Sensitive Blood Test Detects Prion Diseases

A novel assay has been developed that will rapidly screen blood plasma for variant Creutzfeldt-Jacob disease (vCJD).

An integrated antibody-based approach with an improved real-time quaking-induced protein conversion (RT-QuIC) reaction enhanced the detection of vCJD brain tissue diluted into human plasma.

Scientists at the US National Institute of Allergy and Infectious Diseases, (NIAID; Bethesda, MD, USA), collaborated with scientists from Prionics AG, (Schlieren-Zurich, Switzerland), to develop the sensitive bioassay. RT-QuIC, developed only recently, detects the abnormal form of prion protein, which, in purified form, resembles amyloid fibrils. This combined assay, which they call enhanced QuIC (eQuIC), detects approximately 2 attograms (10^-18 grams) per mL of proteinase K–resistant prion protein, a 1014-fold dilution, indicating a 10,000-fold increase in sensitivity compared with previously reported methods of vCJD brain tissue detection.

In addition, in early preclinical studies, the eQuIC screening tool has been found to distinguish between plasma and serum samples from scrapie-infected and uninfected hamsters. This rapid and sensitive screening tool that detects prion diseases, also known as transmissible spongiform encephalopathies, would aid in the prevention of prion disease transmission within and between species because animals and people are commonly infected for years before symptoms of the disease appear.

Byron Caughey, PhD, senior investigator in the NIAID Laboratory of Persistent Viral Diseases, said, ""The eQuIC assay in particular provides a practical, high-throughput, and rapid means of testing for amounts of partially protease-resistant form of the host's prion protein that are several orders of magnitude below those typically required to cause prion disease by intracerebral inoculation into animals."

The authors concluded that the remarkable resistance to inactivation of prions relative to other pathogens also makes it important to develop practical assays for prion contamination in a wide variety of materials, such as foods, feeds, transplanted tissues, medical devices, agricultural wastes and by-products, soils, water sources, and other environmental samples. The article was published on May 10, 2011 in the journal mBIO.

Related Links:
US National Institute of Allergy and Infectious Diseases
Prionics AG