Mechanisms of prion strain selection

描述(申请人提供)：Pron病是一组新出现的人和动物的遗传性神经退行性疾病。人类的Prion病可以由物种间传播引起，例如变异的CreutzFeldt-Jacob病就是由牛海绵状脑病传播给人类引起的。在物种间传播之后，Pron对新宿主物种的适应可能涉及到Pron菌株之间的竞争，直到一种Pron菌株占主导地位。本实验室的长期目标是描述病毒对新寄主物种的适应机制(S)。为了实现这一目标，我们计划研究Pron菌株选择的分子基础。我们发展了一种病毒株系选择模型，仓鼠首先在坐骨神经(I.N.)感染。与昏昏欲睡(DY)株的传染性水貂脑病(TME)，然后I.N.与TME高(HY)株重叠感染。使用这个模型，我们已经定位了Pron菌株选择的位置到腰髓，很可能是在腹侧运动神经元(VMN)。我们假设，在中枢神经系统内，Pron试剂运输和/或Pron试剂复制的改变负责Pron菌株的选择。为了研究这一假说，我们将：i)建立DY TME感染改变逆行示踪物或表位或荧光标记PrPSc从坐骨神经到腰髓VMN的轴突运输的程度；ii)通过Western印迹分析和/或显微解剖VMN的动物生物测定，确定DY TME在VMN中的复制对随后VMN中HY TME复制的影响；iii)通过使用无偏向体视学对VMN种群进行量化来评估DY TME感染VMN对VMN活性的影响。这项研究的结果将定义普恩选择的机制(S)，开始解决普恩竞争的因素(S)，并促进我们对普恩在物种间传递后如何适应新寄主物种的理解。

DESCRIPTION (provided by applicant): Prion diseases are a group of emerging transmissible neurodegenerative diseases of humans and animals. Prion diseases of humans can be caused by interspecies transmission, for example, variant Creutzfeldt-Jacob disease is caused by transmission of bovine spongiform encephalopathy to humans. Following interspecies transmission, adaptation of prions to a new host species can involve competition between prion strains until one prion strain predominates. The long-term goal of this laboratory is to describe the mechanism(s) of prion adaptation to a new host species. In a step to achieve this goal, we plan to investigate the molecular basis of prion strain selection. We have developed a prion strain selection model where hamsters are first infected in the sciatic nerve (i.n.) with the drowsy (DY) strain of transmissible mink encephalopathy (TME), then i.n. superinfected with the hyper (HY) strain of TME. Using this model, we have localized the site of prion strain selection to the lumbar spinal cord, most likely within ventral motor neurons (VMNs). We hypothesize that alterations in prion agent transport and/or prion agent replication are responsible for prion strain selection within the central nervous system. To investigate this hypothesis we will i) establishing the degree to which DY TME infection alters axonal transport of a retrograde tracer or epitope or fluorescently labeled PrPSc from the sciatic nerve to VMNs in the lumbar spinal cord ii) determine the effect of DY TME replication in VMNs has on subsequent HY TME replication in VMNs by Western blot analysis and/or animal bioassay of microdissected VMNs and iii) assess the effect of DY TME infection on the viability of VMNs which are the first cell type infected by HY TME following sciatic nerve inoculation by quantifying VMN populations using unbiased stereology. Results from the aims in this proposal will define the mechanism(s) of prion selection, begin to address the factor(s) that prions compete for, and advance our understanding of how prions adapt to a new host species following interspecies transmission.