Cytosolic DNA-sensing immune response and viral infection.

How host cells recognize many kinds of RNA and DNA viruses and initiate innate antiviral responses against them has not yet been fully elucidated. Over the past decade, investigations into the mechanisms underlying these antiviral responses have focused extensively on immune surveillance sensors that recognize virus-derived components (such as lipids, sugars and nucleic acids). The findings of these studies have suggested that antiviral responses are mediated by cytosolic or intracellular compartment sensors and their adaptor molecules (e.g., TLR, myeloid differentiation primary response 88, retinoic acid inducible gene-I, IFN-β promoter stimulator-1, cyclic GMP-AMP synthase and stimulator of IFN genes axis) for the primary sensing of virus-derived nucleic acids, leading to production of type I IFNs, pro-inflammatory cytokines and chemokines by the host cells. Thus, host cells have evolved an elaborate host defense machinery to recognize and eliminate virus infections. In turn, to achieve sustained viral infection and induce pathogenesis, viruses have also evolved several counteracting strategies for achieving immune escape by targeting immune sensors, adaptor molecules, intracellular kinases and transcription factors. In this review, we discuss recent discoveries concerning the role of the cytosolic nucleic acid-sensing immune response in viral recognition and control of viral infection. In addition, we consider the regulatory machinery of the cytosolic nucleic acid-sensing immune response because these immune surveillance systems must be tightly regulated to prevent aberrant immune responses to self and non-self-nucleic acids.