Monitoring of chronic wasting disease using real-time quaking-induced conversion assay in Japan

Monitoring of chronic wasting disease using real-time quaking-induced conversion assay in Japan

Akio SUZUKI, Kazuhei SAWADA, Temuulen ERDENEBAT, Takeshi YAMASAKI, Minoru TOBIUME, Kinuyo SUGA, Motohiro HORIUCHI

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Keywords: chronic wasting disease, prion, prion protein, real-time quaking-induced conversion, scrapie

Abstract

There has been no report on Chronic wasting disease (CWD) cases in Japan to date; however, there is concern about the geographic spread of CWD. To clarify the CWD status in Japan, we conducted CWD monitoring using real-time quaking-induced conversion (RT-QuIC) assay which can detect the low level of CWD prions. A total of 690 obex samples collected from sika deer and Reeves's muntjac in Hokkaido and Honshu was tested for CWD prions. No CWD-positive cases were found, suggesting that CWD is nonexistent in Japan. Our results also indicate that RT-QuIC assay is useful for continuous monitoring of CWD. Furthermore, nucleotide sequence analysis of the PrP gene revealed sika deer in Japan harbor CWD susceptible allele.

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As the prion diseases in ruminant, the possibility of CWD occurring naturally in aged deer cannot be ruled out. Additionally, Japan imports large amounts of dry pasture and hay cube from the U.S. and Canada every year [1]. CWD prions from carcasses of CWD-affected deer that died outside and/or excreted into the environment can contaminate pastures and soil, and they persist for many years once excreted into the environment [5, 17]. Therefore, even if no live deer are imported, if hay production areas overlap with CWD outbreak areas, there is a possibility that CWD prions will enter Japan with the imported hay. In this study, CWD status was monitored about 10 years after the previous report [13]. No CWD cases were again disclosed in Japan. CWD spreads horizontally from deer to deer, whichever in the field or in the ranch [4]. Additionally, there is an increase in demands on venison in Japan [16]. Thus, continuous monitoring is necessary for an earlier response and securing the safety of deer products.

https://www.jstage.jst.go.jp/article/jvms/advpub/0/advpub_21-0368/_pdf/-char/en

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