Vector-borne Virus Research Center, Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China.
Elife. 2021 Jul 2;10:e64603. doi: 10.7554/eLife.64603.
Numerous piercing-sucking insects can horizontally transmit viral pathogens together with saliva to plant phloem, but the mechanism remains elusive. Here, we report that an important rice reovirus has hijacked small vesicles, referred to as exosomes, to traverse the apical plasmalemma into saliva-stored cavities in the salivary glands of leafhopper vectors. Thus, virions were horizontally transmitted with exosomes into rice phloem to establish the initial plant infection during vector feeding. The purified exosomes secreted from cultured leafhopper cells were enriched with virions. Silencing the exosomal secretion-related small GTPase Rab27a or treatment with the exosomal biogenesis inhibitor GW4869 strongly prevented viral exosomal release in vivo and in vitro. Furthermore, the specific interaction of the 15-nm-long domain of the viral outer capsid protein with Rab5 induced the packaging of virions in exosomes, ultimately activating the Rab27a-dependent exosomal release pathway. We thus anticipate that exosome-mediated viral horizontal transmission is the conserved strategy hijacked by vector-borne viruses.
许多刺吸式昆虫可以在水平方向上将病毒病原体与唾液一起通过韧皮部传送到植物中，但具体机制仍不清楚。在这里，我们报告称，一种重要的水稻呼肠孤病毒劫持了小泡，称为外泌体，穿过顶端质膜进入叶蝉介体唾液储存腔中的唾液腺。因此，病毒颗粒与外泌体一起通过水平传播进入水稻韧皮部，在介体取食过程中建立初始植物感染。从培养的叶蝉细胞中纯化的外泌体富含病毒颗粒。沉默与外泌体分泌相关的小 GTPase Rab27a 或用外泌体生物发生抑制剂 GW4869 处理，强烈阻止了体内和体外病毒外泌体的释放。此外，病毒外壳蛋白的 15nm 长结构域与 Rab5 的特异性相互作用诱导了病毒颗粒在 外泌体中的包装，最终激活了依赖 Rab27a 的外泌体释放途径。因此，我们预计外泌体介导的病毒水平传播是介体传播病毒劫持的保守策略。
