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

朊病毒株和亚株对朊病毒人畜共患潜力和进化的贡献

• 批准号: 10711575
• 负责人: Jason C Bartz
• 金额: $ 58.19万
• 依托单位: CREIGHTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10711575
• 关键词: Animals; Biochemical; Biological Assay; Chronic Wasting Disease; Data; Development; Digestion; Disease; Drowsiness; Drug resistance; Encephalopathies; Environment; Evaluation; Evolution; Excision; Frequencies; Generations; Genotype; Goals; Hamsters; Human; In Vitro; Methods; Mink; Modeling; Molecular Conformation; Mus; Mutation; Pathogenicity; Peptide Hydrolases; Pharmaceutical Preparations; PrP; PrPSc Proteins; Prions; Procedures; Production; Property; Proteins; Role; Testing; Vaccination; Work; Zoonoses; cervid; cross-species transmission; detection method; disease transmission; in vivo; prevent; prion-like; resistant strain; thermostability; transmission process

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).

朊病毒是仅具有传染性的蛋白质人畜共患病原体，可以在新的复制环境中快速进化。 朊病毒株由 PrPSc 的株特异性构象编码，PrPSc 是宿主编码的感染形式 朊病毒蛋白，PrPC。 Collinge 和 Clarke 假设朊病毒株是一种优势朊病毒株的混合物 和亚系。为了支持这一假设，我们和其他人已经证明：i）用抗朊病毒治疗朊病毒 药物可能导致耐药菌株的出现，ii) 物理方法（例如热稳定性） 部分失活的朊病毒可以选择具有改变的菌株特性的朊病毒，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，直接证据表明先前存在的 缺乏亚株，因此亚株对朊病毒进化的贡献尚未确定 探索过。这项工作的长期目标是防止朊病毒进化到新的复制环境。这 本申请的总体目标是确定主要朊病毒菌株和 朊病毒亚株到种间传播。在此应用中，我们将测试以下假设：朊病毒 亚菌株驱动朊病毒传播至新的 PrP 基因型。该假设基于我们的新发现 从生物学克隆的仓鼠适应的嗜睡 (DY) 传染性菌株中选择性减少 PrPSc 水貂脑病（TME）使用两种机制不同的方法，允许出现和 分离与 DY 不同的预先存在的亚株。而且，这个亚种竟然还有一个 与 DY TME 不同的宿主范围。为了检验我们的假设，我们将首先探讨 使用互补方法（构象法）从稳定和不稳定的朊病毒菌株中分离出预先存在的亚菌株 稳定性、蛋白酶消化、热稳定性）以选择性地减少优势菌株的数量。频率和 将使用互补的体外朊病毒检测方法来确定分离的亚株的多样性 动物生物测定。其次，我们将利用以下方法探索经过充分研究的仓鼠/小鼠物种屏障 互补的体外和体内方法，以确定优势菌株和 亚株到种间传播。主应变与主应变之间的应变干扰的概念 将测试亚株的种间传播。这些研究意义重大，因为它对于 了解亚菌株对朊病毒进化的贡献作为当前的朊病毒治疗方法 开发（疫苗接种、抗朊病毒药物、环境缓解程序）针对的是优势菌株。它 因此，这些方法可能会无意中导致先前存在的朊病毒株的出现 具有改变的人畜共患潜力和/或增加的致病性。总的来说，这些研究将直接测试 Collinge 和 Clark 的朊病毒应变动力学模型将允许更精确地评​​估朊病毒的潜力 菌株适应新的复制环境（例如，慢性消耗性疾病传播给人类）。