Links Updated: Jan. 2, 2011
Links Updated: Jan. 2, 2011
2001;323:11 (7 July, 2001)
Judy Siegel-Itzkovich, Jerusalem
A urine test can detect the prion that causes bovine spongiform encephalopathy (BSE) in animals and Creutzfeldt-Jakob disease (CJD) in humans, according to Jerusalem researchers who are developing a commercial kit for this purpose. Infected animals and humans can be identified even when asymptomatic. The test might make it possible to save unaffected cows from slaughter when some in a herd have been found to be infected. In addition, it might be possible to identify carriers of the human variant and prevent them from donating blood, while other people could give blood even if they spent time in affected countries.
The discovery that a protease resistant prion isoform can be found in the urine of hamsters, cows, and humans was made by Dr Ruth Gabizon and colleagues in the neurology department of Hadassah University Hospital, Ein Kerem, Jerusalem. Their findings have been published electronically as a "paper in press" in the Journal of Biological Chemistry (June 21, 2001) (PDF File).
The only known component of the prion, PrPSc, has been found mostly in the brains, but not in the blood, of animals and humans infected with prion diseases. But the Israeli researchers have shown that a protease resistant PrP isoform can also be detected in the urine of infected animals and people. Dr Gabizon noted in the journal article that "most important, the PrP isoform was also found in the urine of hamsters inoculated with prions long before the appearance of clinical signs."
The Hadassah team has so far easily identified BSE from urine samples taken from over 50 British cows in which the disease had been diagnosed; the samples had been sent to Israel by the Veterinary Laboratory Agency in the United Kingdom, along with samples from healthy cows. "In the blind test, we quickly picked out the affected animals," Dr Gabizon said. She and her team, under the auspices of Hadassah's research and development arm, Hadassit, will be producing a commercial kit for testing animal and human urine. Although it has not yet been proved that human carriers of CJD can pass the disease on to people via blood transfusions, the possibility has raised much concern. A US Food and Drug Administration advisory committee last week recommended further restrictions on blood donations that some experts said would further cut the number of available blood donors by more than 5% because of people's concern about CJD.
Dr Gabizon said that almost no one had looked at the urine for prions because they thought it did not pass through the kidneys. Working since last September, she and her doctoral student Gideon Shaked were looking for other substances in hamsters' urine and found the tiny prion particles, thus realising that they do not break down in the kidneys.
A decade ago Dr Gabizon worked in the laboratory of Professor Stanley Prusiner, the American discoverer of the prion who recently received the Nobel prize for medicine for this achievement. Since returning to Jerusalem, she has devoted herself to work on prions.
e-Network Forum Editor's Note: In a BBC report (July 6, 2001), scientists in Switzerland claim to have a blood test for variant CJD. Concerns have arisen that fear of a false-positive result may deter healthy persons from donating blood.