Prions can't hide now

Sep 21, 2012

The world is one step closer to a noninvasive screening for prion-caused infections like BSE.

Researchers at the University of Melbourne in Australia have recently identified tells of prion diseases like BSE which can be detected in the blood of infected animals. This discovery could pave the way for a blood test screening for prion-caused neurological disorders in humans, and perhaps animals, too. Such a possibility could replace current invasive and/or lethal detection methods for animals suspected to carry prion-caused neurological disorders.

The study—conducted by professors Shayne Bellingham, Bradley Coleman and Andrew Hill and published in the Oxford Journals’ Nucleic Acid Research—built on prior research and understanding regarding exosomes. It found that the exosomes of prion-affected cells could be detected in the bloodstream of mice and primates infected with prion diseases. For more information on exosomes, see below under the “more information” heading.

The official statement from the University of Melbourne on the subject of the study hailed the discovery as placing diagnostic tests for neurological disorders in humans, like Creutzfeldt- Jakob Disease (CJD), on the horizon.

Hill, one of the primary researchers on the study, spoke of the possibility as a boon to anyone who lived in the UK during the first outbreak of BSE as well as the blood banks of the world.

“This might provide a way to screen people who have spent time in the UK, who currently face restrictions on their ability to donate blood,” he said.

“With a simple blood test, nurses could deem a prospective donor’s blood as healthy, with the potential to significantly boost critical blood stocks.”

Anyone who lived in the UK during the suspicious years of 1980-1996 is banned from giving blood in most developed countries. Over 200 deaths in the UK in the 1990s are credited to consumption of BSE-tainted beef and cattle products.

Variant-CJD in humans has been tied to consumption of BSE-tainted beef products.

But the findings have important potential for agriculture, too. Supposing a screening process could be developed via blood test for BSE, scrapie in sheep and chronic wasting disease in deer and other cervids, the economic benefit could be spectacular.

Current tests for BSE involve the post-mortem analyses of brain tissue of suspect cattle. There exists no test to detect the disease in live cattle or in muscle tissues. In sheep suspected of scrapie—a prion-caused neurodegenerative disease similar to BSE—there are a couple live-animal testing options, including third eyelid and rectal biopsies which gather lymphoid tissues. Both tests, however, must be conducted under local anesthetics.

More information

Very simply put, exosomes are tiny packets of information released by cells. They carry unique markers which can be used to identify the type or status of the cell which created them. These identifying markers can be anything from active proteins to actual genetic material from the creator cell. In the case of exosomes and prions, it appears the exosomes can even spread the misfolded proteins that are the infectious prion.

Much is still unknown about exosomes as they are a relatively recent scientific discovery. That said, identification of the unique genetic markers in exosomes from some forms of cancer cells has been demonstrated as a possible means of cancer screening. The researchers concluded the same could be true of the neurological disorders caused by prions.

“In summary, our results strongly support the hypothesis that exosomes released from prion-infected neuronal cells have a distinct miRNA signature that may be utilized for the identification of prion infection.”

Additionally, the discussion portion of the study suggested, “This research also has potential diagnostic implications for other neurodegenerative diseases in which exosomes have been identified to play a role including Alzheimer’s disease, amyotrophic lateral sclerosis and Parkinson’s disease.” — Kerry Halladay, WLJ Editor