samples.

In their study, the NIAID scientists used RT-QuIC to detect prion infections in deer known to have chronic wasting disease and sheep known to have scrapie. In scrapie-infected hamsters, they found surprisingly high levels of prions in nasal fluids, pointing to such fluids as possible sources of contagion in various prion diseases.

Along with optimizing their existing applications in the laboratory, Dr. Caughey and his colleagues are teaming up with a number of other laboratories around the world to extend the practical and scientific applications of RT-QuIC. Related testing approaches might also aid the diagnoses of similar neurodegenerative protein diseases, such as Alzheimer's, Huntington's, and Parkinson's diseases.