Williams Elizabeth S, O'Toole Donal, Miller Michael W, Kreeger Terry J, Jewell Jean E
1 Wyoming State Veterinary Laboratory, Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, Wyoming 82070, USA.
2 Colorado Division of Parks and Wildlife, Wildlife Health Program, 4330 Laporte Avenue, Fort Collins, Colorado 80521-2153, USA.
J Wildl Dis. 2018 Jul;54(3):460-470. doi: 10.7589/2017-12-299. Epub 2018 May 1.
We conducted a 10-yr study to establish whether chronic wasting disease (CWD) was readily transmissible to domestic cattle ( Bos taurus) following oral inoculation or by cohousing cattle with captive cervids in outdoor research facilities where CWD was enzootic. Calves ( n=12) were challenged orally on one occasion using brain homogenate derived from CWD-infected mule deer ( Odocoileus hemionus). Five uninoculated cattle served as unchallenged controls. Two other groups of cattle ( n=10-11/group) were housed outdoors for 10 yr in captive cervid research facilities. The environmentally challenged cattle were exposed to CWD-associated prions through common paddocks, feed, and water and via direct daily contact with known and potentially infected mule deer or wapiti ( Cervus canadensis) throughout the decade-long study period. None of the exposed cattle developed neurologic disease during the study. We euthanized cattle surviving to 10 yr postchallenge and examined all for lesions or disease-associated prion protein (PrP) by histopathology, immunohistochemistry, and western immunoblot analysis of central nervous system and lymphoid tissue. None had evidence of PrP accumulation. We conclude that the risks of CWD transmission to cattle following oral inoculation or after prolonged exposure to contaminated environments are low.
我们开展了一项为期10年的研究，以确定在口服接种或在慢性消耗病（CWD）为地方病的户外研究设施中将牛与圈养的鹿类动物混养后，慢性消耗病是否易于传播给家牛（Bos taurus）。使用来自感染CWD的骡鹿（Odocoileus hemionus）的脑匀浆对12头犊牛进行了一次口服攻毒。5头未接种的牛作为未攻毒对照。另外两组牛（每组10 - 11头）在圈养鹿类动物的研究设施中户外饲养10年。在长达十年的研究期间，环境暴露组的牛通过共用牧场、饲料和水，以及每天与已知和可能感染的骡鹿或马鹿（Cervus canadensis）直接接触，接触与CWD相关的朊病毒。在研究期间，所有暴露的牛均未出现神经疾病。我们对存活至攻毒后10年的牛实施安乐死，并通过组织病理学、免疫组织化学以及对中枢神经系统和淋巴组织进行western免疫印迹分析，检查所有牛是否有病变或与疾病相关的朊病毒蛋白（PrP）。没有一头牛有PrP积累的证据。我们得出结论，口服接种或长期暴露于受污染环境后，CWD传播给牛的风险较低。
