Zoonotic potential of CWD and influence of environmental contamination on prion propagation

摘要 朊病毒疾病可在动物与动物、动物与人和人与人之间传播。 然而，我们仍然不完全了解人类的机制，因素和生物学 控制这种独特的传染因子在个体间传播的过程。之间 慢性消耗性疾病（CWD）是一个严重的问题，因为它 继续在北美的野生和圈养鹿科动物中不受控制地传播。的 慢性消耗病传播给人类的风险是未知的，这是一个主要问题，因为 患病动物的数量及其地理分布正在迅速增加。的机制 CWD在鹿科动物中如此有效地传播也是未知的，但最近的发现 与朊病毒的环境污染有关 该项目的主要目标是研究控制物种屏障的机制， 特别是调查慢性消耗病在确定的条件下感染的可能性 人类我们还将研究环境污染在慢性消耗病传播中的作用， 集中在植物和各种表面作为朊病毒传播的载体。具体目标1， 将研究朊病毒株适应在慢性消耗病人畜共患潜力中的作用。的 这些研究的假设是，物种屏障是一个动态过程， 朊病毒株成熟和进化的时间。我们将研究朊病毒的分子机制 菌株成熟，区分CWD菌株的生化和结构特性， 并且无法将人类PrPC转化为PrPSc并分析大量天然CWD 研究体外人类物种屏障强度的差异。在 具体目标2：我们将检验物种屏障的强度较低的假设， 宿主携带与其他神经系统疾病相关的脑损伤，甚至亚临床 或临床前状况。我们将调查鹿/人类物种屏障是否可以 在表达人PrP的转基因小鼠中， 异常，使用建立的慢性神经退行性疾病（阿尔茨海默氏症和 帕金森病）和急性脑损伤（创伤性脑损伤和中风）。在特定 目的3通过对朊病毒的分析，研究植物作为污染物在朊病毒传播中的作用 与植物的结合，保持感染性和运输PrPSc从土壤到不同的部分， 植物研究将使用天然CWD朊病毒进行，并将进行感染性实验。 在培养的细胞、基因靶向的cervid转基因小鼠和天然宿主（白色尾）中进行 鹿）。我们还将通过以下方式检测从慢性消耗病受影响地区收集的植物中是否存在PrPSc PMCA。在具体目标4中，我们将通过以下方式检验朊病毒在环境中积聚的假设： 逐渐结合到不同的环境表面，在那里它们可以感染动物， 简单的接触。我们将研究PrPSc与各种表面（包括石头， 木材，塑料，玻璃，混凝土，不锈钢和铝），时间持久性的PrPSc和 表面的传染性和环境变化对传染性的影响。我们还将 调查偶然接触受污染的表面而传播疾病的情况 以及这种现象发生的机制。 该项目的研究结果将有助于了解 慢性消耗病，调节这种疾病传播的因素，以及环境的作用 与朊病毒传播有关这些研究对于制定措施以防止进一步的 CWD的传播，并避免新的疾病的出现， 后果

ABSTRACT Prion diseases are transmissible between animal-to-animal, animal-to-human and human-to- human, however, we still do not understand completely the mechanisms, factors and biological processes controlling the inter-individual transmission of this unique infectious agent. Among animal diseases, chronic wasting disease (CWD) represents a serious problem, because it continues to propagate uncontrollably among wild and captive cervids in North America. The risk of CWD transmission to humans is unknown which is a major concern because the number of sick animals and their geographical distribution is rapidly increasing. The mechanism by which CWD propagates so efficiently among cervids is also unknown, but recent findings have implicated environmental contamination with prions. The main goal of this project is to study the mechanisms controlling the species barrier, particularly to investigate the possibility that CWD may, under determined conditions, infect humans. We will also study the role of environmental contamination in CWD transmission, focusing on plants and various surfaces as vectors for prion propagation. In Specific Aim 1 we will investigate the role of prion strain adaptation in the zoonotic potential of CWD. The hypothesis for these studies is that the species barrier is a dynamic process that changes over time when prion strains mature and evolve. We will study the molecular mechanism of prion strain maturation, the biochemical and structural properties that differentiate CWD strains able and unable to convert human PrPC into PrPSc and analyze a large collection of natural CWD specimens to investigate differences on the strength of the human species barrier in vitro. In Specific Aim 2 we will test the hypothesis that the strength of the species barrier is lower in hosts harboring brain damage associated to other neurological diseases or even to subclinical or pre-clinical conditions. We will investigate whether the cervid/human species barrier can be altered in transgenic mice expressing human PrP by the co-existence of another brain abnormality, using established models of chronic neurodegenerative diseases (Alzheimer's and Parkinson's disease) and acute brain damage (traumatic brain injury and stroke). In Specific Aim 3 we will study the role of plants as fomites for prion transmission by analyzing prion binding to plants, retention of infectivity and transport of PrPSc from soil to different parts of the plants. Studies will be done using natural CWD prions and infectivity experiments will be performed in cultured cells, gene-targeted cervidtransgenic mice and the natural host (white tail deer). We will also test plants collected from CWD affected areas for the presence of PrPSc by PMCA. In Specific Aim 4 we will test the hypothesis that prions buildup in the environment by progressively binding to diverse environmental surfaces, where they can infect animals by simple contact. We will study the binding affinity of PrPSc to various surfaces (including stones, wood, plastic, glass, concrete, stainless steel and aluminum), the time permanence of PrPSc and infectivity in the surface and the effect of environmental changes on infectivity. We will also investigate the transmission of the disease through casual contact with contaminated surfaces and the mechanism by which this happen. The findings generated in this project will contribute to understand the zoonotic potential of CWD, the factors modulating the transmission of this disease, and the role the environment plays on prion transmission. These studies are essential to design measures to prevent further propagation of CWD, and to avoid the emergence of new diseases with potentially disastrous consequences.