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From: TSS ()
Subject: PrPSc distribution of a natural case of bovine spongiform encephalopathy
Date: August 8, 2005 at 12:28 pm PST

PrPSc distribution of a natural case of bovine
spongiform encephalopathy

Yoshifumi Iwamaru, Yuka Okubo, Tamako Ikeda, Hiroko Hayashi, Mori-
kazu Imamura, Takashi Yokoyama and Morikazu Shinagawa

Priori Disease Research Center, National Institute of Animal Health, 3-1-5
Kannondai, Tsukuba 305-0856 Japan gan@affrc.go.jp

Abstract

Bovine spongiform encephalopathy (BSE) is a disease of cattle that causes
progressive neurodegeneration of the central nervous system. Infectivity
of BSE agent is accompanied with an abnormal isoform of prion protein
(PrPSc).

The specified risk materials (SRM) are tissues potentially carrying BSE
infectivity. The following tissues are designated as SRM in Japan: the
skull including the brain and eyes but excluding the glossa and the masse-
ter muscle, the vertebral column excluding the vertebrae of the tail, spinal
cord, distal illeum. For a risk management step, the use of SRM in both
animal feed or human food has been prohibited. However, detailed
PrPSc distribution remains obscure in BSE cattle and it has caused con-
troversies about definitions of SRM. Therefore we have examined PrPSc
distribution in a BSE cattle by Western blotting to reassess definitions of
SRM.

The 11th BSE case in Japan was detected in fallen stock surveillance.
The carcass was stocked in the refrigerator. For the detection of PrPSc,
200 mg of tissue samples were homogenized. Following collagenase
treatment, samples were digested with proteinase K. After digestion,
PrPSc was precipitated by sodium phosphotungstate (PTA). The pellets
were subjected to Western blotting using the standard procedure.
Anti-prion protein monoclonal antibody (mAb) T2 conjugated horseradish
peroxidase was used for the detection of PrPSc.

PrPSc was detected in brain, spinal cord, dorsal root ganglia, trigeminal
ganglia, sublingual ganglion, retina. In addition, PrPSc was also detected
in the peripheral nerves (sciatic nerve, tibial nerve, vagus nerve).

Our results suggest that the currently accepted definitions of SRM in
BSE cattle may need to be reexamined.

179

T. Kitamoto (Ed.)
PRIONS
Food and Drug Safety
================

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TSS



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