Why do people get multiple sclerosis? Scientists have been struggling to learn what triggers this devastating autoimmune disease. When MS strikes, the immune system begins to attack the myelin sheaths that protect neurons in the central nervous system. As a result, people may experience trouble walking, fatigue, weakness, vision problems or loss of bladder control.
Connection Between Human Herpesvirus-6A and Multiple Sclerosis:
A new study suggests that multiple sclerosis may be associated in part with human herpesvirus-6A (Frontiers in Immunology, Nov. 26, 2019). Researchers at the Karolinska Institute in Sweden established a new immunological test to distinguish between HHV-6A and HHV-6B. This allowed them to demonstrate that the A form of this herpesvirus was linked to the autoimmune disorder MS. The B form, on the other hand, is unrelated. Before they developed the assay to discriminate between the two, they couldn’t show that either one was truly linked to the disease.
The investigators tested the blood of 8,742 people with MS and compared the samples with 7,215 health control subjects. The data demonstrated that patients with multiple sclerosis were more likely to have antibodies to human herpesvirus-6A than the controls. If people had evidence of exposure to HHV-6A and the Epstein Barr Virus (EBV) as well, the risk of developing MS was even greater. Because herpesvirus-6A has been shown to infect the myelin-producing cells in the brain, there is a potential explanation for how this virus could damage delicate neuronal structures in the brain.
The scientists point out that individuals with the highest antibody response during adolescence were the most likely to develop MS over the next ten years. This, they argue, is evidence that the antibody came first and is not simply a result of the disease. On the other hand, they point out that their evidence indicates an association and does not prove cause and effect.