Imaging RNA virus replication assemblies: bunyaviruses and reoviruses

Abstract

ABSTRACT  RNA viruses replicate in the cytoplasm in close association with host cell membranes. Both viral and cellular factors generate organelle-like structures termed viral factories, viral inclusions or viroplasms. Biochemical, light and electron microscopy analyses, including 3D models, have improved our understanding of the architecture and function of RNA virus replication factories. In these structures, the virus compartmentalizes genome replication and transcription, thus enhancing replication efficiency and protection from host defenses. Recent studies with diverse RNA viruses have elucidated the ultrastructure of replication organelles and shown how these structures act in close coordination with virion assembly. This review focuses on a general description of RNA virus factories and summarizes recent progress in the characterization of those assembled by bunyaviruses and reoviruses. We describe how these viruses modify intracellular membranes; we highlight similarities with the structures induced by viruses of other families, and discuss how these structures might be formed.