Evaluation of the Zoonotic Potential of Transmissible Mink Encephalopathy
Emmanuel E. Comoy 1,*, Jacqueline Mikol 1, Marie-Madeleine Ruchoux 1,
Valérie Durand 1, Sophie Luccantoni-Freire 1, Capucine Dehen 1, Evelyne Correia
1, Cristina Casalone 2, Juergen A. Richt 3, Justin J. Greenlee 4, Juan Maria
Torres 5, Paul Brown 1 and Jean-Philippe Deslys 1
1 CEA, Institute of Emerging Diseases and Innovative Therapies (iMETI),
Division of Prions and Related Diseases (SEPIA), Route du Panorama, BP6, 92265
Fontenay-aux-Roses, France; E-Mails: jacqueline.mikol@wanadoo.fr (J.M.);
mruchoux@yahoo.fr (M.-M.R.); valerie.durand@cea.fr (V.D.);
sophie.luccantoni@cea.fr (S.L.); capucine.dehen@cea.fr (C.D.);
evelyne.correia@cea.fr (E.C.); paulwbrown@comcast.net (P.B.); jpdeslys@cea.fr
(J-P.D.)
2 Istituto Zooprofilattico Sperimentale del Piemonte, Via Bologna 148,
10154 Torino, Italy; E-Mail: cristina.casalone@izsto.it (C.C.)
3 Kansas State University, College of Veterinary Medicine, K224B Mosier
Hall, Manhattan, Kansas 66506-5601 USA; E-Mail: jricht@vet.k-state.edu
4 National Animal Disease Center, USDA, Agricultural Research Service, 1920
Dayton Ave, Ames, Iowa 50010 USA; E-Mail: justin.greenlee@ars.usda.gov
(J.J.G.)
5 Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria,
Madrid, Spain; E-mail: jmtorres@inia.es
* Author to whom correspondence should be addressed; E-Mail:
emmanuel.comoy@cea.fr (E.E.C.); Tel.: +33-46-54-90-05; Fax: +33-46-54-93-19.
Received: 27 June 2013; in revised form: 28 July 2013 / Accepted: 30 July 2013 /
Published: 30 July 2013
Abstract: Successful transmission of Transmissible Mink Encephalopathy
(TME) to cattle supports the bovine hypothesis for 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 indicate 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 but distinct from c-BSE. TME derived from another donor species (raccoon)
induced a similar disease with even shorter incubation periods. L-BSE and
cattle-adapted TME were also transmissible to transgenic mice expressing human
prion protein (PrP). Secondary transmissions to transgenic mice expressing
bovine PrP maintained the features of the three tested bovine 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 these strains, and
therefore the possible presence of L-BSE for many decades prior to its
identification in USA and Europe.
Keywords: primate; prion; transgenic mice; TME; cattle; raccoon; zoonotic
potential
1. Introduction
Transmissible Mink Encephalopathy (TME) is a rare prion disease affecting
ranch-reared mink that was reported in four isolated outbreaks in the USA in
1947, 1961, 1963 and 1985 [1], and in several other outbreaks in Canada, East
Germany, Finland and the former USSR during the same time period, with
prevalence rates as high as 100% and an estimated incubation period of 6 months
[2]. Epidemiological studies suggested that each outbreak was due to dietary
infection. Several experimental exposures of mink to ruminant prions were
performed to identify the exact origin of TME. Low efficiency and rate of
transmission were observed after inoculation of mink with sheep scrapie [3] and
elk-derived Chronic Wasting Disease (CWD) [4] isolates with an incubation time
of 2–3 years, while a 100% success rate of transmission was obtained within 12
months post-exposure to classical Bovine Spongiform Encephalopathy (c-BSE) [5].
However, in all cases, the resulting diseases differed from TME. Conversely, TME
was experimentally transmitted to cattle [6,7] inducing a prion disease distinct
from c-BSE within 16 to 28 months. Experimental transmissions to conventional
and transgenic rodent models suggested similarities between TME and L-BSE [8,9],
an atypical cattle prion strain that was incidentally identified several years
ago in aged cattle through systematic testing within the framework of the
European BSE epizootic [10]. It was speculated that sporadic atypical cattle BSE
(H- and/or L- type) might be at the origin of c-BSE [11,12]. These observations
support the hypothesis of a bovine origin to TME.
Currently, classical BSE is the only animal transmissible spongiform
encephalopathy (TSE) considered as a zoonotic disease, since it induces a
variant of Creutzfeldt-Jakob disease (CJD) in humans [13–15]. We, and others,
demonstrated that the cynomolgus macaque, previously used to demonstrate the
transmissibility of human prion diseases [16], constitutes a relevant
experimental model to assess the BSE risk for humans [14,17–20]. The same
species was also susceptible to L-BSE [21,22], developing a disease distinct
from c-BSE. Taken together, these results suggested a low cattle-to-primate
species barrier and raised questions about the zoonotic potential of different
bovine prion strains. We chose to assess the risk for human health linked to
TME-related prion strains by evaluating the transmissibility of cattle-adapted
TME in this cynomolgus macaque model, in comparison to raccoon TME as a
non-ruminant source of the same prion strain. In parallel, we used transgenic
mice overexpressing human or bovine prion protein (PrP) to assess the relevance
of our results for human situation.
2. Results and Discussion
2.1. Transmission of Cattle-Adapted TME in Experimental Models
A primate intracerebrally inoculated with the equivalent of 40 mg of a
TME-infected cattle brain (second passage) developed the first neurological
signs of disease after less than twenty months of incubation (Table 1). It first
showed slowness and weak tremors amplifying with time. Clinical signs then
evolved with ataxia, hypermetria, poor vision, and apparent cognitive
impairment. Appetite remained normal during the entire 3.5 months clinical
period (limited weight loss) and no behavioral changes were noticed (total
survival period 23 months). The presence of cerebral spongiosis and
protease-resistant prion protein (PrPres) deposition (detailed hereafter)
confirmed the presence of prion disease. When another, non-ruminant, source of
TME was injected, disease occurred with a similar period of survival (Table
1).
Table 1. Survival (incubation and clinical duration) in months of
individual cynomolgus macaques exposed to different prion strains.
In parallel, several but not all the transgenic mice overexpressing human
(Met/Met) PrP (tg650 mice) intracerebrally inoculated with cattle-adapted TME
inoculum exhibited cerebral PrPres: partial transmission (75 %) occurred in
humanized mice that died after about 18 months of incubation (Figure 1).
2.2. Transmission of other cattle prion strains
From these results, cattle-adapted TME represents the third cattle prion
strain (together with c-BSE and L-BSE) experimentally demonstrated to be
transmissible to non-human primates. We confirmed in this study the previously
described transmissibility of both L-BSE and c-BSE in both experimental primates
[14,21] and transgenic [23,24] models.
In the primate model, exposure to L-BSE-infected cattle brain induced a
clinical picture with incubation time and duration of illness that are similar
to those observed after exposure to cattle-adapted TME, even after exposure to
as little as 2.5 mg of brain tissue (Table 1). Conversely, c-BSE infected
primates developed a different clinical picture, as previously described
[14,21], with longer incubation periods even when they were exposed to 100 mg of
brain tissue.
A comparison of incubation periods confirmed and magnified the higher
virulence of L-BSE for macaque compared to c-BSE, which we had previously
observed [21]. Moreover, since incubation periods classically increase with the
dilution of initial infectious amount in experimental prion diseases, the
similarity of incubation durations for primates exposed to either 25 or 2.5 mg
of L-BSE-infected brain is in favor of a substantial amount of infectivity in
the brains of cattle infected with the L-BSE prion strain.
Figure 1. Transmission studies of bovine prion strains to transgenic mice
overexpressing human (tg650) or bovine (tg110) PrP. Tg650 mice (colored in blue)
were intracerebrally inoculated with 20 μl of 10 % brain homogenate from cattle
infected with adapted TME, L-BSE or c-BSE strains. Tg110 mice (colored in red)
were inoculated directly with the same cattle inocula, or with brains from
macaques or tg650 mice previously exposed to those cattle inocula. vCJD inoculum
was injected as controls. Transmission results are expressed as rates of
transmission (%), number of recipient mice (in brackets), and mean ± standard
deviation of their incubation periods.
In the model of transgenic mice overexpressing human (Met/Met) PrP (tg650
mice), an incomplete transmission rate of 25% of L-BSE was observed after an
incubation period of similar duration (18 months) to those from cattle
TME-exposed animals, while a 100% transmission rate was observed with c-BSE, but
with longer incubations (animals were euthanized 27 months post inoculation,
corresponding to the lifespan of these animals in our facilities). These
observations are consistent with the results obtained with L-BSE strain by
Beringue et al., in this transgenic model [24] and by Kong in another humanized
mouse model [25], suggesting a less efficient transmission of L-BSE and TME than
c-BSE in this transgenic model, but with a shorter evolution when it
occurs.
The overexpression of PrP in transgenic mice is often criticized as an
element helping to force the way through the species barrier and extrapolation
of our results in this model to the human situation should be taken with
caution, since transgenic mice expressing physiological levels of human PrP are
resistant to L-BSE [26]. Nevertheless, it must be noted that these ‘physiologic’
mice are also resistant to c-BSE, impairing its relevance for assessing the
zoonotic potential of animal prion strains. In any case, an efficient
transmission of these prion strains to primate, possibly in the presence of a
weak cattle-to-primate species barrier, may be extrapolated from our results in
the macaque model, which is strengthened by the transgenic model and the current
absence of any argument for a zoonotic potential of prion strains derived from
other ruminants (ovine or caprine classical or atypical scrapie, wild ruminant
CWD).
2.3. Comparative Pathologies of the Diseases Induced by the Different
Cattle Prions
The macaque inoculated with cattle-adapted TME showed widespread cortical
spongiosis similar to that in both primates exposed to L-BSE (Figure 2). The
spongiosis profile for these three animals was superimposable, with less
pronounced lesions in the medulla and cerebellum in cattle TME-infected animal
than in L-BSE animals (Figure 3). In the c-BSE-inoculated macaques, spongiosis
profiles were different, with more discrete cortical spongiosis and lesions
mainly affecting the thalamus, medulla oblongata and cerebellum. When we used a
non-cattle (raccoon) TME source, a similar spongiosis profile was observed but
with slight modifications (cortical lesions were less pronounced and pallidum
and cerebellum were virtually spared).
Primates inoculated with L-BSE or cattle TME exhibited a similar diffuse
laminar synaptic pattern of PrPres depositions (either fine and sandy or roughly
granular) but no evidence of plaques, even when stained with thioflavine T (data
not shown), whereas c-BSE-infected animals had weak diffuse synaptic labeling
but multiple intensely-stained PrPres aggregates and characteristic plaques
[21].
Figure 2. Histopathology and PrPres immunostaining. Spongiosis (A–D) and
PrPres deposition (E–H) in frontal cortex in primates infected with
cattle-adapted TME (A, E), L-BSE (B, F), classical BSE (C, G) or raccoon TME (D,
H) (original magnification x200 for spongiosis and x400 for PrPres staining).
Immunostaining of PrPres was performed with 3F4 monoclonal anti-PrP antibody
after proteinase K treatment as previously described [21]. No staining was
observed in the brain of control healthy primates (data not shown) under these
conditions.
Figure 3. Spongiosis profiles in infected primates. Lesional profiles
(based on spongiosis) in primates exposed to cattle-adapted TME (A) L-BSE (B),
c-BSE (C) and raccoon TME (D) were defined according to the scoring and areas
described by Parchi et al. [27]. Spongiosis profile of c-BSE primates is
depicted as the mean among 5 primates exposed to c-BSE. Frontal Cortex (FC)
,Temporal Cortex (TC), Parietal Cortex (PC), Occipital Cortex (OC), Hippocampus
(HI), Entorhinal Cortex (EC),Striatum (ST), Putamen (PUT), Pallidum (PAL),
Thalamus (TH), Substantia Nigra (SN), Periventricular Gray (PG), Locus coeruleus
(LC), Medulla (ME), Cerebellum (granules) (CB), Cerebellum (molecular layer)
(CB), Purkinje cells (PK).
2.3. PrPres Detection: Strain Discrimination by Proteinase K Sensitivity
and Antibody Reactivity
We previously demonstrated that the technique that we developed for typing
and classifying prion strains in small ruminants might also be used to
discriminate L-BSE from c-BSE in experimentally infected macaques [21]. Briefly,
this technique is based on the strain-dependent threshold of removal of the
octapeptides under controlled conditions of proteolysis, in which this
N-terminal region is highly resistant to proteolysis for scrapie and sporadic
CJD prions, but weakly resistant for c-BSE and undetectable for L-BSE.
Figure 4. Electrophoretic analysis and differential sensitivity to
proteolysis of PrPres in various experimental prion diseases of primates and
transgenic mice overexpressing human PrP. PrPres from brain homogenates
(primates or transgenic mice Tg650 overexpressing human PrP experimentally
infected with cattle-adapted TME, L-BSE or c-BSE) were purified with high
concentrations of proteinase K, and detected with monoclonal antibodies
recognizing the octapeptide region (Saf-32) or the core (Sha-31) of the protein.
The membrane blotted with Saf-32 was overexposed compared to the membrane
blotted with Sha-31.
Under these experimental conditions, PrPres in both primates and Tg650
exposed to cattle-adapted TME behaved like PrPres derived from corresponding
animals infected with L-BSE [21] (Figure 4). A 19 kDa non-glycosylated band was
observed with the anti-core antibody Sha-31, with an equal distribution between
mono- and diglycosylated bands. With the anti-octapeptide antibody Saf-32,
almost no immunoreactivity was detectable for these animals. In parallel, c-BSE
infected animals exhibited the expected features, including a 20 kDa non
glycosylated band with Sha-31, predominance of diglycosylated band and a weak
immunoreactivity with Saf-32 (only observable when overexposing the membrane),
suggesting that c-BSE related PrPres is more resistant to proteolysis than
L-BSE- or TME-related PrPres (the macaque infected with raccoon TME exhibited
glycophoretic profiles and resistance to proteolysis resistance similar to the
macaque infected with cattle TME, data not shown). We previously described the
biochemical similarities between PrPres derived from L-BSE infected macaque and
cortical MM2 sporadic CJD: those observations suggest a link between these two
uncommon prion phenotypes in a primate model (it is to note that such a link has
not been observed in other models less relevant from the human situation as
hamsters or transgenic mice overexpressing ovine PrP [28]). We speculate that a
group of related animal prion strains (L-BSE, c-BSE and TME) would have a
zoonotic potential and lead to prion diseases in humans with a type 2 PrPres
molecular signature (and more specifically type 2B for vCJD).
Strain signatures were also assessed in bioassays in transgenic mice
overexpressing bovine PrP (tg110). Those mice were intracerebrally inoculated
with cattle-adapted TME, L-BSE or c-BSE isolates issued from cattle, macaque or
tg650 recipients (vCJD samples were also included as controls) (Figure 1). All
the inoculated mice developed a TSE, with similar incubation periods whatever
the source (cattle, primate, Tg650 mice or human), but related to the original
prion strain: mean periods ranged from 216 to 233 days for cattle-adapted TME
and from 226 to 238 days for L-BSE, while c-BSE led to longer incubation periods
ranging from 309 to 362 days. This biochemical strain typing protocol was
adapted (preferential use of Bar-233 antibody for protein core detection) and
applied to Tg110 mice (Figure 5). The respective features (size of non
glycosylated band, proportion of glycosylated forms, resistance of octapeptide
regions to proteolysis) that were observed in primates and Tg650 mice for each
original prion strain (cattle TME, L-BSE or c-BSE) were also observed in this
model, regardless of the host from which the prion originated.
Figure 5. Electrophoretic analysis and differential sensitivity to
proteolysis of PrPres in various experimental prion diseases of transgenic mice
overexpressing bovine PrP. Transgenic mice Tg110 overexpressing bovine PrP were
inoculated with brain tissue from cattle, primate, or Tg650 mice experimentally
infected with cattle-adapted TME, L-BSE or c-BSE, or brain tissue from a vCJD
patient. The brains were homogenized and PrPres was purified with high
concentrations of proteinase K, and detected with monoclonal antibodies that
recognize either the octapeptide region (Saf-32) or the core (Bar-233) of the
protein. The membrane blotted with Saf-32 was overexposed compared to the
membrane blotted with Bar-233.
3. Experimental Section
3.1. Ethics Statement
Primates and mice were housed and handled in accordance with the European
Directive 2010/63 related to animal protection and welfare in research, under
the constant internal surveillance of veterinarians. Animals were handled under
anesthesia to limit stress, and euthanasia was performed for ethical reasons
when animals lost autonomy.
3.2. Experimental Animals
Captive-bred 2-5 year-old male cynomolgus macaques (Macaca fascicularis)
were provided by Noveprim (Mauritius), checked for the absence of common primate
pathogens before importation, and handled in accordance to national guidelines.
Transgenic mice overexpressing human (tg650 [23]) or bovine (tg110 [29]) PrP
were internally bred at CEA (Fontenay-aux-Roses, France). Animals housed in
level-3 animal care facilities (agreement numbers A 92-032-02 for animal care
facilities, 92-189 for animal experimentation) were regularly examined at least
once a week.
3.3. Experimental Inoculations
The TME inocula were derived from a second passage in cattle (#A263, [7])
or the first passage from mink to raccoon (#R5-6, [30]). The L-BSE inoculum (mix
of brainstem and thalamus) was derived from an asymptomatic 15 year-old Italian
Piemontese cow (#1088, [10]), and the c-BSE inocula were derived from infected
UK cattle. Macaques and mice were intracerebrally (i.c.) inoculated with 1% or
10% brain homogenates in a 5% glucose solution.
3.4. Neuropathology and Immunohistochemistry
Tissues were fixed in formalin 4% for histological examination.
Neuropathology and immunohistochemical detection of protease-resistant prion
protein (PrPres) were performed on brain sections as previously described
[21].
3.4. PrPres Analysis
PrP was purified according to the TeSeE purification protocol (Bio-Rad), in
adapted conditions of proteolysis for strain discrimination as previously
described [21], using Bar-233, Sha-31 or Saf-32 antibodies.
4. Conclusions
We have shown that cattle-adapted TME is the third cattle prion strain
(joining classical and L-type BSE) to be transmissible both to non-human
primates and transgenic mice overexpressing human PrP. However, the successful
transmission of raccoon TME to primate, inducing a disease with similar features
as cattle TME, extends this notion to TME-related strains independent of host
origin. Pathological, biochemical and bioassay investigations converged to
demonstrate the similarity between cattle-adapted TME and L-BSE. Together with
previous experiments performed in ovinized and bovinized transgenic mice and
hamsters [8,9] indicating similarities between TME and L-BSE, the data support
the hypothesis that L-BSE could be the origin of the TME outbreaks in North
America and Europe during the mid-1900s. The corollary of this notion is the
longstanding existence of atypical bovine prion cases in those countries during
the same period, if not earlier. Although the risk of L-BSE for public health
must be further assessed through studies using the oral route of exposure before
drawing definitive conclusions, these data underline the importance of a
potential zoonotic risk of L-BSE in the management of consumer protection,
particularly in the context of the current relaxation of European policy with
respect to BSE.
Acknowledgments
The authors acknowledge Health Canada and the NIAID-NIH PO1 AI 77774-01
“Pathogenesis, Transmission and Detection of Zoonotic Prion Diseases” for
funding parts of those experiments. The authors thanks J.-L. Villotte and V.
Beringue for their generous gift of transgenic mice overexpressing human PrP, as
well as Christophe Durand, Onofrio Bevilacqua and Sébastien Jacquin for the
excellent daily care they gave to the animals.
Conflict of Interest
The CEA owns a patent covering the BSE diagnostic tests commercialized by
the company Bio-Rad.
References
SNIP...
>>>We previously described the biochemical similarities between
PrPres derived from L-BSE infected macaque and cortical MM2 sporadic CJD: those
observations suggest a link between these two uncommon prion phenotypes in a
primate model (it is to note that such a link has not been observed in other
models less relevant from the human situation as hamsters or transgenic mice
overexpressing ovine PrP [28]). We speculate that a group of related animal
prion strains (L-BSE, c-BSE and TME) would have a zoonotic potential and lead to
prion diseases in humans with a type 2 PrPres molecular signature (and more
specifically type 2B for vCJD)<<<
2003 Singeltary Submission to FDA ;
Asante/Collinge et al have major findings on sporadic CJD, why in the hell
is this not making big news in the USA? ($$$) the fact that with the new
findings from Collinge et al, that BSE transmission to the 129-methionine
genotype can lead to an alternate phenotype which is indistinguishable from type
2 PrPSc, the commonest sporadic CJD, i only ponder how many of the sporadic CJDs
in the USA are tied to this alternate phenotype? these new findings are very
serious, and should have a major impact on the way sporadic CJDs are now treated
as opposed to the vCJD that was thought to be the only TSE tied to ingesting
beef, in the medical/surgical arena. these new findings should have a major
impact on the way sporadic CJD is ignored, and should now be moved to the
forefront of research as with vCJD/nvCJD. the USA has many TSEs, the USA lacks
sufficient testing for TSEs in cattle, and the USA still refuses to rapid TSE
test USA cattle in sufficient numbers to find, when the late Dr. Richard Marsh
had proven that mink had gone down with a TSE (TME), from being fed on 95%+
downer cattle.
From: Terry S. Singeltary Sr. [flounder@wt.net]
Sent: Tuesday, July 29, 2003 1:03 PM
Cc: ggraber@cvm.fda.gov; Linda.Grassie@fda.gov; BSE-L
Subject: Docket No. 2003N-0312 Animal Feed Safety System [TSS SUBMISSION TO
DOCKET 2003N-0312]
Greetings FDA,
my name is Terry S. Singeltary Sr., i lost my mother to hvCJD (Heidenhain
Variant Creutzfeldt Jakob Disease).
i would kindly like to comment on the proposed HACCP method of detecting
and or preventing TSEs in the human/animal feed supply.
it seems to me by implementing something that was designed for Astronauts
instead of cattle, something that the GAO has already stated is terribly flawed
(HACCP), i find it very disturbing to continue to insist on refusing to use
rapid TSE TESTING in sufficient numbers to find TSEs, as with other Countries
that they too once thought they were BSE free. for example, it took Italy 1
MILLION rapid TSE tests since 2001 to find 102 cases of BSE. THE USA has only
tested 48,000 cattle in the 14 years of surveillance. there is documented proof
that indeed the USA cattle have been infected with a TSE for decades, but the
FDA/USDA and other USA Gov. agencies continue to conveniently ignore these
findings. YOU must not ignore what Richard Marsh found. Plus, you must not
ignore Asante/Collinge new findings that BSE transmission to the 129-methionine
genotype can lead to an alternate phenotype that is indistinguishable from type
2 PrPSc, the commonest _sporadic_ CJD. The USA has been feeding ruminant
by-products back to cattle, deer, elk and sheep for decades, and TSEs in these
species have been recycled for feed for decades in the USA. The rendering
process here in the USA will not kill this agent. to implement any HACCP over
massive rapid TSE testing is only prolonging the inevitable, and will only allow
the agent to spread further. it is simply a band-aid approach to something that
needs a tourniquet...
From: Terry S. Singeltary Sr. [flounder9@verizon.net]
Sent: Monday, July 24, 2006 1:09 PM
To: FSIS RegulationsComments
Subject: [Docket No. FSIS-2006-0011] FSIS Harvard Risk Assessment of Bovine
Spongiform Encephalopathy (BSE)
Page 1 of 98
8/3/2006
Greetings FSIS,
I would kindly like to comment on the following ;
response to Singeltary et al ;
Monday, January 08, 2001 3:03 PM
A kind greetings from Bacliff, Texas !
I have often pondered if the whole damn mad cow follies started over here
in the USA, and somehow, the USA shipped it over to the UK ?
It happened with S. Korea and CWD, via Canada. see ;
The disease was confirmed only in elk in the Republic of Korea in 2001,
2004 and 2005. Epidemiological investigations showed that CWD was introduced via
importation of infected elk from Canada between 1994 and 1997.
but I still am not so sure that the mad cow follies did not start long ago
right here in the USA i.e. Richard Marsh and deadstock downer cattle to those
mink, and then the USA shipped it to hell and back. just pondering out loud
here. ...tss
The exact same recipe for B.S.E. existed in the U.S. for years
and years. In reading over the Qualitative Analysis of BSE
Risk Factors-1, this is a 25 page report by the
USDA:APHIS:VS. It could have been done in one page. The
first page, fourth paragraph says it all;
"Similarities exist in the two countries usage of continuous
rendering technology and the lack of usage of solvents,
however, large differences still remain with other risk factors
which greatly reduce the potential risk at the national level."
Then, the next 24 pages tries to down-play the high risks of
B.S.E. in the U.S., with nothing more than the cattle to sheep
ratio count, and the geographical locations of herds and flocks.
That's all the evidence they can come up with, in the next 24
pages.
Something else I find odd, page 16;
"In the United Kingdom there is much concern for a specific
continuous rendering technology which uses lower
temperatures and accounts for 25 percent of total output. This
technology was _originally_ designed and imported from the
United States. However, the specific application in the
production process is _believed_ to be different in the two
countries."
A few more factors to consider, page 15;
"Figure 26 compares animal protein production for the two
countries. The calculations are based on slaughter numbers,
fallen stock estimates, and product yield coefficients. This
approach is used due to variation of up to 80 percent from
different reported sources. At 3.6 million tons, the United
States produces 8 times more animal rendered product than
the United Kingdom."
"The risk of introducing the BSE agent through sheep meat and
bone meal is more acute in both relative and absolute terms in
the United Kingdom (Figures 27 and 28). Note that sheep
meat and bone meal accounts for 14 percent, or 61 thousand
tons, in the United Kingdom versus 0.6 percent or 22 thousand
tons in the United States. For sheep greater than 1 year, this is
less than one-tenth of one percent of the United States supply."
"The potential risk of amplification of the BSE agent through
cattle meat and bone meal is much greater in the United States
where it accounts for 59 percent of total product or almost 5
times more than the total amount of rendered product in the
United Kingdom."
Considering, it would only take _one_ scrapie infected sheep
to contaminate the feed. Considering Scrapie has run rampant
in the U.S. for years, as of Aug. 1999, 950 scrapie infected
flocks. Also, Considering only one quarter spoonful of scrapie
infected material is lethal to a cow. Considering all this, the
sheep to cow ration is meaningless. As I said, it's 24 pages of
B.S.e.
To be continued...
Terry S. Singeltary Sr. P.O. Box 42 Bacliff, Texas USA
_____________________________________________________________________
snip...see full text ;
Monday, June 3, 2013
Unsuccessful oral transmission of scrapie from British sheep to
cattle
Thursday, August 15, 2013
Stability properties of PrPSc from cattle with experimental transmissible
spongiform encephalopathies: use of a rapid whole homogenate, protease-free
assay
Sunday, July 21, 2013
Welsh Government and Food Standards Agency Wales Joint Public Consultation
on the Proposed Transmissible Spongiform Encephalopathies (Wales) Regulations
2013 Singeltary Submission WG18417
Saturday, July 6, 2013
Small Ruminant Nor98 Prions Share Biochemical Features with Human
Gerstmann-Sträussler-Scheinker Disease and Variably Protease-Sensitive
Prionopathy
Research Article
Tuesday, July 21, 2009
Transmissible mink encephalopathy - review of the etiology
http://transmissible-mink-encephalopathy.blogspot.com/2009/07/transmissible-mink-encephalopathy.html
Saturday, December 01, 2007
Phenotypic Similarity of Transmissible Mink Encephalopathy in Cattle and
L-type Bovine Spongiform Encephalopathy in a Mouse Model
Sunday, December 10, 2006
Transmissible Mink Encephalopathy TME
Thursday, March 29, 2012
atypical Nor-98 Scrapie has spread from coast to coast in the USA 2012
NIAA Annual Conference April 11-14, 2011San Antonio, Texas
Friday, July 26, 2013
Voluntary Scrapie Program USA UPDATE July 26, 2013 increase in FY 2013 is
not statistically meaningful due to the sample size
Sunday, August 25, 2013
Prion2013 Chronic Wasting Disease CWD risk factors, humans, domestic cats,
blood, and mother to offspring transmission
Friday, August 16, 2013
*** Creutzfeldt-Jakob disease (CJD) biannual update August 2013 U.K. and
Contaminated blood products induce a highly atypical prion disease devoid of
PrPres in primates
Sunday, August 11, 2013
Creutzfeldt-Jakob Disease CJD cases rising North America updated report
August 2013
*** Creutzfeldt-Jakob Disease CJD cases rising North America with Canada
seeing an extreme increase of 48% between 2008 and 2010
TSS
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