Swedish medical researchers from Karolinska Institutet have developed a new method to separate between two types of a common herpes
) that has been linked to multiple sclerosi
s (MS). By analyzing antibodies in the blood against the most divergent proteins of herpesvirus 6A and 6B, the medical scientists were able to show that Multiple Sclerosis
patients carry the herpesvirus 6A
to a greater extent than healthy individuals.
The study findings that was published in Frontiers in Immunology
, point to a role for HHV-6A
in the development of Multiple Sclerosis.
is an autoimmune disease that affects the central nervous system. The cause of the disease is unclear, but one plausible explanation is a virus tricks the immune system to attack the body's own tissue. Human herpes
virus 6 (HHV-6)
has previously been associated with MS, but in those studies, it wasn't possible to distinguish between 6A and 6B. Through virus isolation from ill individuals, researchers have been able to show that HHV-6B can cause mild conditions such as roseola in children, but it has been unclear if HHV-6A
is the cause of any disease.
As many as 80 percent of all children globally are infected with the HHV-6 virus before two years of age, and many also carry protection in the form of antibodies against this particular virus for the rest of their lives. But since it hasn't been possible to tell the two variants apart post-infection, it has been difficult to say whether HHV-6A
or B is a risk factor for Multiple Sclerosis
Via this new study however, the researchers were able to distinguish between the A and B virus by analyzing antibodies in the blood against the proteins immediate early protein 1A and 1B (IE1A and IE1B), that diverge the most between the two viruses.
Dr Anna Fogdell-Hahn, associate Professor at the Department of Clinical Neuroscience at Karolinska Institutet and one of the study's senior authors told Thailand Medical
News, "This is a big breakthrough for both the Multiple Sclerosis
virus research. For one, it supports the theory that HHV-6A
could be a contributing factor to the development of Multiple Sclerosis
. On top of that, we are now able, with this new method, to find out how common these two different types of HHV-6 are, something we haven't been able to do previously."
The team from Karolinska Institutet compared antibody levels in blood samples of some 8,700 Multiple Sclerosis
patients against more than 7,200 healthy people whose gender, date of birth, date of blood sample and other factors matched those with MS. They concluded that people with Multiple Sclerosis
had a 55 percent higher risk of carrying antibodies against the HHV-6A
protein than the control group. In a subgroup of almost 5
00 people whose blood samples were drawn before the onset of the disease, the risk of developing Multiple Sclerosis
in the future was more than doubled if they had a 6A viral infection. The younger the people were when the virus was first discovered in the blood, the higher the risk was of developing Multiple Sclerosis
in the future. HHV-6B, on the other hand, was not positively associated with Multiple Sclerosis.
Instead Multiple Sclerosis
patients had lower levels of antibodies toward IE1B than those without Multiple Sclerosis
The antibodies toward Epstein-Barr virus (EBV), another herpes
virus that is also associated with Multiple Sclerosis
, were analyzed with the same method, and the researchers were able to show that individuals affected with both viruses had an even greater risk of Multiple Sclerosis
. This indicates that several virus infections could be acting jointly to increase the risk of Multiple Sclerosis.
Dr Anna Fogdell-Hahn concluded, "Both HHV-6A
and 6B can infect our brain cells, but they do it in slightly different ways. Therefore, it is now interesting to go forward and attempt to map out exactly how the viruses could affect the onset of Multiple Sclerosis
It has long been suspected that the herpes
virus which affects almost 86 percent of the world population, as a result of long term infection has numerous effects and causes numerous diseases in the human body not just multiple sclerosis.
Reference : Elin Engdahl et al, Increased Serological Response Against Human Herpesvirus 6A Is Associated With Risk for Multiple Sclerosis, Frontiers in Immunology (2019). DOI: 10.3389/fimmu.2019.02715