Is There a Role for Human Herpesvirus–6 in the Course of Multiple Sclerosis?

Abstract

Historically multiple sclerosis (MS) has been associated with many different viruses, including several members of the Herpesviridae family. However, no human or animal virus has been identified as a true “cause” of MS; rather, the epidemiologic and diagnostic data suggest that viral infection may be a cofactor affecting the pathogenesis of MS. Human herpesvirus-6 (HHV-6) is a ubiquitous herpesvirus associated with a common childhood illness, roseola, and this virus is one of those most recently associated with MS. During the past decade, a number of investigations have examined anti—HHV-6-specific antibody responses, HHV-6 viral DNA, or HHV-6 presence in central nervous system (CNS) tissue in both MS patients and controls. There is a growing body of evidence associating HHV-6 infection of the CNS with MS in at least a subpopulation of patients, although the specific factors that define the vulnerable subpopulation(s) of MS patients have not been elucidated. This evidence is provocative but not definitive, and it does not distinguish between HHV-6 as a causal agent in MS versus HHV-6 as a cofactor. Although more clinically based data are needed, the controversy surrounding HHV-6 and MS has again focused attention on the role of viral infection in the clinical and pathologic course of MS. (Int J MS Care. 2002; 4: 30–31, 36–39)