Grapevine fanleaf virus replication occurs on endoplasmic reticulum-derived membranes

Area of Science:

• Plant virology
• Molecular plant pathology
• Cell biology

Background:

• Grapevine fanleaf nepovirus (GFLV) causes significant damage to grapevines.
• GFLV infection leads to substantial changes in host cell endomembranes, forming a viral compartment.
• Understanding the formation and function of this viral compartment is crucial for controlling GFLV.

Purpose of the Study:

• To identify the site of GFLV replication within the host cell.
• To elucidate the role of host endomembranes and lipid synthesis in GFLV replication.
• To investigate the localization and transport of GFLV proteins.

Main Methods:

• Immunoconfocal microscopy to visualize viral components and compartment formation.
• Use of transgenic T-BY2 protoplasts expressing fluorescent proteins in the ER and Golgi apparatus.
• Treatment with Brefeldin A to inhibit vesicle trafficking and Cerulenin to inhibit lipid synthesis.

Main Results:

• The perinuclear compartment was confirmed as the site of GFLV replication, containing viral RNA and replication proteins.
• GFLV replication induced depletion and redistribution of cortical ER membranes to form the viral compartment.
• Inhibition of ER-Golgi vesicle trafficking and de novo lipid synthesis significantly inhibited GFLV replication.
• Viral movement proteins (2B and 2C) were found to be transported towards the cell periphery.

Conclusions:

• GFLV replication is dependent on the recruitment of ER-derived membranes and de novo lipid synthesis.
• The formation of the viral compartment is a key event orchestrated by the virus, utilizing host membrane resources.
• Differential localization of viral proteins suggests distinct roles in replication and cell-to-cell movement.