Central nervous system complications in human herpesvirus-6 infection

Human herpesvirus-6 (HHV-6) is the causative agent of the common childhood infectious disease, exanthem subitum. After the virus was recently isolated from humans, it was found to be closely related to human cytomegalovirus (CMV), and was thus classified within the beta subgroup of human herpesviruses. HHV-6 possesses neurotropism in vitro, and it has been suggested that primary infection can cause complications of the central nervous system (CNS), including febrile seizures and encephalitis/encephalopathy. There is also speculation that the direct invasion of the virus into the CNS may play an important role in causing these neurological complications. Moreover, there are several reports which have suggested an association between HHV-6 and a variety of neurological disorders in adults. This paper will briefly review our virological understanding of the virus, and summarize recent findings regarding HHV-6 as an etiologic agent for CNS infection.