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

摘要 Prion病可在动物间、动物间、人与人之间传播。 然而，我们仍然不完全了解人类的发病机制、因素和生物学行为。 控制这种独特的感染性病原体在个体间传播的过程。其中 动物疾病，慢性消耗性疾病(CWD)是一个严重的问题，因为它 继续在北美野生和圈养的鹿群中无节制地繁殖。这个 慢性萎缩性脑病传染给人类的风险尚不清楚，这是一个主要的担忧，因为 患病动物的数量和地理分布正在迅速增加。这个机制是通过 CWD在宫颈中的传播效率如此之高也是未知的，但最近的发现已经 牵涉到普恩病毒对环境的污染。 该项目的主要目标是研究物种屏障的控制机制， 特别是调查慢性萎缩性胃炎在确定的条件下可能会感染 人类。我们还将研究环境污染在CWD传播中的作用， 聚焦于植物和各种表面，作为Pron传播的载体。在具体目标1中，我们 将研究Pron菌株适应在CWD人畜共患病潜力中的作用。这个 这些研究的假设是，物种屏障是一个动态的过程， Pron菌株成熟和进化的时间。我们将研究Pron的分子机制 菌株成熟度，区分CWD菌株的生化和结构特征 无法将人类PrPC转换为PrPSc并分析大量天然CWD 在体外研究人类物种屏障强度的差异。在……里面 具体目标2我们将检验物种屏障强度较低的假设 宿主存在与其他神经系统疾病或甚至亚临床相关的脑损伤 或者是临床前的状况。我们将调查Cervid/人类的物种屏障是否可以 表达人PrP的转基因小鼠因另一个大脑的共存而发生改变 使用已建立的慢性神经退行性疾病(阿尔茨海默氏症和阿尔茨海默病)模型 帕金森氏症)和急性脑损伤(创伤性脑损伤和中风)。具体而言 目的3我们将通过分析普恩病毒来研究植物作为普恩病毒传递载体的作用。 PrPSc与植物的结合、感染性的保持以及PrPSc从土壤到土壤不同部分的运输 植物。研究将使用天然的CWD普恩病毒进行，传染性实验将 在培养细胞、基因靶向的宫颈转基因小鼠和自然宿主(白尾)中进行 鹿)。此外，我们亦会测试从CWD受影响地区收集的植物是否含有PrPSc。 PMCA。在特定的目标4中，我们将测试普恩病毒在环境中积累的假设 逐渐结合到不同的环境表面，在那里它们可以通过 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)、PrPSc和 表面的传染性和环境变化对传染性的影响。我们还将 调查通过偶然接触受污染表面传播疾病的情况 以及发生这种情况的机制。 在这个项目中产生的发现将有助于理解人畜共患病的潜力 CWD、调节这种疾病传播的因素以及环境的作用 在普恩病毒传播上发挥作用。这些研究对于设计预防进一步的措施至关重要 传播慢性萎缩性脑病，避免出现新的具有潜在灾难性的疾病 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.