Vector-borne Virus Research Center, State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China.
London Research and Development Centre, Agriculture and Agri-Food Canada, London, Ontario, Canada.
PLoS Pathog. 2022 May 9;18(5):e1010506. doi: 10.1371/journal.ppat.1010506. eCollection 2022 May.
Viruses can hijack autophagosomes as the nonlytic release vehicles in cultured host cells. However, how autophagosome-mediated viral spread occurs in infected host tissues or organs in vivo remains poorly understood. Here, we report that an important rice reovirus, rice gall dwarf virus (RGDV) hijacks autophagosomes to traverse multiple insect membrane barriers in the midgut and salivary gland of leafhopper vector to enhance viral spread. Such virus-containing double-membraned autophagosomes are prevented from degradation, resulting in increased viral propagation. Mechanistically, viral nonstructural protein Pns11 induces autophagy and embeds itself in the autophagosome membranes. The autophagy-related protein 5 (ATG5)-ATG12 conjugation is essential for initial autophagosome membrane biogenesis. RGDV Pns11 specifically interacts with ATG5, both in vitro and in vivo. Silencing of ATG5 or Pns11 expression suppresses ATG8 lipidation, autophagosome formation, and efficient viral propagation. Thus, Pns11 could directly recruit ATG5-ATG12 conjugation to induce the formation of autophagosomes, facilitating viral spread within the insect bodies. Furthermore, Pns11 potentially blocks autophagosome degradation by directly targeting and mediating the reduced expression of N-glycosylated Lamp1 on lysosomal membranes. Taken together, these results highlight how RGDV remodels autophagosomes to benefit viral propagation in its insect vector.
病毒可以劫持自噬体作为培养宿主细胞中非溶细胞性释放载体。然而,在体内受感染的宿主组织或器官中,自噬体介导的病毒传播是如何发生的,目前仍知之甚少。在这里,我们报告称,一种重要的水稻呼肠孤病毒,即水稻丛矮病毒(RGDV),可以劫持自噬体,从而穿越叶蝉媒介的中肠和唾液腺中的多种昆虫膜屏障,增强病毒的传播。这种含有双层膜的自噬体被阻止降解,导致病毒增殖增加。在机制上,病毒非结构蛋白 Pns11 诱导自噬,并嵌入自噬体膜中。自噬相关蛋白 5(ATG5)-ATG12 连接对于初始自噬体膜生物发生至关重要。RGDV Pns11 可在体外和体内与 ATG5 特异性相互作用。沉默 ATG5 或 Pns11 的表达会抑制 ATG8 脂质化、自噬体形成和有效的病毒增殖。因此,Pns11 可以直接招募 ATG5-ATG12 连接来诱导自噬体的形成,从而促进病毒在昆虫体内的传播。此外,Pns11 可能通过直接靶向和介导溶酶体膜上 N-糖基化 Lamp1 的减少表达来阻止自噬体的降解。总之,这些结果强调了 RGDV 如何重塑自噬体,以有利于其在昆虫媒介中的病毒传播。