Monday, April 03, 2017

Accessing transmissibility and diagnostic marker of skin prions

Accessing transmissibility and diagnostic marker of skin prions. 

Zou, Wen-Quan Kong, Qingzhong Safar, Jiri G. Case Western Reserve University, Cleveland, OH, United States

The fatal, transmissible animal and human prion diseases are characterized by the deposition in the brain of a proteinase K (PK)-resistant infectious prion protein (PrPSc), an isoform derived from the cellular protein (PrPC) through misfolding. A definitive antemortem diagnosis is virtually impossible for most patients because of the difficulty in obtaining the brain tissues by biopsy. Recently, PrPSc has been reported to be detected in the skin of experimentally or naturally scrapie-infected animals (Thomzig et al., 2007). Consistent with this finding, we have observed PK-resistant PrP in the skin of a patient with variant Creutzfeldt-Jakob disease (vCJD), an acquired form of human prion disease caused by bovine prion (Notari et al., 2010). Unexpectedly, our latest preliminary study identified two types of PK-resistant PrP molecules [with gel mobility similar to the PrPSc types 1 and 2 from the brain of sporadic CJD (sCJD)] in the fibroblast cells extracted from the skin of clinical sCJD patients and asymptomatic subjects carrying PrP mutations linked to familial CJD (fCJD). We also detected PrPSc in the skin of humanized transgenic (Tg) mice inoculated intracerebrally with a human prion. Moreover, prion infectivity has been observed in the skin of infected greater kudu (Cunningham et al., 2004) and a murine prion inoculated to mice via skin scarification can not only propagate in the skin, but also spread to the brain to cause prion disease (Wathne et al., 2012). We hypothesize that the skin of patients with prion disease harbors prion infectivity and the presence of PK-resistant PrP in the skin is a novel diagnostic marker for preclinical CJD patients. To test the hypotheses, we propose to (1) determine prion infectivity of the skin- derived fibroblasts and skin of sCJD patients and asymptomatic PrP-mutation carriers using humanized Tg mouse bioassay, (2) to pinpoint the earliest stage at which PrPSc becomes detectable in the skin of prion- infected Tg mice, and (3) to detect PrPSc in the skin of various human prion diseases, using conventional as well as highly sensitive RT-QuIC assays for both (2) and (3). If successful, our proposal may not only help prevent potential transmission of human prion diseases but also enable definitive and less intrusive antemortem diagnosis of prion diseases. Finally, knowledge generated from this study may also enhance our understanding of other neurodegenerative diseases such as Alzheimer's disease.

Public Health Relevance

Currently it is unclear whether or not the skin of patients with prion diseases is infectious and, moreover, there is no alternative preclinical definitive testing or the brain biopsy in the prion diseases. The aim of our proposal is to address the issues by detection of the infectivity of patients' skin samples using animal bioassay and a new highly sensitive RT-QuIC assay. We believe that our study will not only provide insights into the pathogenesis and transmissibility of prion disease but also will develop preclinical definitive testing for prion disease.

Funding Agency


National Institute of Health (NIH)


National Institute of Neurological Disorders and Stroke (NINDS)


Exploratory/Developmental Grants (R21)

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Special Emphasis Panel (ZRG1-IDM-X (02)M)

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Wong, May

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Case Western Reserve University




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United States

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Foutz, Aaron; Appleby, Brian S; Hamlin, Clive et al. (2016) Diagnostic and Prognostic Value of Human Prion Detection in Cerebrospinal Fluid. Ann Neurol :

Das, Alvin S; Zou, Wen-Quan (2016) Prions: Beyond a Single Protein. Clin Microbiol Rev 29:633-58

TUESDAY, MAY 10, 2016 

Accessing transmissibility and diagnostic marker of skin prions

Accumulation of Pathological Prion Protein PrPSc in the Skin of Animals with Experimental and Natural Scrapie

Achim Thomzig ,Walter Schulz-Schaeffer ,Arne Wrede,Wilhelm Wemheuer,Bertram Brenig,Christine Kratzel,Karin Lemmer,Michael Beekes Published: May 25, 2007


Prion infectivity and its molecular marker, the pathological prion protein PrPSc, accumulate in the central nervous system and often also in lymphoid tissue of animals or humans affected by transmissible spongiform encephalopathies. Recently, PrPSc was found in tissues previously considered not to be invaded by prions (e.g., skeletal muscles). Here, we address the question of whether prions target the skin and show widespread PrPSc deposition in this organ in hamsters perorally or parenterally challenged with scrapie. In hamsters fed with scrapie, PrPScwas detected before the onset of symptoms, but the bulk of skin-associated PrPSc accumulated in the clinical phase. PrPSc was localized in nerve fibres within the skin but not in keratinocytes, and the deposition of PrPSc in skin showed no dependence from the route of infection and lymphotropic dissemination. The data indicated a neurally mediated centrifugal spread of prions to the skin. Furthermore, in a follow-up study, we examined sheep naturally infected with scrapie and detected PrPSc by Western blotting in skin samples from two out of five animals. Our findings point to the skin as a potential reservoir of prions, which should be further investigated in relation to disease transmission. Author Summary

Transmissible spongiform encephalopathies (TSEs), or prion diseases, are fatal neurodegenerative diseases affecting the central nervous system. According to the prion hypothesis, TSEs are caused by proteinaceous infectious particles (“prions”) that consist essentially of PrPSc, an aberrant form of the prion protein with a pathologically altered folding and/or aggregation structure. Scrapie of sheep, chronic wasting disease (CWD) of deer, bovine spongiform encephalopathy (BSE) of cattle, and variant Creutzfeldt-Jakob disease (vCJD) of humans are prominent examples of acquired prion diseases. To further pinpoint the peripheral tissues that could serve as reservoirs of prions in the mammalian body and from which these pathogens could be potentially disseminated into the environment and transmitted to other individuals, we examined the skin of hamsters perorally challenged with scrapie and of naturally infected scrapie sheep for the presence of PrPSc. We show that PrPSc can accumulate in the skin at late stages of incubation, and that the protein is located primarily in small nerve fibres within this organ. The question of whether the skin may also provide a reservoir for prions in CWD, BSE, or vCJD, and the role of the skin in relation to the natural transmission of scrapie in the field needs further investigation. Discussion In this study we have shown that the skin provides a reservoir for PrPSc, the biochemical marker of prion infectivity, in five different hamster TSE models, independently of whether the animals were challenged with scrapie via the p.o., i.c., or f.p. route, cerebral implantation of scrapie-contaminated s.w., or i.c. inoculation of a hamster-adapted BSE agent. Furthermore, PrPSc could be demonstrated for the first time in skin specimens from sheep naturally infected with scrapie, though in a limited number of sites investigated and at low amounts. In a time-course study using hamsters fed with scrapie agent, we were able to detect PrPSc in the skin before the onset of clinical symptoms, but the bulk of skin-associated PrPSc accumulated in the clinical phase of the disease. From our Western blot findings, the final concentration of PrPSc in the skin of hamsters seems to be approximately 5,000–10,000 times lower than that found in the brain. This would correspond to an infectivity titre of ~ 1 × 105 to 2 × 105 50% i.c. infective doses (ID50i.c.) per gram of skin tissue. A similar infectivity titre was previously estimated from Western blot findings for skeletal muscle tissue of clinically ill hamsters perorally challenged with 263K scrapie [23]. 

A Kiss of a Prion: New Implications for Oral Transmissibility 

The transmissibility of scrapie among sheep (intraspecies) is well recognized. It must be emphasized that horizontal transfer (from one individual to another) of scrapie is the main route of infection, because vertical transmission of disease from mother to offspring via milk or placental tissue occurs infrequently. Thus, in view of the report by Maddison et al, the oral transmissibility of prions among sheep may serve as a major route for horizontal scrapie transfer. This occurrence is plausible because sheep often lick each other. Maddison et al [10] indicate that, because of the similarities in prion tissue distribution, their implications for the oral transmission of ovine scrapie might be true for other prion diseases, such as cervid chronic wasting disease and human vCJD. If this is true for humans, a kiss of a prion may sometimes have lethal consequences.

PERSON TO PERSON TRANSMISSION OF THE TSE PRION DISEASE, never say never. as the disease mutates, it becomes more virulent in some cases, and cwd is efficiently transmitted from cervid to cervid. there are now multiple strains of CWD in cervids, as with the TSE prion disease in bovine, sheep and goats, and we now have the atypical TSE in these species, that have mutated, and some strains _have_ become more virulent. we now have younger humans dying from the TSE prion disease, with shorter incubation period, and that are much younger. human to human casual transmission of the TSE prion disease...again, never say never. ...TSS

see more here;

The occurrence of the disease in a patient who had contact with cases of familial C.J.D., but was not genetically related, has been described in Chile (Galvez et al., 1980) and in France (Brown et al., 1979b). In Chile the patient was related by marriage, but with no consanguinity, and had social contact with subsequently affected family members for 13 years before developing the disease. The contact case in France also married into a family in which C.J.D. was prevalent and had close contact with an affected member. In neither instance did the spouse of the non-familial case have the disease. The case described in this report was similarly related to affected family members and social contact had occurred for 20 years prior to developing C.J.D. If contact transmission had occurred, the minimum transmission period would be 11 years. Contact between sporadic cases has not been described and it is remarkable that possible contact transmissions have all been with familial cases. No method of transmission by casual social contact has been suggested.

***The occurrence of contact cases raises the possibility that transmission in families may be effected by an unusually virulent strain of the agent.

snip...see full text here;


Prion-Seeding Activity Is widely Distributed in Tissues of Sporadic Creutzfeldt-Jakob Disease Patients

TUESDAY, MARCH 28, 2017 

Passage of scrapie to deer results in a new phenotype upon return passage to sheep


*** Amyloid‑β accumulation in the CNS in human growth hormone recipients in the UK ***

Terry S. Singeltary Sr. 

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