Blood-Based Assay Detects vCJD Prion Infection

A prototype blood test for diagnosis of variant Creutzfeldt-Jakob disease (vCJD) in symptomatic individuals could allow development of large-scale screening tests for asymptomatic vCJD prion infection.

A solid-state binding matrix was utilized to capture and concentrate disease-associated prion proteins; this was coupled to direct immunodetection of surface-bound material.

Scientists from the Medical Research Council (MRC) Prion Unit, based at University College London (United Kingdom), working with the National Prion Clinic at the National Hospital for Neurology and Neurosurgery (NHNN; London, United Kingdom) tested 190 blood samples, including 21 from individuals known to have vCJD. The blood test was able to detect blood spiked with a dilution of vCJD to within one part per ten billion–100,000 times more sensitive than any other method developed so far.

Variant CJD, the human form of bovine spongiform encephalopathy (BSE) commonly known as mad cow disease first emerged in 1995. The disease, which affects the brain, is believed to have passed from cattle to humans through infected food. It causes personality change, loss of body function, and eventually death.

Prions, the infectious proteins that cause vCJD and other fatal prion diseases, can inhabit a person's body for up to 50 years before presenting symptoms. During this time there is a chance a carrier of vCJD infection could pass on the infection to others, for example through blood transfusion or even through surgical and medical instruments because prions can easily attach onto metal surfaces.

The work was published online in the February 3, 2011, edition of the Lancet. Lead author Dr. Graham Jackson, program leader at the MRC Prion Unit, said: "This test comes at the end of many years of meticulous, painstaking research in our Unit and the NHS National Prion Clinic. Although further larger studies are needed to confirm its effectiveness, it's the best hope yet of a successful early diagnostic test for the disease. This test could potentially go on to allow blood services to screen the population for vCJD infection, assess how many people in the UK are silent carriers and prevent onward transmission of the disease.”

Related Links:
Medical Research Council Prion Unit
National Hospital for Neurology and Neurosurgery