procedures-for-identifying-infectious-prions-after-passage-through

Procedures for Identifying Infectious Prions After Passage Through the Digestive System of an Avian Species

Infectious prion (PrPRes) material is likely the cause of fatal, neurodegenerative transmissible spongiform encephalopathy (TSE) diseases1. Transmission ...

USDA

Cerebrospinal fluid (CSF) has been examined as a possible source for preclinical diagnosis of prion diseases in hamsters and sheep. The present report describes the detection of chronic wasting disease (CWD) in the CSF of elk and evaluates its usefulness as an antemortem test for CWD. The CSF from 6 captive and 31 free-ranging adult elk was collected at necropsy and evaluated for the presence of the abnormal isoform of the prion protein that has been associated with CWD (PrP(CWD)) via protein misfolding cyclic amplification. Additionally, the obex from each animal was examined by immunohistochemistry (IHC). Four out of 6 captive animals were CWD-positive and euthanized due to signs of terminal CWD. The remaining 2 were CWD negative. None of the 31 free-range animals showed overt signs of CWD, but 12 out of 31 tested positive for CWD by IHC. Protein misfolding cyclic amplification detected PrP(CWD) from 3 of the 4 captive animals showing clinical signs of CWD and none of the nonclinical animals that were CWD positive by IHC. The data suggests that CWD prions can be detected in the CSF of elk, but only relatively late in the course of the disease.

Detection of prion protein in the cerebrospinal fluid of elk (Cervus canadensis nelsoni) with chronic wasting disease using protein misfolding cyclic amplification.

Chronic wasting disease (CWD), the only known prion disease endemic in wildlife, is a persistent problem in both wild and captive North American cervid populations. This disease continues to spread and cases are found in new areas each year. Indirect transmission can occur via the environment and is thought to occur by the oral and/or intranasal route. Oral transmission has been experimentally demonstrated and although intranasal transmission has been postulated, it has not been tested in a natural host until recently. Prions have been shown to adsorb strongly to clay particles and upon oral inoculation the prion/clay combination exhibits increased infectivity in rodent models. Deer and elk undoubtedly and chronically inhale dust particles routinely while living in the landscape while foraging and rutting. We therefore hypothesized that dust represents a viable vehicle for intranasal CWD prion exposure. To test this hypothesis, CWD-positive brain homogenate was mixed with montmorillonite clay (Mte), lyophilized, pulverized and inoculated intranasally into white-tailed deer once a week for 6 weeks. Deer were euthanized at 95, 105, 120 and 175 days post final inoculation and tissues examined for CWD-associated prion proteins by immunohistochemistry. Our results demonstrate that CWD can be efficiently transmitted utilizing Mte particles as a prion carrier and intranasal exposure.

Intranasal inoculation of white-tailed deer (Odocoileus virginianus) with lyophilized chronic wasting disease prion particulate complexed to montmorillonite clay.

Chronic wasting disease (CWD) adversely affects both wild and captive cervid populations. A vaccine to prevent CWD would be a highly desirable tool to aid in disease management. To this end, we tested in mule deer a combination of CWD vaccines consisting of cervid prion peptide sequences 168-VDQYNNQNTFVHDC-182 and 145-NDYEDRYYRENMYRYPNQ-164 that had previously been shown to delay onset of clinical disease and increase survival in a mouse-adapted scrapie model. Thirteen captive mule deer (Odocoileus hemionus) were divided into vaccine (n=7) and control groups (n=6), and given prime and boost vaccinations intramuscularly 5 wk apart. Eight weeks postprime (3 wk postboost), all animals were challenged via natural exposure to an environment contaminated with infective CWD prions. Deer were monitored intermittently for prion infection by rectal and tonsil biopsies beginning 275 days postchallenge. All vaccinates responded to both peptide conjugates present in the combination vaccine as measured by enzyme-linked immunosorbent assay. However, all deer eventually became infected regardless of vaccine status.

Immunization with a synthetic peptide vaccine fails to protect mule deer (Odocoileus hemionus) from chronic wasting disease.

Mechanisms for the spread of transmissible spongiform encephalopathy diseases, including chronic wasting disease (CWD) in North American cervids, are incompletely understood, but primary routes include horizontal and environmental transmission. Birds have been identified as potential vectors for a number of diseases, where they ingest or are exposed to infected material and later shed the disease agent in new areas after flying substantial distances. We recently identified American crows (Corvus brachyrhynchos) as having the potential to translocate infectious prions in their feces. Our results suggest that this common, migratory North American scavenger is capable of translocating infectious prions to disease-free areas, potentially seeding CWD infection where no other initial source of pathogen establishment is forthcoming. Here we speculate on the role avian scavengers, like American crows, might play in the spatial dissemination of CWD. We also consider the role mammalian scavengers may play in dispersing prions.

Tracy A Nichols

Animal and Plant Health Inspection Service,
Wildlife Services,
National Wildlife Research Center,
Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center

USDA

Procedures for Identifying Infectious Prions After Passage Through the Digestive System of an Avian Species

Tracy A Nichols

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Animal and Plant Health Inspection Service,Wildlife Services,National Wildlife Research Center,Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center

USDA

Procedures for Identifying Infectious Prions After Passage Through the Digestive System of an Avian Species

Animal and Plant Health Inspection Service,
Wildlife Services,
National Wildlife Research Center,
Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center