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Research Project:
TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
Location:
Virus and Prion Diseases of Livestock
Title:
Transmission
of Chronic Wasting Disease Agent of Mule Deer
(Cwd**md) to Suffolk Sheep by Intracerebral Route
Authors
Submitted to: European Society of
Veterinary Pathology
Publication Type: Abstract
Publication Acceptance Date: June 5,
2006
Publication Date: August 31, 2006
Citation: Hamir, A., Kunkle, R., Cutlip,
R., Miller, J., Williams, E., Richt, J.
2006. Transmission of chronic wasting
disease agent of mule deer (CWD**md) to
Suffolk sheep by intracerebral route
[abstract]. European Society of
Veterinary Pathology 24th Annual
Meeting. Paper No. P63. p. 171-172.
Technical Abstract:
Chronic wasting disease (CWD) is a
transmissible spongiform encephalopathy
(TSE) that has been identified in
captive and free-ranging cervids in the
U.S. since 1967. To determine the
transmissibility of CWD to sheep, 8
Suffolk lambs [4 QQ and 4 QR at codon
171 of prion protein (PRNP) gene] were
inoculated intracerebrally with a pooled
brain suspension from 28 mule deer
naturally affected with CWD (CWD**md).
Two other lambs (1 QQ and 1 QR at codon
171 of the PRNP gene) were kept as
non-inoculated controls. Within 36
months post inoculation (MPI), 2 animals
became sick and were euthanized. Only 1
sheep (euthanized at 35 MPI) showed
clinical signs that were consistent with
those described for scrapie. Microscopic
lesions of spongiform encephalopathy
(SE) were only seen in the sheep with
the clinical signs of TSE and its
tissues were positive for the abnormal
prion protein (PrP**res) by
immunohistochemistry and Western blot.
Between 36 and 60 MPI, 3 other sheep
were euthanized because of conditions
unrelated to TSE. The remaining 3 sheep
remained non-clinical at the termination
of the study (72 MPI) and were
euthanized at that time. One of the 3
animals revealed SE and its tissues were
positive for PrP**res. Both sheep
positive for PrP**res were homozygous QQ
at codon 171. Retrospective examination
of the PRNP genotype of the 2
TSE-positive animals revealed that the
sheep with clinical prion disease
(euthanized at 35 MPI) was heterozygous
(AV) and the sheep with the sub-clinical
disease (euthanized at 72 MPI) was
homozygous (AA) at codon 136 of the
PRNP. These findings demonstrate that
transmission of the CWD**md agent to
sheep via the intracerebral route is
possible. Interestingly, the host
genotype may play a significant part in
successful transmission and incubation
period of CWD**md.
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