Evidence of Correlation between Virus Infection and Incidence of multiple sclerosis

According to The Scientist, (1) researchers have found strong evidence for the hypothesis that there is some correlation between multiple sclerosis and a variant of herpes virus infection in humans.(2) The hypothesis itself is not very new: in fact as early as 1990’s scientists had suspected that a common form of herpes virus, known as human herpesvirus 6 (HHV6), could be related to the development of multiple sclerosis in humans. However, subsequent tests had failed to establish this correlation conclusively as the results of various tests were not consistent.

Now Researchers think they know why. It turns out that the HHV6 virus itself actually consists of two related but distinct variants: HHV6A and HHV6B. Very likely, the inconsistencies in the results of previous tests has been due to not distinguishing the two variants. However, researchers have now found ways to distinguish the two types by distinguishing their antibodies. By doing so, they have shown that high levels of HHV6A antibodies strongly correlate with multiple sclerosis, while HHV6B antibodies actually correlate to lower risk of multiple sclerosis. Their conclusions are based on studying more than 16000 people, comprising 7842 individuals with multiple sclerosis and 7215 healthy individuals used as control. Whether this correlation signifies causation or not is still a matter of debate, but the sheer number of participants makes these findings statistically very strong. At the very least, this work draws attention to the need for more studies on the HHV6 virus.

~~ Moe Azadeh

1. https://www.the-scientist.com/news-opinion/type-of-herpes-virus-tied-to-multiple-sclerosis-66949
2. E. Engdahl et al., “Increased serological response against human herpesvirus 6A is associated with risk for multiple sclerosis,” Frontiers in Immunology, doi:10.3389/fimmu.2019.02715, 2019.