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Research Project:
TRANSMISSION, DIFFERENTIATION, AND PATHOBIOLOGY OF
TRANSMISSIBLE SPONGIFORM ENCEPHALOPATHIES
Location:
Virus and Prion Diseases of Livestock
Title:
Bovine
Spongiform Encephalopathy: what is "Atypical BSE"
and can we detect it?
Author
Submitted to: Animal Health Research
Reviews
Publication Type: Abstract
Publication Acceptance Date: October 17,
2006
Publication Date: N/A
Technical Abstract:
Transmissible spongiform encephalopathy
(TSE) agents induce fatal
neurodegenerative diseases in humans and
in some other mammalian species. Human
TSEs include Creutzfeldt¿Jakob disease
(CJD), Gerstmann-Sträussler-Scheinker
(GSS) syndrome, Kuru and Fatal Familial
Insomnia (FFI). In animals, several
distinct TSE diseases are recognized:
scrapie in sheep and goats,
transmissible mink encephalopathy (TME)
in mink, chronic wasting disease (CWD)
in cervids, and bovine spongiform
encephalopathy (BSE) in cattle. BSE was
first detected in 1986 in the United
Kingdom and is the most likely cause of
variant CJD in humans. BSE in cattle is
a neurological disease with a
characteristic molecular pattern of the
protease-resistant prion protein,
PrP**res. This BSE 'signature' has also
been identified in BSE-induced TSEs of
both domestic cats and exotic ruminant
species. Since 2004, some cases of prion
diseases in cattle have been described
which show unusual or atypical features
as assessed by the molecular
characterization of PrP**res and/or
histopathology, when compared to the
unique features of previously described
BSE. These atypical BSE cases have been
characterized by Western blot and have
been referred to as H- (i.e., high
molecular weight) or L-type (i.e., low
molecular weight type). These atypical
BSE cases have been found mainly in
cattle older than 8 years. In the U.S.,
three cases of BSE have been diagnosed
so far. Case 1 represented a typical BSE
isolate, identified in an animal
imported from Canada. Cases 2 and 3 were
identified in animals raised in the U.S.
and revealed an unusual molecular
PrP**res pattern, consistent with
atypical BSE cases described as H-type
in Europe. It should be noted that the
Western Blot method applied for BSE
confirmatory tests in the U.S. has been
able to detect both H-type and L-type
BSE cases when using known positive
European samples.
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