Virus-Induced Encephalitis

Certain neurotropic RNA and DNA viruses can induce a life-threatening disease in the central nervous system, which is referred to as encephalitis. Viruses that cause encephalitis generally induce inflammation in brain tissue (cerebral edema) and kill neurons via a direct or indirect mechanism. These cellular insults culminate in intracerebral hemorrhage, bleeding in the brain, and brain damage. While encephalitis is a relatively rare disease, this disease costs the United States approximately $2 billion/year. RNA viruses that cause encephalitis include certain arboviruses, Astroviruses, and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herpes simplex virus type 1 (HSV-1) causes 38% of all encephalitis cases, which is more than the other viruses that cause encephalitis. Two other herpesviruses, varicella zoster virus and human cytomegalovirus, can also induce encephalitis. This chapter discusses the main virus families that cause encephalitis, their replication cycle, animal models used to examine encephalitis, clinical features of encephalitis, and therapeutic strategies. Finally, mechanisms by which these viruses cause encephalitis are discussed.