title: Transolfactory neuroinvasion by viruses threatens the human brain.
abstract: Viral neuroinvasion via the olfactory system has been investigated in a variety of virus-animal models by scientists in many fields including virologists, pathologists, and neurologists. In humans, herpes simplex virus type 1 (HSV-1), human herpesvirus 6 (HHV-6), Borna disease virus, rabies virus, and influenza A virus have been shown to take the olfactory route for neuroinvasion based on forensic and post-mortem specimens. This article briefly summarizes the anatomy, physiology, and immunology of the olfactory system and presents a battery of neurovirulent viruses that may threaten the human brain by invading through this peripheral pathway, especially focusing on two of the most intensively studied viruses--HSV-1 and influenza A virus. Viruses may insidiously invade the olfactory neural network not only to precipitate encephalitis/encephalopathy but also to promote the development of neurodegenerative and demyelinating disorders. Substantial information obtained by analyzing human specimens is required to argue for or against this hypothesis.
authors.forename: I
authors.initials: I
authors.lastname: Mori
mesh_terms: D000818:Animals; D001921:Brain / Q000276:immunology / Q000821:virology*; D006801:Humans; D009831:Olfactory Mucosa / Q000276:immunology / Q000821:virology*; D014777:Virus Diseases / Q000276:immunology / Q000821:virology*; D018406:Virus Physiological Phenomena
keywords: virus; olfactory neuron; human brain; encephalitis; neurodegenerative disorders.