- Title: EXPERIMENTAL SECOND PASSAGE OF CHRONIC WASTING
DISEASE (CWD (MULE DEER)) AGENT TO CATTLE
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- Authors
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- Hamir, Amirali Kunkle, Robert Miller, Janice - ARS RETIRED
Greenlee, Justin Richt, Juergen
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- Submitted to: Journal of Comparative Pathology Publication
Type: Peer Reviewed Journal Publication Acceptance Date: July 25, 2005
Publication Date: January 1, 2006 Citation: Hamir, A.N., Kunkle, R.A.,
Miller, J.M., Greenlee, J.J., Richt, J.A. 2006. Experimental second passage
of chronic wasting disease (CWD(mule deer)) agent to cattle. Journal of
Comparative Pathology. 134(1):63-69.
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- Interpretive Summary:
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- To compare the findings of experimental first and second
passage of chronic wasting disease (CWD) in cattle, 6 calves were inoculated
into the brain with CWD-mule deer agent previously (first) passaged in
cattle. Two other uninoculated calves served as controls. Beginning 10-12
months post inoculation (PI), all inoculates lost appetite and weight.
Five animals subsequently developed clinical signs of central nervous
system (CNS) abnormality. By 16.5 months PI, all cattle had been euthanized
because of poor prognosis. None of the animals showed microscopic lesions
of spongiform encephalopathy (SE) but the CWD agent was detected in their
CNS tissues by 2 laboratory techniques (IHC and WB). These findings demonstrate
that inoculated cattle amplify CWD agent but also develop clinical CNS
signs without manifestation of microscopic lesions of SE. This situation
has also been shown to occur following inoculation of cattle with another
TSE agent, namely, sheep scrapie. The current study confirms previous
work that indicates that the diagnostic tests currently used for confirmation
of bovine spongiform encephalopathy (BSE) in the U.S. would detect CWD
in cattle, should it occur naturally. Furthermore, it raises the possibility
of distinguishing CWD from BSE in cattle due to the absence of microscopic
lesions and a unique multifocal distribution of PrPres, as demonstrated
by IHC, which in this study, appears to be more sensitive than the WB.
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- Technical Abstract:
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- To compare clinicopathological findings of first and
second passage of chronic wasting disease (CWD) in cattle, a group of
calves (n=6) were intracerebrally inoculated with CWD-mule deer agent
previously (first) passaged in cattle. Two other uninoculated calves served
as controls. Beginning 10-12 months post inoculation (PI), all inoculates
lost appetite and lost weight. Five animals subsequently developed clinical
signs of central nervous system (CNS) abnormality. By 16.5 months PI,
all cattle had been euthanized because of poor prognosis. None of the
animals showed microscopic lesions of spongiform encephalopathy (SE) but
PrPres was detected in their CNS tissues by immunohistochemistry (IHC)
and Western blot (WB) techniques. These findings demonstrate that intracerebrally
inoculated cattle not only amplify CWD PrPres but also develop clinical
CNS signs without manifestation of morphologic lesions of SE. This situation
has also been shown to occur following inoculation of cattle with another
TSE agent, scrapie. The current study confirms previous work that indicates
the diagnostic techniques currently used for confirmation of bovine spongiform
encephalopathy (BSE) in the U.S. would detect CWD in cattle, should it
occur naturally. Furthermore, it raises the possibility of distinguishing
CWD from BSE in cattle due to the absence of neuropathologic lesions and
a unique multifocal distribution of PrPres, as demonstrated by IHC, which
in this study, appears to be more sensitive than the WB.
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