Study: can multiple sclerosis be caused by herpes viruses?

Study: can multiple sclerosis be caused by herpes viruses?

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Increased risk of multiple sclerosis from herpes virus?

Using an analysis method newly developed by researchers, two different types of the herpes virus HHV-6 can be identified. Based on the findings, scientists suspect that the virus promotes the development of multiple sclerosis (MS). Herpes virus 6A was much more common among study participants suffering from MS. Could a herpes virus variant be a trigger for multiple sclerosis?

In the current investigation by the Karolinska Institutet, a new method was developed that can differentiate between two different types of the herpes virus HHV-6. So far this has not been possible. The results of the study were published in the English language journal "Frontiers in Immunology".

People with MS carry certain herpes viruses to a greater extent

By analyzing antibodies in the blood against a wide variety of proteins of the herpes virus 6A and 6B, the researchers were able to determine that MS patients carry the herpes virus 6A to a greater extent compared to healthy people. The results of the investigation indicate a role of HHV-6A in the development of multiple sclerosis (medical: encephalomyelitis disseminata).

What is multiple sclerosis?

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system. The cause of the disease is still unclear, but a plausible explanation is that a virus causes the immune system to attack the body's own tissue.

It has not been possible to differentiate between 6A and 6B in herpes

Human herpes virus 6 (HHV-6) has not previously been associated with MS. In previous studies, however, it was not possible to differentiate between 6A and 6B. By isolating the virus, the researchers were able to show that HHV-6B can cause, for example, virus infection such as rosola (three-day fever) in children. However, it was unclear whether HHV-6A is the cause of diseases.

Up to 80 percent of young children carry HHV-6

It is estimated that up to 80 percent of all children two years old are infected with the HHV-6 virus, and many children benefit from lifelong protection in the form of antibodies to this specific virus. So far it has not been possible to distinguish between the two variants after infection, which makes it very difficult to assess whether HHV-6A or B is a risk factor for MS.

Breakthrough in research into MS and herpes

In the current study, however, the researchers were able to differentiate between the A and B viruses by analyzing antibodies in the blood and proteins that differ most between the two viruses. "This is a major breakthrough for research into the MS and herpes virus," study author Professor Anna Fogdell-Hahn from the Karolinska Institutet reports in a press release.

Does HHV-6A contribute to MS?

HHV-6A could be a contributing factor in the development of MS. With their new method, researchers are now able to find out how common the two different types of HHV-6 are. This was not possible in the past.

People with MS often carried antibodies to the HHV-6A protein

The team compared the antibody levels in blood samples from around 8,700 MS patients with the blood samples from over 7,200 healthy people. The researchers concluded that people with MS were 55 percent more likely to have antibodies to the HHV-6A protein than the control group.

6A virus infection significantly increased the risk of MS

In a subgroup of almost 500 people whose blood samples were taken before the onset of the disease, the risk of developing MS was more than doubled if there was a 6A virus infection. The younger people were when the virus was first discovered in blood, the higher the risk of developing MS in the future. However, HHV-6B infections were not associated with MS.

How does the Epstein-Barr virus affect the risk of MS?

Antibodies against the Epstein-Barr virus (EBV), another herpes virus, which is also associated with MS, were analyzed using the same method. The researchers found that people who were affected by both viruses were at an even higher risk of MS. This suggests that multiple viral infections could work together to increase the risk of MS.

More research is needed

“Both HHV-6A and 6B can infect our brain cells, but they do it in slightly different ways. So it is now interesting to continue researching and trying to figure out exactly how the viruses could affect the outbreak of MS, ”adds Anna Fogdell-Hahn. (as)

Editor's note: In an earlier version of this post, an image with cold sores was used that incorrectly suggested a connection between cold sores and MS. In fact, other herpes viruses are believed to be the cause of MS. We have therefore exchanged the picture.

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.


  • Elin Engdahl, Rasmus Gustafsson, Jesse Huang, Martin Biström, Izaura Lima Bomfim et al .: Increased Serological Response Against Human Herpesvirus 6A Is Associated With Risk for Multiple Sclerosis, in Frontiers in Immunology (query: 30.11.2019), Frontiers in Immunology
  • MS linked to variant of common herpes virus through new method, Karolinska Institutet (query: 30.11.2019), Karolinska Institutet

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