While the presence of bovine spongiform encephalopathy (BSE) infectivity in the blood of clinically affected sheep has been proven by intraspecies blood-transfusion experiments, this question has remained open in the case of BSE-affected cattle. Although the absence of infectivity can be anticipated from the restriction of the agent to neuronal tissues in this species, evidence for this was still lacking. This particularly concerns the production and use of medicinal products and other applications containing bovine blood or preparations thereof. We therefore performed a blood-transfusion experiment from cattle in the clinical end stage of disease after experimental challenge with either classical (C-BSE) or atypical (H- and l-) BSE into calves at 4–6 months of age. The animals were kept in a free-ranging group for 10 years. Starting from 24 months post-transfusion, a thorough clinical examination was performed every 6 weeks in order to detect early symptoms of a BSE infection. Throughout the experiment, the clinical picture of all animals gave no indication of a BSE infection. Upon necropsy, the brainstem samples were analysed by BSE rapid test as well as by the highly sensitive Protein Misfolding Cyclic Amplification (PMCA), all with negative results. These results add resilient data to confirm the absence of BSE infectivity in the donor blood collected from C-, H- and l-BSE-affected cattle even in the final clinical phase of the disease. This finding has important implications for the risk assessment of bovine blood and blood products in the production of medicinal products and other preparations.

中文翻译：

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经种内输血证实，在疾病临床终末期牛的血液中不存在经典和非典型（H-和L-）BSE感染性

虽然已通过种内输血实验证明受临床影响的绵羊血液中存在牛海绵状脑病 (BSE) 传染性，但在受 BSE 影响的牛的情况下，这个问题仍然悬而未决。尽管可以从该物种的神经元组织中限制该试剂来预期不存在传染性，但仍然缺乏这方面的证据。这尤其涉及含有牛血或其制剂的医药产品和其他应用的生产和使用。因此，在经典 (C-BSE) 或非典型 (H- 和l-) BSE 在 4-6 个月大的小牛身上发生。这些动物在自由放养组中饲养了 10 年。从输血后 24 个月开始，每 6 周进行一次彻底的临床检查，以检测 BSE 感染的早期症状。在整个实验过程中，所有动物的临床表现均未表明 BSE 感染。尸检后，脑干样本通过 BSE 快速测试以及高度敏感的蛋白质错误折叠循环扩增 (PMCA) 进行分析，所有结果均为阴性。这些结果增加了弹性数据，以确认从 C-、H- 和l收集的供体血液中不存在 BSE 传染性-BSE 影响的牛，即使在疾病的最后临床阶段。这一发现对牛血和血液制品在医药产品和其他制剂生产中的风险评估具有重要意义。