When sprayed into the air, prions that cause mad cow and other neurodegenerative diseases may be in one of their most lethal forms.
A new study has revealed one short exposure to sprayed prions can be 100 percent lethal in mice. While the discovery doesn’t present any foreseeable public health threat, it comes as a surprise to scientists who study prion-based diseases and calls existing safety rules for laboratories and slaughterhouses into question.
“Common knowledge is that prions aren’t airborne, and can’t cause infection that way,” said neuropathologist Adriano Aguzzi of University Hospital Zurich, co-author of a study appearing today in PLoS Pathogens. “We were totally surprised and also a bit frightened at how efficient [airborne infections] were.”
Most infectious diseases are spread by bacteria or viruses, which use genes to copy themselves. But prions are a third form of disease discovered in 1982, and they’re made only of misfolded proteins. The molecules resemble regular proteins found in the brain cells and other nervous tissues, but their abnormal shape converts healthy proteins into long fibrils that ultimately kill cells.
Like a chain reaction, fibrils create more prions until the host dies from destroyed brain and nervous tissue. All prion infections are 100 percent fatal, and symptoms appear suddenly months or years after infection.
“Prions are like an enemy within, the alien in some B-movie that transforms people to an evil version,” said prion biologist Edward Hoover of Colorado State University, who was not involved in the study. “The immune system doesn’t see them coming.”
Five known human prion diseases exist, including Creutzfeldt-Jakob disease, as well as six non-human diseases, including scrapie, chronic wasting disease and mad cow disease (which sometimes jumps to humans through contaminated meat)....
“My real hope in studying prions is apply what I learn to much more common but similar diseases, such as Alzheimer’s,” Aguzzi said. “Knowing why aggregated proteins damage neurons will allow us to understand how they affect brain function.”
via Airborne Prions Make for 100 Percent Lethal Whiff | Wired Science | Wired.com.