Identification of the first case of atypical scrapie in Japan

Abstract

A Corriedale ewe was confirmed as the first atypical scrapie case during an active surveillance program for transmissible spongiform encephalopathies in small ruminants in Japan. The animal was homozygous for the AF141RQ haplotype of PRNP. The animal showed clinical neurological signs possibly due to listeriosis before culling. Western blot analysis showed an unusual multiple banded pattern with a low-molecular fragment at ~7 kDa. Histopathology revealed suppurative meningoencephalitis caused by listeriosis in the brainstem. Fine granular to globular immunostaining of disease-associated prion proteins was mainly detected in the neuropil of the spinal tract of the trigeminal nerve and in the white matter of the spinocerebellar tract. Based on these results, this case was conclusively diagnosed as atypical scrapie with encephalitic listeriosis.

First case of atypical scrapie in a goat in Japan

“…Atypical scrapie/Nor98 was initially detected in Norway in 1998 [4]. Since then, atypical scrapie cases have been reported in 23 European countries [24], the U.S.A. [17], Canada [18], the Falkland Islands [8], Japan [14], Australia [6], and New Zealand [15]. Although the origin of atypical scrapie remains unclear, affected animals were older (>6 years of age) compared with classical scrapie [3], and atypical cases were detected as single cases in their flock or herd; thus, atypical scrapie is considered a sporadic prion disease or has limited transmissibility under natural conditions [11].…”

“…Although 65 cases of sheep scrapie, including one atypical case that was detected in 2016, have been identified in Japan [14], no case of scrapie in goats has been published, to our knowledge. This report describes the identification of the first case of atypical goat scrapie in Japan, which was detected through the active national TSE surveillance program.…”

“…The accumulation of PrP Sc in brain tissue was examined by western blot (WB) and immunohistochemical (IHC) analyses. For the atypical scrapie positive control, we used an obex sample from the affected sheep case (A 136 F 141 R 154 Q 171 /A 136 F 141 R 154 Q 171 ) in Japan [14], and the frontal cortex samples from the affected sheep cases (UK1, A 136 R 154 R 171 /A 136 R 154 Q 171 ; UK2, A 136 R 154 R 171 /A 136 H 154 Q 171 ; UK3, A 136 R 154 Q 171 /A 136 R 154 Q 171 ; UK4, A 136 H 154 Q 171 /A 136 H 154 Q 171 ) in the United Kingdom. Following the treatment with proteinase K (PK; Roche Diagnosis Japan, Tokyo, Japan; final concentration of 40 µ g/m l ) for 30 min at 37°C, the samples were electrophoresed on 12% NuPAGE pre-cast gels in NuPAGE MES SDS Running buffer (Invitrogen, Carlsbad, CA, U.S.A.) or 4–20% Criterion TGX pre-cast gels in Tris-Glycine running buffer (Bio-Rad, Hercules, CA, U.S.A.) and electrotransferred onto Immobilon polyvinylidene fluoride membranes (Millipore, Darmstadt, Germany).…”

“…Following the treatment with proteinase K (PK; Roche Diagnosis Japan, Tokyo, Japan; final concentration of 40 µ g/m l ) for 30 min at 37°C, the samples were electrophoresed on 12% NuPAGE pre-cast gels in NuPAGE MES SDS Running buffer (Invitrogen, Carlsbad, CA, U.S.A.) or 4–20% Criterion TGX pre-cast gels in Tris-Glycine running buffer (Bio-Rad, Hercules, CA, U.S.A.) and electrotransferred onto Immobilon polyvinylidene fluoride membranes (Millipore, Darmstadt, Germany). The blotted membranes were probed with the monoclonal antibody (mAb) P4 (R-Biopharm, Darmstadt, Germany) according to a previously described method [14]. IHC for PrP Sc was performed using the mAb T1 [26] or F99/97.6.1 (VMRD, Pullman, WA, U.S.A.) with pretreatment by autoclaving as previously described [21].…”

“…The age of the affected goat and an unaffected littermate in the same farm may raise the possibility that this atypical scrapie goat was a sporadic case with poor transmissibility. The animals expressing the A 136 H 154 Q 171 allele, which is strongly associated with atypical scrapie [5], constitute 0.3% of goats in Japan [14]. Since this disease has demonstrated its transmissibility to other animals [22], continuous monitoring is still required for better understanding the incidence of atypical scrapie in Japan and preventing the spread of disease in advance.…”