Dr Matthew Brownsword

Recent exciting studies have uncovered how membrane-less organelles, also known as biocondensates, are providing cells with rapid response pathways, allowing them to re-organise their cellular contents and adapt to stressful conditions. Their assembly is driven by the phase separation of their RNAs and intrinsically disordered protein components into condensed foci. Among these, stress granules are dynamic cytoplasmic biocondensates that form in response to many stresses, including activation of the integrated stress response or viral infections. Stress granules sit at the crossroads between antiviral signalling and translation because they concentrate signalling proteins and components of the innate immune response, in addition to translation machinery and stalled mRNAs. Consequently, they have been proposed to contribute to antiviral activities, and therefore are targeted by viral countermeasures. Equally, stress granules components can be commandeered by viruses for their own efficient replication. Phase separation processes are an important component of the viral life cycle, for example driving assembly of replication factories or inclusion bodies. Therefore, in this review we will outline the recent understanding of this complex interplay and tug of war between viruses, stress granules and their components.