New test for vCJD-type disease2nd February 2009
A blood test to diagnose transmissible spongiform encephelopathies (TSEs) such as mad cow disease, chronic wasting disease, scrapie and CJD is being developed.
The test has already been used to pinpoint elk infected with fatal chronic wasting disease by the research team.
However, in several years, it may be viable as a cheap and effective way of screening for mad cow disease, as well as a related disease called Creutzfeldt-Jakob disease, or CJD, in humans.
All the researchers had to do was examine blood samples for the presence of damaged cells.
Christoph Sensen of the University of Calgary said that his researchers can now take a blood sample from a live animal and look at the DNA patterns in the blood, to predict six months ahead of time whether an animal is infected with chronic wasting disease.
Researchers had previously tried to diagnose such diseases by examining the brain or other organs, which cannot be done until the organism is in an advanced state.
Instead, the finding studied the small pieces of DNA spat out by dying cells, known as circulating nucleic acids, for patterns, and found them three months before the elk's body began to show symptoms.
Each of the three patterns found corresponds with a particular genetic mutation.
TSEs are a class of diseases that destroy the brain, as they take over the structure of tissues.
Mad cow disease, also known as BSE, swept through herds of British dairy cows in the 1980s. Some people were infected after ingesting beef.
However, fewer than 200 people globally have died in this way.
In the US and Canadian west, chronic wasting disease is found in herds of wild elk and deer.
Sensen said that, in studying these diseases, the researchers are looking at the host response to the infection when the disease puts stress on the body, to see what the host does to fend off the attack.
Like mad cow and CJD, the chronic wasting disease found in deer and elk is always fatal, but the animals response to the disease changes its DNA in a way that the researchers are just beginning to study.
Once a blood test is taken, a researcher amplifies DNA samples using PCR, the polymerase chain reaction.
Export markets of cattle and beef would benefit from a reliable test, since every case of BSE shuts down a country's exports of cattle for a time.
Sensen said that they would have to wait four years until an equivalent test is made available for cattle.
Kevin Keough from the Alberta Prion Research Institute said that there is currently no reliable way to tell if an animal may have a prion infection before it becomes obviously sick.
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Title: New test for vCJD-type disease
Author: Luisetta Mudie
Article Id: 10020
Date Added: 2nd Feb 2009