Cell-autonomous immunity as an integrated immune network against bacterial and viral pathogens.

All cells possess a diverse array of cell-autonomous immune responses that can detect and restrict infections by intracellular pathogens. These intrinsic responses (both passive and active) enable individual cells to autonomously block bacterial and viral invasion and replication. Epithelial and endothelial cells act as a first line of defence, coordinating immune responses that preserve host barrier integrity. These cells can also mount specialized innate immune responses (many of which are triggered by antimicrobial cytokines, such as interferons) to limit the replication and motility of intracellular bacteria and viruses. To counteract these, bacteria and viruses have developed strategies to avoid or antagonize host defences, driving an evolutionary arms race that shapes every aspect of host-pathogen interactions. This Review provides an overview of current knowledge of cell-autonomous immunity against bacteria and viruses. We emphasize the factors underpinning host cell surveillance and restriction of cytosolic pathogens and mechanisms of immune evasion deployed by the invading microorganism.