NSP2 forms viroplasms during Dendrolimus punctatus cypovirus infection

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Reoviruses replicate and assemble within cytoplasmic structures known as viroplasms.
• The specific mechanisms and components of cypovirus viroplasms, particularly those of insect reoviruses, remain largely uncharacterized.

Purpose of the Study:

• To investigate the role of nonstructural proteins in the formation of Dendrolimus punctatus cypovirus (DpCPV) viroplasms.
• To identify which DpCPV proteins are involved in viroplasm assembly and viral particle formation.

Main Methods:

• Expression of all 10 DpCPV genomic segment proteins in Sf9 cells using the Bac-to-Bac system.
• Utilized colocalization, coimmunoprecipitation, and immunoelectron microscopy assays to analyze protein interactions and localization.
• Observed the formation of viroplasm-like structures and viral particle assembly.

Main Results:

• The viral nonstructural protein NSP2 formed viroplasm-like dots in close proximity to the endoplasmic reticulum and intracellular membranes.
• NSP2 demonstrated interactions with multiple structural and nonstructural viral proteins.
• Immunoelectron microscopy showed viral particles within NSP2-formed inclusions near the endoplasmic reticulum and mitochondria.

Conclusions:

• The nonstructural protein NSP2 is proposed to be the primary determinant for forming DpCPV viroplasm structures.
• NSP2 plays a critical role in the assembly of DpCPV, facilitating viral particle formation within the cytoplasm.