Scientists in the United Kingdom (UK) have created a blood test for variant Creutzfeldt-Jakob disease (vCJD), the human form of “mad cow disease” (bovine spongiform encephalopathy, BSE). vCJD is characterized by misshapen prion proteins that form spongelike holes in the brain tissue, causing a degenerative condition that is fatal. There is no treatment for vCJD. The test was developed at the government-funded Medical Research Council (MRC) at University College London (UCL). A recent study using the new screening method yielded encouraging results. The lead author was of the UCL Institute of Neurology in London.
The majority of vCJD cases in humans occurred during an outbreak in the UK in the 1990s, after people ate beef contaminated with BSE. There have been 170 confirmed cases of vCJD in the UK, all of which have resulted in death. One study suggests that as many as one in 4,000 individuals in the UK may currently carry the disease.
The predicament for health officials is two-fold: the lack of an available diagnostic test for vCJD (the disease can only be confirmed via a post-mortem brain matter analysis) and the virus’s dormancy period, which can last for years or even decades before symptoms appear. vCJD transmissions via transfusions containing contaminated blood or blood products are also a growing concern. There have been five transfusion-related cases in the UK.
The new test uses technology based on the fact that prions bind to some metal surfaces, including stainless steel, which was used by the researchers. Investigators used the test on 190 blood samples drawn from 21 patients with vCJD, 27 with sporadic CJD, 42 with other neurological diseases and 100 normal controls. The blood assay detected the infectious prions in 15 of the 21 vCJD samples, a success rate of 71%.
For the six cases in which the test failed to confirm vCJD, the researchers attributed the findings to extremely low prion levels, or lack of them, in the blood.
Although the new blood test for vCJD is 100,000 times more sensitive than previous ones, further studies are needed. “Our findings demonstrate the ability to detect prion infection in blood and show that a donor blood screening test is technically feasible. The use of this test in differential diagnosis of suspected vCJD will be further investigated in large case series,” wrote the authors.
The study, “Detection of Prion Infection in variant Creutzfeldt-Jakob Disease: A Blood-Based Assay,” was published online in the journal Lancet on February 3, 2011.
Sources: BBC News, February 2, 2011, and HealthDay News (online), February 3, 2011