Is HHV-6 really "a ubiquitous, commensal and usually benign beta-herpesvirus"?
The HHV-6 Paradox Blumberg BM, Mock DJ, Powers JM, Ito M, Assouline JG, Baker JV, Chen B, Goodman AD. BACKGROUND: Progressive multifocal leukoencephalopathy (PML) and multiple sclerosis (MS) are demyelinative diseases of the central nervous system (CNS). PML occurs mostly in individuals with AIDS-impaired immunity and is thought to be caused by JC polyoma virus (JCV). In MS a neurotrophic virus trigger is suspected, but the precise etiology remains unknown. Human herpesvirus 6 (HHV6) is a ubiquitous, commensal and usually benign beta-herpesvirus. Some researchers have found evidence for HHV6 infection in MS plaques and sera. We recently demonstrated a high frequency of cells containing HHV6 genome in PML lesions, as well as co-infection of oligodendrocytes by JCV and HHV6. This suggests that HHV6 may be a co-factor in the etiology of PML, and raises questions about its role in other demyelinative diseases. OBJECTIVES: To determine the prevalence and cellular localization of HHV6, JCV