Human herpesvirus-6: neurologic implications of a newly-described viral pathogen.

Discovered only 12 years ago, human herpesvirus-6 (HHV-6) has been associated with central nervous system (CNS) findings such as febrile seizures, encephalitis, meningitis, and possibly multiple sclerosis. These manifestations have been reported in both immunocompetent and immunocompromised individuals. The applications of such sophisticated laboratory tools as polymerase chain reaction, in situ hybridization, immunohistochemical staining, and representational difference analysis have expanded knowledge of the spectrum of CNS disease attributable to HHV-6 while delineating pathogenic mechanisms of both primary HHV-6 infection and reactivation from latency. This article reviews existing knowledge of the CNS manifestations of HHV-6, focusing on both clinical aspects of HHV-6 infection and its pathogenesis on neurologic diseases.