Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Blindern, P.O. Box 1066, 0316, Oslo, Norway.
Norwegian Institute for Nature Research (NINA), Torgarden, P. O. Box 5685, 7485, Trondheim, Norway.
Sci Rep. 2020 Dec 17;10(1):22168. doi: 10.1038/s41598-020-79050-2.
Prion diseases constitute a class of invariably fatal and degenerative encephalopathies. Chronic Wasting Disease (CWD) is a contagious prion disease among cervids, which is spreading and causing marked population declines in USA and Canada. The first outbreak of CWD in Europe was discovered in a reindeer population in Norway in 2016. In the worst-case scenario with continental-wide spreading of CWD in Eurasia, an annual harvest of around 4 million cervids is at stake only in Europe, with huge economic and cultural significance. An in situ origin of CWD was suspected, and it appear urgent to identify the likely cause to prevent future emergences. Here, we document the novel phenomenon of extensive antler cannibalism prior to shedding among reindeer in the CWD-infected population. The extent of antler cannibalism increased over the last decades when CWD emerged, and included ingestion of vascularized antlers. Ingestion of tissues from conspecifics is a risk factor for the emergence of prion diseases, where the presence of extensive antler cannibalism opens the intriguing possibility of a 'Kuru-analogue' origin of CWD among the reindeer in Europe. Based on general insight on pathology of prion diseases and strain selection processes, we propose an hypothesis for how contagious CWD may emerge from sporadic CWD under the unique epidemiological conditions we document here. More research is required to document the presence of prions in reindeer antlers, and whether antler cannibalism actually led to a strain selection process and the emergence of a contagious form of CWD from a sporadic form of CWD.
朊病毒病构成一类不可避免的致命性和退行性脑病。慢性消耗性疾病（CWD）是一种在鹿科动物中传播的传染性朊病毒病，正在美国和加拿大传播，并导致其种群数量显著下降。CWD 在欧洲的首次爆发是 2016 年在挪威的一个驯鹿种群中发现的。在最坏的情况下，如果 CWD 在欧亚大陆范围内广泛传播，仅在欧洲就有大约 400 万头鹿面临每年的捕猎，这具有巨大的经济和文化意义。怀疑 CWD 具有原地起源，因此迫切需要确定可能的原因，以防止未来的出现。在这里，我们记录了在 CWD 感染的种群中，驯鹿在鹿角脱落前广泛发生的鹿角自残现象。当 CWD 出现时，过去几十年间，鹿角自残的程度有所增加，并且包括了对血管化鹿角的摄取。摄取同种动物的组织是朊病毒病出现的一个风险因素，在这种情况下，广泛的鹿角自残现象为欧洲驯鹿中 CWD 的“库鲁类似物”起源提供了一个有趣的可能性。基于对朊病毒病的病理学和菌株选择过程的一般认识，我们提出了一个假设，即在我们记录的独特流行病学条件下，传染性 CWD 如何从散发性 CWD 中出现。需要更多的研究来记录在驯鹿的鹿角中是否存在朊病毒，以及鹿角自残是否真的导致了菌株选择过程，从而使传染性 CWD 从散发性 CWD 中出现。
