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US scientists develop a possible test for BSE

Scott Gottlieb New York

A group of US agricultural scientists have developed a laboratory assay that might lead to the creation of a cheap diagnostic blood test for transmissible spongiform encephalopathies, including bovine spongiform encephalopathy.

The test, developed by private and government researchers working at the US Agricultural Research Service in Ames, Iowa, detects the presence of abnormal proteins called prions that cause transmissible spongiform encephalopathies.

The human form of bovine spongiform encephalitis, variant Creutzfeldt-Jakob (vCJD), is the best known of the group and has affected about 50 people in the world, including 47 in Britain.

Recently, the US Food and Drug Administration barred people who had visited Britain frequently or for long stays between 1980 and 1996 from donating blood in the US because of the possible risk of transmitting vCJD.

The new test works by mixing blood samples containing special antibodies with synthesised prion protein fragments, or peptides, which are labelled with a fluorescent tag. In disease free blood, the antibodies will bind to these peptides. But if abnormal prions are present, the antibodies will bind to those instead, leaving more of the labelled peptides at large.

The results can be measured to detect the presence of abnormal prions. The assay has been successfully used on spongiform illnesses in sheep, elk, mule deer, and hamsters.

Additional research, which will probably take at least a year, must be done to ensure the test is reliable enough to be used in humans and other animals, according to Dr Mary Jo Schmerr, one of the scientists who helped develop the new assay.

Testing for transmissible spongiform encephalopathies is now done by sampling brain or glandular tissue, usually after death. The researchers said the blood test would probably be used first in Britain.

vCJD is rare in the United States, and another spongiform encephalopathy that affects humans, kuru, has never been seen outside New Guinea. There is no known bovine spongiform encephalopathy in US cattle, but sheep are susceptible to scrapie, and other forms of transmissible spongiform encephalopathies infect elk, mule deer, and mink.

"Further development of this assay may lead to a diagnostic test for this fatal disease agent in animals and humans. Such a diagnostic test would be an important tool for the control of these diseases," said Floyd Horn, administrator of the Agriculture Research Service.

The US Department of Agriculture, which oversees the Ames research laboratory, filed for a patent on the new assay. The scientists are now collaborating with laboratories in the United States and Europe, which will apply the test to other species, including humans.
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Rapid Responses:

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vCJD in the USA

Bart Van Everbroeck
bmj.com, 12 Nov 1999 [Full text]

Re: vCJD in the USA * BSE in U.S.

Terry S Singeltary
bmj.com, 15 Nov 1999 [Full text]

Re: vCJD in the USA

R Stewart Longman
bmj.com, 18 Nov 1999 [Full text]

Re: Re: Sporodic CJD

Kay Foster
bmj.com, 3 Apr 2001 [Full text]