Electron microscopy: The key to resolve RNA viruses replication organelles

Positive‐sense single‐stranded RNA viruses significantly reshape intracellular membranes to generate viral replication organelles that form a controlled niche in which nucleic acids, enzymes, and cofactors accumulate to assure an efficient replication of the viral genome. In recent years, advancements in electron microscopy (EM) techniques have enabled imaging of these viral factories in a near‐native state providing significantly higher molecular details that have led to progress in our general understanding of virus biology. In this review, we describe the contribution of the cutting‐edge EM approaches to the current knowledge of replication organelles biogenesis, structure, and functions. Positive‐strand RNA viruses replicate their genome within specialized virus‐induced intracellular compartments called “replication organelles”. Technological advances in electron microscopy allowed detailed characterization of such structures unveiling their three‐dimensional architecture and molecular composition.