Illuminating viral infections in the nervous system

This Review describes the anatomical features of the central nervous system (CNS) barriers and focuses on the way in which the immune system responds to neurotropic viruses that establish latent or persistent infections in the CNS. It also discusses imaging technologies that can be used to understand viral entry and antiviral immune responses in the CNS. Viral infections are a major cause of human disease. Although most viruses replicate in peripheral tissues, some have developed unique strategies to move into the nervous system, where they establish acute or persistent infections. Viral infections in the central nervous system (CNS) can alter homeostasis, induce neurological dysfunction and result in serious, potentially life-threatening inflammatory diseases. This Review focuses on the strategies used by neurotropic viruses to cross the barrier systems of the CNS and on how the immune system detects and responds to viral infections in the CNS. A special emphasis is placed on immune surveillance of persistent and latent viral infections and on recent insights gained from imaging both protective and pathogenic antiviral immune responses.