HHV-6 virus in demyelination

Pietiläinen-Nicklén J, Virtanen JO, Uotila L, Salonen O, Färkkilä M, Koskiniemi M. HHV-6-positivity in diseases with demyelination. J Clin Virol. 2014. pii: S1386-6532(14)00269-8

BACKGROUND:The triggering agent of multiple sclerosis is still unknown and many viruses, including human herpesvirus-6 (HHV-6), are under suspicion. In earlier study we found patients who had HHV-6 reactive OCBs in their CSF. We wanted to investigate whether HHV-6 has an active role in diseases with demyelination.
OBJECTIVE: To analyze the HHV-6-reactive cases in detail and investigate the possible independent role of HHV-6 in the development of central nervous system involvements with demyelination.
STUDY DESIGN: We studied serum and CSF samples that were collected over a period of one year, from all patients who had oligoclonal bands (OCB) in cerebrospinal fluid (CSF). Clinical evaluation was accomplished blinded of HHV-6 analysis and follow-up time was two years. All patients underwent MRI of the head and clinically indicated CSF analysis.
RESULTS: The 17 patients with HHV-6-reactive OCBs were significantly younger and had significantly more IgG-OCBs in comparison to patients without HHV-6-reactive OCBs. Initial diagnoses in patients with HHV-6-reactive OCBs remained the same during the follow-up time.
CONCLUSION: Patients with HHV-6-positive OCBs appear to form a separable group. In progressive neurological diseases HHV-6 may have a role in long-term infection with demyelination.
Then again it may not. 

The case for HHV-6 being causative in MS is not supported by the finding that most MSers do not show evidence of infection. However could it be important in a subset of MSers...yes it could.

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