Origin and Mechanism of Promiscuous Prion Strains

描述（由申请方提供）：大多数朊病毒株感染相对较少的动物物种，但引起牛海绵状脑病（BSE）和变异型克雅氏病（vCJD）的菌株是非常混杂的。BSE/vCJD菌株已在包括人类在内的多种动物物种中引起流行，但尚不清楚这种菌株是如何起源的，以及为什么它特别擅长跨越物种障碍。在这里，我们建议研究如何滥交朊病毒株的起源和确定的分子机制，负责他们的能力，跨越物种的障碍很容易。我们最近报道，辅因子分子调节哺乳动物朊病毒的主要应变特性，包括嗜神经性和PrPSc构象。基于这一关键结果，我们现在将研究辅因子分子是否也在朊病毒的跨物种传播中发挥作用。我们的假设是，朊病毒最初与特定的辅因子形成，将更有可能跨越物种障碍，如果 辅因子是通过调节PrP分子的潜在折叠途径获得的。我们还将表征和分离负责维持BSE/vCJD菌株特性的辅因子分子，包括其感染多种动物物种的能力。为此，我们将采用一种简单的复溶试验，在该试验中可以快速监测BSE/vCJD菌株PrPSc构象的维持。最后，我们将检验这样的假设，即混杂朊病毒菌株是由非混杂菌株产生的，这是在用于回收动物尸体的商业热处理过程中进行构象选择的结果。为了验证这一假设，我们将在实验室中模拟渲染过程，并研究绵羊瘙痒病和鹿CWD是否可以转化为能够感染人类或奶牛的混杂菌株。这些研究将对公众健康产生直接影响。

DESCRIPTION (provided by applicant): Most prion strains infect a relatively small number of animal species, but the strain responsible for bovine spongiform encephalopathy (BSE) and variant Creutzfeldt Jakob disease (vCJD) is remarkably promiscuous. The BSE/vCJD strain has caused epidemics in a wide variety of animal species, including humans, but it is unclear how this strain originated and why it is particularly adept at crossing species barriers. Here, we propose to study how promiscuous prion strains originate and identify the molecular mechanism responsible for their ability to cross species barriers easily. We recently reported that cofactor molecules regulate the major strain properties of mammalian prions, including neurotropism and PrPSc conformation. Building upon this critical result, we will now study whether cofactor molecules also play a role in cross- species transmission of prions. Our hypothesis is that prions originally formed with a particular cofactor will be more likely to cross a species barrier if that cofactor is available by modulating the potential folding pathways for PrP molecules. We will also characterize and isolate the cofactor molecule(s) responsible for maintaining the strain properties of the BSE/vCJD strain, including its ability to infect multiple animal species. To do this, we will employ a simple reconstitution assay in which maintenance of the BSE/vCJD strain PrPSc conformation can be monitored rapidly. Finally, we will test the hypothesis that promiscuous prion strains are created from non- promiscuous strains as a result conformational selection during the commercial heat rendering process used to recycle animal carcasses. To test this hypothesis, we will simulate the rendering process in the laboratory and study whether sheep scrapie and deer CWD can be converted into promiscuous strains capable of infecting humans or cows. These studies will have an immediate impact on public health.