RT-QuIC analysis of cerebrospinal fluid in sporadic Creutzfeldt-Jakob disease
Posted Jun 07 2012 10:13am
1The National CJD Research & Surveillance Unit, University of Edinburgh, Edinburgh, Scotland, UK
2Bristol Institute for Transfusion Sciences, NHS Blood and Transplant, Bristol, UK
3Laboratory of Persistent Viral Disease, NIAID Rocky Mountain Laboratories, National Institutes of Health, Montana, USA ‡Ph: + 44 (0)131 537 3075; Fax: + 44 (0) 131 343 1404
Email: Alison J.E. Green PhD (Alison.Green@ed.ac.uk)
*The National CJD Research & Surveillance Unit, University of Edinburgh, Western, General Hospital, Edinburgh, United Kingdom, EH4 2XU
†Conflicts of Interest There were no conflicts of interest
Publication History Accepted manuscript online: 15 MAR 2012 11:52PM EST Manuscript Accepted: 9 MAR 2012 Manuscript Revised: 24 FEB 2012 Manuscript Received: 30 MAY 2011
Funded by University of Edinburgh Development Trust Scottish Government's Chief Scientists Office Government of Scotland National CJD Research & Surveillance Department of Health and the Scottish Home Office Department of Health Intramural Research Program of the NIAID NIH Department of Health (England) Medical Research Council. Grant Number: G1000681
RT-QuIC analysis of cerebrospinal fluid in sporadic Creutzfeldt-Jakob disease†
Lynne I. McGuire PhD1, Alexander H. Peden PhD1, Christina D. Orrú PhD3, Jason M. Wilham PhD3, Nigel E. Appleford Cbiol2, Gary Mallinson PhD2, Mary Andrews BSc1, Mark W. Head PhD1, Byron Caughey PhD3, Robert G. Will FRCP1, Richard S.G. Knight FRCP1, Alison J.E. Green PhD1,‡,*DOI: 10.1002/ana.23589
Current cerebrospinal fluid (CSF) tests for sporadic Creutzfeldt-Jakob disease (sCJD) are based on the detection of surrogate markers of neuronal damage such as CSF 14-3-3 which are not specific for sCJD. A number of prion protein conversion assays have been developed, including real-time quaking induced conversion (RT-QuIC). The objective of this study is to investigate whether CSF RT-QuIC analysis could be used as a diagnostic test in sCJD.
An exploratory study was undertaken which analysed 108 CSF samples from patients with neuropathologically confirmed sCJD or from control patients. Of the 108 CSF samples 55 were from sCJD patients (30 female, 25 male, aged 31-84 years; 62.1 ± 13.5 years) and 53 were from control patients (26 female, 27 male, aged 43-84 years; 67.8 ± 10.4 years). A confirmatory group of 118 patients were subsequently examined which consisted of 67 cases of neuropathologically confirmed sCJD (33 female, 34 male, aged 39-82 years; 67.5 ± 9.0 years) and 51 control cases (26 female, 25 male, aged 36-87 years; 63.5 ± 11.6 years).
The exploratory study showed that RT-QuIC analysis had a sensitivity of 91% and a specificity of 98% for the diagnosis of sCJD. These results were confirmed in the confirmatory study which showed that CSF RT-QuIC analysis had a sensitivity and specificity of 87% and 100% respectively.
This study shows that CSF RT-QuIC analysis has the potential to be a more specific diagnostic test for sCJD than current CSF tests. ANN NEUROL 2012
Are USDA assurances on mad cow case 'gross oversimplification'?
What irks many scientists is the USDA’s April 25 statement that the rare disease is “not generally associated with an animal consuming infected feed.”
The USDA’s conclusion is a “gross oversimplification,” said Dr. Paul Brown, one of the world’s experts on this type of disease who retired recently from the National Institutes of Health. "(The agency) has no foundation on which to base that statement.”
“We can’t say it’s not feed related,” agreed Dr. Linda Detwiler, an official with the USDA during the Clinton Administration now at Mississippi State.
In the May 1 email to me, USDA’s Cole backed off a bit. “No one knows the origins of atypical cases of BSE,” she said
The argument about feed is critical because if feed is the cause, not a spontaneous mutation, the California cow could be part of a larger outbreak.
1IN SER M UM2; Montpellier, France; 2Anses; Lyon, France; 3Hopitaux Civils de Lyon; Lyon, France
An atypical form of bovine spongiform encephalopathy has been identified in cattle in Europe, North America and Japan and was designed as L-type BSE (L-BSE) due to the lower apparent molecular mass of the unglycosylated, protease-resistant prion protein (PrPres) detected by western blot compared with classical BSE. Experimental evidences from studies in transgenic mice expressing human PrP and in primate models suggest a higher risk of transmission to humans of the L-BSE form than for classical BSE agent. However, a major unresolved issue concerns the potential transmissibility of the L-BSE agent by oral route. To address this question, we infected mouse lemurs (Microcebus murinus), a non-human primate model, with L-BSE by intracerebral or oral route.
Four adult lemurs were intracerebrally (IC) inoculated with 5mg of L-BSE infected brain homogenate of an atypical French BSE case (02-2528). Four young and four adult animals were fed with 5 mg or 50 mg of infected brain. After sacrifice, the brain tissues were biochemically and immunocytochemically investigated for PrPres.
The 4 animals IC inoculated died at 19 and 22 months postinoculation (mpi). They developed blindness, tremor, abnormal posture, incoordinated movements, balance loss. Symptoms get worse according to the disease progression, until severe ataxia. Severe spongiosis was evidenced into the thalamus, the striatum, the mesencephalon, and the brainstem, whereas into the cortex the vacuolisation was weaker. Strong deposits of PrPres were detected into the thalamus, the striatum, and the hippocampus whereas in the cerebral cortex, PrPres was prominently accumulated in plaques.
The orally inoculated animals showed similar clinical symptoms occurring between 27 and 34 mpi. Disease was characterized by progressive prostration, loss of appetite and poor appearance of the fur. Only one adult animal showed disequilibrium. PrPres was strongly accumulated only in the striatum and thalamus and weakly into the cortex. No plaques were evidenced. Two animals that were orally challenged at the age of two years are still alive and healthy 34 months after inoculation. The western blot analysis showed uniform molecular profiles, irrespective of the route or dose of infection, and included notably a PrPres form with low apparent molecular mass (~19 kDa) similar to the PrPres in the original cattle brain. However, the PrPres profile in lemurs was characterized by a higher proportion of di- and mono-glycosylated species (up to 95% of the total signal) than in the bovine L-BSE inoculum (~80%). In addition, small amounts of PrPres were detected by western blotting in the spleen of three animals (one intra-cerebrally inoculated and two fed with 5 mg of cattle brain).
Here, we demonstrate that the L-BSE agent can be transmitted by oral route from cattle to young and adult mouse lemurs. In comparison to IC inoculated animals, orally challenged lemurs were characterized by longer survival periods as expected with this route of infection.