title: The Olfactory Bulb: An Immunosensory Effector Organ during Neurotropic Viral Infections.
abstract: In 1935, the olfactory route was hypothesized to be a portal for virus entry into the central nervous system (CNS). This hypothesis was based on experiments in which nasophayngeal infection with poliovirus in monkeys was prevented from spreading to their CNS via transection of olfactory tracts between the olfactory neuroepithelium (ONE) of the nasal cavity and the olfactory bulb (OB). Since then, numerous neurotropic viruses have been observed to enter the CNS via retrograde transport along axons of olfactory sensory neurons whose cell bodies reside in the ONE. Importantly, this route of infection can occur even after subcutaneous inoculation of arboviruses that can cause encephalitis in humans. While the olfactory route is now accepted as an important pathway for viral entry into the CNS, it is unclear whether it provides a way for infection to spread to other brain regions. More recently, studies of antiviral innate and adaptive immune responses within the olfactory bulb suggest it provides early virologic control. Here we will review the data demonstrating that neurotropic viruses gain access to the CNS initially via the olfactory route with emphasis on findings that suggest the OB is a critical immunosensory effector organ that effectively clears virus.
authors.affiliation: Biological Sciences Department, California State Polytechnic University , 3801 West Temple Ave., Pomona, California 91768, United States.
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Durrant
authors.forename: Soumitra
authors.initials: S
authors.lastname: Ghosh
authors.forename: Robyn S
authors.initials: RS
authors.lastname: Klein
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D020805:Central Nervous System Viral Diseases / Q000150:complications / Q000473:pathology*; D006801:Humans; D007249:Inflammation / Q000209:etiology / Q000517:prevention & control*; D018241:Neuroectodermal Tumors, Primitive, Peripheral; D009830:Olfactory Bulb / Q000473:pathology* / Q000821:virology*; D018034:Olfactory Receptor Neurons / Q000473:pathology / Q000821:virology; D058309:Receptors, Prostaglandin E, EP4 Subtype / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: D000893:Anti-Inflammatory Agents; D058309:Receptors, Prostaglandin E, EP4 Subtype
keywords: Olfactory bulb; encephalitis; neuroinvasion; olfactory sensory neurons; virus