Two year MS study shows that relapse correlates with HHV-6A reactivation

A new study shows that multiple sclerosis patients with HHV-6 have higher risk of relapse and poor response to IFN-beta treatment. In a two year study, a group from the top hospital in Spain demonstrated that HHV-6 was found more often during relapses than during remission. Patients with higher HHV-6 DNA loads in the serum did not fare well, while those who had clearance of HHV-6 fared much better. The prevalence of HHV-6 in whole blood diminished from 64.8% before interferon treatment started, to 41.4% at the end of the 24 month trial. Of interest, there was no correlation between EBV DNA loads in the serum and disease progression.

Interferon beta (IFN-beta) is a common treatment in MS. Although the conventional wisdom is that the mechanism of action is “unkown”, interferon is a natural antiviral that is often used for treatment of hepatitis  and enteroviruses. Interferon naturally inhibits viral replication, and in fact interferon was originally tested in MS patients because of its antiviral propertites.

The authors suggest that the exacerbations in MS could be explained by an immune reaction to the active replication, and that HHV-6 could be involved in MS through several mechanisms including a) increased death of HHV-6 infected neurons, astrocytes and oligodendrocytes, b) viral interference with the phosphorylation of myelin basic protein or c) increasing the glutamate level in the spinal fluid. HHV-6 is able to induce inflammation and demyelination. It has also been suggested that HHV-6 can interfere with the remyelination process.

The authors suggest further trials with other potential antivirals.

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