Pathogen-associated molecular patterns (PAMPs) are by themselves not enough to set off a full innate immune response to viral infection. Instead, structural changes to the actin cytoskeleton primed the activation of RIG-I-like receptors (RLRs), a family of intracellular RNA sensors that detect many types of viral RNA. When primed RLRs then encountered viral RNA, they set off an innate immune response that led to the production of interferons.