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Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions
Sandra Pritzkow, Rodrigo Morales , Fabio Moda 3, Uffaf Khan, Glenn C.
Telling, Edward Hoover, Claudio Soto
correspondence
email 3Present address: IRCCS Foundation Carlo Besta Neurological
Institute, 20133 Milan, Italy
Publication stage: In Press Corrected Proof
Open Access
Highlights
•Grass plants bind prions from contaminated brain and excreta •Prions from
different strains and species remain bound to living plants •Hamsters fed with
prion-contaminated plant samples develop prion disease •Stems and leaves from
grass plants grown in infected soil contain prions
Summary
Prions are the protein-based infectious agents responsible for prion
diseases. Environmental prion contamination has been implicated in disease
transmission. Here, we analyzed the binding and retention of infectious prion
protein (PrPSc) to plants. Small quantities of PrPSc contained in diluted brain
homogenate or in excretory materials (urine and feces) can bind to wheat grass
roots and leaves. Wild-type hamsters were efficiently infected by ingestion of
prion-contaminated plants. The prion-plant interaction occurs with prions from
diverse origins, including chronic wasting disease. Furthermore, leaves
contaminated by spraying with a prion-containing preparation retained PrPSc for
several weeks in the living plant. Finally, plants can uptake prions from
contaminated soil and transport them to aerial parts of the plant (stem and
leaves). These findings demonstrate that plants can efficiently bind infectious
prions and act as carriers of infectivity, suggesting a possible role of
environmental prion contamination in the horizontal transmission of the disease.
This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Received: October 31, 2014; Received in revised form: February 4, 2015;
Accepted: April 15, 2015; Published Online: May 14, 2015
© 2015 The Authors. Published by Elsevier Inc.
snip...
RESULTS
Prions Bind to Plants and Bound-PrPSc Efficiently Sustain Prion
Replication
To study whether plants can interact with prions, we exposed wheat grass
roots and leaves to brain homogenate from hamsters that have succumbed to prion
disease induced by experimental inoculation with the 263K prion strain. The
presence of PrPSc and infectivity attached to the plants was studied in vitro
using the protein misfolding cyclic amplification (PMCA) technique and in vivo
by infectivity bioassays. For in vitro analyses, the plant tissues (roots and
leaves) were incubated for 16 hr with serial dilutions of 263K-brain homogenate
ranging from 10 1 to 10 8. Roots and leaves were washed thoroughly and analyzed
for the presence of PrPSc by serial PMCA (Morales et al., 2012). The results
show that even highly diluted PrPSc can bind to roots and leaves and sustain
PrPC conversion (Figure 1A). Although a direct comparison cannot be made,
because of differences on the effective surface, roots appear to retain PrPSc
better than leaves. However, both roots and leaves capture PrPSc efficiently,
even at very small concentrations, equivalent to those present in biological
fluids, such as blood and urine (Chen et al., 2010). By comparing the detection
of PrPSc-bound to plants (Figure 1A) with an experiment in which the same
dilutions of 263K brain homogenate were added directly to the tubes containing
normal brain homogenate and an equivalent piece of leaves or roots (Figure 1B),
we can estimate that a high proportion of PrPSc present in the sample was
attached to the plant tissue. Importantly, no detection of PrPSc was observed
when leaves and roots were exposed to normal brain homogenate (Figure 1C).
However, comparing PMCA amplification in the presence (Figure 1B) or in the
absence (Figure S1A) of plant tissue, it is possible to appreciate that plants
(both leaves and roots) partially inhibits the PMCA reaction. This explains why
in most of the experiments with plants, protease-resistant PrPSc is only
observed after two rounds of PMCA. In our current PMCA settings, no
false-positive PrPSc signals were ever detectable when samples did not contain
PrPSc inoculum (Figure S1B). These results indicate that leaves and roots can
efficiently bind PrPSc, which remains able to catalyze PrPC to PrPSc conversion,
leading to prion replication. In these experiments, plant tissues were incubated
with prions for 16 hr, but a similar experiment in which roots and leaves were
exposed to a 10 5 dilution of 263K brain homogenate for different times, we
found that as little as 2 min of incubation was sufficient for the efficient
contamination of plants (Figure S2).
Animals Can Be Infected by Oral Administration of Prion-Contaminated
Plants
To investigate whether prion-contaminated plants were able to infect
animals by ingestion, leaves and roots previously incubated with either
263K-infected or control hamster brain homogenates were orally administered into
naive hamsters. After exposure, plants were extensively washed five times with
water and animals were fed with dried material. As positive controls, we orally
administered 750 ml of 5% 263K brain homogenate (same material used to
contaminate plant tissue). All animals that ingested prion contaminated leaves
and roots developed typical prion disease. Although the incubation times were
significantly longer in animals ingesting prions attached to leaves and roots as
compared with those fed directly with the brain material, the differences were
not as high as one could have expected (Figure 2A). Indeed, incubation periods
were 147 ± 10,
159 ± 10, and 164 ± 13 days (mean ± SEM) for the groups inoculated with
brain homogenate, and prion contaminated roots and leaves, respectively. Prion
disease was confirmed by histological study of PrPSc deposition, astrogliosis,
and brain vacuolation (Figure 2B), as well as by biochemical detection of
protease-resistant PrPSc by western blot (Figure 2C). None of the animals
inoculated with leaves and roots exposed to normal brain homogenate developed
disease up to 550 days post-inoculation. Histological analysis did not show any
PrPSc staining or disease specific alteration in control animals.
Plants Bind Prions from Different Strains and Species To analyze
prion-plant interaction with other species and strains of the prion agent, we
performed similar studies as described in Figure 1, by incubating leaves and
roots with a preparation containing hamster, murine, cervid, and human prions
corresponding to the Hyper, 301C, CWD, and vCJD prion strains, respectively.
PrPSc from these strains and species showed good amplification by PMCA, using
homologous substrates (Figure S3A). In all cases, leaves and roots bound prions
from these species and retained the ability to replicate in vitro (Figure S3B),
indicating that the interaction of PrPSc with plants is a general feature of
infectious prions.
Contamination of Plants with Prions Excreted in Urine and Feces
Under natural conditions, it is likely that the main source of prions in
the environment comes from secretory and excretory fluids, such as saliva,
urine, and feces. We and others have shown that PrPSc is released in these
fluids and excretions in various animal species (Gonzalez-Romero et al., 2008;
Haley et al., 2009, 2011; Maddison et al., 2010; Terry et al., 2011; Moda et
al., 2014). It has been estimated that the amount of infectious prions spread by
excreta during the animals’ lifespan could match or even surpass the quantity
present in the brain of a symptomatic individual (Tamgu¨ ney et al., 2009). To
study whether plant tissue can be contaminated by waste products excreted from
prion-infected hamsters and deer, leaves and roots were incubated with samples
of urine and feces and the presence of PrPSc analyzed by serial rounds of PMCA.
For these experiments, plant tissues were incubated for 1 hr with urine or feces
homogenates obtained either from 263K-infected hamsters or CWD-affected cervids.
This time was chosen because longer incubation with these biological fluids
affected the integrity of the plant tissue. After being thoroughly washed and
dried, PrPSc attached to leaves and roots was detected by PMCA. The results
clearly show that PrPSc was readily detectable after three or four rounds of
PMCA in samples of wheat grass leaves and roots exposed to both urine and feces
from 263K sick hamsters (Figure 3A) and CWD-affected cervids (Figure 3B).
Comparing these results with studies of the direct detection of PrPSc in urine
and feces (Figures 3A and 3B), it seems that the majority of PrPSc present in
these waste products was effectively attached to leaves and roots. No signal was
observed in plant tissue exposed to urine or feces coming from non-infected
hamsters.
Prions Bind to Living Plants
To investigate a more natural scenario for prion contamination of living
plants, we sprayed the leaves of wheat grass with a preparation containing 1%
263K hamster brain homogenate. Plants were let to grow for different times after
exposure, and PrPSc was detected in the leaves by PMCA in duplicates for each
time point. The results show that PrPSc was able to bind to leaves and remained
attached to the living plants for at least 49 days after exposure (Figure 4).
Considering that PrPSc signal was detectable normally in the second or third
round of PMCA without obvious trend in relation to time, we conclude that the
relative amount of PrPSc present in leaves did not appear to change
substantially over time. These data indicate that PrPSc can be retained in
living plants for at least several weeks after a simple contact with prion
contaminated materials, and PrPSc remains competent to drive prion
replication.
Plants Uptake Prions from Contaminated Soil
The experiments described above were done by exposure of the surface of
leaves and roots with different solutions containing prions. To evaluate whether
living plants can uptake PrPSc from contaminated soil, we grew barley grass
plants on soil that was contaminated by addition of 263K brain homogenate.
Plants were grown for 1 or 3 weeks under conditions that carefully prevented any
direct contact of the aerial part of the plant with the soil. After this time,
pieces of stem and leaves were collected and analyzed for the presence of PrPSc
by PMCA. As shown in Figure 5A, all plants grown for 3 weeks in contaminated
soil contained PrPSc in their stem, albeit in small quantities that required
four serial rounds of PMCA for detection. One of the four plants analyzed
contained a detectable amount of PrPSc in the leaves (Figure 5B), indicating
that prions were uptaken from the soil and transported into the aerial parts of
the plants, far from the soil. These results differ from a recent article
reporting that infectious prions were not detectable in above the ground tissues
of wheat plants exposed to CWD prions (Rasmussen et al., 2014). The lack of
detection in this article is most likely due to the low sensitive techniques
(western blots or ELISA) employed to analyze the presence of PrPSc. Indeed, as
we reported previously, PMCA has a power of detection, which is several millions
times higher than western blots or ELISA (Saa´ et al., 2006). In order to
estimate the amount of PrPSc present in stem and leaves coming from contaminated
soil, we performed a quantitative PMCA study, as previously described (Chen et
al., 2010). Unfortunately, by comparing the PMCA amplification in the absence or
the presence of plant tissue, it is possible to conclude that stems and leaves
substantially interfered with the PMCA procedure, and thus the calculation
cannot be very precise (Figure S4). Indeed, after two rounds of PMCA we cannot
detect any protease-resistant PrPSc, but on the third round we observed the
maximum amplification (10 9), presumably because at this round the concentration
of PMCA inhibitors has been reduced enough to permit good amplification. At this
point, we can estimate that the amount of PrPSc that reaches the stem and leaves
from contaminated soil is equivalent to the PrPSc concentration present in a
10 6 to 10 9 dilution of sick brain homogenate. Nevertheless, this result is
interesting, because it indicates that the amount of prions uptaken from soil
and transported to aerial parts of the plant is within the infectious range.
Indeed, titration studies showed that the last infectious dilution of a 263K
brain homogenate is 10 9 (Gregori et al., 2006).
DISCUSSION
This study shows that plants can efficiently bind prions contained in brain
extracts from diverse prion infected animals, including CWD-affected cervids.
PrPSc attached to leaves and roots from wheat grass plants remains capable of
seeding prion replication in vitro. Surprisingly, the small quantity of PrPSc
naturally excreted in urine and feces from sick hamster or cervids was enough to
efficiently contaminate plant tissue. Indeed, our results suggest that the
majority of excreted PrPSc is efficiently captured by plants’ leaves and roots.
Moreover, leaves can be contaminated by spraying them with a prion-containing
extract, and PrPSc remains detectable in living plants for as long as the study
wasperformed (several weeks). Remarkably, prion contaminated plants transmit
prion disease to animals upon ingestion, producing a 100% attack rate and
incubation periods not substantially longer than direct oral administration of
sick brain homogenates. Finally, an unexpected but exciting result was that
plants were able to uptake prions from contaminated soil and transport them to
aerial parts of the plant tissue. Although it may seem farfetched that plants
can uptake proteins from the soil and transport it to the parts above the
ground, there are already published reports of this phenomenon (McLaren et al.,
1960; Jensen and McLaren, 1960; Paungfoo-Lonhienne et al., 2008). The high
resistance of prions to degradation and their ability to efficiently cross
biological barriers may play a role in this process. The mechanism by which
plants bind, retain, uptake, and transport prions is unknown. Weare currently
studying the way in which prions interact with plants using purified,
radioactively labeled PrPSc to determine specificity of the interaction,
association constant, reversibility, saturation, movement, etc.
Epidemiological studies have shown numerous instances of scrapie or CWD
recurrence upon reintroduction of animals on pastures previously exposed to
prion-infected animals. Indeed, reappearance of scrapie has been documented
following fallow periods of up to 16 years (Georgsson et al., 2006), and
pastures were shown to retain infectious CWD prions for at least 2 years after
exposure (Miller et al., 2004). It is likely that the environmentally mediated
transmission of prion diseases depends upon the interaction of prions with
diverse elements, including soil, water, environmental surfaces, various
invertebrate animals, and plants. However, since plants are such an important
component of the environment and also a major source of food for many animal
species, including humans, our results may have far-reaching implications for
animal and human health. Currently, the perception of the risk for
animal-to-humanprion transmissionhas beenmostly limited to consumption or
exposure to contaminated meat; our results indicate that plants might also be an
important vector of transmission that needs to be considered in risk
assessment.
snip...see full text here ;
Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions
Friday, September 27, 2013
Uptake of Prions into Plants
Tuesday, December 20, 2011
CHRONIC WASTING DISEASE CWD WISCONSIN Almond Deer (Buckhorn Flats)
FarmUpdate DECEMBER 2011The CWD infection rate was nearly 80%, the highest ever
in a North American captive herd. RECOMMENDATION: That the Board approve the
purchase of 80acres of land for $465,000 for the Statewide Wildlife Habitat
Program inPortage 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). The owners of the
quarantined herd have entered into a fence maintenance agreement with the Iowa
Department of Agriculture and Land Stewardship,which requires the owners to
maintain the 8’ foot perimeter fence around the herd premises for five years
after the depopulation was complete and the premises had been cleaned and
disinfected CWD is a progressive, fatal, degenerative neurological disease of
farmed and free-ranging deer, elk, and moose. There is no known treatment or
vaccine for CWD. CWD is not a disease that affects humans.On July 18, 2012, USDA
Animal and Plant Health Inspection Service’s (APHIS)National Veterinary Services
Lab in Ames, IA confirmed that a male whitetail deer harvested from a hunting
preserve in southeast IA was positive for CWD. An investigation revealed that
this animal had just been introduced into the hunting preserve from the
above-referenced captive deer herd in north-central Iowa.The captive deer herd
was immediately quarantined to prevent the spread of CWD. The herd has remained
in quarantine until its depopulation on August 25 to 27, 2014.The Iowa
Department of Agriculture and Land Stewardship participated in a joint operation
to depopulate the infected herd with USDA Veterinary Services, which was the
lead agency, and USDA Wildlife Services.Federal indemnity funding became
available in 2014. USDA APHIS appraised the captive deer herd of 376 animals at
that time, which was before depopulation and testing, at $1,354,250. At that
time a herd plan was developed with the owners and officials from USDA and the
Iowa Department of Agriculture and Land Stewardship.Once the depopulation was
complete and the premises had been cleaned and disinfected, indemnity of
$917,100.00 from the USDA has been or will be paid to the owners as compensation
for the 356 captive deer depopulated.The Iowa Department of Agriculture and Land
Stewardship operates a voluntary CWD program for farms that sell live animals.
Currently 145 Iowa farms participate in the voluntary program. The
above-referenced captive deer facility left the voluntary CWD program prior to
the discovery of the disease as they had stopped selling live animals. All deer
harvested in a hunting preserve must be tested for CWD. -30-
*** 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 beencut 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.
Tuesday, October 07, 2014
*** Wisconsin white-tailed deer tested positive for CWD on a Richland
County breeding farm, and a case of CWD has been discovered on a Marathon County
hunting preserve
*** Wisconsin 16 age limit on testing dead deer Game Farm CWD Testing
Protocol Needs To Be Revised
Approximately 4,200 fawns, defined as deer under 1 year of age, were
sampled from the eradication zone over the last year. The majority of fawns
sampled were between the ages of 5 to 9 months, though some were as young as 1
month.
*** Two of the six fawns with CWD detected were 5 to 6 months old.
All six of the positive fawns were taken from the core area of the CWD
eradication zone where the highest numbers of positive deer have been
identified. ...
snip...
"Finding CWD prions in both lymph and brain tissues of deer this young is
slightly surprising," said Langenberg, "and provides information that CWD
infection and illness may progress more rapidly in a white-tailed deer than
previously suspected. Published literature suggests that CWD doesn't cause
illness in a deer until approximately 16 months of age. Our fawn data shows that
a few wild white-tailed deer may become sick from CWD or may transmit the
disease before they reach that age of 16 months." ... see full text and more
here ; Saturday, February 04, 2012
Wisconsin 16 MONTH age limit on testing dead deer Game Farm CWD Testing
Protocol Needs To Be Revised
Thursday, July 03, 2014
*** How Chronic Wasting Disease is affecting deer population and what’s the
risk to humans and pets?
Tuesday, July 01, 2014
*** CHRONIC WASTING DISEASE CWD TSE PRION DISEASE, GAME FARMS, AND
POTENTIAL RISK FACTORS THERE FROM
===========================================
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.
”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.”
Tuesday, October 21, 2014
Pennsylvania Department of Agriculture Tenth Pennsylvania Captive Deer
Tests Positive for Chronic Wasting Disease CWD TSE PRION DISEASE
Thursday, October 23, 2014
FIRST CASE OF CHRONIC WASTING DISEASE CONFIRMED IN OHIO ON PRIVATE PRESERVE
Thursday, April 02, 2015
OHIO CONFIRMS SECOND POSTIVE CHRONIC WASTING DISEASE CWD on Yoder's
properties near Millersburg
Wednesday, February 11, 2015
World Class Whitetails quarantined CWD deer Daniel M. Yoder charged with
two counts of tampering with evidence
Tuesday, July 01, 2014
*** CHRONIC WASTING DISEASE CWD TSE PRION DISEASE, GAME FARMS, AND
POTENTIAL RISK FACTORS THERE FROM ***
Thursday, July 03, 2014
*** How Chronic Wasting Disease is affecting deer population and what’s the
risk to humans and pets? ***
Friday, April 24, 2015
The placenta shed from goats with classical scrapie is infectious to goat
kids and lambs
Wednesday, April 22, 2015
Circulation of prions within dust on a scrapie affected farm
Thursday, April 30, 2015
Immediate and ongoing detection of prions in the blood of hamsters and deer
following oral, nasal, or blood inoculations
***please read this***
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
Tuesday, December 16, 2014
Evidence for zoonotic potential of ovine scrapie prions
Hervé Cassard,1, n1 Juan-Maria Torres,2, n1 Caroline Lacroux,1, Jean-Yves
Douet,1, Sylvie L. Benestad,3, Frédéric Lantier,4, Séverine Lugan,1, Isabelle
Lantier,4, Pierrette Costes,1, Naima Aron,1, Fabienne Reine,5, Laetitia
Herzog,5, Juan-Carlos Espinosa,2, Vincent Beringue5, & Olivier Andréoletti1,
Affiliations Contributions Corresponding author Journal name: Nature
Communications Volume: 5, Article number: 5821 DOI: doi:10.1038/ncomms6821
Received 07 August 2014 Accepted 10 November 2014 Published 16 December 2014
Article tools Citation Reprints Rights & permissions Article metrics
Abstract
Although Bovine Spongiform Encephalopathy (BSE) is the cause of variant
Creutzfeldt Jakob disease (vCJD) in humans, the zoonotic potential of scrapie
prions remains unknown. Mice genetically engineered to overexpress the human
prion protein (tgHu) have emerged as highly relevant models for gauging the
capacity of prions to transmit to humans. These models can propagate human
prions without any apparent transmission barrier and have been used used to
confirm the zoonotic ability of BSE. Here we show that a panel of sheep scrapie
prions transmit to several tgHu mice models with an efficiency comparable to
that of cattle BSE. The serial transmission of different scrapie isolates in
these mice led to the propagation of prions that are phenotypically identical to
those causing sporadic CJD (sCJD) in humans. These results demonstrate that
scrapie prions have a zoonotic potential and raise new questions about the
possible link between animal and human prions.
Subject terms: Biological sciences• Medical research At a glance
why do we not want to do TSE transmission studies on chimpanzees $
5. A positive result from a chimpanzee challenged severly would likely
create alarm in some circles even if the result could not be interpreted for
man. I have a view that all these agents could be transmitted provided a large
enough dose by appropriate routes was given and the animals kept long enough.
Until the mechanisms of the species barrier are more clearly understood it might
be best to retain that hypothesis.
snip...
R. BRADLEY
Friday, January 30, 2015
Scrapie: a particularly persistent pathogen
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.
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.
*** We conclude that TSE infectivity is likely to survive burial for long
time periods with minimal loss of infectivity and limited movement from the
original burial site. However PMCA results have shown that there is the
potential for rainwater to elute TSE related material from soil which could lead
to the contamination of a wider area. These experiments reinforce the importance
of risk assessment when disposing of TSE risk materials.
*** The results show that even highly diluted PrPSc can bind efficiently to
polypropylene, stainless steel, glass, wood and stone and propagate the
conversion of normal prion protein. For in vivo experiments, hamsters were ic
injected with implants incubated in 1% 263K-infected brain homogenate. Hamsters,
inoculated with 263K-contaminated implants of all groups, developed typical
signs of prion disease, whereas control animals inoculated with non-contaminated
materials did not.
PRION 2014 CONFERENCE
CHRONIC WASTING DISEASE CWD
A FEW FINDINGS ;
Conclusions. To our knowledge, this is the first established experimental
model of CWD in TgSB3985. We found evidence for co-existence or divergence of
two CWD strains adapted to Tga20 mice and their replication in TgSB3985 mice.
Finally, we observed phenotypic differences between cervid-derived CWD and
CWD/Tg20 strains upon propagation in TgSB3985 mice. Further studies are underway
to characterize these strains.
We conclude that TSE infectivity is likely to survive burial for long time
periods with minimal loss of infectivity and limited movement from the original
burial site. However PMCA results have shown that there is the potential for
rainwater to elute TSE related material from soil which could lead to the
contamination of a wider area. These experiments reinforce the importance of
risk assessment when disposing of TSE risk materials.
The results show that even highly diluted PrPSc can bind efficiently to
polypropylene, stainless steel, glass, wood and stone and propagate the
conversion of normal prion protein. For in vivo experiments, hamsters were ic
injected with implants incubated in 1% 263K-infected brain homogenate. Hamsters,
inoculated with 263K-contaminated implants of all groups, developed typical
signs of prion disease, whereas control animals inoculated with non-contaminated
materials did not.
Our data establish that meadow voles are permissive to CWD via peripheral
exposure route, suggesting they could serve as an environmental reservoir for
CWD. Additionally, our data are consistent with the hypothesis that at least two
strains of CWD circulate in naturally-infected cervid populations and provide
evidence that meadow voles are a useful tool for CWD strain typing.
Conclusion. CWD prions are shed in saliva and urine of infected deer as
early as 3 months post infection and throughout the subsequent >1.5 year
course of infection. In current work we are examining the relationship of
prionemia to excretion and the impact of excreted prion binding to surfaces and
particulates in the environment.
Conclusion. CWD prions (as inferred by prion seeding activity by RT-QuIC)
are shed in urine of infected deer as early as 6 months post inoculation and
throughout the subsequent disease course. Further studies are in progress
refining the real-time urinary prion assay sensitivity and we are examining more
closely the excretion time frame, magnitude, and sample variables in
relationship to inoculation route and prionemia in naturally and experimentally
CWD-infected cervids.
Conclusions. Our results suggested that the odds of infection for CWD is
likely controlled by areas that congregate deer thus increasing direct
transmission (deer-to-deer interactions) or indirect transmission
(deer-to-environment) by sharing or depositing infectious prion proteins in
these preferred habitats. Epidemiology of CWD in the eastern U.S. is likely
controlled by separate factors than found in the Midwestern and endemic areas
for CWD and can assist in performing more efficient surveillance efforts for the
region.
Conclusions. During the pre-symptomatic stage of CWD infection and
throughout the course of disease deer may be shedding multiple LD50 doses per
day in their saliva. CWD prion shedding through saliva and excreta may account
for the unprecedented spread of this prion disease in nature.
see full text and more ;
Monday, June 23, 2014
*** PRION 2014 CONFERENCE CHRONIC WASTING DISEASE CWD
*** Infectious agent of sheep scrapie may persist in the environment for at
least 16 years***
Gudmundur Georgsson1, Sigurdur Sigurdarson2 and Paul Brown3
New studies on the heat resistance of hamster-adapted scrapie agent:
Threshold survival after ashing at 600°C suggests an inorganic template of
replication
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel
Production
Detection of protease-resistant cervid prion protein in water from a
CWD-endemic area
A Quantitative Assessment of the Amount of Prion Diverted to Category 1
Materials and Wastewater During Processing
Rapid assessment of bovine spongiform encephalopathy prion inactivation by
heat treatment in yellow grease produced in the industrial manufacturing process
of meat and bone meals
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...
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
BSE RUMINANT FEED BAN FOR CERVIDS AND PETS IN THE USA ?
in short, there is none, and never has been.
I am concerned with pets as well.
I strongly, strenuously, urge the FDA et al and scientist (minus the
industry, politicians, and lobbyist there from on all issues), to revisit the
foolish voluntary ban on ruminant feed to cervids, and adopt an immediate
measure to make mandatory the ban of all ruminant feed to all cervids and pets.
... TSS
FDA WARNING LETTER (14-ATL-04) adulterated under Section 402(a)(4) [21
U.S.C. 342(a)(4)] of the Act, protein derived from mammalian tissues to feeds
that may be used for ruminants [21 C.F.R. 589.2000(e)(1)(iii)(B)]
2013
Sunday, December 15, 2013
FDA PART 589 -- SUBSTANCES PROHIBITED FROM USE IN ANIMAL FOOD OR FEED
VIOLATIONS OFFICIAL ACTION INDICATED OIA UPDATE DECEMBER 2013 UPDATE
Tuesday, December 23, 2014
FDA PART 589 -- SUBSTANCES PROHIBITED FROM USE IN ANIMAL FOOD OR FEED
VIOLATIONS OFFICIAL ACTION INDICATED OAI UPDATE DECEMBER 2014 BSE TSE PRION
DOCKET-- 03D-0186 -- FDA Issues Draft Guidance on Use of Material From Deer
and Elk in Animal Feed; Availability Date: Fri, 16 May 2003 11:47:37 -0500 EMC 1
Terry S. Singeltary Sr. Vol #: 1 http://www.fda.gov/ohrms/dockets/dailys/03/Jun03/060903/060903.htm
PLEASE SEE FULL TEXT SUBMISSION ;
Discussion: The C, L and H type BSE cases in Canada exhibit molecular
characteristics similar to those described for classical and atypical BSE cases
from Europe and Japan. *** This supports the theory that the importation of BSE
contaminated feedstuff is the source of C-type BSE in Canada. *** It also
suggests a similar cause or source for atypical BSE in these countries. ***
see page 176 of 201 pages...tss
*** Singeltary reply ;
Molecular, Biochemical and Genetic Characteristics of BSE in Canada
Susceptibility of European Red Deer (Cervus elaphus elaphus) to Alimentary
Challenge with Bovine Spongiform Encephalopathy
Mark P. Dagleish , * E-mail: mark.dagleish@moredun.ac.uk
Affiliation: Moredun Research Institute, Pentlands Science Park, Bush Loan,
Penicuik, Near Edinburgh EH26 0PZ, United Kingdom
⨯ Stuart Martin, Affiliation: Animal Health & Veterinary Laboratories
Agency Lasswade, Pentlands Science Park, Bush Loan, Penicuik, Near Edinburgh
EH26 0PZ, United Kingdom
⨯ Philip Steele, Affiliation: Moredun Research Institute, Pentlands Science
Park, Bush Loan, Penicuik, Near Edinburgh EH26 0PZ, United Kingdom
⨯ Jeanie Finlayson, Affiliation: Moredun Research Institute, Pentlands
Science Park, Bush Loan, Penicuik, Near Edinburgh EH26 0PZ, United Kingdom
⨯ Samantha L. Eaton, Affiliation: Neurobiology Division, The Roslin
Institute at, Royal (Dick) School of Veterinary Studies, University of
Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, United Kingdom
⨯ Sílvia Sisó, Affiliation: Animal Health & Veterinary Laboratories
Agency Lasswade, Pentlands Science Park, Bush Loan, Penicuik, Near Edinburgh
EH26 0PZ, United Kingdom
⨯ Paula Stewart, Affiliation: Neurobiology Division, The Roslin Institute
at, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter
Bush Campus, Midlothian, EH25 9RG, United Kingdom
⨯ Natalia Fernández-Borges, Affiliation: CIC bioGUNE, Parque tecnológico de
Bizkaia, Derio 48160, Spain
⨯ Scott Hamilton, Affiliation: Moredun Research Institute, Pentlands
Science Park, Bush Loan, Penicuik, Near Edinburgh EH26 0PZ, United Kingdom
⨯ Yvonne Pang, Affiliation: Moredun Research Institute, Pentlands Science
Park, Bush Loan, Penicuik, Near Edinburgh EH26 0PZ, United Kingdom
⨯ Francesca Chianini, Affiliation: Moredun Research Institute, Pentlands
Science Park, Bush Loan, Penicuik, Near Edinburgh EH26 0PZ, United Kingdom
⨯ Hugh W. Reid, Affiliation: Moredun Research Institute, Pentlands Science
Park, Bush Loan, Penicuik, Near Edinburgh EH26 0PZ, United Kingdom
⨯ Wilfred Goldmann, Affiliation: Neurobiology Division, The Roslin
Institute at, Royal (Dick) School of Veterinary Studies, University of
Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, United Kingdom
⨯ Lorenzo González, Affiliation: Animal Health & Veterinary
Laboratories Agency Lasswade, Pentlands Science Park, Bush Loan, Penicuik, Near
Edinburgh EH26 0PZ, United Kingdom
⨯ Joaquín Castilla, Affiliations: CIC bioGUNE, Parque tecnológico de
Bizkaia, Derio 48160, Spain, IKERBASQUE, Basque Foundation for Science, Bilbao
48013, Bizkaia, Spain
⨯ [ ... ], Martin Jeffrey Affiliation: Animal Health & Veterinary
Laboratories Agency Lasswade, Pentlands Science Park, Bush Loan, Penicuik, Near
Edinburgh EH26 0PZ, United Kingdom
⨯ [ view all ] [ view less ] Susceptibility of European Red Deer (Cervus
elaphus elaphus) to Alimentary Challenge with Bovine Spongiform Encephalopathy
Mark P. Dagleish, Stuart Martin, Philip Steele, Jeanie Finlayson, Samantha L.
Eaton, Sílvia Sisó, Paula Stewart, Natalia Fernández-Borges, … Scott Hamilton,
Yvonne Pang PLOS x Published: January 23, 2015 DOI: 10.1371/journal.pone.0116094
Abstract
European red deer (Cervus elaphus elaphus) are susceptible to the agent of
bovine spongiform encephalopathy, one of the transmissible spongiform
encephalopathies, when challenged intracerebrally but their susceptibility to
alimentary challenge, the presumed natural route of transmission, is unknown. To
determine this, eighteen deer were challenged via stomach tube with a large dose
of the bovine spongiform encephalopathy agent and clinical signs, gross and
histological lesions, presence and distribution of abnormal prion protein and
the attack rate recorded. Only a single animal developed clinical disease, and
this was acute with both neurological and respiratory signs, at 1726 days post
challenge although there was significant (27.6%) weight loss in the preceding
141 days. The clinically affected animal had histological lesions of vacuolation
in the neuronal perikaryon and neuropil, typical of transmissible spongiform
encephalopathies. Abnormal prion protein, the diagnostic marker of transmissible
encephalopathies, was primarily restricted to the central and peripheral nervous
systems although a very small amount was present in tingible body macrophages in
the lymphoid patches of the caecum and colon. Serial protein misfolding cyclical
amplification, an in vitro ultra-sensitive diagnostic technique, was positive
for neurological tissue from the single clinically diseased deer. All other
alimentary challenged deer failed to develop clinical disease and were negative
for all other investigations. These findings show that transmission of bovine
spongiform encephalopathy to European red deer via the alimentary route is
possible but the transmission rate is low. Additionally, when deer carcases are
subjected to the same regulations that ruminants in Europe with respect to the
removal of specified offal from the human food chain, the zoonotic risk of
bovine spongiform encephalopathy, the cause of variant Creutzfeldt-Jakob
disease, from consumption of venison is probably very low.
snip...
Discussion This investigation resulted in the first and only known case, to
date, of clinical disease or accumulation of abnormal PrPd in any cervid species
due to oral challenge with BSE. The increase in incubation period compared to
European red deer challenged with BSE intra-cerebrally (1060 days) [33] compared
to oral challenge (1727 days) is approximately 60% and similar to the
differences observed in incubation periods for sheep or goats when challenged
with TSE agents by these two routes [40,41]. The neurological clinical signs
observed could be broadly related to the spongiform encephalopathy and the
accumulation of PrPd in that the restlessness, stereotypic head movements and
pacing may be due to compromise of the nucleus accumbens [42], found in the
striatum, and the laboured breathing due to the lesions in the medulla, where
the respiratory centre is located [43]. Alternatively, the laboured and audible
mouth breathing may have been due to, or contributed to by, compromise of either
of the recurrent laryngeal nerves resulting in some degree of laryngeal
paralysis but we were unable to determine this. Apart from the gradual loss of
body weight, the speed of onset of clinical signs and progression was very rapid
but animal welfare requirements precluded any further longitudinal study of
these. The clinical signs described for this animal are broadly similar to those
reported for clinical BSE in European red deer challenged via the intracerebral
route [33], clinical cases of CWD in deer [44] and clinical cases of BSE in
cattle [45].
snip...see full text ;
*** Singeltary reply ;
ruminant feed ban for cervids in the United States ?
31 Jan 2015 at 20:14 GMT
*** 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.
Sunday, May 3, 2015
PRION2015 FORT COLLINS
TSS
Friday, May 15, 2015
Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions
Report
