Experimental Transmission of the Chronic Wasting Disease Agent to Swine after Oral or Intracranial Inoculation

ABSTRACT Chronic wasting disease (CWD) is a naturally occurring, fatal neurodegenerative disease of cervids. The potential for swine to serve as hosts for the agent of CWD is unknown. The purpose of this study was to investigate the susceptibility of swine to the CWD agent following experimental oral or intracranial inoculation. Crossbred piglets were assigned to three groups, intracranially inoculated (n = 20), orally inoculated (n = 19), and noninoculated (n = 9). At approximately the age at which commercial pigs reach market weight, half of the pigs in each group were culled (“market weight” groups). The remaining pigs (“aged” groups) were allowed to incubate for up to 73 months postinoculation (mpi). Tissues collected at necropsy were examined for disease-associated prion protein (PrPSc) by Western blotting (WB), antigen capture enzyme immunoassay (EIA), immunohistochemistry (IHC), and in vitro real-time quaking-induced conversion (RT-QuIC). Brain samples from selected pigs were also bioassayed in mice expressing porcine prion protein. Four intracranially inoculated aged pigs and one orally inoculated aged pig were positive by EIA, IHC, and/or WB. By RT-QuIC, PrPSc was detected in lymphoid and/or brain tissue from one or more pigs in each inoculated group. The bioassay was positive in four out of five pigs assayed. This study demonstrates that pigs can support low-level amplification of CWD prions, although the species barrier to CWD infection is relatively high. However, detection of infectivity in orally inoculated pigs with a mouse bioassay raises the possibility that naturally exposed pigs could act as a reservoir of CWD infectivity. IMPORTANCE We challenged domestic swine with the chronic wasting disease agent by inoculation directly into the brain (intracranially) or by oral gavage (orally). Disease-associated prion protein (PrPSc) was detected in brain and lymphoid tissues from intracranially and orally inoculated pigs as early as 8 months of age (6 months postinoculation). Only one pig developed clinical neurologic signs suggestive of prion disease. The amount of PrPSc in the brains and lymphoid tissues of positive pigs was small, especially in orally inoculated pigs. Regardless, positive results obtained with orally inoculated pigs suggest that it may be possible for swine to serve as a reservoir for prion disease under natural conditions.

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Generation of human chronic wasting disease in transgenic mice

Acta Neuropathologica Communications ◽

10.1186/s40478-021-01262-y ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Zerui Wang ◽

Kefeng Qin ◽

Manuel V. Camacho ◽

Ignazio Cali ◽

Jue Yuan ◽

...

Keyword(s):

Transgenic Mice ◽

Prion Disease ◽

Protein Misfolding ◽

Chronic Wasting Disease ◽

Cellular Prion Protein ◽

Spongiform Encephalopathy ◽

Species Barrier ◽

Wasting Disease ◽

Bona Fide

AbstractChronic wasting disease (CWD) is a cervid prion disease caused by the accumulation of an infectious misfolded conformer (PrPSc) of cellular prion protein (PrPC). It has been spreading rapidly in North America and also found in Asia and Europe. Although bovine spongiform encephalopathy (i.e. mad cow disease) is the only animal prion disease known to be zoonotic, the transmissibility of CWD to humans remains uncertain. Here we report the generation of the first CWD-derived infectious human PrPSc by elk CWD PrPSc-seeded conversion of PrPC in normal human brain homogenates using in vitro protein misfolding cyclic amplification (PMCA). Western blotting with human PrP selective antibody confirmed that the PMCA-generated protease-resistant PrPSc was derived from the human PrPC substrate. Two lines of humanized transgenic mice expressing human PrP with either Val or Met at the polymorphic codon 129 developed clinical prion disease following intracerebral inoculation with the PMCA-generated CWD-derived human PrPSc. Diseased mice exhibited distinct PrPSc patterns and neuropathological changes in the brain. Our study, using PMCA and animal bioassays, provides the first evidence that CWD PrPSc can cross the species barrier to convert human PrPC into infectious PrPSc that can produce bona fide prion disease when inoculated into humanized transgenic mice.

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Efficient In Vitro Amplification of Chronic Wasting Disease PrPRES

Journal of Virology ◽

10.1128/jvi.00635-07 ◽

2007 ◽

Vol 81 (17) ◽

pp. 9605-9608 ◽

Cited By ~ 71

Author(s):

Timothy D. Kurt ◽

Matthew R. Perrott ◽

Carol J. Wilusz ◽

Jeffrey Wilusz ◽

Surachai Supattapone ◽

...

Keyword(s):

Transgenic Mice ◽

Prion Protein ◽

Protein Misfolding ◽

Chronic Wasting Disease ◽

Body Fluids ◽

The Body ◽

Wasting Disease ◽

Highly Efficient ◽

Significant Step

ABSTRACT Chronic wasting disease (CWD) of cervids is associated with conversion of the normal cervid prion protein, PrPC, to a protease-resistant conformer, PrPCWD. Here we report the use of both nondenaturing amplification and protein-misfolding cyclic amplification (PMCA) to amplify PrPCWD in vitro. Normal brains from deer, transgenic mice expressing cervid PrPC [Tg(cerPrP)1536 mice], and ferrets supported amplification. PMCA using normal Tg(cerPrP)1536 brains as the PrPC substrate produced >6.5 × 109-fold amplification after six rounds. Highly efficient in vitro amplification of PrPCWD is a significant step toward detection of PrPCWD in the body fluids or excreta of CWD-susceptible species.

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Failure To Detect Prion Infectivity in Ticks following Prion-Infected Blood Meal

mSphere ◽

10.1128/msphere.00741-20 ◽

2020 ◽

Vol 5 (5) ◽

Author(s):

Ronald A. Shikiya ◽

Anthony E. Kincaid ◽

Jason C. Bartz ◽

Travis J. Bourret

Keyword(s):

Prion Disease ◽

Blood Meal ◽

Red Deer ◽

Chronic Wasting Disease ◽

Mule Deer ◽

Geographic Range ◽

Lymphoid Tissues ◽

Wasting Disease ◽

Prion Infection ◽

Prion Infectivity

ABSTRACT Chronic wasting disease (CWD) is an emerging and fatal contagious prion disease that affects cervids, including mule deer, white-tailed deer, black-tailed deer, red deer reindeer, elk, and moose. CWD prions are widely distributed throughout the bodies of CWD-infected animals and are found in the nervous system, lymphoid tissues, muscle, blood, urine, feces, and antler velvet. The mechanism of CWD transmission in natural settings is unknown. Potential mechanisms of transmission include horizontal, maternal, or environmental routes. Due to the presence of prions in the blood of CWD-infected animals, the potential exists for invertebrates that feed on mammalian blood to contribute to the transmission of CWD. The geographic range of the Rocky Mountain Wood tick, Dermancentor andersoni, overlaps with CWD throughout the northwest United States and southwest Canada, raising the possibility that D. andersoni parasitization of cervids may be involved in CWD transmission. We investigated this possibility by examining the blood meal of D. andersoni that fed upon prion-infected hamsters for the presence of prion infectivity by animal bioassay. None of the hamsters inoculated with a D. andersoni blood meal that had been ingested from prion-infected hamsters developed clinical signs of prion disease or had evidence for a subclinical prion infection. Overall, the data do not demonstrate a role for D. andersoni in the transmission of prion disease. IMPORTANCE Chronic wasting disease (CWD) is an emerging prion disease that affects cervids, including mule deer, white-tailed deer, black-tailed deer, red deer reindeer, elk, and moose. The mechanism of CWD transmission in unknown. Due to the presence of prions in the blood of CWD-infected animals, it is possible for invertebrates that feed on cervid blood to contribute to the transmission of CWD. We examined the blood meal of D. andersoni, a tick with a similar geographic range as cervids, that fed upon prion-infected hamsters for the presence of prion infectivity by animal bioassay. None of the D. andersoni blood meals that had been ingested from prion-infected hamsters yielded evidence of prion infection. Overall, the data do not support a role of D. andersoni in the transmission of prion disease.

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Species barriers for chronic wasting disease by in vitro conversion of prion protein

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2007.10.087 ◽

2007 ◽

Vol 364 (4) ◽

pp. 796-800 ◽

Cited By ~ 16

Author(s):

Li Li ◽

Michael B. Coulthart ◽

Aru Balachandran ◽

Avi Chakrabartty ◽

Neil R. Cashman

Keyword(s):

Prion Protein ◽

Chronic Wasting Disease ◽

Wasting Disease

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Inhibition of Protease-Resistant Prion Protein Formation in a Transformed Deer Cell Line Infected with Chronic Wasting Disease

Journal of Virology ◽

10.1128/jvi.80.2.596-604.2006 ◽

2006 ◽

Vol 80 (2) ◽

pp. 596-604 ◽

Cited By ~ 48

Author(s):

Gregory J. Raymond ◽

Emily A. Olsen ◽

Kil Sun Lee ◽

Lynne D. Raymond ◽

P. Kruger Bryant ◽

...

Keyword(s):

Cell Line ◽

Prion Protein ◽

Chronic Wasting Disease ◽

Transmissible Spongiform Encephalopathy ◽

Mule Deer ◽

Simian Virus 40 ◽

Spongiform Encephalopathy ◽

Wasting Disease ◽

Neuronal Marker

ABSTRACT Chronic wasting disease (CWD) is an emerging transmissible spongiform encephalopathy (prion disease) of North American cervids, i.e., mule deer, white-tailed deer, and elk (wapiti). To facilitate in vitro studies of CWD, we have developed a transformed deer cell line that is persistently infected with CWD. Primary cultures derived from uninfected mule deer brain tissue were transformed by transfection with a plasmid containing the simian virus 40 genome. A transformed cell line (MDB) was exposed to microsomes prepared from the brainstem of a CWD-affected mule deer. CWD-associated, protease-resistant prion protein (PrPCWD) was used as an indicator of CWD infection. Although no PrPCWD was detected in any of these cultures after two passes, dilution cloning of cells yielded one PrPCWD-positive clone out of 51. This clone, designated MDBCWD, has maintained stable PrPCWD production through 32 serial passes thus far. A second round of dilution cloning yielded 20 PrPCWD-positive subclones out of 30, one of which was designated MDBCWD2. The MDBCWD2 cell line was positive for fibronectin and negative for microtubule-associated protein 2 (a neuronal marker) and glial fibrillary acidic protein (an activated astrocyte marker), consistent with derivation from brain fibroblasts (e.g., meningeal fibroblasts). Two inhibitors of rodent scrapie protease-resistant PrP accumulation, pentosan polysulfate and a porphyrin compound, indium (III) meso-tetra(4-sulfonatophenyl)porphine chloride, potently blocked PrPCWD accumulation in MDBCWD cells. This demonstrates the utility of these cells in a rapid in vitro screening assay for PrPCWD inhibitors and suggests that these compounds have potential to be active against CWD in vivo.

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Exposure Risk of Chronic Wasting Disease in Humans

Viruses ◽

10.3390/v12121454 ◽

2020 ◽

Vol 12 (12) ◽

pp. 1454

Author(s):

Satish K. Nemani ◽

Jennifer L. Myskiw ◽

Lise Lamoureux ◽

Stephanie A. Booth ◽

Valerie L. Sim

Keyword(s):

Chronic Wasting Disease ◽

Prion Diseases ◽

Causal Link ◽

In Vivo Studies ◽

Spongiform Encephalopathy ◽

Strain Typing ◽

Species Barrier ◽

Wasting Disease

The majority of human prion diseases are sporadic, but acquired disease can occur, as seen with variant Creutzfeldt–Jakob disease (vCJD) following consumption of bovine spongiform encephalopathy (BSE). With increasing rates of cervid chronic wasting disease (CWD), there is concern that a new form of human prion disease may arise. Currently, there is no evidence of transmission of CWD to humans, suggesting the presence of a strong species barrier; however, in vitro and in vivo studies on the zoonotic potential of CWD have yielded mixed results. The emergence of different CWD strains is also concerning, as different strains can have different abilities to cross species barriers. Given that venison consumption is common in areas where CWD rates are on the rise, increased rates of human exposure are inevitable. If CWD was to infect humans, it is unclear how it would present clinically; in vCJD, it was strain-typing of vCJD prions that proved the causal link to BSE. Therefore, the best way to screen for CWD in humans is to have thorough strain-typing of harvested cervids and human CJD cases so that we will be in a position to detect atypical strains or strain shifts within the human CJD population.

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Longitudinal Detection of Prion Shedding in Saliva and Urine by Chronic Wasting Disease-Infected Deer by Real-Time Quaking-Induced Conversion

Journal of Virology ◽

10.1128/jvi.01118-15 ◽

2015 ◽

Vol 89 (18) ◽

pp. 9338-9347 ◽

Cited By ~ 41

Author(s):

Davin M. Henderson ◽

Nathaniel D. Denkers ◽

Clare E. Hoover ◽

Nina Garbino ◽

Candace K. Mathiason ◽

...

Keyword(s):

Prion Disease ◽

Chronic Wasting Disease ◽

Prion Diseases ◽

Lethal Dose ◽

Disease Course ◽

Wasting Disease ◽

Daily Production ◽

Canadian Provinces ◽

Free Ranging

ABSTRACTChronic wasting disease (CWD) is an emergent, rapidly spreading prion disease of cervids. Shedding of infectious prions in saliva and urine is thought to be an important factor in CWD transmission. To help to elucidate this issue, we applied anin vitroamplification assay to determine the onset, duration, and magnitude of prion shedding in longitudinally collected saliva and urine samples from CWD-exposed white-tailed deer. We detected prion shedding as early as 3 months after CWD exposure and sustained shedding throughout the disease course. We estimated that the 50% lethal dose (LD50) for cervidized transgenic mice would be contained in 1 ml of infected deer saliva or 10 ml of urine. Given the average course of infection and daily production of these body fluids, an infected deer would shed thousands of prion infectious doses over the course of CWD infection. The direct and indirect environmental impacts of this magnitude of prion shedding on cervid and noncervid species are surely significant.IMPORTANCEChronic wasting disease (CWD) is an emerging and uniformly fatal prion disease affecting free-ranging deer and elk and is now recognized in 22 U.S. states and 2 Canadian provinces. It is unique among prion diseases in that it is transmitted naturally through wild populations. A major hypothesis to explain CWD's florid spread is that prions are shed in excreta and transmitted via direct or indirect environmental contact. Here we use a rapidin vitroassay to show that infectious doses of CWD prions are in fact shed throughout the multiyear disease course in deer. This finding is an important advance in assessing the risks posed by shed CWD prions to animals as well as humans.

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Cervid Prion Protein Polymorphisms: Role in Chronic Wasting Disease Pathogenesis

International Journal of Molecular Sciences ◽

10.3390/ijms22052271 ◽

2021 ◽

Vol 22 (5) ◽

pp. 2271

Author(s):

Maria Immaculata Arifin ◽

Samia Hannaoui ◽

Sheng Chun Chang ◽

Simrika Thapa ◽

Hermann M. Schatzl ◽

...

Keyword(s):

Prion Protein ◽

Chronic Wasting Disease ◽

In Vivo Studies ◽

Wasting Disease ◽

Endogenous Factors ◽

Prion Strains ◽

Free Ranging

Chronic wasting disease (CWD) is a prion disease found in both free-ranging and farmed cervids. Susceptibility of these animals to CWD is governed by various exogenous and endogenous factors. Past studies have demonstrated that polymorphisms within the prion protein (PrP) sequence itself affect an animal’s susceptibility to CWD. PrP polymorphisms can modulate CWD pathogenesis in two ways: the ability of the endogenous prion protein (PrPC) to convert into infectious prions (PrPSc) or it can give rise to novel prion strains. In vivo studies in susceptible cervids, complemented by studies in transgenic mice expressing the corresponding cervid PrP sequence, show that each polymorphism has distinct effects on both PrPC and PrPSc. It is not entirely clear how these polymorphisms are responsible for these effects, but in vitro studies suggest they play a role in modifying PrP epitopes crucial for PrPC to PrPSc conversion and determining PrPC stability. PrP polymorphisms are unique to one or two cervid species and most confer a certain degree of reduced susceptibility to CWD. However, to date, there are no reports of polymorphic cervid PrP alleles providing absolute resistance to CWD. Studies on polymorphisms have focused on those found in CWD-endemic areas, with the hope that understanding the role of an animal’s genetics in CWD can help to predict, contain, or prevent transmission of CWD.

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Novel Strain of the Chronic Wasting Disease Agent Isolated From Experimentally Inoculated Elk With LL132 Prion Protein

Scientific Reports ◽

10.1038/s41598-020-59819-1 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 4

Author(s):

Jo Moore ◽

Trudy Tatum ◽

Soyoun Hwang ◽

Catherine Vrentas ◽

M. Heather West Greenlee ◽

...

Keyword(s):

Prion Protein ◽

Chronic Wasting Disease ◽

Wasting Disease ◽

Disease Agent

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Lack of Transmission of Chronic Wasting Disease to Cynomolgus Macaques

Journal of Virology ◽

10.1128/jvi.00550-18 ◽

2018 ◽

Vol 92 (14) ◽

Cited By ~ 18

Author(s):

Brent Race ◽

Katie Williams ◽

Christina D. Orrú ◽

Andrew G. Hughson ◽

Lori Lubke ◽

...

Keyword(s):

South Korea ◽

Human Health ◽

Prion Disease ◽

Chronic Wasting Disease ◽

Cynomolgus Macaque ◽

Health Concern ◽

Species Barrier ◽

Wasting Disease ◽

Cynomolgus Macaques ◽

Canadian Provinces

ABSTRACT Chronic wasting disease (CWD) is a fatal prion disease that can infect deer, elk, and moose. CWD was first recognized in captive deer kept in wildlife facilities in Colorado from 1967 to 1979. CWD has now been detected in 25 U.S. states, 2 Canadian provinces, South Korea, Norway, and Finland. It is currently unknown if humans are susceptible to CWD infection. Understanding the health risk from consuming meat and/or products from CWD-infected cervids is a critical human health concern. Previous research using transgenic mouse models and in vitro conversion assays suggests that a significant species barrier exists between CWD and humans. To date, reported epidemiologic studies of humans consuming cervids in areas where CWD is endemic have found no evidence to confirm CWD transmission to humans. Previously, we reported data from ongoing cross-species CWD transmission studies using two species of nonhuman primates as models. Squirrel monkeys (SM) and cynomolgus macaques (CM) were inoculated by either the intracerebral or oral route with brain homogenates from CWD-infected deer and elk containing high levels of infectivity. SM were highly susceptible to CWD infection, while CM were not. In the present study, we present new data for seven CWD-inoculated CM euthanized 11 to 13 years after CWD inoculation and eight additional uninoculated control CM. New and archival CM tissues were screened for prion infection by using the ultrasensitive real-time quaking-induced conversion (RT-QuIC) assay, immunohistochemistry, and immunoblotting. In this study, there was no clinical, pathological, or biochemical evidence suggesting that CWD was transmitted from cervids to CM. IMPORTANCE Chronic wasting disease (CWD) is a fatal prion disease found in deer, elk, and moose. Since it was first discovered in the late 1960s, CWD has now spread to at least 25 U.S. states, 2 Canadian provinces, South Korea, Norway, and Finland. Eradication of CWD from areas of endemicity is very unlikely, and additional spread will occur. As the range and prevalence of CWD increase, so will the potential for human exposure to CWD prions. It is currently unknown if CWD poses a risk to human health. However, determining this risk is critical to preventing a scenario similar to that which occurred when mad cow disease was found to be transmissible to humans. In the present study, we used cynomolgus macaque monkeys as a surrogate model for CWD transmission to humans. After 13 years, no evidence for CWD transmission to macaques was detected clinically or by using highly sensitive prion disease-screening assays.

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