CWD Ante-Mortem Testing Symposium Texas Disposal Systems Events Pavilion
January 12, 2016
TEXAS PARKS & WILDLIFE
CWD Ante-Mortem Testing Symposium Texas Disposal Systems Events Pavilion
January 12, 2016
9:00 - 9:15 Welcome - Carter Smith and Dr. Andy Schwartz
Morning Session - Dr. T.R. Lansford (Moderator)
9:15 -10:00 Dr. Mike Miller - Distribution and Progression of Prion
Accumulation in Deer and Elk
10:00 - 10:45 Dr. Nathan Shotts - Retropharyngeal Lymph Node Biopsy
Technique
10:00 - 10:45 Break
11:00 - 11:45 Dr. Mike Miller - Detecting Prion Accumulation in Deer and
Elk via Tonsil or Rectal Mucosa Biopsy
11:45 - 12:30 Dr. Nicholas Haley - Live Animal Test Developments for CWO
12:30 - 1:30 Lunch
Afternoon Session - Clayton Wolf (Moderator)
1:30 - 2:15 Dr. Tracy Nichols - Rectal and Tonsil Biopsy as Ante-mortem
Assay and Experimental Assays
2:15 - 3:30 Dr. Randy Pritchard - Regulatory Impacts and Challenges
3:30 - 3:45 Break
3:45 - 5:30 Panel Discussion - Mary Luedeker (Moderator) - How do we use
these tests?
Lead in with modeling comparing detection probabilities between post-mortem
and ante-mortem testing strategies (Dr. Dan Baca).
Disease in Deer and Elk
Chris Siepker1, Nicholas Haley1, W. David Walter2, Matteo Manca3, Laura
Hoon-Hanks4, Ryan Monello5, Jenny Powers5, Justin Greenlee6 , Bruce Thomsen7 ,
Aaron Lehmkuhl7, Gordon Mitchell8, Tracy Nichols9,Byron Caughey3, Edward
Hoover4, and Juergen Richt1.
1. Department of Diagnostic Medicine and Pathobiology, Kansas State
University, Manhattan KS USA 2. United States G e o l o g i c a l Survey, P e n
n s y l v a n i a Cooperative Fish and Wildlife Research Unit, University Park
PA USA 3. TSE/Prion Biochemistry Section, Rocky Mountain Laboratories, National
Institutes of Health, Hamilton, MT USA 3. Department of MIP, Colorado State
University, Fort Collins CO USA 4. National Park Service, Wildlife Health
Branch, Fort Collins CO USA 5. Virus and Prion Research Unit, National Animal
Disease Center, ARS, USDA, Ames IA USA 6. USDA, APHIS, VS, STAS, National
Veterinary Service Laboratories, Ames IA USA 7. National and OIE Reference
Laboratory for Scrapie and CWD, Canadian Food Inspection Agency, Ottawa ON
Canada 8. National Wildlife Research Center Wildlife Services, APHIS, USDA, Fort
Collins CO USA
Chronic wasting disease (CWD) is an e f f i c i e n t l y t r a n smi t t e
d s p o n g i f o r m encephalopathy of cervids (e.g. deer, elk, and moose), and
is the only known prion disease affecting both free-ranging wildlife and captive
animals. The antemortem detection of CWD and other prion diseases has proven
difficult, due in part to difficulties in identifying an appropriate peripheral
tissue specimen and complications with conventional test sensitivity. At
present, biopsies of the recto-
Prion2015 Program Guide 22
anal mucosal-associated lymphoid tissues (RAMALT) have shown promising
sensitivity and are not impractical to collect in live animals. Nasal brush
collections have likewise proven both sensitive and practical for identification
of prion infections in humans. In this study, we evaluated both RAMALT and nasal
brush collections by real time quaking-induced conversion (RT-QuIC), and
compared our findings to RAMALT immu n o h i s t o c h emi s t r y a s we l l a
s conventional postmortem evaluation of obex and retropharyngeal lymph node
tissues from over 700 captive and free-ranging deer and elk in areas with
endemic CWD. We correlated our results with various clinical findings, including
pathological stage of infection as determined by obex scoring, PrP genotype,
age, and sex. While the sensitivity of RAMALT RT-QuIC analyses exceeded that of
RAMALT IHC (69-80% vs. >44%) and nasal brush collections (15-30%), the
sensitivity of both biopsy and nasal brush analyses were dependent primarily on
clinical stage of disease, although PrP genotype was also an important predictor
of sample positivity. Our findings further demonstrate the potential and
limitations of antemortem sample analyses by RT-QuIC in the identification and
management of prion diseases.
==================
P200 Clinical Stage of Infection is Critical in the Antemortem Diagnosis of
Chronic Wasting Disease in Deer and Elk.
Chris Siepker1, Nicholas Haley1, W. David Walter2, Laura Hoon-Hanks7, Ryan
Monello3, Jenny Powers3, Bruce Thomsen4, Justin Greenlee4, Aaron Lehmkuhl4,
Gordon Mitchell5, Tracy Nichols6, Edward Hoover7, Juergen Richt1
1Department of Diagnostic Medicine and Pathobiology, Kansas State
University, Manhattan, KS, USA, 2United States G e o l o g i c a l Survey, P e n
n s y l v a n i a Cooperative Fish & Wildlife Research Unit, Pennsylvania
State University, University Park, PA 16802, USA, 3National Park Service,
Wildlife Health Branch, Fort Collins, CO, USA, 4USDA, APHIS, VS, STAS, National
Veterinary Service Laboratories, Ames, IA, USA, 5National and OIE Reference
Laboratory for Scrapie and CWD Ottawa Laboratory Fallowfield Canadian Food
Inspection Agency, Ottawa, ON, Canada, 6National Wildlife Research Center
Wildlife Services APHIS, USDA, Fort Collins, CO, USA, 7Department of MIP,
Colorado State University, Fort Collins, CO, USA
Chronic wasting disease (CWD) is an e f f i c i e n t l y t r a n smi t t e
d s p o n g i f o r m encephalopathy of cervids (e.g. deer, elk, and moose), and
is the only known prion disease affecting both free-ranging wildlife and captive
animals. The antemortem detection of CWD and other prion diseases has proven
difficult, due in part to difficulties in identifying an appropriate peripheral
tissue specimen and complications with conventional test sensitivity. At
present, biopsies of the rectoanal mucosal-associated lymphoid tissues (RAMALT)
have shown promising sensitivity and are not impractical to collect in live
animals. Nasal brush collections have likewise proven both sensitive and
practical for identification of prion infections in humans. In this study, we
evaluated both RAMALT and nasal brush collections by real time quaking-induced
conversion (RT-QuIC), and compared our findings to RAMALT immu n o h i s t o c h
emi s t r y a s we l l a s conventional postmortem evaluation of obex and
retropharyngeal lymph node tissues from over 700 captive and free-ranging deer
and elk in areas with endemic CWD. We correlated our results with various
clinical findings, including pathological stage of infection as determined by
obex scoring, PrP genotype, age, and sex. While the sensitivity of RAMALT
RT-QuIC analyses exceeded that of RAMALT IHC (69-80% vs. >44%) and nasal
brush collections (15-30%), the sensitivity of both biopsy and nasal brush
analyses were dependent primarily on clinical stage of disease, although PrP
genotype was also an important predictor of sample positivity. Our findings
further demonstrate the potential and limitations of antemortem sample analyses
by RT-QuIC in the identification and management of prion diseases.
Research Project: Mitigating the Risk of Transmission and Environmental
Contamination of Transmissible Spongiform Encephalopathies Location: Animal
Diseases Research
2015 Annual Report
1a.Objectives (from AD-416): Objective 1: Determine whether goats are a
transmission reservoir for ovine scrapie by developing and validating diagnostic
methods for detecting goat scrapie. Determine the genetic predisposition and
transmission route(s) of goat scrapie.
Subobjective 1.1: Improve eradication efforts by developing improved
methods for antemortem scrapie diagnosis.
Subobjective 1.2: Determine if placenta and milk from goats are potential
sources of scrapie to sheep.
Objective 2: Develop methods to mitigate infectivity of soil-associated
prions by screening soil microbes for potential candidates for bioremediation.
1b.Approach (from AD-416): Scrapie is a complex and rare disorder affecting
outbred farm animals held under a wide variety of husbandry conditions and
exposed to an agent for which the transmissible and pathogenic events remain
largely unknown. The work described in the research plan is an extension of the
previous highly productive studies by this research group, addressing the need
for implementation of federal regulations based on the best available science,
often in the face of relatively small sample numbers in the natural host. The
work includes development of specific management and diagnostic tools and is
presented as an integrated series of research objectives. This approach was
selected over a hypothesis based approach. After consulting Glass and Hall, the
group determined that the work presented in the following plan was best
represented by goal statements rather than hypotheses because the work increases
the density of data necessary for progress and for support of current and
proposed federal regulations. This project addresses only scrapie, the TSE of
sheep and goats. Chronic wasting disease (CWD) is the TSE of North America
cervids (deer and elk). ***No live animal work with CWD is included in this
project plan since CWD is not endemic in Washington State, the disease appears
to be highly communicable, the modes of transmission are unknown, and we do not
have suitable biocontainment facilities to conduct CWD studies in large animals.
3.Progress Report: The National Scrapie Eradication program in the U.S. is
conducted by the state and federal animal disease health regulatory agencies,
with research support by ARS and several land grant universities, in a joint
endeavor with the sheep and goat industries. The comprehensive program of animal
identification, surveillance and genetic selection has resulted in a decrease of
scrapie prevalence by 88%. As prevalence falls, remaining potential sources of
infection will be monitored. The transmissible spongiform encephalopathies (TSE)
project at the Animal Disease Research Unit, Pullman, Washington, includes an
integrated examination of modes of transmission (both intraspecies and
interspecies), diagnostic test development and refinement, and delineation of
species-specific and genetically controlled differences in pathogenesis. In
FY15, progress was reported in each of these research areas.
Objective 1: Transmission of scrapie by placenta, blood and milk. Exposure
of the newborn lamb or kid to infectious prions shed by the postparturient
ewe/doe is probably the most efficient route of transmission in the field. Our
earlier work demonstrated the role of fetal genotype on transmission by the
ovine placenta. In this Fiscal Year (FY), we completed a study demonstrating
that the caprine placenta, while containing sparse amounts of detectable PrP-Sc,
is infectious to lambs and kids by oral exposure. Experimental oral exposure of
lambs and kids to milk from infected does during the first 2 to 3 days of life
was performed last year and the recipient animals are monitored for evidence of
disease. With an incubation period of 24-36 months, the study is expected to
yield useful information in FY16. These studies of experimental disease are
complemented by ongoing observations on transmission in our mixed herd of
infected goats and sheep.
Objective 2: Diagnosis and genetics of the TSEs in ruminant animals: Gold
standard testing of scrapie is performed by immunohistochemistry of formalin
fixed tissues, using lymphoid tissue to detect early disease and brain tissue to
detect advanced disease. Antemortem tissue based testing requires expertise in
the field and in the laboratory. We are completing a study examining the effects
of host and biopsy handling on lymphoid follicle frequency and detection of
PrP-Sc. Similarly, immunohistochemistry has been applied to determine the
effects of these factors on the frequency of observing two major cell types
known to accumulate PrPSc in lymphoid tissues—namely, macrophages and follicular
dendritic cells. These studies will be completed in FY16 and will provide
information on any needed refinements in the antemortem testing of sheep and
goats, with possible application to the evolving program of live animal testing
of captive deer and elk.
Genetic variation among animals within each species affects disease
resistance and incubation time: We have previously reported the effect of
genotype on diagnostic accuracy in white tailed deer. We have now completed a
study examining the role of a prion gene polymorphism at residue 127 in goats on
incubation time (reported in accomplishments) and in FY16 will perform studies
on diagnostic accuracy of the current testing modes in goats with this genotype.
Polymorphisms at additional sites (146 and 222) have been reported to be
associated with reduced susceptibility to caprine scrapie. Goat kids were
exposed to scrapie by the oral route on day 1 of life and are being monitored.
Goats with the potentially resistant allele have remained clinically normal for
more than 7 years after oral challenge; control goats lacking this allele
developed disease at 2-3 years of age. We will continue to monitor the 222K
goats for their natural lifespan and will perform extensive necropsy
examinations upon termination to determine whether these animals are a benefit
to the industry or represent a long lived source of prions in goat herds. The
polymorphism at residue 222, while potentially conferring resistance to scrapie,
also presents a diagnostic challenge. Residue 222 is included in the epitope
recognized by the monoclonal antibody used in gold standard diagnostic testing
in the U.S. We have reported the effect of this polymorphism on test sensitivity
(reported in accomplishments). We have previously reported that this
polymorphism is rare in U.S. goats, but in the current work, we presented some
alternatives to testing should this genotype be selected by breeders in the
future.
Examination of the prion distribution in fixed tissues is the basis for
diagnostic testing. In addition, the distribution and intensity of the
immunohistochemical staining are also useful indirect measures of disease
progression. We have reported this effect in our studies of genetics and
diagnosis of chronic wasting disease in white tailed deer. We have now extended
those studies to include Rocky Mountain elk, which have a unique prion
distribution pattern. We continue to work with state and federal agencies
monitoring the effects of genotype on prion disease captive and free-ranging
Rocky Mountain elk, as components of species-specific control programs.
While antemortem and postmortem tissue-based testing is sensitive and
specific, collection of tissues is inconvenient and testing is expensive.
Development of a blood based test might alleviate those problems. We are
conducting a systematic examination of prion-bearing cell types in sheep and
goats and have reported that all three major types of peripheral blood
mononuclear cells—B lymphocytes, T lymphocytes, and monocytes, can harbor prions
and are thus reasonable targets on which to base development of a diagnostic
platform for use during preclinical infection. We have recently reported that
relatively small amounts of blood contain infectious prions and continue to
examine methods for more sensitive and specific detection of PrP-Sc in
circulating cells.
Objective 3: Introduction of disease by novel routes: While direct contact
with prion-bearing tissues remains the most likely source of infection in sheep
and goats, the introduction of disease through fomites or through contact with
other species has not been ruled out. We originally intended to examine the role
of soil or premise contamination with prions after removal of infected sheep.
However, the success of the eradication program at reducing scrapie prevalence
to nearly undetectable levels over a relatively short amount of time suggests
that environmental routes are not highly efficient. ***However, prevalence of
chronic wasting disease in farmed and free-ranging cervids continues to climb
and as the disease is discovered in an increasing number of states and
provinces, the threat of transmission to sheep remains under investigation. In
conjunction with the Canadian Food Inspection Agency, we are completing a study
delineating methods for discriminating between a TSE of ovine and cervid origin
in sheep, using both conventional in vitro prion characterization methods and in
vivo studies with a panel of transgenic mice. The study will be concluded in
FY16; preliminary findings show differences in incubation time and molecular
folding patterns that may be useful in determining the origin of TSEs of sheep
in the CWD endemic zones.
In a continued effort to reduce research dependence on bioassay, work
continued on the creation of cultured cell lines with robust permissiveness to
natural isolates of prions. Work continued on the immortalization of caprine
microglia cell lines with different prion genotypes of interest. Studies also
continued in the optimization of the scrapie permissiveness of a caprine prion
protein-transfected rabbit kidney epithelial cell line. Factors associated with
cellular permissiveness to infection were also determined in a study that
compared the transcriptomes of clones from an immortalized ovine microglia cell
line but that differ greatly in permissiveness to natural source isolates (i.e.,
hindbrain) of classical scrapie prions.
4.Accomplishments 1. The placenta of goats with scrapie is infectious to
goat kids and lambs. The placenta of sheep is a highly infectious source of
scrapie prions and is well known to play a major role in natural transmission.
Goats, too, are a natural host of classical scrapie and are frequently raised
with sheep, but the potential routes of natural transmission from goats to sheep
have not been studied. ARS researchers at the Animal Disease Research Unit in
Pullman, Washington, have now demonstrated that the placenta shed from a goat,
despite its relatively sparse accumulation of the disease-associated form of the
prion protein, is infectious to newborn lambs and goat kids by oral exposure.
This accomplishment provides a scientific basis for regulatory and veterinary
consideration as to the possible modes of transmission risk of scrapie from
goats to sheep.
2. Prions were detected in small volume blood samples obtained from sheep
with preclinical scrapie. Initial studies that demonstrated the potential for
developing a blood-based live animal diagnostic test for classical scrapie in
sheep were based on blood sample volumes many times more than routinely used in
the practice of veterinary medicine. ARS researchers at the Animal Disease
Research Unit in Pullman, Washington, have now demonstrated that infectious
prions can be detected from much smaller blood sample volumes, even during
preclinical infection. This study supports further development of a safe and
highly efficient blood-based diagnostic test for preclinical scrapie infection
in sheep. It demonstrates the utility of using the small blood sample volumes
already routinely collected for diagnostic purposes.
3. A prion gene polymorphism that prolongs scrapie incubation in goats.
Scrapie eradication in sheep is based in part on strong genetic resistance to
classical scrapie infection. However, knowledge regarding the implications of
differing genotypes in goats is incomplete. ARS researchers at the Animal
Disease Research Unit in Pullman, Washington, have now demonstrated that the
appearance of clinical signs associated with scrapie can be significantly
delayed in goats with a prion gene polymorphism at codon 127. This
accomplishment helps explain why goats with this polymorphism may be
underrepresented in surveys of scrapie infected goat herds. Additionally, this
accomplishment suggests that scrapie eradication programs might need to include
longer trace-back histories when investigating scrapie-exposed goats of this
genotype.
4. A prion gene polymorphism that reduces the sensitivity of some
diagnostic tests for caprine scrapie. Gold standard diagnostic testing for
caprine scrapie is performed by monoclonal antibody immunohistochemistry. While
this assay is highly specific, the sensitivity of the assay is limited by the
use of a single monoclonal antibody directed to a variable portion of the prion
molecule. ARS researchers at the Animal Disease Research Unit in Pullman,
Washington, have confirmed that the monoclonal antibody currently used for
testing in the U.S. fails to detect prions in goats homozygous for a prion
polymorphism at codon 222. The study was performed by developing a digital image
segmentation and analysis algorithm to objectively measure spatially diverse
PrPSc accumulation profiles in the hindbrain of goats with naturally acquired
classical scrapie. Comparisons were also made under the standardized conditions
and reagents currently utilized by regulatory agencies. This accomplishment
provides the scientific basis for modification of the assay should this prion
genotype become more prevalent in the U.S. goat herd.
***5. Delineation of the progression of abnormal prion accumulation in the
brain of elk with chronic wasting disease. Diagnostic testing for the
transmissible spongiform encephalophathies (TSE) of elk is performed by
examination of a single section of brain, using a monoclonal antibody that
detects the abnormal prion protein. Collaborative research including scientists
from the Colorado State University Diagnostic Laboratory, the U.S. Department of
Agriculture Animal Health Inspection Service, the Canadian Food Inspection
Agency, and the ARS Animal Disease Research Unit in Pullman, Washington, has
demonstrated that the abnormal prion in this section of brain has a unique and
relatively consistent pattern of accumulation as disease progresses. The study
complements the earlier work performed by ARS and others on the effect of prion
genotype on disease progression in elk and in white tailed deer. The scoring
system described in these studies may be useful for estimating prion
distribution throughout the infected animal and potentially for estimating the
duration of infection, facilitating epidemiologic studies in infected herds.
Review Publications Schneider, D.A., Madsen-Bouterse, S.A., Zhuang, D.,
Truscott, T.C., Dassanayake, R.P., O'Rourke, K.I. 2015. The placenta shed from
goats with classical scrapie is infectious to goat kids and lambs. Journal of
General Virology. doi: 10.1099/vir.0.000151.
Munoz-Gutierrez, J.F., Schneider, D.A., Baszler, T.V., Dinkel, K.D.,
Greenlee, J.J., Nicholson, E.M., Stanton, J.J. 2015. hTERT-immortalized ovine
microglia propagate natural scrapie isolates. Virus Research. 198:35-43.
Dassanayake, R.P., White, S.N., Madsen-Bouterse, S.A., Schneider, D.A.,
O'Rourke, K.I. 2015. Role of PRNP S127 allele in experimental goat infection
with classical caprine scrapie. Animal Genetics. doi: 10.1111/age.12291.
Dassanayake, R.P., Truscott, T.C., Zhuang, D., Schneider, D.A.,
Madsen-Bouterse, S.A., Young, A.J., Stanton, J.B., Davis, W.C., O’Rourke, K.I.
2015. Classical natural ovine scrapie prions are detected in practical volumes
of blood by lamb and transgenic mouse bioassay. Journal of Veterinary Science.
16(2):179-186.
Madsen-Bouterse, S.A., Schneider, D.A., Dassanayake, R.P., Truscott, T.C.,
Zhuang, D., Kumpula-Mcwhirter, N., O'Rourke, K.I. 2015. PRNP variants in goats
reduce sensitivity of detection of PrPSc by immunoassay. Journal of Veterinary
Diagnostic Investigation. 27(3):332-343.
Spraker, T.R., Gidlewski, T., Powers, J.G., Nichols, T., Balachandran, .A.,
Cummins, B., Wild, M.A., Vercauteren, K., O'Rourke, K. 2015. Progressive
accumulation of the abnormal conformer of the prion protein and spongiform
encephalopathy in the obex of nonsymptomatic and symptomatic Rocky Mountain elk
(Cervus elaphus nelsoni) with chronic wasting disease. Journal of Veterinary
Diagnostic Investigation. doi: 10.117/1040638715593368.
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES Title: Antemortem detection of chronic
wasting disease prions in nasal brush collections and rectal biopsies from
white-tailed deer by real time quaking-induced conversion
Authors
item Haley, Nicholas - item Siepker, Chris - item Walter, W. David - item
Thomsen, Bruce - item Greenlee, Justin item Lehmkuhl, Aaron - item Richt, Jürgen
-
Submitted to: Journal of Clinical Microbiology Publication Type: Peer
Reviewed Journal Publication Acceptance Date: November 27, 2015 Publication
Date: N/A
Interpretive Summary: Chronic Wasting Disease (CWD), a fatal
neurodegenerative disease that occurs in farmed and wild cervids (deer and elk)
of North America, is a transmissible spongiform encephalopathy (TSE). TSEs are
caused by infectious proteins called prions that are resistant to various
methods of decontamination and environmental degradation. Early diagnosis of CWD
in wild and captive herds would be very helpful to controlling the spread of
CWD, for which there are not yet any preventative or treatment measures
available. The purpose of this study was to test a laboratory method of prion
detection (real-time Quaking Induced Conversion; RT-QuIC) that has the potential
to detect very low levels of infectious prions in samples collected from live
animals against the gold standard diagnostic where abnormal prion in tissues is
stained on a microscope slide. This study reports that RT-QuIC detects more
cases of CWD than standard methods, but also can identify a small number of
animals without CWD as being positive. In the case of CWD, where it is likely
that large numbers of animals within a herd may be positive, misidentifying a
negative as a positive may have less of an impact than in the case of other
prion diseases such as bovine spongiform encephalopathy considering that this
test allows testing much larger numbers of samples with a faster turn around
time than traditional methods. This information could have an impact on
regulatory and wildlife officials developing plans to reduce or eliminate CWD
and cervid farmers that want to ensure that their herd remains CWD-free.
Technical Abstract: Chronic wasting disease (CWD), a transmissible spongiform
encephalopathy of cervids, was first documented nearly fifty years ago in
Colorado and Wyoming and has since spread to cervids in 23 states, 2 Canadian
provinces, and the Republic of Korea. The increasing expansion of this disease
makes the development of sensitive diagnostic assays and antemortem sampling
techniques crucial for the mitigation of spread; this is especially true in
cases of relocation/reintroduction of farmed or free-ranging deer and elk, or
surveillance studies in private or protected herds where depopulation may be
contraindicated. This study sought to evaluate the sensitivity of the real-time
quaking-induced conversion (RT-QuIC) assay in samples collected antemortem.
Antemortem findings were then compared to results from ante- and postmortem
samples evaluated using the current gold standard diagnostic assay,
immunohistochemistry (IHC). Recto-anal mucosal associated lymphoid tissue
(RAMALT) biopsies and nasal brush collections from three separate herds of
farmed white-tailed deer (n=409) were evaluated, along with standard postmortem
microscopic analysis of brainstem at the level of the obex and retropharyngeal
lymph nodes. We hypothesized the sensitivity of RT-QuIC would be comparable to
IHC in antemortem tissues, and would correlate with both genotype and stage of
clinical disease. ***Our results showed that RAMALT testing by RT-QuIC had the
highest sensitivity (69.8%) when compared to postmortem testing. This data
suggests that RT-QuIC, like IHC, is a fairly sensitive assay for detection of
CWD prions in rectal biopsies and other antemortem samples, and with further
investigation has potential for large scale and rapid automated testing for CWD
diagnosis.
Research Project: Transmission, Differentiation, and Pathobiology of
Transmissible Spongiform Encephalopathies 2015 Annual Report
1a.Objectives (from AD-416): 1. Investigate the pathobiology of atypical
transmissible spongiform encephalopathies (TSEs) in natural hosts. A.
Investigate the pathobiology of atypical scrapie. B. Investigate the
pathobiology of atypical bovine spongiform encephalopathy (BSE). 2. Investigate
the horizontal transmission of TSEs. A. Assess the horizontal transmission of
sheep scrapie in the absence of lambing. B. Determine routes of transmission in
chronic wasting disease (CWD) infected premises. C. Assess oral transmission of
CWD in reindeer. 3. Investigate determinants of CWD persistence. A. Determine
CWD host range using natural routes of transmission. B. Investigate the
pathobiology of CWD.
1b.Approach (from AD-416): The studies will focus on three animal
transmissible spongiform encephalopathy (TSE) agents found in the United States:
bovine spongiform encephalopathy (BSE); scrapie of sheep and goats; and chronic
wasting disease (CWD) of deer, elk, and moose. The research will address sites
of accumulation, routes of infection, environmental persistence, and ante mortem
diagnostics with an emphasis on controlled conditions and natural routes of
infection. Techniques used will include clinical exams, histopathology,
immunohistochemistry and biochemical analysis of proteins. The enhanced
knowledge gained from this work will help mitigate the potential for
unrecognized epidemic expansions of these diseases in populations of animals
that could either directly or indirectly affect food animals.
3.Progress Report: Research efforts directed toward meeting objective 1 of
our project plan include work in previous years starting with the inoculation of
animals for studies designed to address the pathobiology of atypical scrapie,
atypical bovine spongiform encephalopathy (BSE), as well as a genetic version of
BSE. Post-mortem examination of the animals inoculated with atypical scrapie has
been initiated and laboratory analysis of the tissues is ongoing. Atypical BSE
animals have developed disease and evaluation of the samples is currently
underway. Animals inoculated with a genetic version of BSE have developed
disease with a manuscript reporting these results was published (2012), and
additional laboratory comparisons of genetic BSE to atypical and classical BSE
are ongoing. In addition, we have investigated the possibility that atypical
scrapie was present earlier than previously detected in the national flock by
analyzing archived field isolates using methods that were unavailable at the
time of original diagnosis. Sample quality was sufficiently degraded that modern
methods, beyond those applied to the tissues at the time the tissues were
archived, were not suitable for evaluation. In research pertaining to objective
2, "Investigate the horizontal transmission of TSEs", we have initiated a study
to determine if cohousing non-lambing scrapie inoculated sheep is sufficient to
transmit scrapie to neonatal lambs. At this time, scrapie free ewes have lambed
in the presence of scrapie inoculated animals and the lambs are cohoused with
these inoculated animals.
4.Accomplishments 1. Changes in retinal function in cattle can be used to
identify different types of bovine spongiform encephalopathy (BSE). BSE belongs
to a group of fatal, transmissible protein misfolding diseases known as
transmissible spongiform encephalopathies (TSEs). Like other protein misfolding
diseases including Parkinson's disease and Alzheimer's disease, TSEs are
generally not diagnosed until the onset of disease after the appearance of
unequivocal clinical signs. As such, identification of the earliest clinical
signs of disease may facilitate diagnosis. The retina is the most accessible
part of the central nervous system. ARS scientist in Ames IA described
antemortem changes in retinal function and thickness that are detectable in BSE
inoculated animals up to 11 months prior to the appearance of any other signs of
clinical disease. Differences in the severity of these clinical signs reflect
the amount of PrPSc accumulation in the retina and the resulting inflammatory
response of the tissue. These results are the earliest reported clinical signs
associated with TSE infection and provide a basis for understanding the
pathology and evaluating therapeutic interventions. Further, this work shows
that High-type BSE and classical BSE can be differentiated by eye examination
alone, the first time BSE strains have been differentiable in a live animal.
2. Sheep genetics influences the susceptibility of sheep to scrapie. Sheep
scrapie is a transmissible spongiform encephalopathy that can be transmitted
between affected animals resulting in significant economic losses in affected
flocks. The prion protein gene (PRNP) profoundly influences the susceptibility
of sheep to the scrapie agent and the tissue levels and distribution of PrPSc in
affected sheep. In this study, sheep of 3 different prion genetic types (denoted
VRQ/VRQ, VRQ/ARR and ARQ/ARR) were inoculated and subsequently euthanized upon
onset of disease. Disease aspects were uniform across genotypes and consistent
with manifestations of classical scrapie. Mean survival time differences were
associated with the genetic type such that VRQ/VRQ sheep survived 18 months,
whereas VRQ/ARR and ARQ/ARR sheep survived 60 and 56 months, respectively.
Microscopic evaluation revealed similar accumulations in central nervous system
tissues regardless of host genetic type. PrPSc in lymphoid tissue was
consistently abundant in VRQ/VRQ, present but confined to tonsil or
retropharyngeal lymph node in 4/5 VRQ/ARR, and totally absent in ARQ/ARR sheep.
The results of this study demonstrate the susceptibility of sheep with the
ARQ/ARR genotype to scrapie by the intracranial inoculation route with PrPSc
accumulation in CNS tissues, but prolonged incubation times and lack of PrPSc in
lymphoid tissue. These results are important for science based policy with
regard to testing of sheep for scrapie where some live animal testing is
conducted using lymphoid tissues which would not detect scrapie in some specific
genetic types which could limit the national scrapie eradication program.
Review Publications Greenlee J.J. 2014. The prion diseases of animals. In:
McManus, L.M., Mitchell, R.N., editors. Pathobiology of Human Disease. San
Diego: Elsevier. p. 1124-1133.
Greenlee, J.J., Kunkle, R.A., Richt, J.A., Nicholson, E.M., Hamir, A.N.
2014. Lack of prion accumulation in lymphoid tissues of PRNP ARQ/ARR sheep
intracranially inoculated with the agent of scrapie. PLoS One. 9(9):e108029.
Greenlee, J.J., West Greenlee, M.,H. 2015. The transmissible spongiform
encephalopathies of livestock. ILAR Journal. 56(1):7-25.
Munoz-Gutierrez, J.F., Schneider, D.A., Baszler, T.V., Dinkel, K.D.,
Greenlee, J.J., Nicholson, E.M., Stanton, J.J. 2015. hTERT-immortalized ovine
microglia propagate natural scrapie isolates. Virus Research. 198:35-43.
Nicholson, E.M. 2015. Detection of the disease-associated form of the prion
protein in biological samples. Bioanalysis. 7(2):253-261.
West Greenlee, M.H., Smith, J.D., Platt, E.M., Juarez, J.R., Timms, L.L,
Greenlee, J.J. 2015. Changes in retinal function and morphology are early
clinical signs of disease in cattle with bovine spongiform encephalopathy. PLoS
ONE. 10(3):e0119431.
Comoy, E.E., Mikol, J., Luccantoni-Freire, S., Correia, E.,
Lescoutra-Etchegaray, N., Durand, V., Dehen, C., Andreoletti, O., Casalone, C.,
Richt, J.A., Greenlee, J.J., Baron, T., Benestad, S., Brown, P., Deslys, J.
2015. Transmission of scrapie prions to primate after an extended silent
incubation period. Scientific Reports. 5:11573.
DOI: 10.7589/2014-12-284 Journal of Wildlife Diseases, 51(4), 2015, pp.
801–810 # Wildlife Disease Association 2015
AGE AND REPEATED BIOPSY INFLUENCE ANTEMORTEM PRPCWD TESTING IN MULE DEER
(ODOCOILEUS HEMIONUS) IN COLORADO, USA
Chris Geremia,1,6,7 Jennifer A. Hoeting,2 Lisa L. Wolfe,3 Nathan L.
Galloway,4 Michael F. Antolin,4 Terry R. Spraker,5 Michael W. Miller,3 and N.
Thompson Hobbs1
1 Natural Resource Ecology Laboratory, Graduate Degree Program in Ecology,
1499 Campus Delivery, Colorado State University, Fort Collins, Colorado, 80523,
USA 2 Department of Statistics, 1877 Campus Delivery, Colorado State University,
Fort Collins, Colorado 80523, USA 3 Colorado Division of Parks
andWildlife,Wildlife Health Program, 4330 Laporte Avenue, Fort Collins, Colorado
80521,USA 4 Department of Biology, 1878 Campus Delivery, Colorado State
University, Fort Collins, Colorado 80523, USA 5 Colorado State Diagnostics
Laboratory, College of Veterinary Medicine, Colorado State University, Fort
Collins, Colorado 80523, USA 6 Current address: Yellowstone Center for
Resources, P.O. Box 168, Yellowstone National Park, Mammoth Hot Springs, Wyoming
82190, USA 7 Corresponding author (email: chris_geremia@nps.gov)
ABSTRACT: Biopsy of rectal mucosa–associated lymphoid tissue provides a
useful, but imperfect, live-animal test for chronic wasting disease (CWD) in
mule deer (Odocoileus hemionus). It is difficult and expensive to complete these
tests on free-ranging animals, and wildlife health managers will benefit from
methods that can accommodate test results of varying quality. To this end, we
developed a hierarchical Bayesian model to estimate the probability that an
individual is infected based on test results. Our model was estimated with the
use of data on 210 adult female mule deer repeatedly tested during 2010214. The
ability to identify infected individuals correctly declined with age and may
have been influenced by repeated biopsy. Fewer isolated lymphoid follicles
(where PrPCWD accumulates) were obtained in biopsies of older deer and the
proportion of follicles showing PrPCWD was reduced. A deer’s genotype in the
prion gene (PRNP) also influenced detection. At least five follicles were needed
in a biopsy to assure a 95%accurate test in PRNP genotype 225SS deer.
Key words: Bayesian, capture–mark–recapture, chronic wasting disease, mule
deer, prion, test sensitivity.
snip...
DISCUSSION
Reliably detecting prion infection inmule deer requires some consideration
of sample quality. Our findings resemble earlier work suggesting examination of
at least nine lymphoid follicles in a tonsil biopsy might be necessary to
determine CWD status in mule deer accurately (Wolfe et al. 2002).We found that
examining five follicles in a rectal biopsy of 225SS mule deer, regardless of
age, should ensure 95% probability of an accurate test; negative results were
less conclusive for deer genotypes including phenylalanine (225SF, 225FF).
Importantly, examining fewer follicles providedmeaningful, but less certain
information about the disease status of the individual. For example, fewer than
five follicles were observed in 13 of 31 (42%) tests on animals that were
confirmed PrPCWD negative postmortem. These less-conclusive live tests ensured
61% probability of the correct result when one follicle was obtained, and
increased to 82% with two follicles, 91% with three, and 94% with four.
Likewise, we encountered four apparent false-negative results in 225SS deer. In
each case, we could not ensure a 95% accurate test based on deer
FIGURE 5. Sum of positive and negative lymphoid follicles detected in
rectal-anal mucosa tissue by age in known chronic wasting disease positive
female mule deer (Odocoileus hemionus) that were annually captured and tested
for chronic wasting disease in north-central Colorado, USA during 2010–14.
FIGURE 6. Probabilities of a false-negative test by age for total lymphoid
follicles (positive and negative combined) obtained in a rectal-anal mucosa
tissue biopsy estimated from a Bayesian model fit to data on female mule deer
(Odocoileus hemionus) that were annually captured and tested for chronic wasting
disease (CWD) in north-central Colorado, USA during 2010–14. Horizontal lines at
0.01 and 0.05 correspond to 0.99 and 0.95 probability of detecting CWD when
animal is CWD positive, respectively.
GEREMIA ET AL.—AGE AND CWD TESTING OF LIVE ANIMALS 807
age and numbers of follicles in biopsies.
Rarely have individual animals infected with prion disease been repeatedly
tested after a positive test. Instead, infected animals have generally been
presumed to remain positive if retested because postmortem exams have confirmed
their infection status (e.g.,Wolfe et al. 2007; Gona´ lez et al. 2008). This
belief appears well-founded based on evidence that prion diseases are
progressive and that the proportion of positive lymphoid follicles increases
over the course of infection (e.g., Fox et al. 2006). Given this
well-established pattern, we were surprised that nearly half of the follow-up
biopsies collected fromdeer that had already yielded a positive biopsy were
negative.
Repeated biopsy of the rectal mucosa may have given rise to these
false-negative tests. Isolated lymphoid follicles show dynamic properties,
including de novo formation in adult animals (Lorenz et al. 2003).
Gut-associated lymphoid tissue serves a variety of mucosal barrier defense
functions, and isolated lymphoid follicles have been suggested to play a role in
mucosal repair (Sipos et al. 2010). If the damage resulting from a biopsy
stimulated new isolated lymphoid follicles to form in adjacent rectal mucosa,
then the follicles available for subsequent sampling would be a mix of newer and
older follicles. Because new follicles (#12 mo old) would not have the same
opportunity for prion accumulation as older follicles, their presence in nearby
spans of mucosa could dilute or supplant the IHC-positive follicle pool in
subsequent samples even as PrPCWD accumulation progressed unabated in static
lymphoid structures that remain undisturbed. This phenomenon could explain the
static or declining proportion of positive follicles observed in biopsies from
some infected individuals that were repeatedly sampled (Fig. 4) as well as the
pattern of increasing follicle counts in repeatedly sampled individuals in the
face of aging (Fig. 3). If isolated lymphoid follicle formation occurs in
response to rectal mucosa biopsy, then repeated sampling could lower the
likelihood of detecting infected animals, particularly in individuals
genetically inclined toward more gradual disease progression. Alternatively, we
implicitly assumed no laboratory errors occurred in the processing of biopsy
samples. However, because three of the four false-negative cases came from the
same year’s IHC accession, we cannot preclude the possibility of a systematic
error somewhere in the course of testing.
The decline in the proportion of isolated lymphoid follicles showing PrPCWD
in older deer did not appear to be solely the result of repeated testing and
associated disruption of tissue structure. Among eight deer that were biopsy
positive on first testing, the proportion of follicles showing PrPCWD in
122-yr-old deer was 100% (n52), whereas proportions ranged from 27% to 100%
(mean of proportions 63%) in $3-yr-old deer (n56). We speculate that the higher
proportion of positive follicles in young mule deer may result from greater
activity in the immature lymphatic system or greater exposure because of close
association with an infected dam or contaminated environment. Regardless of
whether the foregoing observations were an artifact of small sample size, in the
absence of repeated biopsy, age appeared to decrease ability to detect infection
because fewer isolated lymphoid follicles were obtained in biopsies of older
deer.
Every test sample is not the same; each individual exhibits unique
variation, and the technique for estimating CWD infection that we developed here
can account for some of these complications. Disease status becomes a
probabilistic statement conditioned on the current test result, previous disease
status, and infection and test sensitivity probabilities. Therefore, uncertainty
in sampling becomes incorporated into the placement of individuals into discrete
disease categories. This step forward allows us to make explicit probabilistic
statements
808 JOURNAL OF WILDLIFE DISEASES, VOL. 51, NO. 4, OCTOBER 2015
about whether an individual is infected and the chance that a test result
is correct. With CWD, rather than conclude that an individual is not infected
based on a test with few follicles or decide that the test was inconclusive, we
can now state the probability that an individual is truly infected.
Consequently, we can make conclusions that “a 90% chance exists that this
deer is not infected, based on the results.” Surveillance and containment
programs for CWD benefit from an ability to diagnose animals correctly with the
use of antemortem tests. Our model can easily be applied to surveillance on mule
deer, facilitating use of all available samples regardless of total follicle
counts. Probabilistic estimates of the infection status of each tested
individual could then be used to provide 95% credible intervals of population
prevalence that account for differences in test quality. Our model is robust to
differences in population prevalence except when prevalence is low (e.g.,
,0.02%), because the detection and infection parameters become
inestimable.
When planning surveillance in areas where disease may not occur, we
recommend assuming values for the test detection parameters to allow for
estimation of population prevalence. Our approach also has application to CWD
screening for transport of wild or captive deer or targeted culling efforts.
Individuals could be identified that require additional testing to confirm
disease status with desired levels of certainty, although our approach cannot
account for misdiagnosing deer in early stages of infection when PrPCWD is
undetectable (Wolfe et al. 2002, 2007). In light of our findings, further
attention to the potential for repeated sampling to lower the probability of
detecting infection via rectal mucosa biopsy appears warranted before such
approaches are substituted for more conventional surveillance that relies on
samples collected postmortem.
CHRONIC WASTING DISEASE CWD TSE PRION AKA MAD COW TYPE DISEASE
Friday, January 01, 2016
Bayesian Modeling of Prion Disease Dynamics in Mule Deer Using Population
Monitoring and Capture-Recapture Data
Chris Geremia, Michael W. Miller, Jennifer A. Hoeting, Michael F. Antolin,
N. Thompson Hobbs PLOS x Published: October 28, 2015 DOI:
10.1371/journal.pone.0140687
Abstract
Epidemics of chronic wasting disease (CWD) of North American Cervidae have
potential to harm ecosystems and economies. We studied a migratory population of
mule deer (Odocoileus hemionus) affected by CWD for at least three decades using
a Bayesian framework to integrate matrix population and disease models with
long-term monitoring data and detailed process-level studies. We hypothesized
CWD prevalence would be stable or increase between two observation periods
during the late 1990s and after 2010, with higher CWD prevalence making deer
population decline more likely. The weight of evidence suggested a reduction in
the CWD outbreak over time, perhaps in response to intervening harvest-mediated
population reductions. Disease effects on deer population growth under current
conditions were subtle with a 72% chance that CWD depressed population growth.
With CWD, we forecasted a growth rate near one and largely stable deer
population. Disease effects appear to be moderated by timing of infection,
prolonged disease course, and locally variable infection. Long-term outcomes
will depend heavily on whether current conditions hold and high prevalence
remains a localized phenomenon.
Discussion
The protracted time-scale of the CWD outbreak is much longer than the
timespan of our research, which limits our ability to identify the true
explanation of our findings. Nonetheless, our research suggests that, at least
for the foreseeable future (e.g., decades), mule deer populations sharing the
overall survival and infection probabilities estimated from our analyses may
persist but likely will not thrive where CWD becomes established as an endemic
infectious disease.
‘’Nonetheless, our research suggests that, at least for the foreseeable
future (e.g., decades), mule deer populations sharing the overall survival and
infection probabilities estimated from our analyses may persist but likely will
not thrive where CWD becomes established as an endemic infectious disease. ‘’
*** Bayesian Modeling of Prion Disease Dynamics in Mule Deer Using
Population Monitoring and Capture-Recapture Data
‘’Mountain lions prey selectively on CWD infected deer [33] and CWD could
result in an abundance of vulnerable prey, thereby enhancing mountain lion
survival and reproduction [20].’’
please see ;
‘’preliminary results suggesting that bobcats (Lynx rufus) may be
susceptible to white-tailed deer (Odocoileus virginianus) chronic wasting
disease agent.’’
references on Feline Spongiform Encephalopathy FSE toward the bottom, see ;
Assessing Transmissible Spongiform Encephalopathy Species Barriers with an
In Vitro Prion Protein Conversion Assay
Tuesday, December 15, 2015
Chronic Wasting Disease will cause a Wyoming deer herd to go virtually
extinct in 41 years, a five-year study predicts
Study: Chronic Wasting Disease kills 19% of deer herd annually
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
***Title: Transmission of chronic wasting disease to sentinel reindeer
(Rangifer tarandus tarandus)
Authors
item Moore, S - item Kunkle, Robert item Nicholson, Eric item Richt,
Juergen item Hamir, Amirali item Waters, Wade item Greenlee, Justin
Submitted to: American College of Veterinary Pathologists Meeting
Publication Type: Abstract Only Publication Acceptance Date: August 12, 2015
Publication Date: N/A
Technical Abstract:
Chronic wasting disease (CWD) is a naturally-occurring, fatal
neurodegenerative disease of North American cervids. Reindeer (Rangifer tarandus
tarandus) are susceptible to CWD following oral challenge, but CWD has not been
reported in free-ranging caribou (Rangifer tarandus caribou) or farmed reindeer.
Potential contact between CWD-affected cervids and Rangifer species that are
free-ranging or co-housed on farms presents a potential risk of CWD
transmission. The aims of this study were to 1) investigate the transmission of
CWD from white-tailed deer (Odocoileus virginianus; CWD-wtd), mule deer
(Odocoileus hemionus; CWD-md), or elk (Cervus elaphus nelsoni; CWD-elk) to
reindeer via the intracranial route, and 2) to assess for direct and indirect
horizontal transmission to non-inoculated sentinels. Three groups of 5 reindeer
fawns were challenged intracranially with CWD-wtd, CWD-md, or CWD-elk. Two years
after challenge of inoculated reindeer, non-inoculated control reindeer were
introduced into the same pen as the CWD-wtd inoculated reindeer (n=4) or into a
pen adjacent to the CWD-md inoculated reindeer (n=2). Reindeer were allowed to
develop clinical disease. At death/euthanasia a complete necropsy examination
was performed, including immunohistochemical testing of tissues for
disease-associated CWD prion protein (PrP-CWD). Intracranially challenged
reindeer developed clinical disease from 21 months post-inoculation (MPI).
PrP-CWD was detected in 5/6 sentinel reindeer although only 2/6 developed
clinical disease during the study period (<57 div="" mpi="">
***We have shown that reindeer are susceptible to CWD from various cervid
sources and can transmit CWD to naive reindeer both directly and indirectly.
Last Modified: 12/3/2015
***PrP-CWD was detected in 5/6 sentinel reindeer although only 2/6
developed clinical disease during the study period (<57 div="" mpi="">
***We have shown that reindeer are susceptible to CWD from various cervid
sources and can transmit CWD to naive reindeer both directly and indirectly.
Tuesday, September 29, 2015
*** Transmission of chronic wasting disease to sentinel reindeer (Rangifer
tarandus tarandus) can transmit CWD to naive reindeer both directly and
indirectly
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
*** Infectious agent of sheep scrapie may persist in the environment for at
least 16 years ***
Gudmundur Georgsson1, Sigurdur Sigurdarson2 and Paul Brown3
*** Spraker suggested an interesting explanation for the occurrence of CWD.
The deer pens at the Foot Hills Campus were built some 30-40 years ago by a Dr.
Bob Davis. At or abut that time, allegedly, some scrapie work was conducted at
this site. When deer were introduced to the pens they occupied ground that had
previously been occupied by sheep.
PL1
Using in vitro prion replication for high sensitive detection of prions and
prionlike proteins and for understanding mechanisms of transmission.
Claudio Soto
Mitchell Center for Alzheimer's diseases and related Brain disorders,
Department of Neurology, University of Texas Medical School at Houston.
Prion and prion-like proteins are misfolded protein aggregates with the
ability to selfpropagate to spread disease between cells, organs and in some
cases across individuals. I n T r a n s m i s s i b l e s p o n g i f o r m
encephalopathies (TSEs), prions are mostly composed by a misfolded form of the
prion protein (PrPSc), which propagates by transmitting its misfolding to the
normal prion protein (PrPC). The availability of a procedure to replicate prions
in the laboratory may be important to study the mechanism of prion and
prion-like spreading and to develop high sensitive detection of small quantities
of misfolded proteins in biological fluids, tissues and environmental samples.
Protein Misfolding Cyclic Amplification (PMCA) is a simple, fast and efficient
methodology to mimic prion replication in the test tube. PMCA is a platform
technology that may enable amplification of any prion-like misfolded protein
aggregating through a seeding/nucleation process. In TSEs, PMCA is able to
detect the equivalent of one single molecule of infectious PrPSc and propagate
prions that maintain high infectivity, strain properties and species
specificity. Using PMCA we have been able to detect PrPSc in blood and urine of
experimentally infected animals and humans affected by vCJD with high
sensitivity and specificity. Recently, we have expanded the principles of PMCA
to amplify amyloid-beta (Aβ) and alphasynuclein (α-syn) aggregates implicated in
Alzheimer's and Parkinson's diseases, respectively. Experiments are ongoing to
study the utility of this technology to detect Aβ and α-syn aggregates in
samples of CSF and blood from patients affected by these diseases.
=========================
***Recently, we have been using PMCA to study the role of environmental
prion contamination on the horizontal spreading of TSEs. These experiments have
focused on the study of the interaction of prions with plants and
environmentally relevant surfaces. Our results show that plants (both leaves and
roots) bind tightly to prions present in brain extracts and excreta (urine and
feces) and retain even small quantities of PrPSc for long periods of time.
Strikingly, ingestion of prioncontaminated leaves and roots produced disease
with a 100% attack rate and an incubation period not substantially longer than
feeding animals directly with scrapie brain homogenate. Furthermore, plants can
uptake prions from contaminated soil and transport them to different parts of
the plant tissue (stem and leaves). Similarly, prions bind tightly to a variety
of environmentally relevant surfaces, including stones, wood, metals, plastic,
glass, cement, etc. Prion contaminated surfaces efficiently transmit prion
disease when these materials were directly injected into the brain of animals
and strikingly when the contaminated surfaces were just placed in the animal
cage. These findings demonstrate that environmental materials can efficiently
bind infectious prions and act as carriers of infectivity, suggesting that they
may play an important role in the horizontal transmission of the disease.
========================
Since its invention 13 years ago, PMCA has helped to answer fundamental
questions of prion propagation and has broad applications in research areas
including the food industry, blood bank safety and human and veterinary disease
diagnosis.
see ;
Wednesday, December 16, 2015
Objects in contact with classical scrapie sheep act as a reservoir for
scrapie transmission
Objects in contact with classical scrapie sheep act as a reservoir for
scrapie transmission
Timm Konold1*, Stephen A. C. Hawkins2, Lisa C. Thurston3, Ben C. Maddison4,
Kevin C. Gough5, Anthony Duarte1 and Hugh A. Simmons1
1 Animal Sciences Unit, Animal and Plant Health Agency Weybridge,
Addlestone, UK, 2 Pathology Department, Animal and Plant Health Agency
Weybridge, Addlestone, UK, 3 Surveillance and Laboratory Services, Animal and
Plant Health Agency Penrith, Penrith, UK, 4 ADAS UK, School of Veterinary
Medicine and Science, University of Nottingham, Sutton Bonington, UK, 5 School
of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington,
UK
Classical scrapie is an environmentally transmissible prion disease of
sheep and goats. Prions can persist and remain potentially infectious in the
environment for many years and thus pose a risk of infecting animals after
re-stocking. In vitro studies using serial protein misfolding cyclic
amplification (sPMCA) have suggested that objects on a scrapie affected sheep
farm could contribute to disease transmission. This in vivo study aimed to
determine the role of field furniture (water troughs, feeding troughs, fencing,
and other objects that sheep may rub against) used by a scrapie-infected sheep
flock as a vector for disease transmission to scrapie-free lambs with the prion
protein genotype VRQ/VRQ, which is associated with high susceptibility to
classical scrapie. When the field furniture was placed in clean accommodation,
sheep became infected when exposed to either a water trough (four out of five)
or to objects used for rubbing (four out of seven). This field furniture had
been used by the scrapie-infected flock 8 weeks earlier and had previously been
shown to harbor scrapie prions by sPMCA. Sheep also became infected (20 out of
23) through exposure to contaminated field furniture placed within pasture not
used by scrapie-infected sheep for 40 months, even though swabs from this
furniture tested negative by PMCA. This infection rate decreased (1 out of 12)
on the same paddock after replacement with clean field furniture. Twelve grazing
sheep exposed to field furniture not in contact with scrapie-infected sheep for
18 months remained scrapie free. The findings of this study highlight the role
of field furniture used by scrapie-infected sheep to act as a reservoir for
disease re-introduction although infectivity declines considerably if the field
furniture has not been in contact with scrapie-infected sheep for several
months. PMCA may not be as sensitive as VRQ/VRQ sheep to test for environmental
contamination.
snip...
Discussion
Classical scrapie is an environmentally transmissible disease because it
has been reported in naïve, supposedly previously unexposed sheep placed in
pastures formerly occupied by scrapie-infected sheep (4, 19, 20). Although the
vector for disease transmission is not known, soil is likely to be an important
reservoir for prions (2) where – based on studies in rodents – prions can adhere
to minerals as a biologically active form (21) and remain infectious for more
than 2 years (22). Similarly, chronic wasting disease (CWD) has re-occurred in
mule deer housed in paddocks used by infected deer 2 years earlier, which was
assumed to be through foraging and soil consumption (23).
Our study suggested that the risk of acquiring scrapie infection was
greater through exposure to contaminated wooden, plastic, and metal surfaces via
water or food troughs, fencing, and hurdles than through grazing. Drinking from
a water trough used by the scrapie flock was sufficient to cause infection in
sheep in a clean building. Exposure to fences and other objects used for rubbing
also led to infection, which supported the hypothesis that skin may be a vector
for disease transmission (9). The risk of these objects to cause infection was
further demonstrated when 87% of 23 sheep presented with PrPSc in lymphoid
tissue after grazing on one of the paddocks, which contained metal hurdles, a
metal lamb creep and a water trough in contact with the scrapie flock up to 8
weeks earlier, whereas no infection had been demonstrated previously in sheep
grazing on this paddock, when equipped with new fencing and field furniture.
When the contaminated furniture and fencing were removed, the infection rate
dropped significantly to 8% of 12 sheep, with soil of the paddock as the most
likely source of infection caused by shedding of prions from the
scrapie-infected sheep in this paddock up to a week earlier.
This study also indicated that the level of contamination of field
furniture sufficient to cause infection was dependent on two factors: stage of
incubation period and time of last use by scrapie-infected sheep. Drinking from
a water trough that had been used by scrapie sheep in the predominantly
pre-clinical phase did not appear to cause infection, whereas infection was
shown in sheep drinking from the water trough used by scrapie sheep in the later
stage of the disease. It is possible that contamination occurred through
shedding of prions in saliva, which may have contaminated the surface of the
water trough and subsequently the water when it was refilled. Contamination
appeared to be sufficient to cause infection only if the trough was in contact
with sheep that included clinical cases. Indeed, there is an increased risk of
bodily fluid infectivity with disease progression in scrapie (24) and CWD (25)
based on PrPSc detection by sPMCA. Although ultraviolet light and heat under
natural conditions do not inactivate prions (26), furniture in contact with the
scrapie flock, which was assumed to be sufficiently contaminated to cause
infection, did not act as vector for disease if not used for 18 months, which
suggest that the weathering process alone was sufficient to inactivate prions.
PrPSc detection by sPMCA is increasingly used as a surrogate for
infectivity measurements by bioassay in sheep or mice. In this reported study,
however, the levels of PrPSc present in the environment were below the limit of
detection of the sPMCA method, yet were still sufficient to cause infection of
in-contact animals. In the present study, the outdoor objects were removed from
the infected flock 8 weeks prior to sampling and were positive by sPMCA at very
low levels (2 out of 37 reactions). As this sPMCA assay also yielded 2 positive
reactions out of 139 in samples from the scrapie-free farm, the sPMCA assay
could not detect PrPSc on any of the objects above the background of the assay.
False positive reactions with sPMCA at a low frequency associated with de novo
formation of infectious prions have been reported (27, 28). This is in contrast
to our previous study where we demonstrated that outdoor objects that had been
in contact with the scrapie-infected flock up to 20 days prior to sampling
harbored PrPSc that was detectable by sPMCA analysis [4 out of 15 reactions
(12)] and was significantly more positive by the assay compared to analogous
samples from the scrapie-free farm. This discrepancy could be due to the use of
a different sPMCA substrate between the studies that may alter the efficiency of
amplification of the environmental PrPSc. In addition, the present study had a
longer timeframe between the objects being in contact with the infected flock
and sampling, which may affect the levels of extractable PrPSc. Alternatively,
there may be potentially patchy contamination of this furniture with PrPSc,
which may have been missed by swabbing. The failure of sPMCA to detect
CWD-associated PrP in saliva from clinically affected deer despite confirmation
of infectivity in saliva-inoculated transgenic mice was associated with as yet
unidentified inhibitors in saliva (29), and it is possible that the sensitivity
of sPMCA is affected by other substances in the tested material. In addition,
sampling of amplifiable PrPSc and subsequent detection by sPMCA may be more
difficult from furniture exposed to weather, which is supported by the
observation that PrPSc was detected by sPMCA more frequently in indoor than
outdoor furniture (12). A recent experimental study has demonstrated that
repeated cycles of drying and wetting of prion-contaminated soil, equivalent to
what is expected under natural weathering conditions, could reduce PMCA
amplification efficiency and extend the incubation period in hamsters inoculated
with soil samples (30). This seems to apply also to this study even though the
reduction in infectivity was more dramatic in the sPMCA assays than in the sheep
model. Sheep were not kept until clinical end-point, which would have enabled us
to compare incubation periods, but the lack of infection in sheep exposed to
furniture that had not been in contact with scrapie sheep for a longer time
period supports the hypothesis that prion degradation and subsequent loss of
infectivity occurs even under natural conditions.
In conclusion, the results in the current study indicate that removal of
furniture that had been in contact with scrapie-infected animals should be
recommended, particularly since cleaning and decontamination may not effectively
remove scrapie infectivity (31), even though infectivity declines considerably
if the pasture and the field furniture have not been in contact with
scrapie-infected sheep for several months. As sPMCA failed to detect PrPSc in
furniture that was subjected to weathering, even though exposure led to
infection in sheep, this method may not always be reliable in predicting the
risk of scrapie infection through environmental contamination. These results
suggest that the VRQ/VRQ sheep model may be more sensitive than sPMCA for the
detection of environmentally associated scrapie, and suggest that extremely low
levels of scrapie contamination are able to cause infection in susceptible sheep
genotypes.
Keywords: classical scrapie, prion, transmissible spongiform
encephalopathy, sheep, field furniture, reservoir, serial protein misfolding
cyclic amplification
Wednesday, December 16, 2015
*** Objects in contact with classical scrapie sheep act as a reservoir for
scrapie transmission ***
Circulation of prions within dust on a scrapie affected farm
Kevin C Gough1, Claire A Baker2, Hugh A Simmons3, Steve A Hawkins3 and Ben
C Maddison2*
Abstract
Prion diseases are fatal neurological disorders that affect humans and
animals. Scrapie of sheep/goats and Chronic Wasting Disease (CWD) of deer/elk
are contagious prion diseases where environmental reservoirs have a direct link
to the transmission of disease. Using protein misfolding cyclic amplification we
demonstrate that scrapie PrPSc can be detected within circulating dusts that are
present on a farm that is naturally contaminated with sheep scrapie. The
presence of infectious scrapie within airborne dusts may represent a possible
route of infection and illustrates the difficulties that may be associated with
the effective decontamination of such scrapie affected premises.
snip...
Discussion
We present biochemical data illustrating the airborne movement of scrapie
containing material within a contaminated farm environment. We were able to
detect scrapie PrPSc within extracts from dusts collected over a 70 day period,
in the absence of any sheep activity. We were also able to detect scrapie PrPSc
within dusts collected within pasture at 30 m but not at 60 m distance away from
the scrapie contaminated buildings, suggesting that the chance of contamination
of pasture by scrapie contaminated dusts decreases with distance from
contaminated farm buildings. PrPSc amplification by sPMCA has been shown to
correlate with infectivity and amplified products have been shown to be
infectious [14,15]. These experiments illustrate the potential for low dose
scrapie infectivity to be present within such samples. We estimate low ng levels
of scrapie positive brain equivalent were deposited per m2 over 70 days, in a
barn previously occupied by sheep affected with scrapie. This movement of dusts
and the accumulation of low levels of scrapie infectivity within this
environment may in part explain previous observations where despite stringent
pen decontamination regimens healthy lambs still became scrapie infected after
apparent exposure from their environment alone [16]. The presence of sPMCA
seeding activity and by inference, infectious prions within dusts, and their
potential for airborne dissemination is highly novel and may have implications
for the spread of scrapie within infected premises. The low level circulation
and accumulation of scrapie prion containing dust material within the farm
environment will likely impede the efficient decontamination of such scrapie
contaminated buildings unless all possible reservoirs of dust are removed.
Scrapie containing dusts could possibly infect animals during feeding and
drinking, and respiratory and conjunctival routes may also be involved. It has
been demonstrated that scrapie can be efficiently transmitted via the nasal
route in sheep [17], as is also the case for CWD in both murine models and in
white tailed deer [18-20].
The sources of dust borne prions are unknown but it seems reasonable to
assume that faecal, urine, skin, parturient material and saliva-derived prions
may contribute to this mobile environmental reservoir of infectivity. This work
highlights a possible transmission route for scrapie within the farm
environment, and this is likely to be paralleled in CWD which shows strong
similarities with scrapie in terms of prion dissemination and disease
transmission. The data indicate that the presence of scrapie prions in dust is
likely to make the control of these diseases a considerable challenge.
Friday, December 14, 2012
DEFRA U.K. What is the risk of Chronic Wasting Disease CWD being introduced
into Great Britain? A Qualitative Risk Assessment October 2012
snip...
In the USA, under the Food and Drug Administration’s BSE Feed Regulation
(21 CFR 589.2000) most material (exceptions include milk, tallow, and gelatin)
from deer and elk is prohibited for use in feed for ruminant animals. With
regards to feed for non-ruminant animals, under FDA law, CWD positive deer may
not be used for any animal feed or feed ingredients. For elk and deer considered
at high risk for CWD, the FDA recommends that these animals do not enter the
animal feed system. However, this recommendation is guidance and not a
requirement by law.
Animals considered at high risk for CWD include:
1) animals from areas declared to be endemic for CWD and/or to be CWD
eradication zones and
2) deer and elk that at some time during the 60-month period prior to
slaughter were in a captive herd that contained a CWD-positive animal.
Therefore, in the USA, materials from cervids other than CWD positive
animals may be used in animal feed and feed ingredients for non-ruminants.
The amount of animal PAP that is of deer and/or elk origin imported from
the USA to GB can not be determined, however, as it is not specified in TRACES.
It may constitute a small percentage of the 8412 kilos of non-fish origin
processed animal proteins that were imported from US into GB in 2011.
Overall, therefore, it is considered there is a __greater than negligible
risk___ that (nonruminant) animal feed and pet food containing deer and/or elk
protein is imported into GB.
There is uncertainty associated with this estimate given the lack of data
on the amount of deer and/or elk protein possibly being imported in these
products.
snip...
36% in 2007 (Almberg et al., 2011). In such areas, population declines of
deer of up to 30 to 50% have been observed (Almberg et al., 2011). In areas of
Colorado, the prevalence can be as high as 30% (EFSA, 2011). The clinical signs
of CWD in affected adults are weight loss and behavioural changes that can span
weeks or months (Williams, 2005). In addition, signs might include excessive
salivation, behavioural alterations including a fixed stare and changes in
interaction with other animals in the herd, and an altered stance (Williams,
2005). These signs are indistinguishable from cervids experimentally infected
with bovine spongiform encephalopathy (BSE). Given this, if CWD was to be
introduced into countries with BSE such as GB, for example, infected deer
populations would need to be tested to differentiate if they were infected with
CWD or BSE to minimise the risk of BSE entering the human food-chain via
affected venison.
snip...
The rate of transmission of CWD has been reported to be as high as 30% and
can approach 100% among captive animals in endemic areas (Safar et al.,
2008).
snip...
In summary, in endemic areas, there is a medium probability that the soil
and surrounding environment is contaminated with CWD prions and in a
bioavailable form. In rural areas where CWD has not been reported and deer are
present, there is a greater than negligible risk the soil is contaminated with
CWD prion.
snip...
In summary, given the volume of tourists, hunters and servicemen moving
between GB and North America, the probability of at least one person travelling
to/from a CWD affected area and, in doing so, contaminating their clothing,
footwear and/or equipment prior to arriving in GB is greater than negligible.
For deer hunters, specifically, the risk is likely to be greater given the
increased contact with deer and their environment. However, there is significant
uncertainty associated with these estimates.
snip...
Therefore, it is considered that farmed and park deer may have a higher
probability of exposure to CWD transferred to the environment than wild deer
given the restricted habitat range and higher frequency of contact with tourists
and returning GB residents.
snip...
Saturday, January 31, 2015
European red deer (Cervus elaphus elaphus) are susceptible to Bovine
Spongiform Encephalopathy BSE by Oral Alimentary route
I strenuously once again urge the FDA and its industry constituents, to
make it MANDATORY that all ruminant feed be banned to all ruminants, and this
should include all cervids as soon as possible for the following
reasons...
======
In the USA, under the Food and Drug Administrations BSE Feed Regulation (21
CFR 589.2000) most material (exceptions include milk, tallow, and gelatin) from
deer and elk is prohibited for use in feed for ruminant animals. With regards to
feed for non-ruminant animals, under FDA law, CWD positive deer may not be used
for any animal feed or feed ingredients. For elk and deer considered at high
risk for CWD, the FDA recommends that these animals do not enter the animal feed
system.
***However, this recommendation is guidance and not a requirement by law.
======
31 Jan 2015 at 20:14 GMT
*** Ruminant feed ban for cervids in the United States? ***
31 Jan 2015 at 20:14 GMT
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
Title: Scrapie transmits to white-tailed deer by the oral route and has a
molecular profile similar to chronic wasting disease
Authors
item Greenlee, Justin item Moore, S - item Smith, Jodi - item Kunkle,
Robert item West Greenlee, M -
Submitted to: American College of Veterinary Pathologists Meeting
Publication Type: Abstract Only Publication Acceptance Date: August 12, 2015
Publication Date: N/A Technical Abstract: The purpose of this work was to
determine susceptibility of white-tailed deer (WTD) to the agent of sheep
scrapie and to compare the resultant PrPSc to that of the original inoculum and
chronic wasting disease (CWD). We inoculated WTD by a natural route of exposure
(concurrent oral and intranasal (IN); n=5) with a US scrapie isolate. All
scrapie-inoculated deer had evidence of PrPSc accumulation. PrPSc was detected
in lymphoid tissues at preclinical time points, and deer necropsied after 28
months post-inoculation had clinical signs, spongiform encephalopathy, and
widespread distribution of PrPSc in neural and lymphoid tissues. Western
blotting (WB) revealed PrPSc with 2 distinct molecular profiles. WB on cerebral
cortex had a profile similar to the original scrapie inoculum, whereas WB of
brainstem, cerebellum, or lymph nodes revealed PrPSc with a higher profile
resembling CWD. Homogenates with the 2 distinct profiles from WTD with clinical
scrapie were further passaged to mice expressing cervid prion protein and
intranasally to sheep and WTD. In cervidized mice, the two inocula have distinct
incubation times. Sheep inoculated intranasally with WTD derived scrapie
developed disease, but only after inoculation with the inoculum that had a
scrapie-like profile. The WTD study is ongoing, but deer in both inoculation
groups are positive for PrPSc by rectal mucosal biopsy. In summary, this work
demonstrates that WTD are susceptible to the agent of scrapie, two distinct
molecular profiles of PrPSc are present in the tissues of affected deer, and
inoculum of either profile readily passes to deer.
White-tailed Deer are Susceptible to Scrapie by Natural Route of Infection
Jodi D. Smith, Justin J. Greenlee, and Robert A. Kunkle; Virus and Prion
Research Unit, National Animal Disease Center, USDA-ARS
Interspecies transmission studies afford the opportunity to better
understand the potential host range and origins of prion diseases. Previous
experiments demonstrated that white-tailed deer are susceptible to sheep-derived
scrapie by intracranial inoculation. The purpose of this study was to determine
susceptibility of white-tailed deer to scrapie after a natural route of
exposure. Deer (n=5) were inoculated by concurrent oral (30 ml) and intranasal
(1 ml) instillation of a 10% (wt/vol) brain homogenate derived from a sheep
clinically affected with scrapie. Non-inoculated deer were maintained as
negative controls. All deer were observed daily for clinical signs. Deer were
euthanized and necropsied when neurologic disease was evident, and tissues were
examined for abnormal prion protein (PrPSc) by immunohistochemistry (IHC) and
western blot (WB). One animal was euthanized 15 months post-inoculation (MPI)
due to an injury. At that time, examination of obex and lymphoid tissues by IHC
was positive, but WB of obex and colliculus were negative. Remaining deer
developed clinical signs of wasting and mental depression and were necropsied
from 28 to 33 MPI. Tissues from these deer were positive for scrapie by IHC and
WB. Tissues with PrPSc immunoreactivity included brain, tonsil, retropharyngeal
and mesenteric lymph nodes, hemal node, Peyer’s patches, and spleen. This work
demonstrates for the first time that white-tailed deer are susceptible to sheep
scrapie by potential natural routes of inoculation. In-depth analysis of tissues
will be done to determine similarities between scrapie in deer after
intracranial and oral/intranasal inoculation and chronic wasting disease
resulting from similar routes of inoculation.
see full text ;
PO-039: A comparison of scrapie and chronic wasting disease in white-tailed
deer
Justin Greenlee, Jodi Smith, Eric Nicholson US Dept. Agriculture;
Agricultural Research Service, National Animal Disease Center; Ames, IA USA
White-tailed deer are susceptible to the agent of sheep scrapie by
intracerebral inoculation
snip...
It is unlikely that CWD will be eradicated from free-ranging cervids, and
the disease is likely to continue to spread geographically [10]. However, the
potential that white-tailed deer may be susceptible to sheep scrapie by a
natural route presents an additional confounding factor to halting the spread of
CWD. This leads to the additional speculations that
1) infected deer could serve as a reservoir to infect sheep with scrapie
offering challenges to scrapie eradication efforts and
2) CWD spread need not remain geographically confined to current endemic
areas, but could occur anywhere that sheep with scrapie and susceptible cervids
cohabitate.
This work demonstrates for the first time that white-tailed deer are
susceptible to sheep scrapie by intracerebral inoculation with a high attack
rate and that the disease that results has similarities to CWD. These
experiments will be repeated with a more natural route of inoculation to
determine the likelihood of the potential transmission of sheep scrapie to
white-tailed deer. If scrapie were to occur in white-tailed deer, results of
this study indicate that it would be detected as a TSE, but may be difficult to
differentiate from CWD without in-depth biochemical analysis.
2012
PO-039: A comparison of scrapie and chronic wasting disease in white-tailed
deer
Justin Greenlee, Jodi Smith, Eric Nicholson US Dept. Agriculture;
Agricultural Research Service, National Animal Disease Center; Ames, IA USA
snip...
The results of this study suggest that there are many similarities in the
manifestation of CWD and scrapie in WTD after IC inoculation including early and
widespread presence of PrPSc in lymphoid tissues, clinical signs of depression
and weight loss progressing to wasting, and an incubation time of 21-23 months.
Moreover, western blots (WB) done on brain material from the obex region have a
molecular profile similar to CWD and distinct from tissues of the cerebrum or
the scrapie inoculum. However, results of microscopic and IHC examination
indicate that there are differences between the lesions expected in CWD and
those that occur in deer with scrapie: amyloid plaques were not noted in any
sections of brain examined from these deer and the pattern of immunoreactivity
by IHC was diffuse rather than plaque-like.
*** After a natural route of exposure, 100% of WTD were susceptible to
scrapie.
Deer developed clinical signs of wasting and mental depression and were
necropsied from 28 to 33 months PI. Tissues from these deer were positive for
PrPSc by IHC and WB. Similar to IC inoculated deer, samples from these deer
exhibited two different molecular profiles: samples from obex resembled CWD
whereas those from cerebrum were similar to the original scrapie inoculum. On
further examination by WB using a panel of antibodies, the tissues from deer
with scrapie exhibit properties differing from tissues either from sheep with
scrapie or WTD with CWD. Samples from WTD with CWD or sheep with scrapie are
strongly immunoreactive when probed with mAb P4, however, samples from WTD with
scrapie are only weakly immunoreactive. In contrast, when probed with mAb’s 6H4
or SAF 84, samples from sheep with scrapie and WTD with CWD are weakly
immunoreactive and samples from WTD with scrapie are strongly positive. This
work demonstrates that WTD are highly susceptible to sheep scrapie, but on first
passage, scrapie in WTD is differentiable from CWD.
2011
*** After a natural route of exposure, 100% of white-tailed deer were
susceptible to scrapie.
White-tailed Deer are Susceptible to Scrapie by Natural Route of Infection
Jodi D. Smith, Justin J. Greenlee, and Robert A. Kunkle; Virus and Prion
Research Unit, National Animal Disease Center, USDA-ARS
Interspecies transmission studies afford the opportunity to better
understand the potential host range and origins of prion diseases. Previous
experiments demonstrated that white-tailed deer are susceptible to sheep-derived
scrapie by intracranial inoculation. The purpose of this study was to determine
susceptibility of white-tailed deer to scrapie after a natural route of
exposure. Deer (n=5) were inoculated by concurrent oral (30 ml) and intranasal
(1 ml) instillation of a 10% (wt/vol) brain homogenate derived from a sheep
clinically affected with scrapie. Non-inoculated deer were maintained as
negative controls. All deer were observed daily for clinical signs. Deer were
euthanized and necropsied when neurologic disease was evident, and tissues were
examined for abnormal prion protein (PrPSc) by immunohistochemistry (IHC) and
western blot (WB). One animal was euthanized 15 months post-inoculation (MPI)
due to an injury. At that time, examination of obex and lymphoid tissues by IHC
was positive, but WB of obex and colliculus were negative. Remaining deer
developed clinical signs of wasting and mental depression and were necropsied
from 28 to 33 MPI. Tissues from these deer were positive for scrapie by IHC and
WB. Tissues with PrPSc immunoreactivity included brain, tonsil, retropharyngeal
and mesenteric lymph nodes, hemal node, Peyer’s patches, and spleen. This work
demonstrates for the first time that white-tailed deer are susceptible to sheep
scrapie by potential natural routes of inoculation. In-depth analysis of tissues
will be done to determine similarities between scrapie in deer after
intracranial and oral/intranasal inoculation and chronic wasting disease
resulting from similar routes of inoculation.
see full text ;
PL1
Using in vitro prion replication for high sensitive detection of prions and
prionlike proteins and for understanding mechanisms of transmission.
Claudio Soto
Mitchell Center for Alzheimer's diseases and related Brain disorders,
Department of Neurology, University of Texas Medical School at Houston.
Prion and prion-like proteins are misfolded protein aggregates with the
ability to selfpropagate to spread disease between cells, organs and in some
cases across individuals. I n T r a n s m i s s i b l e s p o n g i f o r m
encephalopathies (TSEs), prions are mostly composed by a misfolded form of the
prion protein (PrPSc), which propagates by transmitting its misfolding to the
normal prion protein (PrPC). The availability of a procedure to replicate prions
in the laboratory may be important to study the mechanism of prion and
prion-like spreading and to develop high sensitive detection of small quantities
of misfolded proteins in biological fluids, tissues and environmental samples.
Protein Misfolding Cyclic Amplification (PMCA) is a simple, fast and efficient
methodology to mimic prion replication in the test tube. PMCA is a platform
technology that may enable amplification of any prion-like misfolded protein
aggregating through a seeding/nucleation process. In TSEs, PMCA is able to
detect the equivalent of one single molecule of infectious PrPSc and propagate
prions that maintain high infectivity, strain properties and species
specificity. Using PMCA we have been able to detect PrPSc in blood and urine of
experimentally infected animals and humans affected by vCJD with high
sensitivity and specificity. Recently, we have expanded the principles of PMCA
to amplify amyloid-beta (Aβ) and alphasynuclein (α-syn) aggregates implicated in
Alzheimer's and Parkinson's diseases, respectively. Experiments are ongoing to
study the utility of this technology to detect Aβ and α-syn aggregates in
samples of CSF and blood from patients affected by these diseases.
=========================
***Recently, we have been using PMCA to study the role of environmental
prion contamination on the horizontal spreading of TSEs. These experiments have
focused on the study of the interaction of prions with plants and
environmentally relevant surfaces. Our results show that plants (both leaves and
roots) bind tightly to prions present in brain extracts and excreta (urine and
feces) and retain even small quantities of PrPSc for long periods of time.
Strikingly, ingestion of prioncontaminated leaves and roots produced disease
with a 100% attack rate and an incubation period not substantially longer than
feeding animals directly with scrapie brain homogenate. Furthermore, plants can
uptake prions from contaminated soil and transport them to different parts of
the plant tissue (stem and leaves). Similarly, prions bind tightly to a variety
of environmentally relevant surfaces, including stones, wood, metals, plastic,
glass, cement, etc. Prion contaminated surfaces efficiently transmit prion
disease when these materials were directly injected into the brain of animals
and strikingly when the contaminated surfaces were just placed in the animal
cage. These findings demonstrate that environmental materials can efficiently
bind infectious prions and act as carriers of infectivity, suggesting that they
may play an important role in the horizontal transmission of the disease.
========================
Since its invention 13 years ago, PMCA has helped to answer fundamental
questions of prion propagation and has broad applications in research areas
including the food industry, blood bank safety and human and veterinary disease
diagnosis.
see ;
98 | Veterinary Record | January 24, 2015
EDITORIAL
Scrapie: a particularly persistent pathogen
Cristina Acín
Resistant prions in the environment have been the sword of Damocles for
scrapie control and eradication. Attempts to establish which physical and
chemical agents could be applied to inactivate or moderate scrapie infectivity
were initiated in the 1960s and 1970s,with the first study of this type focusing
on the effect of heat treatment in reducing prion infectivity (Hunter and
Millson 1964). Nowadays, most of the chemical procedures that aim to inactivate
the prion protein are based on the method developed by Kimberlin and
collaborators (1983). This procedure consists of treatment with 20,000 parts per
million free chlorine solution, for a minimum of one hour, of all surfaces that
need to be sterilised (in laboratories, lambing pens, slaughterhouses, and so
on). Despite this, veterinarians and farmers may still ask a range of questions,
such as ‘Is there an official procedure published somewhere?’ and ‘Is there an
international organisation which recommends and defines the exact method of
scrapie decontamination that must be applied?’
From a European perspective, it is difficult to find a treatment that could
be applied, especially in relation to the disinfection of surfaces in lambing
pens of affected flocks. A 999/2001 EU regulation on controlling spongiform
encephalopathies (European Parliament and Council 2001) did not specify a
particular decontamination measure to be used when an outbreak of scrapie is
diagnosed. There is only a brief recommendation in Annex VII concerning the
control and eradication of transmissible spongiform encephalopathies (TSE
s).
Chapter B of the regulation explains the measures that must be applied if
new caprine animals are to be introduced to a holding where a scrapie outbreak
has previously been diagnosed. In that case, the statement indicates that
caprine animals can be introduced ‘provided that a cleaning and disinfection of
all animal housing on the premises has been carried out following
destocking’.
Issues around cleaning and disinfection are common in prion prevention
recommendations, but relevant authorities, veterinarians and farmers may have
difficulties in finding the specific protocol which applies. The European Food
and Safety Authority (EFSA ) published a detailed report about the efficacy of
certain biocides, such as sodium hydroxide, sodium hypochlorite, guanidine and
even a formulation of copper or iron metal ions in combination with hydrogen
peroxide, against prions (EFSA 2009). The report was based on scientific
evidence (Fichet and others 2004, Lemmer and others 2004, Gao and others 2006,
Solassol and others 2006) but unfortunately the decontamination measures were
not assessed under outbreak conditions.
The EFSA Panel on Biological Hazards recently published its conclusions on
the scrapie situation in the EU after 10 years of monitoring and control of the
disease in sheep and goats (EFSA 2014), and one of the most interesting findings
was the Icelandic experience regarding the effect of disinfection in scrapie
control. The Icelandic plan consisted of: culling scrapie-affected sheep or the
whole flock in newly diagnosed outbreaks; deep cleaning and disinfection of
stables, sheds, barns and equipment with high pressure washing followed by
cleaning with 500 parts per million of hypochlorite; drying and treatment with
300 ppm of iodophor; and restocking was not permitted for at least two years.
Even when all of these measures were implemented, scrapie recurred on several
farms, indicating that the infectious agent survived for years in the
environment, even as many as 16 years after restocking (Georgsson and others
2006).
In the rest of the countries considered in the EFSA (2014) report,
recommendations for disinfection measures were not specifically defined at the
government level. In the report, the only recommendation that is made for sheep
is repopulation with sheep with scrapie-resistant genotypes. This reduces the
risk of scrapie recurrence but it is difficult to know its effect on the
infection.
Until the EFSA was established (in May 2003), scientific opinions about TSE
s were provided by the Scientific Steering Committee (SSC) of the EC, whose
advice regarding inactivation procedures focused on treating animal waste at
high temperatures (150°C for three hours) and high pressure alkaline hydrolysis
(SSC 2003). At the same time, the TSE Risk Management Subgroup of the Advisory
Committee on Dangerous Pathogens (ACDP) in the UK published guidance on safe
working and the prevention of TSE infection. Annex C of the ACDP report
established that sodium hypochlorite was considered to be effective, but only if
20,000 ppm of available chlorine was present for at least one hour, which has
practical limitations such as the release of chlorine gas, corrosion,
incompatibility with formaldehyde, alcohols and acids, rapid inactivation of its
active chemicals and the stability of dilutions (ACDP 2009).
In an international context, the World Organisation for Animal Health (OIE)
does not recommend a specific disinfection protocol for prion agents in its
Terrestrial Code or Manual. Chapter 4.13 of the Terrestrial Code, General
recommendations on disinfection and disinsection (OIE 2014), focuses on
foot-and-mouth disease virus, mycobacteria and Bacillus anthracis, but not on
prion disinfection. Nevertheless, the last update published by the OIE on bovine
spongiform encephalopathy (OIE 2012) indicates that few effective
decontamination techniques are available to inactivate the agent on surfaces,
and recommends the removal of all organic material and the use of sodium
hydroxide, or a sodium hypochlorite solution containing 2 per cent available
chlorine, for more than one hour at 20ºC.
The World Health Organization outlines guidelines for the control of TSE s,
and also emphasises the importance of mechanically cleaning surfaces before
disinfection with sodium hydroxide or sodium hypochlorite for one hour (WHO
1999).
Finally, the relevant agencies in both Canada and the USA suggest that the
best treatments for surfaces potentially contaminated with prions are sodium
hydroxide or sodium hypochlorite at 20,000 ppm. This is a 2 per cent solution,
while most commercial household bleaches contain 5.25 per cent sodium
hypochlorite. It is therefore recommended to dilute one part 5.25 per cent
bleach with 1.5 parts water (CDC 2009, Canadian Food Inspection Agency
2013).
So what should we do about disinfection against prions? First, it is
suggested that a single protocol be created by international authorities to
homogenise inactivation procedures and enable their application in all
scrapie-affected countries. Sodium hypochlorite with 20,000 ppm of available
chlorine seems to be the procedure used in most countries, as noted in a paper
summarised on p 99 of this issue of Veterinary Record (Hawkins and others 2015).
But are we totally sure of its effectiveness as a preventive measure in a
scrapie outbreak? Would an in-depth study of the recurrence of scrapie disease
be needed?
What we can conclude is that, if we want to fight prion diseases, and
specifically classical scrapie, we must focus on the accuracy of diagnosis,
monitoring and surveillance; appropriate animal identification and control of
movements; and, in the end, have homogeneous and suitable protocols to
decontaminate and disinfect lambing barns, sheds and equipment available to
veterinarians and farmers. Finally, further investigations into the resistance
of prion proteins in the diversity of environmental surfaces are required.
References
snip...
98 | Veterinary Record | January 24, 2015
Persistence of ovine scrapie infectivity in a farm environment following
cleaning and decontamination
Steve A. C. Hawkins, MIBiol, Pathology Department1, Hugh A. Simmons, BVSc
MRCVS, MBA, MA Animal Services Unit1, Kevin C. Gough, BSc, PhD2 and Ben C.
Maddison, BSc, PhD3 + Author Affiliations
1Animal and Plant Health Agency, Woodham Lane, New Haw, Addlestone, Surrey
KT15 3NB, UK 2School of Veterinary Medicine and Science, The University of
Nottingham, Sutton Bonington, Loughborough, Leicestershire LE12 5RD, UK 3ADAS
UK, School of Veterinary Medicine and Science, The University of Nottingham,
Sutton Bonington, Loughborough, Leicestershire LE12 5RD, UK E-mail for
correspondence: ben.maddison@adas.co.uk Abstract Scrapie of sheep/goats and
chronic wasting disease of deer/elk are contagious prion diseases where
environmental reservoirs are directly implicated in the transmission of disease.
In this study, the effectiveness of recommended scrapie farm decontamination
regimens was evaluated by a sheep bioassay using buildings naturally
contaminated with scrapie. Pens within a farm building were treated with either
20,000 parts per million free chorine solution for one hour or were treated with
the same but were followed by painting and full re-galvanisation or replacement
of metalwork within the pen. Scrapie susceptible lambs of the PRNP genotype
VRQ/VRQ were reared within these pens and their scrapie status was monitored by
recto-anal mucosa-associated lymphoid tissue. All animals became infected over
an 18-month period, even in the pen that had been subject to the most stringent
decontamination process. These data suggest that recommended current guidelines
for the decontamination of farm buildings following outbreaks of scrapie do
little to reduce the titre of infectious scrapie material and that environmental
recontamination could also be an issue associated with these premises.
SNIP...
Discussion
Thorough pressure washing of a pen had no effect on the amount of
bioavailable scrapie infectivity (pen B). The routine removal of prions from
surfaces within a laboratory setting is treatment for a minimum of one hour with
20,000 ppm free chlorine, a method originally based on the use of brain
macerates from infected rodents to evaluate the effectiveness of decontamination
(Kimberlin and others 1983). Further studies have also investigated the
effectiveness of hypochlorite disinfection of metal surfaces to simulate the
decontamination of surgical devices within a hospital setting. Such treatments
with hypochlorite solution were able to reduce infectivity by 5.5 logs to lower
than the sensitivity of the bioassay used (Lemmer and others 2004). Analogous
treatment of the pen surfaces did not effectively remove the levels of scrapie
infectivity over that of the control pens, indicating that this method of
decontamination is not effective within a farm setting. This may be due to the
high level of biological matrix that is present upon surfaces within the farm
environment, which may reduce the amount of free chlorine available to
inactivate any infectious prion. Remarkably 1/5 sheep introduced into pen D had
also became scrapie positive within nine months, with all animals in this pen
being RAMALT positive by 18 months of age. Pen D was no further away from the
control pen (pen A) than any of the other pens within this barn. Localised hot
spots of infectivity may be present within scrapie-contaminated environments,
but it is unlikely that pen D area had an amount of scrapie contamination that
was significantly different than the other areas within this building.
Similarly, there were no differences in how the biosecurity of pen D was
maintained, or how this pen was ventilated compared with the other pens. This
observation, perhaps, indicates the slower kinetics of disease uptake within
this pen and is consistent with a more thorough prion removal and
recontamination. These observations may also account for the presence of
inadvertent scrapie cases within other studies, where despite stringent
biosecurity, control animals have become scrapie positive during challenge
studies using barns that also housed scrapie-affected animals (Ryder and others
2009). The bioassay data indicate that the exposure of the sheep to a farm
environment after decontamination efforts thought to be effective in removing
scrapie is sufficient for the animals to become infected with scrapie. The main
exposure routes within this scenario are likely to be via the oral route, during
feeding and drinking, and respiratory and conjunctival routes. It has been
demonstrated that scrapie infectivity can be efficiently transmitted via the
nasal route in sheep (Hamir and others 2008), as is the case for CWD in both
murine models and in white-tailed deer (Denkers and others 2010, 2013).
Recently, it has also been demonstrated that CWD prions presented as dust when
bound to the soil mineral montmorillonite can be infectious via the nasal route
(Nichols and others 2013). When considering pens C and D, the actual source of
the infectious agent in the pens is not known, it is possible that biologically
relevant levels of prion survive on surfaces during the decontamination regimen
(pen C). With the use of galvanising and painting (pen D) covering and sealing
the surface of the pen, it is possible that scrapie material recontaminated the
pens by the movement of infectious prions contained within dusts originating
from other parts of the barn that were not decontaminated or from other areas of
the farm.
Given that scrapie prions are widespread on the surfaces of affected farms
(Maddison and others 2010a), irrespective of the source of the infectious prions
in the pens, this study clearly highlights the difficulties that are faced with
the effective removal of environmentally associated scrapie infectivity. This is
likely to be paralleled in CWD which shows strong similarities to scrapie in
terms of both the dissemination of prions into the environment and the facile
mode of disease transmission. These data further contribute to the understanding
that prion diseases can be highly transmissible between susceptible individuals
not just by direct contact but through highly stable environmental reservoirs
that are refractory to decontamination.
The presence of these environmentally associated prions in farm buildings
make the control of these diseases a considerable challenge, especially in
animal species such as goats where there is lack of genetic resistance to
scrapie and, therefore, no scope to re-stock farms with animals that are
resistant to scrapie.
Scrapie Sheep Goats Transmissible spongiform encephalopathies (TSE)
Accepted October 12, 2014. Published Online First 31 October 2014
Monday, November 3, 2014
Persistence of ovine scrapie infectivity in a farm environment following
cleaning and decontamination
PPo3-22:
Detection of Environmentally Associated PrPSc on a Farm with Endemic
Scrapie
Ben C. Maddison,1 Claire A. Baker,1 Helen C. Rees,1 Linda A. Terry,2 Leigh
Thorne,2 Susan J. Belworthy2 and Kevin C. Gough3 1ADAS-UK LTD; Department of
Biology; University of Leicester; Leicester, UK; 2Veterinary Laboratories
Agency; Surry, KT UK; 3Department of Veterinary Medicine and Science; University
of Nottingham; Sutton Bonington, Loughborough UK
Key words: scrapie, evironmental persistence, sPMCA
Ovine scrapie shows considerable horizontal transmission, yet the routes of
transmission and specifically the role of fomites in transmission remain poorly
defined. Here we present biochemical data demonstrating that on a
scrapie-affected sheep farm, scrapie prion contamination is widespread. It was
anticipated at the outset that if prions contaminate the environment that they
would be there at extremely low levels, as such the most sensitive method
available for the detection of PrPSc, serial Protein Misfolding Cyclic
Amplification (sPMCA), was used in this study. We investigated the distribution
of environmental scrapie prions by applying ovine sPMCA to samples taken from a
range of surfaces that were accessible to animals and could be collected by use
of a wetted foam swab. Prion was amplified by sPMCA from a number of these
environmental swab samples including those taken from metal, plastic and wooden
surfaces, both in the indoor and outdoor environment. At the time of sampling
there had been no sheep contact with these areas for at least 20 days prior to
sampling indicating that prions persist for at least this duration in the
environment. These data implicate inanimate objects as environmental reservoirs
of prion infectivity which are likely to contribute to disease transmission.
HIGHEST INFECTION RATE ON SEVERAL CWD CONFIRMED CAPTIVES
CHRONIC WASTING DISEASE CWD WISCONSIN Almond Deer (Buckhorn Flats) Farm
Update DECEMBER 2011
The CWD infection rate was nearly 80%, the highest ever in a North American
captive herd.
RECOMMENDATION: That the Board approve the purchase of 80 acres of land for
$465,000 for the Statewide Wildlife Habitat Program in Portage County and
approve the restrictions on public use of the site.
SUMMARY:
For Immediate Release Thursday, October 2, 2014
Dustin Vande Hoef 515/281-3375 or 515/326-1616 (cell) or
Dustin.VandeHoef@IowaAgriculture.gov
*** TEST RESULTS FROM CAPTIVE DEER HERD WITH CHRONIC WASTING DISEASE
RELEASED 79.8 percent of the deer tested positive for the disease
DES MOINES – The Iowa Department of Agriculture and Land Stewardship today
announced that the test results from the depopulation of a quarantined captive
deer herd in north-central Iowa showed that 284 of the 356 deer, or 79.8% of the
herd, tested positive for Chronic Wasting Disease (CWD).
*** see history of this CWD blunder here ;
On June 5, 2013, DNR conducted a fence inspection, after gaining approval
from surrounding landowners, and confirmed that the fenced had been cut or
removed in at least four separate locations; that the fence had degraded and was
failing to maintain the enclosure around the Quarantined Premises in at least
one area; that at least three gates had been opened;and that deer tracks were
visible in and around one of the open areas in the sand on both sides of the
fence, evidencing movement of deer into the Quarantined Premises.
The overall incidence of clinical CWD in white-tailed deer was 82%
Species (cohort) CWD (cases/total) Incidence (%) Age at CWD death (mo)
”The occurrence of CWD must be viewed against the contest of the locations
in which it occurred. It was an incidental and unwelcome complication of the
respective wildlife research programmes. Despite it’s subsequent recognition as
a new disease of cervids, therefore justifying direct investigation, no specific
research funding was forthcoming. The USDA veiwed it as a wildlife problem and
consequently not their province!” page 26.
Sunday, January 06, 2013
USDA TO PGC ONCE CAPTIVES ESCAPE
*** "it‘s no longer its business.”
CWD, spreading it around...
for the game farm industry, and their constituents, to continue to believe
that they are _NOT_, and or insinuate that they have _NEVER_ been part of the
problem, will only continue to help spread cwd. the game farming industry, from
the shooting pens, to the urine mills, the antler mills, the sperm mills, velvet
mills, shooting pens, to large ranches, are not the only problem, but it is
painfully obvious that they have been part of the problem for decades and
decades, just spreading it around, as with transportation and or exportation and
or importation of cervids from game farming industry, and have been proven to
spread cwd. no one need to look any further than South Korea blunder ;
===========================================
spreading cwd around...
Between 1996 and 2002, chronic wasting disease was diagnosed in 39 herds of
farmed elk in Saskatchewan in a single epidemic. All of these herds were
depopulated as part of the Canadian Food Inspection Agency’s (CFIA) disease
eradication program. Animals, primarily over 12 mo of age, were tested for the
presence CWD prions following euthanasia. Twenty-one of the herds were linked
through movements of live animals with latent CWD from a single infected source
herd in Saskatchewan, 17 through movements of animals from 7 of the secondarily
infected herds.
***The source herd is believed to have become infected via importation of
animals from a game farm in South Dakota where CWD was subsequently diagnosed
(7,4). A wide range in herd prevalence of CWD at the time of herd depopulation
of these herds was observed. Within-herd transmission was observed on some
farms, while the disease remained confined to the introduced animals on other
farms.
spreading cwd around...
Friday, May 13, 2011
Chronic Wasting Disease (CWD) outbreaks and surveillance program in the
Republic of Korea
Hyun-Joo Sohn, Yoon-Hee Lee, Min-jeong Kim, Eun-Im Yun, Hyo-Jin Kim,
Won-Yong Lee, Dong-Seob Tark, In- Soo Cho, Foreign Animal Disease Research
Division, National Veterinary Research and Quarantine Service, Republic of Korea
Chronic wasting disease (CWD) has been recognized as an important prion
disease in native North America deer and Rocky mountain elks. The disease is a
unique member of the transmissible spongiform encephalopathies (TSEs), which
naturally affects only a few species. CWD had been limited to USA and Canada
until 2000.
On 28 December 2000, information from the Canadian government showed that a
total of 95 elk had been exported from farms with CWD to Korea. These consisted
of 23 elk in 1994 originating from the so-called “source farm” in Canada, and 72
elk in 1997, which had been held in pre export quarantine at the “source
farm”.Based on export information of CWD suspected elk from Canada to Korea, CWD
surveillance program was initiated by the Ministry of Agriculture and Forestry
(MAF) in 2001.
All elks imported in 1997 were traced back, however elks imported in 1994
were impossible to identify. CWD control measures included stamping out of all
animals in the affected farm, and thorough cleaning and disinfection of the
premises. In addition, nationwide clinical surveillance of Korean native
cervids, and improved measures to ensure reporting of CWD suspect cases were
implemented.
Total of 9 elks were found to be affected. CWD was designated as a
notifiable disease under the Act for Prevention of Livestock Epidemics in 2002.
Additional CWD cases - 12 elks and 2 elks - were diagnosed in 2004 and
2005.
Since February of 2005, when slaughtered elks were found to be positive,
all slaughtered cervid for human consumption at abattoirs were designated as
target of the CWD surveillance program. Currently, CWD laboratory testing is
only conducted by National Reference Laboratory on CWD, which is the Foreign
Animal Disease Division (FADD) of National Veterinary Research and Quarantine
Service (NVRQS).
In July 2010, one out of 3 elks from Farm 1 which were slaughtered for the
human consumption was confirmed as positive. Consequently, all cervid – 54 elks,
41 Sika deer and 5 Albino deer – were culled and one elk was found to be
positive. Epidemiological investigations were conducted by Veterinary
Epidemiology Division (VED) of NVRQS in collaboration with provincial veterinary
services.
Epidemiologically related farms were found as 3 farms and all cervid at
these farms were culled and subjected to CWD diagnosis. Three elks and 5
crossbreeds (Red deer and Sika deer) were confirmed as positive at farm 2.
All cervids at Farm 3 and Farm 4 – 15 elks and 47 elks – were culled and
confirmed as negative.
Further epidemiological investigations showed that these CWD outbreaks were
linked to the importation of elks from Canada in 1994 based on circumstantial
evidences.
In December 2010, one elk was confirmed as positive at Farm 5.
Consequently, all cervid – 3 elks, 11 Manchurian Sika deer and 20 Sika deer –
were culled and one Manchurian Sika deer and seven Sika deer were found to be
positive. This is the first report of CWD in these sub-species of deer.
Epidemiological investigations found that the owner of the Farm 2 in CWD
outbreaks in July 2010 had co-owned the Farm 5.
In addition, it was newly revealed that one positive elk was introduced
from Farm 6 of Jinju-si Gyeongsang Namdo. All cervid – 19 elks, 15 crossbreed
(species unknown) and 64 Sika deer – of Farm 6 were culled, but all confirmed as
negative.
New studies on the heat resistance of hamster-adapted scrapie agent:
Threshold survival after ashing at 600°C suggests an inorganic template of
replication
The infectious agents responsible for transmissible spongiform
encephalopathy (TSE) are notoriously resistant to most physical and chemical
methods used for inactivating pathogens, including heat. It has long been
recognized, for example, that boiling is ineffective and that higher
temperatures are most efficient when combined with steam under pressure (i.e.,
autoclaving). As a means of decontamination, dry heat is used only at the
extremely high temperatures achieved during incineration, usually in excess of
600°C. It has been assumed, without proof, that incineration totally inactivates
the agents of TSE, whether of human or animal origin.
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel
Production
Histochemical analysis of hamster brains inoculated with the solid residue
showed typical spongiform degeneration and vacuolation. Re-inoculation of these
brains into a new cohort of hamsters led to onset of clinical scrapie symptoms
within 75 days, suggesting that the specific infectivity of the prion protein
was not changed during the biodiesel process. The biodiesel reaction cannot be
considered a viable prion decontamination method for MBM, although we observed
increased survival time of hamsters and reduced infectivity greater than 6 log
orders in the solid MBM residue. Furthermore, results from our study compare for
the first time prion detection by Western Blot versus an infectivity bioassay
for analysis of biodiesel reaction products. We could show that biochemical
analysis alone is insufficient for detection of prion infectivity after a
biodiesel process.
Detection of protease-resistant cervid prion protein in water from a
CWD-endemic area
The data presented here demonstrate that sPMCA can detect low levels of
PrPCWD in the environment, corroborate previous biological and experimental data
suggesting long term persistence of prions in the environment2,3 and imply that
PrPCWD accumulation over time may contribute to transmission of CWD in areas
where it has been endemic for decades. This work demonstrates the utility of
sPMCA to evaluate other environmental water sources for PrPCWD, including
smaller bodies of water such as vernal pools and wallows, where large numbers of
cervids congregate and into which prions from infected animals may be shed and
concentrated to infectious levels.
A Quantitative Assessment of the Amount of Prion Diverted to Category 1
Materials and Wastewater During Processing
Keywords:Abattoir;bovine spongiform encephalopathy;QRA;scrapie;TSE
In this article the development and parameterization of a quantitative
assessment is described that estimates the amount of TSE infectivity that is
present in a whole animal carcass (bovine spongiform encephalopathy [BSE] for
cattle and classical/atypical scrapie for sheep and lambs) and the amounts that
subsequently fall to the floor during processing at facilities that handle
specified risk material (SRM). BSE in cattle was found to contain the most oral
doses, with a mean of 9864 BO ID50s (310, 38840) in a whole carcass compared to
a mean of 1851 OO ID50s (600, 4070) and 614 OO ID50s (155, 1509) for a sheep
infected with classical and atypical scrapie, respectively. Lambs contained the
least infectivity with a mean of 251 OO ID50s (83, 548) for classical scrapie
and 1 OO ID50s (0.2, 2) for atypical scrapie. The highest amounts of infectivity
falling to the floor and entering the drains from slaughtering a whole carcass
at SRM facilities were found to be from cattle infected with BSE at rendering
and large incineration facilities with 7.4 BO ID50s (0.1, 29), intermediate
plants and small incinerators with a mean of 4.5 BO ID50s (0.1, 18), and
collection centers, 3.6 BO ID50s (0.1, 14). The lowest amounts entering drains
are from lambs infected with classical and atypical scrapie at intermediate
plants and atypical scrapie at collection centers with a mean of 3 × 10−7 OO
ID50s (2 × 10−8, 1 × 10−6) per carcass. The results of this model provide key
inputs for the model in the companion paper published here.
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***
===============
==========================================
***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.
==========================================
PRION 2015 CONFERENCE FT. COLLINS CWD RISK FACTORS TO HUMANS
*** LATE-BREAKING ABSTRACTS PRION 2015 CONFERENCE ***
O18
Zoonotic Potential of CWD Prions
Liuting Qing1, Ignazio Cali1,2, Jue Yuan1, Shenghai Huang3, Diane Kofskey1,
Pierluigi Gambetti1, Wenquan Zou1, Qingzhong Kong1 1Case Western Reserve
University, Cleveland, Ohio, USA, 2Second University of Naples, Naples, Italy,
3Encore Health Resources, Houston, Texas, USA
*** These results indicate that the CWD prion has the potential to infect
human CNS and peripheral lymphoid tissues and that there might be asymptomatic
human carriers of CWD infection.
==================
***These results indicate that the CWD prion has the potential to infect
human CNS and peripheral lymphoid tissues and that there might be asymptomatic
human carriers of CWD infection.***
==================
P.105: RT-QuIC models trans-species prion transmission
Kristen Davenport, Davin Henderson, Candace Mathiason, and Edward Hoover
Prion Research Center; Colorado State University; Fort Collins, CO USA
Conversely, FSE maintained sufficient BSE characteristics to more
efficiently convert bovine rPrP than feline rPrP. Additionally, human rPrP was
competent for conversion by CWD and fCWD.
***This insinuates that, at the level of protein:protein interactions, the
barrier preventing transmission of CWD to humans is less robust than previously
estimated.
================
***This insinuates that, at the level of protein:protein interactions, the
barrier preventing transmission of CWD to humans is less robust than previously
estimated.***
================
*** These results would seem to suggest that CWD does indeed have zoonotic
potential, at least as judged by the compatibility of CWD prions and their human
PrPC target. Furthermore, extrapolation from this simple in vitro assay suggests
that if zoonotic CWD occurred, it would most likely effect those of the PRNP
codon 129-MM genotype and that the PrPres type would be similar to that found in
the most common subtype of sCJD (MM1).***
*** The potential impact of prion diseases on human health was greatly
magnified by the recognition that interspecies transfer of BSE to humans by beef
ingestion resulted in vCJD. While changes in animal feed constituents and
slaughter practices appear to have curtailed vCJD, there is concern that CWD of
free-ranging deer and elk in the U.S. might also cross the species barrier.
Thus, consuming venison could be a source of human prion disease. Whether BSE
and CWD represent interspecies scrapie transfer or are newly arisen prion
diseases is unknown. Therefore, the possibility of transmission of prion disease
through other food animals cannot be ruled out. There is evidence that vCJD can
be transmitted through blood transfusion. There is likely a pool of unknown size
of asymptomatic individuals infected with vCJD, and there may be asymptomatic
individuals infected with the CWD equivalent. These circumstances represent a
potential threat to blood, blood products, and plasma supplies.
now, let’s see what the authors said about this casual link, personal
communications years ago. see where it is stated NO STRONG evidence. so, does
this mean there IS casual evidence ???? “Our conclusion stating that we found no
strong evidence of CWD transmission to humans”
From: TSS (216-119-163-189.ipset45.wt.net)
Subject: CWD aka MAD DEER/ELK TO HUMANS ???
Date: September 30, 2002 at 7:06 am PST
From: "Belay, Ermias"
To: Cc: "Race, Richard (NIH)" ; ; "Belay, Ermias"
Sent: Monday, September 30, 2002 9:22 AM
Subject: RE: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS
Dear Sir/Madam,
In the Archives of Neurology you quoted (the abstract of which was attached
to your email), we did not say CWD in humans will present like variant CJD. That
assumption would be wrong. I encourage you to read the whole article and call me
if you have questions or need more clarification (phone: 404-639-3091). Also, we
do not claim that "no-one has ever been infected with prion disease from eating
venison." Our conclusion stating that we found no strong evidence of CWD
transmission to humans in the article you quoted or in any other forum is
limited to the patients we investigated.
Ermias Belay, M.D. Centers for Disease Control and Prevention
-----Original Message-----
From: Sent: Sunday, September 29, 2002 10:15 AM
To: rr26k@nih.gov; rrace@niaid.nih.gov; ebb8@CDC.GOV
Subject: TO CDC AND NIH - PUB MED- 3 MORE DEATHS - CWD - YOUNG HUNTERS
Sunday, November 10, 2002 6:26 PM ......snip........end..............TSS
Thursday, April 03, 2008
A prion disease of cervids: Chronic wasting disease 2008 1: Vet Res. 2008
Apr 3;39(4):41 A prion disease of cervids: Chronic wasting disease Sigurdson CJ.
snip...
*** twenty-seven CJD patients who regularly consumed venison were reported
to the Surveillance Center***,
snip... full text ;
CJD is so rare in people under age 30, one case in a billion (leaving out
medical mishaps), that four cases under 30 is "very high," says Colorado
neurologist Bosque. "Then, if you add these other two from Wisconsin [cases in
the newspaper], six cases of CJD in people associated with venison is very, very
high." Only now, with Mary Riley, there are at least seven, and possibly eight,
with Steve, her dining companion. "It's not critical mass that matters,"
however, Belay says. "One case would do it for me." The chance that two people
who know each other would both contact CJD, like the two Wisconsin sportsmen, is
so unlikely, experts say, it would happen only once in 140 years.
Given the incubation period for TSEs in humans, it may require another
generation to write the final chapter on CWD in Wisconsin. "Does chronic wasting
disease pass into humans? We'll be able to answer that in 2022," says Race.
Meanwhile, the state has become part of an immense experiment.
I urge everyone to watch this video closely...terry
*** you can see video here and interview with Jeff's Mom, and scientist
telling you to test everything and potential risk factors for humans ***
*** These results would seem to suggest that CWD does indeed have zoonotic
potential, at least as judged by the compatibility of CWD prions and their human
PrPC target. Furthermore, extrapolation from this simple in vitro assay suggests
that if zoonotic CWD occurred, it would most likely effect those of the PRNP
codon 129-MM genotype and that the PrPres type would be similar to that found in
the most common subtype of sCJD (MM1).***
***This information will have a scientific impact since it is the first
study that demonstrates the transmission of scrapie to a non-human primate with
a close genetic relationship to humans. This information is especially useful to
regulatory officials and those involved with risk assessment of the potential
transmission of animal prion diseases to humans.
***This observation strengthens the questioning of the harmlessness of
scrapie to humans, at a time when protective measures for human and animal
health are being dismantled and reduced as c-BSE is considered controlled and
being eradicated. Our results underscore the importance of precautionary and
protective measures and the necessity for long-term experimental transmission
studies to assess the zoonotic potential of other animal prion strains.
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
Title: Evaluation of the zoonotic potential of transmissible mink
encephalopathy
Authors
item Comoy, Emmanuel - item Mikol, Jacqueline - item Ruchoux,
Marie-Madeleine - item Durand, Valerie - item Luccantoni-Freire, Sophie - item
Dehen, Capucine - item Correia, Evelyne - item Casalone, Cristina - item Richt,
Juergen item Greenlee, Justin item Torres, Juan Maria - item Brown, Paul - item
Deslys, Jean-Philippe -
Submitted to: Pathogens Publication Type: Peer Reviewed Journal Publication
Acceptance Date: July 30, 2013 Publication Date: July 30, 2013 Citation: Comoy,
E.E., Mikol, J., Ruchoux, M., Durand, V., Luccantoni-Freire, S., Dehen, C.,
Correia, E., Casalone, C., Richt, J.A., Greenlee, J.J., Torres, J.M., Brown, P.,
Deslys, J. 2013. Evaluation of the zoonotic potential of transmissible mink
encephalopathy. Pathogens. 2:(3)520-532.
Interpretive Summary: Cases of bovine spongiform encephalopathy (BSE) or
mad cow disease can be subclassified into at least 3 distinct disease forms with
the predominate form known as classical BSE and the others collectively referred
to as atypical BSE. Atypical BSE can be further subdivided into H-type and
L-type cases that are distinct from classical BSE and from each other. Both of
the atypical BSE subtypes are believed to occur spontaneously, whereas classical
BSE is spread through feeding contaminated meat and bone meal to cattle.
Transmissible mink encephalopathy (TME) is another prion disease that transmits
to cattle and show similarities to L-type BSE when subjected to laboratory
testing. The purpose of this study was to use non-human primates (cynomologous
macaque) and transgenic mice expressing the human prion protein to determine if
TME could represent a potential risk to human health. TME from two sources
(cattle and raccoons) was able to infect non-human primates and transgenic mice
after exposure by the intracranial route. This result suggest that humans may be
able to replicate TME prions after an exposure that allows infectious material
access to brain tissue. At this time, it is unknown whether non-human primates
or transgenic mice would be susceptible to TME prions after oral exposure. The
results obtained in these animal models were similar to those obtained for
L-type BSE. Although rare, the existence of TME and that it transmits to cattle,
non-human primates, and transgenic mice suggest that feed bans preventing the
feeding of mammalian tissues to cattle should stay in place and that regular
prion surveillance during the slaughter should remain in place. Parties with
interest in the cattle and beef industries and regulatory officials responsible
for safe feeding practices of cattle will be interested in this work. Technical
Abstract: Successful transmission of Transmissible Mink Encephalopathy (TME) to
cattle supports the bovine hypothesis to the still controversial origin of TME
outbreaks. Human and primate susceptibility to classical Bovine Spongiform
Encephalopathy (c-BSE) and the transmissibility of L-type BSE to macaques assume
a low cattle-to-primate species barrier: we therefore evaluated the zoonotic
potential of cattle-adapted TME. In less than two years, this strain induced in
cynomolgus macaques a neurological disease similar to L-BSE and distinct from
c-BSE. TME derived from another donor species (raccoon) induced a similar
disease with shorter incubation periods.
*** L-BSE and cattle-adapted TME were also transmissible to transgenic mice
expressing human PrP. Interestingly, secondary transmissions to transgenic mice
expressing bovine PrP showed the maintenance of prion strain features for the
three tested bovine prion strains (cattle TME, c-BSE and L-BSE) regardless of
intermediate host.
*** Thus, TME is the third animal prion strain transmissible to both
macaques and humanized transgenic mice, suggesting zoonotic potentials that
should be considered in the risk analysis of animal prion diseases for human
health.
*** Moreover, the similarities between TME and L-BSE are highly suggestive
of a link between those strains, and of the presence of L-BSE decades prior to
its identification in USA and Europe.
Research Project: TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
Title: Scrapie transmits to white-tailed deer by the oral route and has a
molecular profile similar to chronic wasting disease
Authors
item Greenlee, Justin item Moore, S - item Smith, Jodi - item Kunkle,
Robert item West Greenlee, M -
Submitted to: American College of Veterinary Pathologists Meeting
Publication Type: Abstract Only Publication Acceptance Date: August 12, 2015
Publication Date: N/A Technical Abstract: The purpose of this work was to
determine susceptibility of white-tailed deer (WTD) to the agent of sheep
scrapie and to compare the resultant PrPSc to that of the original inoculum and
chronic wasting disease (CWD). We inoculated WTD by a natural route of exposure
(concurrent oral and intranasal (IN); n=5) with a US scrapie isolate. All
scrapie-inoculated deer had evidence of PrPSc accumulation. PrPSc was detected
in lymphoid tissues at preclinical time points, and deer necropsied after 28
months post-inoculation had clinical signs, spongiform encephalopathy, and
widespread distribution of PrPSc in neural and lymphoid tissues. Western
blotting (WB) revealed PrPSc with 2 distinct molecular profiles. WB on cerebral
cortex had a profile similar to the original scrapie inoculum, whereas WB of
brainstem, cerebellum, or lymph nodes revealed PrPSc with a higher profile
resembling CWD. Homogenates with the 2 distinct profiles from WTD with clinical
scrapie were further passaged to mice expressing cervid prion protein and
intranasally to sheep and WTD. In cervidized mice, the two inocula have distinct
incubation times. Sheep inoculated intranasally with WTD derived scrapie
developed disease, but only after inoculation with the inoculum that had a
scrapie-like profile. The WTD study is ongoing, but deer in both inoculation
groups are positive for PrPSc by rectal mucosal biopsy. In summary, this work
demonstrates that WTD are susceptible to the agent of scrapie, two distinct
molecular profiles of PrPSc are present in the tissues of affected deer, and
inoculum of either profile readily passes to deer.
Monday, November 16, 2015
*** Docket No. APHIS-2007-0127 Scrapie in Sheep and Goats Terry Singeltary
Sr. Submission ***
Saturday, December 12, 2015
*** CHRONIC WASTING DISEASE CWD TSE PRION REPORT DECEMBER 14, 2015
TEXAS CHRONIC WASTING DISEASE CWD TSE PRION
Tuesday, December 29, 2015
*** TEXAS MONTHLY CHRONIC WASTING DISEASE CWD JANUARY 2016 DEER BREEDERS
STILL DON'T GET IT $
Chronic Wasting Unease
*** The emergence of a deadly disease has wildlife officials and deer
breeders eyeing each other suspiciously. ***
Saturday, October 03, 2015
TEXAS CHRONIC WASTING DISEASE CWD TSE PRION GOD MUST NOT BE A TEXAN 2002 TO
2015
Monday, November 16, 2015
*** TEXAS PARKS AND WILDLIFE DEPARTMENT EXECUTIVE DIRECTOR ORDER NO.
015-006
*** Chronic Wasting Disease (CWD) immediate danger to the white-tailed deer
and mule deer resources of Texas
Saturday, November 14, 2015
TEXAS CAPTIVE BREEDER CHRONIC WASTING DISEASE CWD 2 MORE SUSPECTS DECTECTED
BRINGING NUMBER TO 7 DETECTED IN CAPTIVE BREEDER (if/when the last two are
confirmed).
Thursday, November 05, 2015
*** TPW Commission Adopts Interim Deer Breeder Movement Rules
Friday, October 09, 2015
Texas TWA Chronic Wasting Disease TSE Prion Webinars and Meeting October
2015
Thursday, September 24, 2015
TEXAS Hunters Asked to Submit Samples for Chronic Wasting Disease CWD TSE
Prion Testing
*** I cannot stress enough to all of you, for the sake of your family and
mine, before putting anything in the freezer, have those deer tested for CWD.
...terry
***raw and uncut
Sunday, August 23, 2015
TAHC Chronic Wasting Disease CWD TSE Prion and how to put lipstick on a pig
and take her to the dance in Texas
Friday, August 07, 2015
*** Texas CWD Captive, and then there were 4 ?
Thursday, August 06, 2015
*** WE HAVE LOST TEXAS TO CWD TASK FORCE CATERING TO INDUSTRY
Tuesday, July 21, 2015
*** Texas CWD Medina County Herd Investigation Update July 16, 2015 ***
Wednesday, July 01, 2015
*** TEXAS Chronic Wasting Disease Detected in Medina County Captive Deer
Wednesday, March 18, 2015
*** Chronic Wasting Disease CWD Confirmed Texas Trans Pecos March 18, 2015
Wednesday, March 25, 2015
*** Chronic Wasting Disease CWD Cases Confirmed In New Mexico 2013 and 2014
UPDATE 2015
Friday, August 14, 2015
*** Susceptibility of cattle to the agent of chronic wasting disease from
elk after intracranial inoculation
Friday, August 14, 2015
Carcass Management During a Mass Animal Health Emergency Draft Programmatic
Environmental Impact Statement—August 2015
Tuesday, September 22, 2015
*** Host Determinants of Prion Strain Diversity Independent of Prion
Protein Genotype
Friday, August 28, 2015
*** Chronic Wasting Disease CWD TSE Prion Diagnostics and subclinical
infection
*** Thursday, January 14, 2016
*** EMERGING ANIMAL DISEASES Actions Needed to Better Position USDA to
Address Future Risks Report to the Chairman, Committee on Energy and Commerce,
House of Representatives December 2015 GAO-16-132
*** GAO
Saturday, December 12, 2015
CREUTZFELDT JAKOB DISEASE CJD TSE PRION REPORT DECEMBER 14, 2015
MOM
Thursday, December 24, 2015
Revisiting the Heidenhain Variant of Creutzfeldt-Jakob Disease: Evidence
for Prion Type Variability Influencing Clinical Course and Laboratory Findings
Article type: Research Article
Evidence for human transmission of amyloid-β pathology and cerebral amyloid
angiopathy
07 02:27 AM
Terry S. Singeltary Sr. said:
re-Evidence for human transmission of amyloid-? pathology and cerebral
amyloid angiopathy
Nature 525, 247?250 (10 September 2015) doi:10.1038/nature15369 Received 26
April 2015 Accepted 14 August 2015 Published online 09 September 2015 Updated
online 11 September 2015 Erratum (October, 2015)
I would kindly like to comment on the Nature Paper, the Lancet reply, and
the newspaper articles.
***snip...see full text ;
Subject: 1992 IN CONFIDENCE TRANSMISSION OF ALZHEIMER TYPE PLAQUES TO
PRIMATES POSSIBILITY ON A TRANSMISSIBLE PRION REMAINS OPEN
BSE101/1 0136
IN CONFIDENCE
CMO
From: . Dr J S Metiers DCMO
4 November 1992
TRANSMISSION OF ALZHEIMER TYPE PLAQUES TO PRIMATES
1. Thank you for showing me Diana Dunstan's letter. I am glad that MRC have
recognised the public sensitivity of these findings and intend to report them in
their proper context. 'This hopefully will avoid misunderstanding and possible
distortion by the media to portray the results as having more greater
significance than the findings so far justify.
2. Using a highly unusual route of transmission (intra-cerebral injection)
the researchers have demonstrated the transmission of a pathological process
from two cases one of severe Alzheimer's disease the other of
Gerstmann-Straussler disease to marmosets. However they have not demonstrated
the transmission of either clinical condition as the "animals were behaving
normally when killed". As the report emphasises the unanswered question is
whether the disease condition would have revealed itself if the marmosets had
lived longer. They are planning further research to see if the conditions, as
opposed to the partial pathological process, is transmissible.
what are the implications for public health?
3. The route 'of transmission is very specific and in the natural state of
things highly unusual. However it could be argued that the results reveal a
potential risk, in that brain tissue from these two patients has been shown to
transmit a pathological process. Should therefore brain tissue from such cases
be regarded as potentially infective? Pathologists, morticians, neuro surgeons
and those assisting at neuro surgical procedures and others coming into contact
with "raw" human brain tissue could in theory be at risk. However, on a priori
grounds given the highly specific route of transmission in these experiments
that risk must be negligible if the usual precautions for handling brain tissue
are observed.
1
92/11.4/1.1
BSE101/1 0137
4. The other dimension to consider is the public reaction. To some extent
the GSS case demonstrates little more than the transmission of BSE to a pig by
intra-cerebral injection. If other prion diseases can be transmitted in this way
it is little surprise that some pathological findings observed in GSS were also
transmissible to a marmoset. But the transmission of features of Alzheimer's
pathology is a different matter, given the much greater frequency of this
disease and raises the unanswered question whether some cases are the result of
a transmissible prion. The only tenable public line will be that "more research
is required’’ before that hypothesis could be evaluated. The possibility on a
transmissible prion remains open. In the meantime MRC needs carefully to
consider the range and sequence of studies needed to follow through from the
preliminary observations in these two cases. Not a particularly comfortable
message, but until we know more about the causation of Alzheimer's disease the
total reassurance is not practical.
J S METTERS Room 509 Richmond House Pager No: 081-884 3344 Callsign: DOH
832 llllYc!eS 2 92/11.4/1.2
>>> The only tenable public line will be that "more research is
required’’ <<<
>>> possibility on a transmissible prion remains
open<<<
O.K., so it’s about 23 years later, so somebody please tell me, when is
"more research is required’’ enough time for evaluation ?
Self-Propagative Replication of Ab Oligomers Suggests Potential
Transmissibility in Alzheimer Disease
Received July 24, 2014; Accepted September 16, 2014; Published November 3,
2014
*** Singeltary comment PLoS ***
Alzheimer’s disease and Transmissible Spongiform Encephalopathy prion
disease, Iatrogenic, what if ?
Posted by flounder on 05 Nov 2014 at 21:27 GMT
Wednesday, January 13, 2016
ALS-Causing Mutations Significantly Perturb the Self-Assembly and
Interaction with Nucleic Acid of the Intrinsically Disordered Prion-Like Domain
of TDP-43
Research Article
Wednesday, January 13, 2016
An efficient procedure for removal and inactivation of alpha-synuclein
assemblies from laboratory materials
***>>>An efficient procedure for removal and inactivation of
alpha-synuclein assemblies from laboratory materials<<<***
***>>> This retrospective study, however, does not definitively
exclude the possibility that a-synucleinopathy can transmit between humans.
<<<***
An efficient procedure for removal and inactivation of alpha-synuclein
assemblies from laboratory materials ???
Tuesday, December 1, 2015
Sorting Out Release, Uptake and Processing of Alpha-Synuclein During
Prion-Like Spread of Pathology
Thursday, December 3, 2015
Transmission of Soluble and Insoluble α-Synuclein to Mice
Tuesday, September 1, 2015
Evidence for α-synuclein prions causing multiple system atrophy in humans
with parkinsonism
Wednesday, September 2, 2015
Clinically Unsuspected Prion Disease Among Patients With Dementia Diagnoses
in an Alzheimer’s Disease Database
Transmission of Creutzfeldt-Jakob disease to a chimpanzee by electrodes
contaminated during neurosurgery.
Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Sulima MP, Gajdusek DC.
Laboratory of Central Nervous System Studies, National Institute of Neurological
Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
Stereotactic multicontact electrodes used to probe the cerebral cortex of a
middle aged woman with progressive dementia were previously implicated in the
accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger
patients. The diagnoses of CJD have been confirmed for all three cases. More
than two years after their last use in humans, after three cleanings and
repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were
implanted in the cortex of a chimpanzee. Eighteen months later the animal became
ill with CJD. This finding serves to re-emphasise the potential danger posed by
reuse of instruments contaminated with the agents of spongiform
encephalopathies, even after scrupulous attempts to clean them.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8006664&dopt=Abstract
Terry S. Singeltary Sr.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.