HHV-6 and the Central Nervous System

Abstract

Publisher Summary This chapter focuses on evidence suggesting an association of human herpesvirus-6 (HHV-6) with four major disorders of the central nervous system (CNS): childhood febrile seizures, mesial temporal-lobe epilepsy (MTLE), multiple sclerosis (MS), and progressive multifocal leukoencephalopathy (PML). Detection of HHV-6 genome in the brain per se does not necessarily indicate productive infection, and establishing a primary pathogenic role for HHV-6 in CNSdisorders is challenging. Nevertheless, HHV-6 has been associated with aseptic meningoencephalitis, encephalitis, transverse myelitis, Guilain-Barre´ syndrome, and cerebellar astrocytoma. Although the HHV-6A variant has increased neurotropism and is associated with viral persistence and reactivation in the CNS, both HHV-6 variants are clearly neurotropic. HHV-6A has been isolated from the CNS of acquired immuno deficiency syndrome (AIDS) patients with areas of demyelination and associated with MS. MS is the most prevalent demyelinating disease of the CNS. The variability of the diseases suggests that many factors, including genetic and immune components, are involved in the spectrum of clinical syndromes that are defined as MS. The HHV-6B variant is a causative agent of exanthem subitum and accounts for the majority of symptomatic HHV-6 infections in infants.