A neurotropic virus is a virus that is capable of infecting nerve cells, or that does so preferentially. Such viruses are, therefore, able to largely evade the usual immune response as many elements are prevented from reaching the site of infection by the blood-brain barrier.
A disease agent is said to be neuroinvasive if it is capable of entering or infecting the central nervous system, and neurovirulent if it is capable of causing disease within the nervous system. Important neuroinvasive viruses include rabies, which has both high neuroinvasiveness and high neurovirulence, and herpes simplex virus, which has low neuroinvasiveness and high neurovirulence. Others, like poliovirus, can spread neurally, but spread primarily via the blood system in what is called hematogenous dissemination.
Neurotropic viruses that cause acute infection include Japanese Encephalitis, Venezuelan Equine Encephalitis, and California encephalitis viruses; polio, coxsackie, echo, mumps, measles, influenza, and rabies, as well as diseases caused by members of the family Herpesviridae such as herpes simplex, varicella-zoster, cytomegalo, HHV-6, and Epstein-Barr viruses.
Those causing latent infection include herpes simplex and varicella-zoster viruses. Those causing slow virus infection include measles, rubella and JC viruses, and retroviruses such as human T-lymphotropic virus 1 and human immunodeficiency virus.
Neurotropic viruses are increasingly being exploited as research tools, and for their potential use in treatment. In particular, they are being used to improve the understanding of the nervous systems circuits.
Other neurotropic infections
Several diseases, including transmissible spongiform encephalopathy, Kuru, and Creutzfeldt-Jakob disease resemble a slow neurotropic virus infection—but are, in fact, caused by the infectious proteins known as prions.
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