Life cycle of phytoreoviruses visualized by electron microscopy and tomography

Naoyuki Miyazaki,Kenji Iwasaki,Atsushi Nakagawa

doi:10.3389/fmicb.2013.00306

Abstract

Rice dwarf virus and Rice gall dwarf virus, members of the genus Phytoreovirus in the family Reoviridae,are known as agents of rice disease, because their spread results in substantial economic damage in many Asian countries. These viruses are transmitted via insect vectors, and they multiply both in the plants and in the insect vectors. Structural information about the viruses and their interactions with cellular components in the life cycle are essential for understanding viral infection and replication mechanisms. The life cycle of the viruses involves various cellular events such as cell entry, synthesis of viral genome and proteins, assembly of viral components, viral egress from infected cells, and intra- and intercellular transports. This review focuses on the major events underlying the life cycle of phytoreoviruses, which has been visualized by various electron microscopy (EM) imaging techniques, including cryo-electron microscopy and tomography, and demonstrates the advantage of the advanced EM imaging techniques to investigate the viral infection and replication mechanisms.

Highlights

The life cycle of viruses involves various cellular events including cell entry, synthesis of viral genome and proteins, assembly of viral components, and viral egress from infected cells
We describe the life cycle of phytoreoviruses as revealed by various EM imaging techniques, including cryo-electron microscopy and Electron tomography (ET), and immunofluorescence microscopy and immunoelectron microscopy
Phytoreoviruses were chosen for this review because they are the most widely studied of all plant viruses that are currently threatening the stable production of cereal crops (Omura and Mertens, 2005)

Summary

INTRODUCTION

The life cycle of viruses involves various cellular events including cell entry, synthesis of viral genome and proteins, assembly of viral components, and viral egress from infected cells. Rice dwarf virus (RDV), Rice gall dwarf virus (RGDV), and Wound tumor virus are members of the genus Phytoreovirus in the family Reoviridae These viruses are icosahedral double-shelled particles with an average diameter of approximately 70 nm (Takahashi et al, 1994; Miyazaki et al, 2005), and they are known as serious agents of rice diseases that cause economic damage in many Asian countries. Five non-structural proteins (Pns, Pns, Pns, Pns, and Pns12) are associated with the replication cycle of RDV within host cells, which involves synthesis of the viral genome and proteins, assembly of progeny viruses, and intercellular movement, among other processes. RDV Pns is a phosphoprotein localized around the viroplasms and is known to form bundles of minitubules at later stages of www.frontiersin.org

Life cycle of phytoreoviruses

CONCLUSION