Lyman Mathew G, Curanovic Dusica, Enquist Lynn W
Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America.
PLoS Pathog. 2008 May 16;4(5):e1000065. doi: 10.1371/journal.ppat.1000065.
The pseudorabies virus (PRV) Us9 protein plays a central role in targeting viral capsids and glycoproteins to axons of dissociated sympathetic neurons. As a result, Us9 null mutants are defective in anterograde transmission of infection in vivo. However, it is unclear how Us9 promotes axonal sorting of so many viral proteins. It is known that the glycoproteins gB, gC, gD and gE are associated with lipid raft microdomains on the surface of infected swine kidney cells and monocytes, and are directed into the axon in a Us9-dependent manner. In this report, we determined that Us9 is associated with lipid rafts, and that this association is critical to Us9-mediated sorting of viral structural proteins. We used infected non-polarized and polarized PC12 cells, a rat pheochromocytoma cell line that acquires many of the characteristics of sympathetic neurons in the presence of nerve growth factor (NGF). In these cells, Us9 is highly enriched in detergent-resistant membranes (DRMs). Moreover, reducing the affinity of Us9 for lipid rafts inhibited anterograde transmission of infection from sympathetic neurons to epithelial cells in vitro. We conclude that association of Us9 with lipid rafts is key for efficient targeting of structural proteins to axons and, as a consequence, for directional spread of PRV from pre-synaptic to post-synaptic neurons and cells of the mammalian nervous system.
伪狂犬病病毒（PRV）的Us9蛋白在将病毒衣壳和糖蛋白靶向解离的交感神经元轴突过程中发挥核心作用。因此，Us9基因缺失突变体在体内感染的顺行传播方面存在缺陷。然而，目前尚不清楚Us9如何促进众多病毒蛋白的轴突分选。已知糖蛋白gB、gC、gD和gE与感染的猪肾细胞和单核细胞表面的脂筏微区相关，并以Us9依赖的方式被导向轴突。在本报告中，我们确定Us9与脂筏相关，且这种关联对于Us9介导的病毒结构蛋白分选至关重要。我们使用了感染的非极化和极化PC12细胞，这是一种大鼠嗜铬细胞瘤细胞系，在存在神经生长因子（NGF）的情况下会获得交感神经元的许多特征。在这些细胞中，Us9高度富集于耐去污剂膜（DRM）中。此外，降低Us9与脂筏的亲和力会抑制体外感染从交感神经元向上皮细胞的顺行传播。我们得出结论，Us9与脂筏的关联是将结构蛋白有效靶向轴突的关键，因此也是PRV在哺乳动物神经系统中从突触前神经元向突触后神经元和细胞定向传播的关键。
