Nonstructural protein Pns12 of rice dwarf virus is a principal regulator for viral replication and infection in its insect vector

•Nonstructural protein Pns12 of RDV acts as a scaffold for the recruitment of other viral proteins into viroplasm.•Assembly of viroplasms by Pns12 is essential for persistent infection of RDV in vector.•Pns12 of RDV is a principal regulator for viral replication and infection in its insect vector.

Plant reoviruses are thought to replicate and assemble within cytoplasmic structures called viroplasms. The molecular mechanisms underling the formation of the viroplasm during infection of rice dwarf virus (RDV), a plant reovirus, in its leafhopper vector cells remain poorly understood. Viral nonstructural protein Pns12 forms viroplasm-like inclusions in the absence of viral infection, suggesting that the viroplasm matrix is basically composed of Pns12. Here, we demonstrated that core capsid protein P3 and nonstructural protein Pns11 were recruited in the viroplasm by direct interaction with Pns12, whereas nonstructural protein Pns6 was recruited through interaction with Pns11. The introduction of dsRNA from Pns12 gene into cultured insect vector cells or intact insect strongly inhibited such viroplasm formation, preventing efficient viral spread in the leafhopper in vitro and in vivo. Thus, nonstructural protein Pns12 of RDV is a principal regulator for viral replication and infection in its insect vector.