http://bmj.com/cgi/content/full/323/7303/11/a
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News roundup
Scientists discover the prion for BSE in urine
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 (www.jbc.org/cgi/reprint/C100278200v1.pdf).
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.
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