In contrast to WT infection, the IFNβ response to virulence plasmid-cured S. flexneri was not dependent on RIG-I, even in the presence of IFNγ (Fig. 5A), suggesting that either access to the cell cytoplasm (where RIG-I is located) or another activity of the Type III secretion system is required for recognition by RIG-I. Here, RIGI is linked to infection.