A study of 16,000 people suggests that human herpesvirus 6A is a risk factor for developing multiple sclerosis, reinvigorating a neglected hypothesis that the virus could be involved in triggering the disease.
Jan 10, 2020
KATARINA ZIMMER
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However, the association between HHV6 and the disease soon became fraught with controversy as further studies produced discordant results. Complicating matters further, HHV6 turned out to be two related, but distinct variants—HHV6A and HHV6B. Because the two viruses are similar, for a while no method existed to tell whether a patient had been infected with one or the other, or both—making it difficult to draw a definitive association between either of the viruses and the disease.
Now, a collaboration of European researchers has developed a technique capable of distinguishing antibodies against one variant from the other. Using that method in a Swedish cohort of more than 8,700 multiple sclerosis patients and more than 7,200 controls, they found that patients were much more likely to carry higher levels of anti-HHV6A antibodies than healthy people, while they were likelier to carry fewer antibodies against HHV6B. The findings, published last November in Frontiers in Immunology, hint that previous contradictory results may at least be partially explained by the fact that researchers couldn’t distinguish between the two viruses.
“This article now makes a pretty convincing case that it is HHV6A that correlates with multiple sclerosis, and not HHV6B,” remarks Margot Mayer-Pröschel, a neuroscientist at the University of Rochester Medical Center who wasn’t involved in the study. “Researchers can now focus on one of these viruses rather than looking at [both] of them together.”
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