The TSWV Movement Protein NSm Coopts Host Immunity Proteins NtPOX1 and NtPR‐4A to Induce Pathological Vesicles for Viral Replication

Plant-positive single-stranded RNA viruses induce vesicles that are crucial for viral infection, replication and spread. However, the mechanisms underlying the vesicle biogenesis induced by negative single-stranded RNA viruses remain largely unknown. Here, a negative single-stranded RNA virus, tomato spotted wilt orthotospovirus (TSWV) which is a representative member of genus Orthotospovirus in the Tospoviridae family, was used as a model to investigate the mechanisms involving the interaction between the viral and the host plant proteins in vesicle formation and function. We found that the nonstructural protein (NSm) of TSWV, could induce endoplasmic reticulum (ER)-derived pathological vesicle biogenesis. In addition, NSm might hijack the host immunity proteins, NtPOX1 (a peroxidase) and pathogenesis-related protein NtPR-4A, to form a potential tetrameric protein complex with Sar1 (a small GTPase), which was crucial for NSm-induced vesicle biogenesis. The results also showed that these ER-derived pathological vesicles provided sites for TSWV replication. These findings provide novel and robust insights for understanding the infection processes and mechanisms of plant-negative single-stranded RNA viruses.