Current tests to identify specific strains of infectious prions, which cause a range of transmissible diseases (such as mad cow) in animals and humans, can take anywhere from six months to a year to yield results – a time-lag that may put human populations at risk. Now, a group of scientists from The Scripps Research Institute's Florida campus have developed a new method that cuts this critical time lag by several months. The new research was published in the open-access journal PLoS ONE on May 29.
"Because some prion strains are pathogenic for humans and some are not, it's vital that we know the difference when we find them in the field and when we study them in the laboratory," said Corinne Lasmézas, a professor in the Department of Infectology at Scripps Florida who led the study. "Currently, the identification process for mouse-adapted strains takes between six and eight months and can take as long as a year, depending on the strain. Our accelerated method reduces that time to around four months."
The new method for distinguishing among various strains combines a transgenic mouse model with a rapid and sensitive cell-based procedure, the Cell Panel Assay developed by Scripps Florida's Charles Weissmann (chair of the Department of Infectology) and Sukhvir Mahal (senior staff scientist), also investigators on the new study.
"There are about 20 prion strains known in mouse models," Lasmézas said. "We still don't understand what determines the difference among strains even though it's very important, especially for any potential therapeutic development. Our new method should help quicken the pace of research."
Prion diseases, also called spongiform encephalopathies, are a group of closely related, fatal neurodegenerative disorders that affect mammals, including cows, sheep and deer, as well as humans. Different strains of the infectious agent, called a prion, cause mad cow disease, chronic wasting disease, and different forms of scrapie and human Creutzfeldt-Jacob disease.
Mad cow disease has had devastating consequences for bovine livestock populations, particularly in Europe, and for humans who have consumed contaminated beef products.
To date, there have been more than 200 recorded human fatalities worldwide due to mad cow disease. Creutzfeldt-Jacob disease, a low-incidence but always fatal disease, affects humans in all countries.
Prions consist mainly or entirely of an abnormal form of a normal cellular protein. They multiply by converting their normal counterparts into a likeness of themselves, which may aggregate to form deposits called amyloid. Accumulation of different kinds of amyloid plays a role in a wide range of neurodegenerative diseases, including Alzheimer's and Parkinson's diseases.
