Contributions of prion strains and substrains to prion zoonotic potential and evolution

普恩病毒是一种仅含感染性蛋白质的人畜共患病病原体，可以在新的复制环境中快速进化。 PrPSc是由宿主编码的传染性形式PrPSc的菌株特异性构象编码的 Prion蛋白，PrPC。科林奇和克拉克假设普恩病毒株是一种主要的普恩病毒株的混合物。 和亚株。为了支持这一假设，我们和其他人已经证明：i)用反普里昂治疗普鲁恩 药物可导致耐药菌株的出现，ii)物理方法(如热稳定性) 部分失活的Prion可以选择具有改变的菌株特性的Prion，以及iii)给定宿主内的菌株 物种可以有不同的寄主范围。尽管有这些数据，但直接证据表明先前存在的 亚株缺乏，因此，亚株对病毒进化的贡献还没有得到证实。 探索过了。这项工作的长期目标是防止Pron进化到一个新的复制环境。这个 这项应用的总体目标是确定主要的Prion菌株和 亚株对普恩病毒的种间传播。在这个应用程序中，我们将检验的假设是： 亚株驱动病毒传播到一种新的PrP基因。这一假设是基于我们的新发现 生物克隆金黄地鼠嗜睡(DY)株PrPSc的选择性还原 水貂脑病(TME)，使用两种不同的机械方法，允许出现和 分离出一株不同于DY的先前存在的亚株。此外，这种亚型出人意料地有一种 与DY TME不同的主机范围。为了验证我们的假设，我们将首先探索 使用互补方法(构象)从稳定和不稳定的Prion菌株中提取预先存在的亚株 稳定性、酶消化、热稳定性)选择性地去除优势菌株的数量。频率和频率 分离的亚株的多样性将使用互补的体外Pron检测方法和 动物生物化验。第二，我们将探索经过充分研究的仓鼠/小鼠物种障碍 互补的体外和体内方法来确定优势菌株和 亚株到种间传播。主导应变与主应变之间的应变干涉概念 亚株将在物种间传播方面进行测试。这些研究具有重要意义，因为它对 了解亚株作为目前的普恩治疗方法对普恩进化的贡献 发展(疫苗接种、抗病毒药物、环境缓解程序)以优势菌株为目标。它 因此，这些方法可能会在不经意间导致先前存在的Pron菌株的出现 人畜共患病潜势改变和/或致病性增强。总体而言，这些研究将直接测试 Colinger和Clark的Pron应变动力学模型，并将允许更精确地评估Prion的潜力 菌株以适应新的复制环境(例如，将慢性消耗性疾病传播给人类)。

Prions are infectious protein-only zoonotic agents that can rapidly evolve in a new replication environment. Prion strains are encoded by strain-specific conformations of PrPSc, the infectious form of the host-encoded prion protein, PrPC. Collinge and Clarke hypothesized that prion strains are a mixture of a dominant prion strain and substrains. In support of this hypothesis, we and others have shown: i) treatment of prions with anti-prion drugs can result in the emergence of a drug resistant strain, ii) physical methods (e.g. thermostability) that partially inactivate prions can select for prions with altered strain properties, and iii) strains within a given host species can have different host ranges. Despite these data, direct evidence for the existence of preexisting substrains is lacking and, consequently, the contributions of substrains to prion evolution has not been explored. The long-term goal of this work is to prevent prion evolution to a new replicative environment. The overall objective of this application is to determine the relative contributions of the dominant prion strain and substrains to interspecies transmission of prions. In this application we will test the hypothesis is that prion substrains drive prion transmission to a new PrP genotype. The hypothesis is based on our new discovery that selective reduction of PrPSc from the biologically cloned hamster-adapted drowsy (DY) strain of transmissible mink encephalopathy (TME), using two mechanistically different methods, allows for the emergence and isolation of a preexisting substrain that is distinct from DY. Moreover, this substrain unexpectedly has a different host range than DY TME. To test our hypothesis, we will first explore the frequency and diversity of preexisting substrains from stable and unstable prion strains using complimentary methods (conformational stability, protease digestion, thermostability) to selectively depopulate the dominant strain. The frequency and diversity of substrains isolated will be determined using complementary in vitro prion detection methods and animal bioassay. Second, we will explore the well-studied hamster/mouse species barrier using complementary in vitro and in vivo methods to determine the relative contributions of the dominant strain and substrains to interspecies transmission. The concept of strain interference between the dominant strain and substrains will be tested in regards interspecies transmission. These studies are significant since it is critical to understand the contributions of substrains to prion evolution as current prion treatment methods in development (vaccination, anti-prion drugs, environmental mitigation procedures) target the dominant strain. It is therefore possible that these methods will inadvertently result in the emergence of preexisting prion strains with altered zoonotic potential and/or increased pathogenicity. Overall, these studies will directly test the Collinge and Clark model of prion strain dynamics and will allow for a more precise evaluation potential of prion strains to adapt to a new replication environment (e.g., chronic wasting disease transmission to humans).