Experimental oral transmission of chronic wasting disease to sika deer (Cervus nippon)

Abstract

Chronic wasting disease (CWD) affects a broad array of cervid species and continues to be detected in an expanding geographic range. Initially introduced into the Republic of Korea through the importation of CWD-infected elk (Cervus canadensis), additional cases of CWD were subsequently detected in farmed Korean elk and sika deer (Cervus nippon). Wild and farmed sika deer are found in many regions of Asia, North America, and Europe, although natural transmission to this species has not been detected outside of the Republic of Korea. In this study, the oral transmission of CWD to sika deer was investigated using material from CWD-affected elk. Pathological prion (PrP CWD ) immunoreactivity was detected in oropharyngeal lymphoid tissues of one sika deer at 3.9 months post-inoculation (mpi) and was more widely distributed in a second sika deer examined at 10.9 mpi. The remaining four sika deer progressed to clinical disease between 21 and 24 mpi. Analysis of PrP CWD tissue distribution in clinical sika deer revealed widespread deposition in central and peripheral nervous systems, lymphoreticular tissues, and the gastrointestinal tract. Prion protein gene (PRNP) sequences of these sika deer were identical and consistent with those reported in natural sika deer populations. These findings demonstrate the efficient oral transmission of CWD from elk to sika deer.

Review on PRNP genetics and susceptibility to chronic wasting disease of Cervidae

“…In 2001, epidemiological investigations confirmed that CWD was introduced to the Korean peninsula by captive elk (Cervus elaphus nelsoni), imported from Canada in 1994 and 1997 [30,31]. CWD was subsequently detected in farmed elk populations in 2001,2004,2005,2010 and 2016 and since no evidence of natural CWD transmission to sika deer has been documented [32]. In other countries, CWD was not reported until 2016.…”

“…If the E226 and Q226 alleles were equally present in the tested population in China and Korea, the G100 allele was only detected in 3% of the animals, in association with the E226 aa and only the Q226 allele was detected in Europe pure sika. Efficient oral transmission of CWD from Elk to Sika deer was reported [32], but the potential impact of the above-mentioned allelic variations was not tested in this species.…”

Large animal models for chronic wasting disease

“…Oral exposure is thus a plausible route of transmission of CWD prions for cervids in nature. In fact, oral inoculation has resulted in productive infections in moose (Kreeger et al 2006 ), elk (Hamir et al 2006 ; Plummer et al 2017 ), white-tailed and mule deer (Plummer et al 2017 ), red deer (Martin et al 2009 ; Balachandran et al 2010 ), sika deer ( Cervus nippon ) (Sohn et al 2020 ) and reindeer (Mitchell et al 2012 ). As further evidence to support the efficacy of oral infection and to track early CWD pathogenesis, an experimental study (Sigurdson et al 1999 ) was conducted employing mule deer fawns captured outside the CWD endemic region (Miller et al 2000 ; Miller and Williams 2003 ).…”

Differential Accumulation of Misfolded Prion Strains in Natural Hosts of Prion Diseases

“…Transmissible spongiform encephalopathies (TSEs) are a group of fatal, progressive neurodegenerative diseases that result from the misfolding and accumulation of endogenous prion protein (PrP Sc ) [1]. Transmissible and spontaneous prion diseases have been described in a wide variety of species including humans [2], sheep [3][4][5], goats [6], mink [7], cattle [8], white-tailed deer [9], mule deer [9], elk [9,10] camels [11], moose [12], reindeer [13], red deer [14], sika deer [15], cats [16], and various zoo species [17,18].…”