Human Prion Disease Blood Test Has 100% Accuracy

New methods for detecting even latent variant Creutzfeldt-Jakob disease (vCJD) have been developed. The breakthrough could make blood transfusions safer and help early detection and treatment of the disease, according to researchers at McGovern Medical School at The University of Texas Health Science Center at Houston.

Human prion diseases are infectious and invariably fatal neurodegenerative diseases. They include sporadic Creutzfeldt-Jakob disease (sCJD), the most common form, and variant Creutzfeldt-Jakob disease (vCJD), which is caused by the transmission of bovine spongiform encephalopathy – commonly known as mad cow disease – from infected cattle to humans.

Senior author Claudio Soto, M.D., professor in the Department of Neurology and the director of the George and Cynthia Mitchell Center for Alzheimer’s disease and Related Brain Disorders at UTHealth, said:

“Our findings, which need to be confirmed in further studies, suggest that our method of detection could be useful for the noninvasive diagnosis of this disease in pre-symptomatic individuals. Early diagnosis would allow any potential therapy to be given before substantial brain damage has occurred.

In the case of the blood supply, availability of a procedure to efficiently detect small quantities of the infectious agent would allow removal of blood units contaminated with prions, so that new cases can be minimized substantially.”

Silent Killer

Since 1990, 178 people in the United Kingdom have died from vCJD, according to the National CJD Research & Surveillance Unit at the University of Edinburgh.

The disease has claimed an additional 49 people worldwide, including four United States residents, according to the European Centre for Disease Prevention and Control. In a handful of cases, the disease was spread through the donated blood supply.

The disease can lay silent in the body for decades as damage slowly builds in the brain from the misfolded infectious proteins called prions. On average, people infected with vCJD die two years after the development of the first symptoms, which can include psychiatric alterations such as depression, anxiety and hallucinations that progress to more severe dementia, muscle contractions and loss of coordination.

Claudio Soto

Claudio Soto, Ph.D., is in his lab at McGovern Medical School at UTHealth in Houston. Credit: Alex Luster with The Storyhive

Soto’s team analyzed blood samples from 14 cases of vCJD and 153 controls, which included patients affected by sCJD and other neurodegenerative or neurological disorders as well as healthy subjects. To detect the prions, the team used a protein misfolding cyclic amplification assay, invented in Soto’s lab, which mimics the prion replication process in vitro that occurs in prion disease.

The results showed that prions could be detected with 100 percent sensitivity and specificity in blood samples from vCJD patients.

A second study at University of Montpellier in France backs up the evidence. Researchers there tested a similar technique on 18 individuals with vCJD and 238 without. In both, the tests were 100 percent sensitive.

Daisy Bougard, Jean-Philippe Brandel, Maxime Bélondrade, Vincent Béringue, Christiane Segarra, Hervé Fleury, Jean-Louis Laplanche, Charly Mayran, Simon Nicot, Alison Green, Arlette Welaratne, David Narbey, Chantal Fournier-Wirth, Richard Knight, Robert Will, Pierre Tiberghien, Stéphane Haïk, Joliette Coste
Detection of prions in the plasma of presymptomatic and symptomatic patients with variant Creutzfeldt-Jakob disease
Science Translational Medicine 21 Dec 2016: Vol. 8, Issue 370, pp. 370ra182 DOI: 10.1126/scitranslmed.aag1257

Top Image: Luis Concha-Marambio

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