No Adaptation of the Prion Strain in a Heterozygous Case of Variant Creutzfeldt-Jakob Disease
Volume 26, Number 6—June 2020
Dispatch
No Adaptation of the Prion Strain in a Heterozygous Case of Variant Creutzfeldt-Jakob Disease
Aileen Boyle, Chris Plinston, Fraser Laing, Graeme Mackenzie, Robert G. Will, Jean C. Manson, and Abigail B. DiackComments to Author Author affiliations: The Roslin Institute, Easter Bush, Scotland, UK (A. Boyle, C. Plinston, F. Laing, A.B. Diack); Western General Hospital, Edinburgh, Scotland, UK (G. Mackenzie); University of Edinburgh, Edinburgh (R.G. Will, J.C. Manson) Cite This Article
Abstract
We investigated a clinical case of variant Creutzfeldt-Jakob Disease in a person heterozygous for methionine/valine at codon 129 of the prion protein gene and identified the same strain properties in variant Creutzfeldt-Jakob disease in methionine homozygous persons and in bovine spongiform encephalopathy. These results indicate no adaptation of the agent in a different genetic background.
In 2016, a definite case of clinical variant Creutzfeldt-Jakob disease (vCJD) in a person heterozygous for methionine/valine (MV) at codon 129 of the prion protein gene (PRNP 129MV) was reported in the United Kingdom (1). Given the relatively atypical clinical features in this case, we considered it important to ascertain the strain of prion agent to determine whether there had been strain adaption or whether the patient’s genetic background may have influenced the disease phenotype. We conducted a study to determine whether we could isolate the same prion strain from this case of vCJD in a 129MV individual as was identified in previous 129 methionine homozygous (129MM) genotype vCJD cases, consistent with the hypothesis of a causal link to bovine spongiform encephalopathy (BSE).
The clinical features for this patient were consistent with a diagnosis of either vCJD or sporadic Creutzfeldt-Jakob disease (sCJD). Results from magnetic resonance imaging (MRI) of the patient’s brain were suggestive of sCJD on diffusion-weighted imaging (DWI) sequences, although the single coronal fluid-attenuated inversion recovery (FLAIR) sequence in this case was not diagnostic because of movement artifact. Results of cerebrospinal fluid (CSF) real-time quaking-induced conversion assay analysis and the direct detection assay for vCJD infection in the blood were negative. However, at autopsy, neuropathological examination revealed florid plaques, and biochemical analysis of prion protein (PrP) from the brain confirmed a type 2B profile, both characteristic of vCJD (1). Abnormal PrP was also detected in peripheral tissues. Recent studies in which researchers used protein misfolding cyclic amplification in CSF were positive in this case of vCJD, but not in sCJD cases, including those with a heterozygous genotype (2).
The Study We injected 18 RIII mice with 10% wt/vol frozen central nervous system tissue, 0.02 mL intracerebrally and 0.1 mL intraperitoneally, from a 129MV patient with a clinical case of vCJD (1). The vCJD tissue samples were provided by the NHS National Prion Clinic, University College London (UCL) Hospitals (London, UK), and MRC Prion Unit at UCL and sourced through the MRC Edinburgh Brain Bank (Edinburgh, Scotland, UK). The Brain Bank has full ethics approval and consent for the use of tissue in research (East of Scotland Research Ethics Service, Ref 16/ES/0084) and works within the framework of the Human Tissue (Scotland) Act 2006. We conducted inoculation, clinical scoring, and neuropathological and biochemical analysis of the mice as previously described (3–5). Animal studies were conducted according to the regulations of the UK Home Office Animals (Scientific Procedures) Act 1986.
The isolate from the brain of the 129MV patient transmitted successfully; clinical and neuropathological signs associated with prion disease appeared in the mice. We compared the mean incubation period, neuropathological signs, and biochemical analysis with archived records of UK 129MM vCJD central nervous system transmissions and UK BSE transmissions. Methods used for inoculation, clinical scoring, and neuropathological and biochemical analysis of the mice were described in previous publications (3–5).
Clinical signs with individual incubation periods ranging from 300 to 392 days postinfection (dpi) were apparent in the mice. The major clinical signs were a loss of body weight and body condition with eye winking and gait abnormalities. Toward the end of the clinical phase, a wet genital area could also be observed. Pathologically confirmed disease developed in 14 of 16 mice (mean incubation period + SEM 341 + 6 dpi). This finding is within the range of previous transmission studies for UK vCJD in this mouse line (mean incubation 306–387 dpi) and similar to those for BSE (mean incubation 316–335 dpi).
We also generated a transmissible spongiform encephalopathy (TSE) vacuolation profile from clinically affected RIII mice and compared it with profiles from UK vCJD and BSE transmissions (Figure 1). We observed a mild-to-moderate gray matter vacuolation in the medulla, hypothalamus, and septum and moderate vacuolation in the cochlear nucleus and dorsal raphe (Figure 1; Figure 2, panels A, B).
We conducted an immunohistochemical analysis, which showed abnormal PrP deposition throughout the brain of both a granular and punctate nature (Figure 2, panels C–K). There was heavy staining in the brainstem, particularly the superior vestibular and cochlear nuclei, and lower midbrain, where the substantia nigra was often targeted. Most of the thalamic nuclei exhibited staining, but staining was more intense in the habenular, hypothalamus, and the CA2 region of the hippocampus (Figure 2, panels F–K). Punctate staining was also apparent in the mid-layer of the cortex throughout the brain. This pattern of staining was very similar to that observed in a vCJD and BSE transmission in the United Kingdom, with additional observations of granular deposition in the cerebellar cortex and small plaques occurring in the corpus callosum in 2 of the samples.
Biochemical analysis of the MV isolate confirmed the presence of protease-resistant PrP (PrPres). We identified a similar type 2B–like pattern and glycosylation profile in the RIII mice. This profile is characterized by a predominance of the diglycosylated form of PrPres at ≈30 kDa, a monoglycosylated form at ≈27kDa, and an unglycosylated band at ≈19kDa (Appendix Figure). The biochemical profile appears identical between the RIII-MV, RIII-MM, and RIII-BSE isolates tested, although the RIII-BSE isolate appeared to have less PrPres.
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Conclusions This transmission study in RIII mice provides evidence that the prion strain isolated from this confirmed case of vCJD in a 129MV person is the same as that identified in typical 129MM vCJD and BSE cases. Further characterization in a range of mouse models is ongoing. However, transmission to RIII mice in previous studies has led to definitive identification of several strains, vCJD and BSE in particular (6,7).
PRNP codon 129 genotype has been shown to be a major factor influencing disease characteristics of Creutzfeldt-Jakob disease (8), but it has not been established if the same is true of vCJD, because previous vCJD infections in 129MV persons exposed to contaminated blood products have been asymptomatic (9,10). Earlier studies using gene-targeted mice inoculated with vCJD predicted that codon 129 genotype would determine disease susceptibility and incubation periods (11), whereas other transgenic mouse studies demonstrated that BSE could transmit with a different phenotype in mice expressing 129MV than that observed in mice expressing 129MM (12).
The clinical diagnosis in the MV case we report was uncertain while the patient was alive, and it was only at autopsy that neuropathology and biochemistry confirmed vCJD. The neurologic features alone cannot be used to discriminate between sCJD and vCJD, and the MRI findings on DWI imaging favored a diagnosis of sCJD. However, the high sensitivity and specificity of MRI for vCJD were determined by analyzing FLAIR images primarily (13) and recent review suggests that DWI imaging may be less specific than FLAIR imaging in vCJD. It is possible that the phenotype of vCJD in this case may have been altered by the heterozygous PRNP background and investigations including CSF protein misfolding cyclic amplification (2), tonsil biopsy, and perhaps FLAIR MRI may contribute to accurate diagnosis of future heterozygous cases.
The identification of vCJD in a 129MV person may indicate the start of a second wave of vCJD in association with the 129MV genotype which is present in around 45% of the UK population (14), although no further cases have been reported since 2016. This case highlights the need to continue surveillance to identify new cases of vCJD and the need for autopsy and strain typing in persons with prion diseases. Changes in clinical disease phenotype could mask the true diagnosis and may be indicative of potential changes in prion disease strains and infectious properties. Strain identification and assessing the infectious properties of prion diseases are essential components in the management of these diseases and have important implications for public health and in determining the prevalence of BSE-related prion disease in humans.
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Ms. Boyle is a research scientist at The Roslin Institute, University of Edinburgh. Her research interests focus on the strain characterization of human and animal prion diseases using in vivo models.
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Acknowledgments We thank the staff of the Biological Research Facility, Roslin Institute, and of Easter Bush Pathology, R(D)SVS, University of Edinburgh, for technical support. We thank David Summers (University of Edinburgh) for input and discussion on MRI imaging of vCJD.
The vCJD tissue samples were acquired through the Edinburgh Brain Bank, which is supported by the Medical Research Council (MR/L016400/1).
This report presents independent research commissioned and funded by the Department of Health and Social Care, Policy Research Programme (Strain typing of vCJD, 007/0195). The views expressed in this publication are those of the author(s) and not necessarily those of the Department of Health and Social Care. The Diack laboratory is also supported by BBSRC Project BBS/E/D/20002173.
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References
Variant Creutzfeldt–Jakob Disease in a Patient with Heterozygosity at PRNP Codon 129
N Engl J Med 2017; 376:292-294January 19, 2017DOI: 10.1056/NEJMc1610003
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Prions cause lethal neurodegenerative diseases in mammals and are composed of multichain assemblies of misfolded host-encoded cellular prion protein (PrP). A common polymorphism at codon 129 of the PrP gene (PRNP), where either methionine (M) or valine (V) is encoded, affects the susceptibility to prion disease, as well as the incubation period1 and clinical phenotype of prion disease. Human infection with the epizootic prion disease bovine spongiform encephalopathy resulted in variant Creutzfeldt–Jakob disease, which provoked a public health crisis in the United Kingdom and other regions. All definite cases of variant Creutzfeldt–Jakob disease to date have occurred in patients with the MM genotype at PRNP codon 129.1
A 36-year-old man was referred to the United Kingdom National Prion Clinic in August 2015 with personality change. Over a period of 9 months, he had become uncharacteristically irascible and had progressive episodic memory impairment, gait ataxia, and myoclonus. His score on the Mini–Mental State Examination was 25 (with scores ranging from 0 to 30 and higher scores indicating less impairment); clinical examination revealed extraocular eye-movement abnormalities, pyramidal and cerebellar signs, and multifocal myoclonus. Magnetic resonance imaging of the brain (Figure 1FIGURE 1 MRI of the Brain.) revealed restricted diffusion in the basal ganglia, hypothalami, insular cortexes, and medial thalami but not in the pulvinar nuclei.2 Examination of the cerebrospinal fluid for protein 14-3-3 was negative, as was a real-time quaking-induced conversion assay, although these two tests are known to have low sensitivity for variant Creutzfeldt–Jakob disease.3 His genotype at PRNP codon 129 was MV. During the following 6 months, the patient’s condition declined progressively, and severe dysphagia and agitation occurred shortly before his death in February 2016.
At autopsy, histologic examination of the brain revealed frequent florid and cluster plaques in cerebral and cerebellar cortexes, microvacuolar degeneration in neuropil, and immunostaining for abnormal PrP in a stellate pericellular and perivascular distribution. Minute amounts of protease-resistant PrP (PrPSc) were seen in lymphoid tissue of the spleen. Immunoblotting of brain homogenate revealed type 4 PrPSc (according to the London classification system), which is pathognomonic of variant Creutzfeldt–Jakob disease.4 (For more details, see the Supplementary Appendix, available with the full text of this letter at NEJM.org.)
This patient’s clinical features differed from those of typical variant Creutzfeldt–Jakob disease, and his neuroimaging features suggested a diagnosis of sporadic Creutzfeldt–Jakob disease. He did not meet the epidemiologic diagnostic criteria for probable or possible variant Creutzfeldt–Jakob disease,5 yet the results of the neuropathological examination and molecular strain typing were consistent with variant Creutzfeldt–Jakob disease. It remains uncertain whether this case marks the start of a second wave of variant Creutzfeldt–Jakob disease in persons with the MV genotype at PRNP codon 129 (the most common genotype in the United Kingdom), mirroring the long incubation periods seen in persons with the MV genotype who have other acquired prion diseases, notably kuru.1 This case emphasizes the importance of performing an autopsy and molecular strain typing in cases of prion disease to ascertain the prevalence of human prion disease related to bovine spongiform encephalopathy.
snip...see full text ;
>>> This patient’s clinical features differed from those of typical variant Creutzfeldt–Jakob disease, and his neuroimaging features suggested a diagnosis of sporadic Creutzfeldt–Jakob disease. He did not meet the epidemiologic diagnostic criteria for probable or possible variant Creutzfeldt–Jakob disease,5 yet the results of the neuropathological examination and molecular strain typing were consistent with variant Creutzfeldt–Jakob disease. <<<
Many more people could still die from mad cow disease in the UK
SHORT SHARP SCIENCE
By Debora MacKenzie
18 January 2017
It’s finally happened. Until now, vCJD – the deadly disease caused by infection with BSE, or “mad cow disease” – has struck only people with a certain genetic makeup. Now, for the first time, researchers have confirmed a case in someone with different genes – a finding that could mean we have been misdiagnosing a new wave of cases.
THURSDAY, JANUARY 19, 2017
Variant Creutzfeldt–Jakob Disease in a Patient with Heterozygosity at PRNP Codon 129
ZOONOSIS OF SCRAPIE TSE PRION
O.05: Transmission of prions to primates after extended silent incubation periods: Implications for BSE and scrapie risk assessment in human populations
Emmanuel Comoy, Jacqueline Mikol, Valerie Durand, Sophie Luccantoni, Evelyne Correia, Nathalie Lescoutra, Capucine Dehen, and Jean-Philippe Deslys Atomic Energy Commission; Fontenay-aux-Roses, France
Prion diseases (PD) are the unique neurodegenerative proteinopathies reputed to be transmissible under field conditions since decades. The transmission of Bovine Spongiform Encephalopathy (BSE) to humans evidenced that an animal PD might be zoonotic under appropriate conditions. Contrarily, in the absence of obvious (epidemiological or experimental) elements supporting a transmission or genetic predispositions, PD, like the other proteinopathies, are reputed to occur spontaneously (atpical animal prion strains, sporadic CJD summing 80% of human prion cases).
Non-human primate models provided the first evidences supporting the transmissibiity of human prion strains and the zoonotic potential of BSE. Among them, cynomolgus macaques brought major information for BSE risk assessment for human health (Chen, 2014), according to their phylogenetic proximity to humans and extended lifetime. We used this model to assess the zoonotic potential of other animal PD from bovine, ovine and cervid origins even after very long silent incubation periods.
*** We recently observed the direct transmission of a natural classical scrapie isolate to macaque after a 10-year silent incubation period,
***with features similar to some reported for human cases of sporadic CJD, albeit requiring fourfold long incubation than BSE. Scrapie, as recently evoked in humanized mice (Cassard, 2014),
***is the third potentially zoonotic PD (with BSE and L-type BSE),
***thus questioning the origin of human sporadic cases.
We will present an updated panorama of our different transmission studies and discuss the implications of such extended incubation periods on risk assessment of animal PD for human health.
===============
***thus questioning the origin of human sporadic cases***
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***our findings suggest that possible transmission risk of H-type BSE to sheep and human. Bioassay will be required to determine whether the PMCA products are infectious to these animals.
==============
***Transmission data also revealed that several scrapie prions propagate in HuPrP-Tg mice with efficiency comparable to that of cattle BSE. While the efficiency of transmission at primary passage was low, subsequent passages resulted in a highly virulent prion disease in both Met129 and Val129 mice.
***Transmission of the different scrapie isolates in these mice leads to the emergence of prion strain phenotypes that showed similar characteristics to those displayed by MM1 or VV2 sCJD prion.
***These results demonstrate that scrapie prions have a zoonotic potential and raise new questions about the possible link between animal and human prions.
***> Moreover, sporadic disease has never been observed in breeding colonies or primate research laboratories, most notably among hundreds of animals over several decades of study at the National Institutes of Health25, and in nearly twenty older animals continuously housed in our own facility. <***
SATURDAY, JUNE 23, 2018
CDC
***> Diagnosis of Methionine/Valine Variant Creutzfeldt-Jakob Disease by Protein Misfolding Cyclic Amplification
Volume 24, Number 7—July 2018 Dispatch
Monday, April 20, 2020
PRION2020 POSTPONED TO 2021 – DUE TO CORONAVIRUS (COVID-19)
MONDAY, AUGUST 26, 2019
Creutzfeldt Jakob Disease CJD, TSE, Prion, Surveillance Update August 2019
SUNDAY, MARCH 10, 2019
National Prion Disease Pathology Surveillance Center Cases Examined¹ Updated Feb 1, 2019 Variably protease-sensitive prionopathy VPSPr
***> In conclusion, sensory symptoms and loss of reflexes in Gerstmann-Sträussler-Scheinker syndrome can be explained by neuropathological changes in the spinal cord. We conclude that the sensory symptoms and loss of lower limb reflexes in Gerstmann-Sträussler-Scheinker syndrome is due to pathology in the caudal spinal cord. <***
***> The clinical and pathological presentation in macaques was mostly atypical, with a strong emphasis on spinal cord pathology.<***
***> The notion that CWD can be transmitted orally into both new-world and old-world non-human primates asks for a careful reevaluation of the zoonotic risk of CWD. <***
***> All animals have variable signs of prion neuropathology in spinal cords and brains and by supersensitive IHC, reaction was detected in spinal cord segments of all animals.<***
***> In particular the US data do not clearly exclude the possibility of human (sporadic or familial) TSE development due to consumption of venison. The Working Group thus recognizes a potential risk to consumers if a TSE would be present in European cervids.'' Scientific opinion on chronic wasting disease (II) <***
THURSDAY, JANUARY 30, 2020
Docket Number: FDA-2012-D-0307 Recommendations to Reduce the Possible Risk of Transmission of Creutzfeldt-Jakob Disease and Variant Creutzfeldt-Jakob Disease by Blood and Blood Components; Draft Guidance for Industry Draft Guidance for Industry Singeltary Submission
FRIDAY, JANUARY 31, 2020
CJD TSE Prion Blood Products, iatrogenic transmission, Confucius is confused again, WHAT IF? Docket Number: FDA-2012-D-0307
Updated April 3, 2020
Year Total Referrals² Prion Disease Sporadic Familial Iatrogenic vCJD
1999 & earlier 381 230 200 27 3 0
2000 145 102 90 12 0 0
2001 209 118 110 8 0 0
2002 241 144 124 18 2 0
2003 259 160 137 21 2 0
2004 316 181 164 16 0 1³
2005 327 178 156 21 1 0
2006 365 179 159 17 1 2⁴
2007 374 210 191 19 0 0
2008 384 221 205 16 0 0
2009 397 231 210 20 1 0
2010 401 246 218 28 0 0
2011 392 238 214 24 0 0
2012 413 244 221 23 0 0
2013 416 258 223 34 1 0
2014 355 208 185 21 1 1⁵
2015 401 263 243 20 0 0
2016 396 277 248 29 0 0
2017 375 266 247 19 0 0
2018 309 223 204 18 1 0
2019 416 270 240 21 0 0
2020 84 56 21 2 0 0
TOTAL 73566 45037 40108 4349 13 4
1Listed based on the year of death or, if not available, on the year of referral;
2Cases with suspected prion disease for which brain tissue was submitted;
3Disease acquired in the United Kingdom;
4Disease acquired in the United Kingdom in one case and in Saudi Arabia in the other;
5Disease possibly acquired in a Middle Eastern or Eastern European country;
6Includes 14 cases in which the diagnosis is pending, and 19 inconclusive cases;
7Includes 42 (9 from 2019, 33 from 2020) cases with type determination pending in which the diagnosis of vCJD has been excluded.
8The sporadic cases include 3906 cases of sporadic Creutzfeldt-Jakob disease (sCJD), 69 cases of Variably Protease-Sensitive Prionopathy (VPSPr) and 35 cases of sporadic Fatal Insomnia (sFI).
9Total does not include 272 Familial cases diagnosed by blood test only.
Monday, February 3, 2020
Informing Patient Contacts About Iatrogenic Creutzfeldt Jakob Disease
Creutzfeldt Jakob Disease CJD
SUNDAY, DECEMBER 29, 2019
Variant CJD 18 years of research and surveillance Variant CJD
18 years of research and surveillance
BSE INQUIRY
Volume 2: Science
4. The link between BSE and vCJD
Summary
4.29 The evidence discussed above that vCJD is caused by BSE seems overwhelming. Uncertainties exist about the cause of CJD in farmers, their wives and in several abattoir workers. It seems that farmers at least might be at higher risk than others in the general population. 1 Increased ascertainment (ie, increased identification of cases as a result of greater awareness of the condition) seems unlikely, as other groups exposed to risk, such as butchers and veterinarians, do not appear to have been affected. The CJD in farmers seems to be similar to other sporadic CJD in age of onset, in respect to glycosylation patterns, and in strain-typing in experimental mice. Some farmers are heterozygous for the methionine/valine variant at codon 129, and their lymphoreticular system (LRS) does not contain the high levels of PrPSc found in vCJD. It remains a remote possibility that when older people contract CJD from BSE the resulting phenotype is like sporadic CJD and is distinct from the vCJD phenotype in younger people...END..TSS
Diagnosis and Reporting of Creutzfeldt-Jakob Disease Singeltary, Sr et al.
JAMA.2001; 285: 733-734. Vol. 285 No. 6, February 14, 2001 JAMA
Diagnosis and Reporting of Creutzfeldt-Jakob Disease To the Editor: In their Research Letter, Dr Gibbons and colleagues1 reported that the annual US death rate due to Creutzfeldt-Jakob disease (CJD) has been stable since 1985. These estimates, however, are based only on reported cases, and do not include misdiagnosed or preclinical cases. It seems to me that misdiagnosis alone would drastically change these figures. An unknown number of persons with a diagnosis of Alzheimer disease in fact may have CJD, although only a small number of these patients receive the postmortem examination necessary to make this diagnosis. Furthermore, only a few states have made CJD reportable. Human and animal transmissible spongiform encephalopathies should be reportable nationwide and internationally.
Terry S. Singeltary, Sr Bacliff, Tex 1. Gibbons RV, Holman RC, Belay ED, Schonberger LB. Creutzfeldt-Jakob disease in the United States: 1979-1998. JAMA. 2000;284:2322-2323.
Terry S. Singeltary Sr.
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