BACKGROUND: Among the environmental factors associated with multiple sclerosis (MS) causation, some of the strongest associations are with Epstein-Barr virus (EBV), and to a lesser extent human herpesvirus 6 (HHV6). Associations with clinical course are less conclusive, however. METHODS: We evaluated serum anti-EBV-EA-R IgG and anti-HHV6 IgM, and EBV and HHV6 viral load (VL) for their associations with relapse, disability, and progression in disability in a prospective cohort of 198 participants with clinically definite MS. RESULTS: Anti-EBV-EA-R IgG was detected in 81.8% of cases at study entry, and titers remained essentially unchanged during the study. Anti-HHV6 IgM was detected in only one participant, and EBV-VL (29%) and HHV6-VL (1.8%) were detected in a minority of samples, and where detected levels were low. Our previously demonstrated association between anti-HHV6 IgG and relapse hazard was not affected by adjustment for parameters of reactivation. We found no evidence that any of the viral markers were associated with disability or progression in disability. In relation to relapse, only EBV-VL was positively associated, although this was strongly influenced by a single individual. CONCLUSION: Using a prospective cohort design, we found no convincing evidence that reactivation parameters of EBV or HHV6 were associated with subsequent MS relapse hazard or progression in disability, confirming previous findings, and indicating that herpesvirus reactivation is not an important driver of relapse or disability in this established MS population.

Item Type:	Refereed Article
Keywords:	Epstein–Barr virus; human herpesvirus 6; relapse; disability; progression
Research Division:	Medical and Health Sciences
Research Group:	Neurosciences
Research Field:	Central Nervous System
Objective Division:	Health
Objective Group:	Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:	Nervous System and Disorders
Author:	Simpson Jr, S (Dr Steve Simpson JR)
Author:	Taylor, B (Professor Bruce Taylor)
Author:	Blizzard, L (Associate Professor Leigh Blizzard)
Author:	Pittas, F (Dr Fotini Pittas)
Author:	van der Mei, I (Associate Professor Ingrid van der Mei)
ID Code:	92216
Year Published:	2014
Web of Science® Times Cited:	7
Deposited By:	Menzies Institute for Medical Research
Deposited On:	2014-06-10
Last Modified:	2016-10-05
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