Alphaherpesviruses, including pseudorabies virus (PRV), are neuroinvasive pathogens that establish lifelong latency in peripheral ganglia following the initial infection at mucosal surfaces. The establishment of latent infection and subsequent reactivations, during which newly assembled virions are sorted into and transported anterogradely inside axons to the initial mucosal site of infection, rely on axonal bidirectional transport mediated by microtubule-based motors. Previous studies using cultured peripheral nervous system (PNS) neurons have demonstrated that KIF1A, a kinesin-3 motor, mediates the efficient axonal sorting and transport of newly assembled PRV virions. Here we report that KIF1A, unlike other axonal kinesins, is an intrinsically unstable protein prone to proteasomal degradation. Interestingly, PRV infection of neuronal cells leads not only to a nonspecific depletion of KIF1A mRNA but also to an accelerated proteasomal degradation of KIF1A proteins, leading to a near depletion of KIF1A protein late in infection. Using a series of PRV mutants deficient in axonal sorting and anterograde spread, we identified the PRV US9/gE/gI protein complex as a viral factor facilitating the proteasomal degradation of KIF1A proteins. Moreover, by using compartmented neuronal cultures that fluidically and physically separate axons from cell bodies, we found that the proteasomal degradation of KIF1A occurs in axons during infection. We propose that the PRV anterograde sorting complex, gE/gI/US9, recruits KIF1A to viral transport vesicles for axonal sorting and transport and eventually accelerates the proteasomal degradation of KIF1A in axons.IMPORTANCE Pseudorabies virus (PRV) is an alphaherpesvirus related to human pathogens herpes simplex viruses 1 and 2 and varicella-zoster virus. Alphaherpesviruses are neuroinvasive pathogens that establish lifelong latent infections in the host peripheral nervous system (PNS). Following reactivation from latency, infection spreads from the PNS back via axons to the peripheral mucosal tissues, a process mediated by kinesin motors. Here, we unveil and characterize the underlying mechanisms for a PRV-induced, accelerated degradation of KIF1A, a kinesin-3 motor promoting the sorting and transport of PRV virions in axons. We show that PRV infection disrupts the synthesis of KIF1A and simultaneously promotes the degradation of intrinsically unstable KIF1A proteins by proteasomes in axons. Our work implies that the timing of motor reduction after reactivation would be critical because progeny particles would have a limited time window for sorting into and transport in axons for further host-to-host spread.

中文翻译：

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伪狂犬病病毒感染会加速Kinesin-3电机KIF1A的降解。

包括伪狂犬病病毒（PRV）在内的Alphaherpesviruses病毒是神经侵入性病原体，在粘膜表面初次感染后，会在外周神经节中建立终生潜伏期。潜在感染的建立和随后的重新激活，在此过程中，新组装的病毒体被分类并在轴突内部顺行运输至感染的初始粘膜部位，这依赖于基于微管马达的轴突双向运输。以前使用培养的外周神经系统（PNS）神经元进行的研究表明，KIF1A是一种驱动蛋白3的运动因子，可介导新组装的PRV病毒体的有效轴突分选和运输。在这里我们报道，与其他轴突驱动蛋白不同，KIF1A是一种固有的不稳定蛋白，容易发生蛋白酶体降解。有趣的是 PRV感染神经元细胞不仅导致KIF1A mRNA的非特异性耗竭，而且导致KIF1A蛋白的蛋白酶体降解加速，从而导致感染后期KIF1A蛋白几乎耗竭。使用一系列PRV突变体的轴突分选和顺行扩散不足，我们确定PRV US9 / gE / gI蛋白复合物作为病毒因子，促进KIF1A蛋白的蛋白酶体降解。此外，通过使用将神经元从细胞体中流体地和物理地分开的间隔神经元培养，我们发现在感染过程中，KIF1A的蛋白酶体降解发生在轴突中。我们建议PRV顺行分类复合物gE / gI / US9，募集KIF1A到病毒运输囊泡中进行轴突分类和运输，并最终加速轴突中KIF1A的蛋白酶体降解。重要事项伪狂犬病病毒（PRV）是与人类病原体单纯疱疹病毒1和2和水痘带状疱疹病毒有关的α疱疹病毒。甲疱疹病毒是神经侵入性病原体，可在宿主周围神经系统（PNS）中建立终身潜伏感染。从潜伏期重新激活后，感染从PNS经由轴突传播回外围黏膜组织，这是由驱动蛋白运动介导的过程。在这里，我们揭示并表征了PRV诱导的KIF1A加速降解的基本机制，KIF1A是一种可促进轴突中PRV病毒体的分类和运输的kinesin-3电机。我们显示，PRV感染破坏了KIF1A的合成，同时促进了轴突中蛋白酶体对内在不稳定的KIF1A蛋白的降解。