Featured Research

from universities, journals, and other organizations

New Tests Identify Lethal Prion Strains Quickly And Accurately

Date:
December 12, 2007
Source:
Scripps Research Institute
Summary:
Scientists have developed two new tests for prions, infectious proteins that cause a number of diseases including "mad cow disease," and a human counterpart, variant Creutzfeldt-Jakob disease. These advances open the door to better understanding and diagnosis of these troubling conditions.

This micrograph of brain tissue reveals the cytoarchitectural histopathologic changes found in bovine spongiform encephalopathy. The presence of vacuoles, i.e. microscopic "holes" in the gray matter, gives the brain of BSE-affected cows a sponge-like appearance when tissue sections are examined in the lab.
Credit: Dr. Al Jenny

Scientists have developed two new tests for prions, infectious proteins that cause a number of diseases including "mad cow disease," and a human counterpart, variant Creutzfeldt-Jakob disease. These advances open the door to better understanding and diagnosis of these troubling conditions.

Related Articles


One of the new in vitro tests, called the Standard Scrapie Cell Assay, measures prion infectivity levels in a highly accurate and extremely rapid way, producing results in less than two weeks. The second test, called the Cell Panel Assay, allows researchers to quickly distinguish between several prion strains in various cells lines. Using the new assays, the scientists were able to show that four different cell lines exhibited widely different responses to four different strains of the infectious protein particles.

"These new assays vastly accelerate the measurement of prion infectivity and the determination of those cell lines that are able to sustain high infection rates of some prion strains," said Sukhvir P. Mahal, an author of the study who is a senior staff scientist in the laboratory of Charles Weissmann, chair of the Scripps Florida Department of Infectology. "The current test, which takes anywhere from 150 to 250 days and involves large numbers of laboratory mice, is slow, imprecise, and expensive. Our new assays will replace the current mouse brain-bioassays."

The current method of measurement and identification involves injecting a prion-containing sample into the brains of mice and then waiting to see how long it takes for the animals to succumb to disease; the higher the prion level, the less time it takes for them to become lethally infected.

In contrast, the new Standard Scrapie Cell Assay is based on prion-susceptible cell lines. In the test, cells are exposed to prions and then the infected cells are identified and counted using automated imaging equipment.

A Unique Pathogen

Prions (the name stands for proteinaceous infectious particles) are unique infectious pathogens associated with some 15 different diseases, including Bovine Spongiform Encephalopathy ("mad cow") and its rare human form, variant Creutzfeldt-Jacob disease. Infectious prions, which are thought to consist mainly of an abnormally structured or misfolded protein, have the ability to reproduce, despite the fact that they contain no nucleic acid genome as do viruses or bacteria.

Mammalian cells normally produce what is known as cellular prion protein; during infection, the abnormal protein converts production of normal host prion protein to its infectious form. The full details of this process are still not understood.

Prions develop in distinct strains, initially characterized by incubation time and the pattern of brain damage that develops during infection. It is currently thought that strain-specific properties of prions are determined by the three-dimensional structure of the misfolded protein, although the amino acid sequence remains the same. During infection with a single type of prion, several different prion strains can be propagated indefinitely in a single host.

"Some cell lines can be persistently infected by prions and show preference for certain strains," Mahal said. "One intriguing finding of our new study is that a cell line's ability to replicate a particular prion strain is a trait that varies significantly among the members of the cell population-even sibling cell lines may show different relative susceptibilities to various prion strains."

This suggests that the capacity of a cell line to replicate a particular prion strain is controlled epigenetically without any changes to the DNA sequence, she said.

Another fascinating question raised by the study is how cells come to distinguish between prion strains; that is, between the various proteins that differ only in the way they are folded. The exact nature of that recognition process is now the target of a new Scripps Research study using the Cell Panel Assay.

The research is being published in an advanced online edition of the Proceedings of the National Academy of Sciences the week of December 3, 2007.

Other authors of the study, Prion Strain Discrimination In Cell Culture: The Cell Panel Assay, include Christopher A. Baker, Cheryl A. Demczyk, Emery W. Smith, and Charles Weissmann of the Department of Infectology, Scripps Florida; and Christian Julius of the Institute of Neuropathology, University Hospital of Zόrich, Zόrich, Switzerland.

The study was supported by The Scripps Research Institute and the Alafi Family Foundation.


Story Source:

The above story is based on materials provided by Scripps Research Institute. Note: Materials may be edited for content and length.


Cite This Page:

Scripps Research Institute. "New Tests Identify Lethal Prion Strains Quickly And Accurately." ScienceDaily. ScienceDaily, 12 December 2007. <www.sciencedaily.com/releases/2007/12/071204154723.htm>.
Scripps Research Institute. (2007, December 12). New Tests Identify Lethal Prion Strains Quickly And Accurately. ScienceDaily. Retrieved November 22, 2014 from www.sciencedaily.com/releases/2007/12/071204154723.htm
Scripps Research Institute. "New Tests Identify Lethal Prion Strains Quickly And Accurately." ScienceDaily. www.sciencedaily.com/releases/2007/12/071204154723.htm (accessed November 22, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, November 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Could Your Genes Be The Reason You're Single?

Could Your Genes Be The Reason You're Single?

Newsy (Nov. 21, 2014) — Researchers in Beijing discovered a gene called 5-HTA1, and carriers are reportedly 20 percent more likely to be single. Video provided by Newsy
Powered by NewsLook.com
Raw: Baby Okapi Born at Houston Zoo

Raw: Baby Okapi Born at Houston Zoo

AP (Nov. 20, 2014) — The Houston Zoo released video of a male baby okapi. Okapis, also known as the "forest giraffe", are native to the Democratic Republic of the Congo in Central Africa. Video is mute from source. (Nov. 20) Video provided by AP
Powered by NewsLook.com
Your Complicated Job Might Keep Your Brain Young

Your Complicated Job Might Keep Your Brain Young

Newsy (Nov. 20, 2014) — Researchers at the University of Edinburgh found the more complex your job is, the sharper your cognitive skills will likely be as you age. Video provided by Newsy
Powered by NewsLook.com
Mysterious Glow Worms Found in the Amazon

Mysterious Glow Worms Found in the Amazon

Buzz60 (Nov. 20, 2014) — Wildlife photographer Jeff Cremer teamed up with entomologist Aaron Pomerantz and others to investigate a predatory glow worm found in the Amazon. Patrick Jones (@Patrick_E_Jones) explains. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins