From herpes to sclerosis?

Multiple sclerosis has been linked to a certain type of herpes virus

Marina Astvatsaturyan, Echo of Moscow

The study, which covered almost 16 thousand people, pointed to the human herpes virus 6A as a risk factor for the development of multiple sclerosis, which brought back from oblivion the hypothesis about the viral mechanism of triggering the disease.

In the 1990s, it was suggested that the most common type of herpes virus - human herpes virus 6 (HHV6) – may be somehow involved in the development of multiple sclerosis, a neurodegenerative disease characterized by autoimmune reactions against the protective myelin layer covering the central nervous system. However, subsequent studies rejected the idea of a link between herpes virus 6 and multiple sclerosis, as the results were ambiguous.

The situation became even more complicated when it turned out that the human herpes virus 6 is two, albeit related, but still different versions of the virus, 6A and 6B. The lack of a method for distinguishing similar viruses made it difficult to identify the connection of a neurodegenerative disease with a certain type of virus.

According to The Scientist, a team of European scientists has now developed a method for distinguishing antibodies for different variants of the herpes virus 6. The results of its test were published at the end of last year in the journal Frontiers in Immunology (Engdahl et al., Increased Serological Response Against Human Herpesvirus 6A Is Associated With Risk for Multiple Sclerosis) and do not exclude that the inconsistency of the previous results can be explained at least partially by the fact that the researchers did not know how to distinguish between variants of the virus.

Viruses 6A and 6B are two of the eight herpes viruses infecting humans. More is known about variant 6B, most people become infected with it in childhood, which causes the so-called childhood roseola. After the initial infection, the virus, as a rule, becomes inactive, while remaining in the body and sometimes reactivating later. Antibodies against the herpes virus circulate in the blood and in adulthood.

Scientists from the German Cancer Research Center in Heidelberg have found that a special protein – it is known as pre-early protein 1 (immediate–early protein 1) - has different variants of the virus 6A and 6B. Together with researchers from the Karolinska Institute in Stockholm, they analyzed the blood serum of 8,742 Swedish patients with multiple sclerosis, as well as 7,215 healthy people of comparable age and found a positive correlation between the concentration of antibodies to the 6A virus and the presence of the disease, and there was no connection between the level of antibodies to 6B and multiple sclerosis. At the same time, the authors of the study emphasize that the type of virus is not the only risk factor for the development of the disease.

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