Scrapie Agent (Strain 263K) Can Transmit Disease via the Oral Route after Persistence in Soil over Years
Scrapie Agent (Strain 263K) Can Transmit Disease via the Oral Route after Persistence in Soil over Years
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DOI：
10.1371/journal.pone.0000435
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发表时间：
2007-05-09
期刊：
影响因子：
3.7
通讯作者：
Terytze, Konstantin
中科院分区：
文献类型：
--
作者：
Seidel, Bjoern;Thomzig, Achim;Terytze, Konstantin
侵染性生物分子在土壤中的持久性构成了一个巨大的挑战。尤其是在传染性海绵状脑病(TSE)的病原体，如瘙痒病、牛海绵状脑病(BSE)或慢性消耗性疾病(CWD)的病原体--普恩病毒方面，情况尤其如此。各种研究表明，普鲁恩能够在土壤中持续多年而不会失去致病活性。病毒传播到环境中的途径有几种，例如感染性胎盘或羊水。此外，唾液、排泄物或未经消毒的农业有机肥对环境的污染也是可以想象的。在大多数病例中，瘙痒病在野外的自然传播似乎是通过消化道发生的，在以前观察到瘙痒病暴发的牧场上，没有瘙痒病的羊群可能会受到感染。这些发现表明，环境中，特别是土壤中存在持续的传染病。利用室外蒸渗仪模拟了仓鼠适应的263K瘙痒蛋白对标准土壤的污染，并通过Western blotting和仓鼠生物测定分别分析了土壤相关PrPSc的存在和生物活性以及感染性。结果表明，263K抓痒剂在土壤中的存留时间可达29个月以上。引人注目的是，不仅受污染的土壤本身保持了高水平的传染性，叙利亚仓鼠的口服就证明了这一点，而且喂食土壤含水提取物也能够在报告动物中诱发疾病。我们还可以证明，在21个月后提取的土壤中的PrPSc，在蛋白质错误折叠循环扩增(PMCA)反应中提供了一个催化活性种子。因此，PMCA为显著提高田间土壤样本中普里恩的可探测性开辟了一条前景。
The persistence of infectious biomolecules in soil constitutes a substantial challenge. This holds particularly true with respect to prions, the causative agents of transmissible spongiform encephalopathies (TSEs) such as scrapie, bovine spongiform encephalopathy (BSE), or chronic wasting disease (CWD). Various studies have indicated that prions are able to persist in soil for years without losing their pathogenic activity. Dissemination of prions into the environment can occur from several sources, e. g., infectious placenta or amniotic fluid of sheep. Furthermore, environmental contamination by saliva, excrements or non-sterilized agricultural organic fertilizer is conceivable. Natural transmission of scrapie in the field seems to occur via the alimentary tract in the majority of cases, and scrapie-free sheep flocks can become infected on pastures where outbreaks of scrapie had been observed before. These findings point to a sustained contagion in the environment, and notably the soil. By using outdoor lysimeters, we simulated a contamination of standard soil with hamster-adapted 263K scrapie prions, and analyzed the presence and biological activity of the soil-associated PrPSc and infectivity by Western blotting and hamster bioassay, respectively. Our results showed that 263K scrapie agent can persist in soil at least over 29 months. Strikingly, not only the contaminated soil itself retained high levels of infectivity, as evidenced by oral administration to Syrian hamsters, but also feeding of aqueous soil extracts was able to induce disease in the reporter animals. We could also demonstrate that PrPSc in soil, extracted after 21 months, provides a catalytically active seed in the protein misfolding cyclic amplification (PMCA) reaction. PMCA opens therefore a perspective for considerably improving the detectability of prions in soil samples from the field.