Saturday, August 13, 2011

Sensitive detection of prion proteins in blood


Sensitive detection of prion proteins in blood

The incidence of BSE cases in cattle has declined, but the risk of contracting the human form of BSE, vCJD, remains a serious threat. In addition to eating contaminated beef, the disease can be also transmitted from one human being to another through organ and tissue transplantations and blood transfusions. The latter harbors an extreme potential risk, since blood from one donor can infect multiple receivers. Recent research has demonstrated that sensitive detection of prions in blood is possible. Using a combination of Prionics antibody 15B3 and prion amplification, the blood test is 10,000 times more sensitive than previously reported assays.

Prion diseases are caused by aberrantly folded prion proteins that accumulate in the brain, resulting in serious brain damage. Several scientific groups have reported long incubation times for vCJD before clinical symptoms appear. Therefore, an individual incubating vCJD can donate blood and spread the disease to multiple receivers. As low levels of prions are expected to be present in the blood of vCJD patients, sensitive detection of disease-specific prion proteins is of great importance for the safety of human blood donations. A recent publication by the group of Byron Caughey describes a new and very sensitive method for the detection of disease-specific prion proteins in blood or plasma. This eQuIC assay uses amplification of prions together with a concentration step using the Prionics 15B3 antibody.

10,000 fold more sensitive The monoclonal 15B3 antibody (mAb 15B3), developed by Prionics, has been shown to specifically recognize the disease-specific form of the prion protein (PrPSc). In the publication of Caughey and his group, the mAb 15B3 was used to “fish” PrPSc from a blood sample. This concentration step alone, however, did not suffice for the detection of prions in the blood. The researchers therefore used the quaking-induced conversion method to amplify disease-specific prions in the concentrated sample. This combination of concentration and amplification, which the researchers call eQuIC, resulted in a 10,000 fold more sensitive assay than those previously reported. Dilutions of 1014-fold, containing ~2 attogram per milliliter of proteinase K-resistant prion protein, were readily detected.

About the is eQuIC method The method used for prion amplification is the quaking-induced conversion (QuIC) reaction. The method is a cell-free conversion reaction of PrPC to PrPSc in multiwell plates. PrPSc present in the (blood) sample acts as a seed for the conversion of recombinant PrP added to the reaction as a substrate. PrPSc complexes formed in the tube are then disrupted by shaking, providing further scaffolds for prion protein conversion. In the real-time quaking-induced conversion, detection of formed PrPSc is based on thioflavin T fluorescence which is enhanced when bound to prion amyloids. Caughey and colleagues combined the real-time quaking-induced conversion with prior immunoprecipitation using mAb 15B3 and called the method enhanced real-time Quaking-Induced Conversion (eQuIC).

Prion Disease Blood Test Using Immunoprecipitation and Improved Quaking-Induced Conversion

Christina D. Orrú,a Jason M. Wilham,a Lynne D. Raymond,a Franziska Kuhn,b Björn Schroeder,b Alex J. Raeber,b and Byron Caugheya Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA,a and Prionics AG, Zurich, Switzerlandb


A key challenge in managing transmissible spongiform encephalopathies (TSEs) or prion diseases in medicine, agriculture, and wildlife biology is the development of practical tests for prions that are at or below infectious levels. Of particular interest are tests capable of detecting prions in blood components such as plasma, but blood typically has extremely low prion concentrations and contains inhibitors of the most sensitive prion tests. One of the latter tests is quaking-induced conversion (QuIC), which can be as sensitive as in vivo bioassays, but much more rapid, higher throughput, and less expensive. Now we have integrated antibody 15B3-based immunoprecipitation with QuIC reactions to increase sensitivity and isolate prions from inhibitors such as those in plasma samples. Coupling of immunoprecipitation and an improved real-time QuIC reaction dramatically enhanced detection of variant Creutzfeldt-Jakob disease (vCJD) brain tissue diluted into human plasma. Dilutions of 1014-fold, containing ~2 attogram (ag) per ml of proteinase K-resistant prion protein, were readily detected, indicating ~10,000- fold greater sensitivity for vCJD brain than has previously been reported. We also discriminated between plasma and serum samples from scrapie-infected and uninfected hamsters, even in early preclinical stages. This combined assay, which we call “enhanced QuIC” (eQuIC), markedly improves prospects for routine detection of low levels of prions in tissues, fluids, or environmental samples.


Transmissible spongiform encephalopathies (TSEs) are largely untreatable and are difficult to diagnose definitively prior to irreversible clinical decline or death. The transmissibility of TSEs within and between species highlights the need for practical tests for even the smallest amounts of infectivity. A few sufficiently sensitive in vitro methods have been reported, but most have major limitations that would preclude their use in routine diagnostic or screening applications. Our new assay improves the outlook for such critical applications. We focused initially on blood plasma because a practical blood test for prions would be especially valuable for TSE diagnostics and risk reduction. Variant Creutzfeldt-Jakob disease (vCJD) in particular has been transmitted between humans via blood transfusions. Enhanced real-time quaking-induced conversion (eQuIC) provides by far the most sensitive detection of vCJD to date. The 15B3 antibody binds prions of multiple species, suggesting that our assay may be useful for clinical and fundamental studies of a variety of TSEs of humans and animals. Received 8 April 2011 Accepted 12 April 2011 Published 10 May 2011 Citation Orrú CD, et al. 2011. Prion disease blood test using immunoprecipitation and improved quaking-induced conversion. mBio 2(3):e00078-11. doi:10.1128/mBio.00078- 11. Editor Reed Wickner, National Institutes of Health Copyright © 2011 Orrú et al. This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License, which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original author and source are credited. Address correspondence to Byron Caughey,

Friday, July 29, 2011

Real-time quaking-induced conversion A highly sensitive assay for prion detection

Saturday, July 23, 2011


Saturday, November 6, 2010

TAFS1 Position Paper on Position Paper on Relaxation of the Feed Ban in the EU Berne, 2010 TAFS


Archive Number 20101206.4364 Published Date 06-DEC-2010 Subject PRO/AH/EDR> Prion disease update 2010 (11)

PRION DISEASE UPDATE 2010 (11),F2400_P1001_PUB_MAIL_ID:1000,86129

Thursday, July 28, 2011

An Update on the Animal Disease Traceability Framework July 27, 2011

Saturday, June 25, 2011

Transmissibility of BSE-L and Cattle-Adapted TME Prion Strain to Cynomolgus Macaque

"BSE-L in North America may have existed for decades"

Over the next 8-10 weeks, approximately 40% of all the adult mink on the farm died from TME.


The rancher was a ''dead stock'' feeder using mostly (>95%) downer or dead dairy cattle...

Sunday, June 26, 2011

Risk Analysis of Low-Dose Prion Exposures in Cynomolgus Macaque

Thursday, June 23, 2011

Experimental H-type bovine spongiform encephalopathy characterized by plaques and glial- and stellate-type prion protein deposits

Thursday, July 21, 2011

A Second Case of Gerstmann-Sträussler-Scheinker Disease Linked to the G131V Mutation in the Prion Protein Gene in a Dutch Patient Journal of Neuropathology & Experimental Neurology:

August 2011 - Volume 70 - Issue 8 - pp 698-702

Saturday, August 14, 2010

BSE Case Associated with Prion Protein Gene Mutation (g-h-BSEalabama) and VPSPr PRIONPATHY

(see mad cow feed in COMMERCE IN ALABAMA...TSS)

Wednesday, June 15, 2011

Galveston, Texas - Isle port moves through thousands of heifers headed to Russia, none from Texas, Alabama, or Washington, due to BSE risk factor

Thursday, July 28, 2011

An Update on the Animal Disease Traceability Framework July 27, 2011

Monday, June 27, 2011

Zoonotic Potential of CWD: Experimental Transmissions to Non-Human Primates

Thursday, May 26, 2011

Travel History, Hunting, and Venison Consumption Related to Prion Disease Exposure, 2006-2007 FoodNet Population Survey

Journal of the American Dietetic Association Volume 111, Issue 6 , Pages 858-863, June 2011.

Thursday, July 14, 2011

Histopathological Studies of "CH1641-Like" Scrapie Sources Versus Classical Scrapie and BSE Transmitted to Ovine Transgenic Mice (TgOvPrP4)

Monday, June 20, 2011 2011

Annual Conference of the National Institute for Animal Agriculture ATYPICAL NOR-98 LIKE SCRAPIE UPDATE USA

Monday, June 27, 2011

Comparison of Sheep Nor98 with Human Variably Protease-Sensitive Prionopathy and Gerstmann-Sträussler-Scheinker Disease

Thursday, June 2, 2011

USDA scrapie report for April 2011 NEW ATYPICAL NOR-98 SCRAPIE CASES Pennsylvania AND California

Saturday, March 5, 2011


Tuesday, April 26, 2011

sporadic CJD RISING Text and figures of the latest annual report of the NCJDRSU covering the period 1990-2009 (published 11th March 2011)

Thursday, August 4, 2011

Terry Singeltary Sr. on the Creutzfeldt-Jakob Disease Public Health Crisis, Date aired: 27 Jun 2011

Friday, August 12, 2011

Creutzfeldt-Jakob disease (CJD) biannual update (2011/2), Incidents Panel, National Anonymous Tonsil Archive


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