Epstein-Barr virus may be leading cause of multiple sclerosis

It's not easy to figure out what causes a disease. One reason is that the great majority of diseases are caused by a combination of factors. Rather, the majority of diseases are caused by a combination of factors.

Genes are one factor. Some people are born with one or more genes that predispose them to certain diseases. Other influences come from your surroundings and behaviour, such as what you eat, the air you breathe, the amount of physical activity you do, and smoking behaviors. According to new research, some viruses may possibly have a role in the development of multiple sclerosis (MS).

Why does multiple sclerosis affect brain and spinal cord cells?

Multiple sclerosis is a brain and spinal cord disease that can produce a variety of neurological symptoms such as arm and limb weakness, visual loss, difficulties thinking, and severe fatigue. We've learnt that MS is an autoimmune disease over the last 50 years: the immune system targets the brain and/or spinal cord in numerous ways, causing symptoms.

However, we still don't know why: what triggers the immune system's attack? Several viruses have been proposed as MS causes over the years, only to be disproved by future study. As a result, several MS doctors and scientists have ruled out viruses as a cause.

Nonetheless, current data suggests that various infections may be MS triggers. Epstein-Barr virus has the most evidence (EBV). Most people in industrialized countries, such as the United States, contract this virus when they are in their teen or young adult years.

Once a person has been infected, the virus remains dormant in the body for the rest of their lives. It has no adverse effects on most people's health. It can, however, trigger some malignancies in rare cases. Multiple sclerosis has now been linked to it.

Taking a closer look at the Epstein-Barr virus and MS

A significant, long-term Harvard study that was published in the prominent journal Science drew a lot of interest. Over the course of 20 years, blood samples were taken from ten million US military personnel. The samples were examined for signs of EBV infection.

Some of the participants in the study got MS throughout the course of the 20 years. The researchers looked at two groups of people: those who were not infected with EBV when they joined the military but later became sick, and those who were never infected with the virus. People in the first group were 32 times more likely than those in the second to get MS. MS symptoms usually appear five years after an individual is infected with EBV.

What can we deduce from these findings?

The findings show that a new EBV infection is one of the most critical — if not the most essential — factors in the development of MS. But there's more to the story than that. Consider the following scenario: By early adulthood, nearly all persons are persistently infected with EBV, yet only about 1% of those infected develop MS. So, just because someone is infected with EBV does not mean they will have MS. Other variables, in addition to EBV infection, must be involved in the development of MS.

Being born with particular genes that make you vulnerable to MS is probably certainly one of those other causes. Infection with other viruses, in addition to EBV, may be important factors.

But which viruses, exactly? Growing data suggests that EBV's "cousin," human herpesvirus-6A, may potentially play a role in MS onset, in my opinion. Endogenous retroviruses' genes may also have a role.

What are endogenous retroviruses, and what do they do?

Around 8% of the genes we inheritin which we were born with are from ancient viruses known as retroviruses. These viral organisms were able to successfully insert their genes into the genes of animals that came before and after humans. Some of those genes can be activated, resulting in the production of proteins that alter our immune systems. Finally, there is evidence that each of these viruses — EBV, human herpesvirus-6A, and endogenous retroviruses — can co-infect and produce disease.

New study may provide new preventative leads in the future.

If the Epstein-Barr virus is a key element in the development of multiple sclerosis, vaccinations against the virus may help to reduce MS cases. Several research organizations all over the world are working on such vaccinations.

One of the companies that developed the COVID-19 mRNA vaccine is now working on an EBV mRNA vaccine. A vaccine is also being developed by the National Institutes of Health. However, it will be at least a decade before we know if they are beneficial against EBV or the development of MS. Nonetheless, the link between these two diseases may prove to be a significant step in curing multiple sclerosis.