Infectious Prions Detected in Skin of Patients With Neurodegenerative Creutzfeldt-Jakob Disease

MedicalResearch.com Interview with:

The brain of one patient who died from sporadic Creutzfeldt-Jacob disease (sCJD) appears nearly identical to the brain of a mouse inoculated with infectious prions taken from the skin of patients who died from sCJD.

The brain of one patient who died from sporadic Creutzfeldt-Jacob disease (sCJD) appears nearly identical to the brain of a mouse inoculated with infectious prions taken from the skin of patients who died from sCJD.
Case Western Reserve University

 

Byron Caughey, Ph.D.
Senior Investigator
Chief, TSE/prion Biochemistry Section
Laboratory of Persistent Viral Diseases
NIH/NIAID Rocky Mountain Laboratories
Hamilton, MT 

 

 

MedicalResearch.com: Would you briefly explain what is meant by Creutzfeldt-Jakob disease?

Response: Creutzfeldt-Jakob disease (CJD) is an incurable—and ultimately fatal—transmissible, neurodegenerative disorder in the family of prion diseases. Prion diseases can be found in many mammalian species and are due to the conversion of normally harmless prion protein molecules into abnormally folded, aggregated and self-propagating clusters and filaments in the brain. The accumulation of these clusters has been associated with tissue damage that often leaves dying neurons and microscopic sponge-like holes in the brain. In the sporadic and genetic forms of CJD this pathogenic process appears to arise spontaneously in the patient.

However, the transfer of the prion protein aggregates from a Creutzfeldt-Jakob disease patient into another human or experimental animal can initiate the pathogenic process in the recipient. These infectious forms of prion protein are called prions. Human prion diseases include fatal insomnia; kuru; Gerstmann-Straussler-Scheinker syndrome; and variant, familial and sporadic CJD. Sporadic CJD is the most common human prion disease, affecting about one in one million people annually worldwide. Other prion diseases include scrapie in sheep; chronic wasting disease in deer, elk and moose; and bovine spongiform encephalopathy (BSE), or mad cow disease, in cattle.

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Nasal Swab Can Test for Creutzfeldt–Jakob Disease

MedicalResearch.com Interview with:
Zanusso Gianluigi M.D.Ph.D.

Department of Neurosciences, Biomedicine and Movement Sciences
University of Verona
Verona, Italy

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: To determine RT-QuIC assay sensitivity and specificity in cerebrospinal fluid and olfactory mucosa in a large group of patients with a clinical diagnosis of probable, possible or suspect Creutzfeldt–Jakob disease (CJD) and controls.

In these patients, RT-QuIC testing of CSF and olfactory mucosa provided a specificity and sensitivity of 100%.

A softer swab for olfactory mucosa sampling provided the same sensitivity as using a brush .

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Some Prions Can Be Cleared By Infected Organism

MedicalResearch.com Interview with:
Romolo Nonno, DVM, PhD
Istituto Superiore di Sanità
Dipartimento di Sanità Pubblica Veterinaria e Sicurezza Alimentare
Roma Italy

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Previous studies have suggested that prion populations are composed of a variety of conformational variants subjected to Darwinian evolution driven by selective regimes. However, the exact molecular mechanisms that make prions able to self-replicate and mutate are still poorly understood.

A major technical advance in this field has been the discovery of techniques that allow to replicate prions in vitro, outside live organisms. One of these techniques, Protein Misfolding Cyclic Amplification (PMCA), allows to grow prion populations for a very high number of replications in a relatively short time period.

Furthermore it is conceivable that the in vitro environment offers less constraint to prion replication than live animals or cells, due to the absence of active clearance and cell division, which are key players of conformers selection in ex vivo models. These features make PMCA an attractive tool to investigate prion replication, mutation and evolution. By using PMCA, we investigated the in vitro evolution of prion populations derived from natural scrapie. Unexpectedly, we found that the cloud of conformational variants which compose a natural scrapie isolate also includes “defective” variants which, once isolated, are unable to self-sustain in vivo.

Importantly, we found that the defective prion mutant that we have isolated possesses unique biochemical properties in that its prion domain lacks the central region of prion protein, which is invariably present in known infectious mammalian prions.

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An Improved Test for Creutzfeldt-Jakob Disease

Byron Caughey, PhD Senior Investigator Rocky Mountain Laboratories National Institute for Allergy and Infectious Diseases National Institutes of Health Hamilton, Montana 59840MedicalResearch.com Interview with:
Byron Caughey, PhD
Senior Investigator
Rocky Mountain Laboratories
National Institute for Allergy and Infectious Diseases
National Institutes of Health
Hamilton, Montana 59840

MedicalResearch: What is the background for this study? What are the main findings?

Dr. Caughey: One of the challenges in dealing with various neurodegenerative protein misfolding diseases is early and accurate diagnosis. This issue is particularly important with human prion diseases such as Creutzfeldt-Jakob disease (CJD) because the causative prion agents are deadly, transmissible and unusually resistant to decontamination. A recently developed test called Real-Time Quaking-Induced Conversion (RT-QuIC) allows for highly sensitive and specific detection of Creutzfeldt-Jakob disease using human cerebrospinal fluid (CSF) or nasal brushings and is being widely implemented as a key diagnostic tool. However, the currently implemented CSF-based test takes 2.5-5 days and misses 11-23% of Creutzfeldt-Jakob disease cases. We have now markedly improved RT-QuIC analysis of human CSF such that CJD and non-CJD patients can be discriminated in a matter of hours rather than days with enhanced analytical and diagnostic sensitivity. Analysis of 11 Creutzfeldt-Jakob disease patients demonstrated that while 7 were RT-QuIC positive using the previous conditions, 10 were positive using the new assay. In these and further analyses, a total of 46 of 48 CSF samples sporadic Creutzfeldt-Jakob disease patients were positive while all 39 non-CJD patients were negative, giving 95.8% diagnostic sensitivity and 100% specificity.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Caughey: Our improved RT-QuIC assay should allow for much faster, more accurate and practical testing for Creutzfeldt-Jakob disease using patients’ CSF samples.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Caughey: Future studies should be aimed at further evaluating the diagnostic utility of the RT-QuIC test using much larger numbers of CSF specimens and additional diagnostic centers. In a larger sense, the RT-QuIC assay provides a prototype for tests for misfolded protein aggregates that cause many important amyloid diseases, such as Alzheimer’s, Parkinson’s and tauopathies.

Citation:

Rapid and Sensitive RT-QuIC Detection of Human Creutzfeldt-Jakob Disease Using Cerebrospinal Fluid.

Orrú CD, Groveman BR, Hughson AG, Zanusso G, Coulthart MB, Caughey B.

mBio. 2015 Jan 20;6(1). pii: e02451-14. doi: 10.1128/mBio.02451-14.

MedicalResearch.com Interview with:, Byron Caughey, PhD, Senior Investigator, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, & Hamilton, Montana 59840 (2015). An Improved Test for Creutzfeldt-Jakob Disease MedicalResearch.com

Urinary Detection of Prions That Cause Creutzfeldt-Jakob Disease

Claudio Soto, PhD Professor of Neurology Director Mitchell Center for Alzheimer's disease and related Brain Disorders University of Texas Medical School at HoustonMedicalResearch.com Interview with:
Claudio Soto, PhD
Professor of Neurology
Director Mitchell Center for Alzheimer’s disease and related Brain Disorders
University of Texas Medical School at Houston

Medical Research: What are the main findings of the study?

Dr. Soto: In this study we describe for the first time the highly sensitive detection of prions in human urine, specifically in samples from patients affected by the variant form of Creutzfeldt-Jakob disease (vCJD), which is the disease produced by infection with prions associated with bovine spongiform encephalopathy, also known as mad cow disease. For detection we used the protein misfolding cyclic amplification (PMCA) technique which amplifies the amount of abnormal prion protein in a cyclical manner conceptually analogous to the polymerize chain reaction. We detected prions in 13 of the 14 vCJD cases analyzed, and the only negative was a sample coming from a patient under treatment with a experimental drug injected directly into the brain. No false positive were observed in the more than 200 cases analyzed.  The concentration of abnormal prion protein in urine was estimated at 1×10^-16 g/ml, or 3×10^-21 moles/ml, which extrapolates to ~40-100 particles per ml of urine.
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