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From: TSS ()
Subject: Re: 73rd Annual General Session of the International Committee of OIE 22 - 27 May 2005
Date: May 29, 2005 at 5:36 pm PST

In Reply to: 73rd Annual General Session of the International Committee of OIE 22 - 27 May 2005 posted by TSS on May 29, 2005 at 1:24 pm:

Vet Pathol 42:107–108 (2005)
Letters to the Editor
Absence of evidence is not always evidence of absence.
In the article ‘‘Failure to detect prion protein (PrPres) by
immunohistochemistry in striated muscle tissues of animals
experimentally inoculated with agents of transmissible spongiform
encephalopathy,’’ recently published in Veterinary
Pathology (41:78–81, 2004), PrPres was not detected in striated
muscle of experimentally infected elk, cattle, sheep, and
raccoons by immunohistochemistry (IHC). Negative IHC,
however, does not exclude the presence of PrPSc. For example,
PrPres was detected in skeletal muscle in 8 of 32
humans with the prion disease, sporadic Creutzfeldt-Jakob
disease (CJD), using sodium phosphotungstic acid (NaPTA)
precipitation and western blot.1 The NaPTA precipitation,
described by Wadsworth et al.,3 concentrates the abnormal
isoform of the prion, PrPres, from a large tissue homogenate
volume before western blotting. This technique has increased
the sensitivity of the western blot up to three orders
of magnitude and could be included in assays to detect
PrPres. Extremely conspicuous deposits of PrPres in muscle
were detected by IHC in a recent case report of an individual
with inclusion body myositis and CJD.2 Here, PrPres was
detected in the muscle by immunoblotting, IHC, and paraf-
fin-embedded tissue blot. We would therefore caution that,
in addition to IHC, highly sensitive biochemical assays and
bioassays of muscle are needed to assess the presence or
absence of prions from muscle in experimental and natural
TSE cases.
Christina Sigurdson, Markus Glatzel, and Adriano Aguzzi
Institute of Neuropathology
University Hospital of Zurich
Zurich, Switzerland
1 Glatzel M, Abela E, et al: Extraneural pathologic prion
protein in sporadic Creutzfeldt-Jakob disease. N Engl J
Med 349(19):1812–1820, 2003
2 Kovacs GG, Lindeck-Pozza E, et al: Creutzfeldt-Jakob
disease and inclusion body myositis: abundant diseaseassociated
prion protein in muscle. Ann Neurol 55(1):
121–125, 2004
3 Wadsworth JDF, Joiner S, et al: Tissue distribution of protease
resistant prion protein in variant CJD using a highly
sensitive immuno-blotting assay. Lancet 358:171–180,
2001. ...............


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