Zika Virus Subverts Stress Granules to Promote and Restrict Viral Gene Expression

Flaviviruses limit the cell stress response by preventing the formation of stress granules and utilize different proteins involved in the stress granule pathway to modulate viral gene expression. In this study, we investigated the formation of stress granules during Zika virus (ZIKV) infection and the role stress granule proteins play during the viral life cycle. Using immunofluorescence and confocal microscopy, we determined that ZIKV disrupted the formation of arsenite-induced stress granules and changed the subcellular distribution, but not the abundance or integrity, of stress granule proteins. To investigate the role of different stress granule proteins in ZIKV infection we used target-specific siRNAs to deplete six proteins, namely Ataxin2, G3BP1, HuR, TIA-1, TIAR and YB1. Depletion of TIA-1 and TIAR affected ZIKV protein and RNA levels, but viral titers did not change. Conversely, depletion of Ataxin2 and YB-1 decreased virion production despite having only a small effect on ZIKV protein and expression. Notably, however, depletion of G3BP1 and HuR decreased and increased ZIKV gene expression and virion production, respectively. Using an MR766 Gaussia luciferase reporter genome together with knockdown and overexpression assays, G3BP1 and HuR were found to modulate ZIKV replication. These data indicate that ZIKV disrupts the formation of stress granules by sequestering stress granule proteins required for replication, where G3BP1 functions to promote ZIKV infection, while HuR exhibits an antiviral effect. The consequence of ZIKV re-localizing and subverting select stress granule proteins might have broader consequences on cellular RNA homeostasis and contribute to cellular gene dysregulation and ZIKV pathogenesis.