Alphavirus neurovirulence

Due to their parasitic, obligate, intracellular nature, evolution favors viruses with the ability to evade the barriers and impediments the host organism utilizes to limit their ability to replicate or cause cellular dysfunction. Avoidance of host defense mechanisms and successful replication often leads to virulence, the ability to cause fatal disease. Neurovirulent viruses alter the highly sensitive nature and critical functioning of the central nervous system (CNS) leading to fatal encephalitis or, in the event of recovery, severe neurological sequelae. With 20 viruses known to cause human encephalitis, arboviruses (arthropod-borne viruses) represent a signicant public health threat as emerging infectious diseases both in the United States and worldwide. The focus of this review, arboviruses in the Alphavirus genus in the family Togaviridae, contains three viruses capable of causing human encephalitis: Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV). No specic therapy or vaccine is currently available against these viruses.