Emerging research, revealed in part due to the COVID pandemic, is showing a potential link between autoimmune disorders and viral infections, experts say.
“We’re on the cusp of some new knowledge,” said Akiko Iwasaki, a virologist at Yale studying long COVID and cancer. “I’m excited that we are at this juncture today where we may be able to reveal this link in a more rigorous way.”
In January, a research group at Harvard showed what they said could be a causal link between Epstein-Barr, the virus that causes mononucleosis, and multiple sclerosis.
Study author Alberto Ascherio, professor of epidemiology and nutrition at Harvard Chan School, said though the link has been suspected for a while, this is the most conclusive research yet.
“The hypothesis that EBV causes MS has been investigated by our group and others for several years, but this is the first study providing compelling evidence of causality,” he said in a press release. “This is a big step because it suggests that most MS cases could be prevented by stopping EBV infection, and that targeting EBV could lead to the discovery of a cure for MS.”
Dr. Jaime Imitola, director of the Division of Multiple Sclerosis and Translational Neuroimmunology at the University of Connecticut, said genetics plays a role as well, as do environmental factors.
However, Imitola said, if someone is genetically predisposed to get multiple sclerosis and contracts mononucleosis in their teens, it appears the person is more likely to contract MS in about a decade. He likened it to a car accident.
“The theory is, when you get these three things, it's like the perfect accident,” he said. “So, you go right now out to the street, but your tires are very smooth and your brake doesn't work, I will tell you that you're going to get into an accident. So the probability that you get into an accident is higher. That's the same with MS.”
It’s important to note that not everyone who contracts mono — often called the “kissing disease” — will get MS.
“Ninety-four percent of the population will have antibodies against mononucleosis,” Imitola said. “So, it's difficult to look into the haystack, who's going to get MS? Because everybody gets mono.”
And it takes years, sometimes decades, for the virus to result in MS.
“We know that when kids get mono, they get mono about probably 12, 13, 14, 15, and MS will show up, probably, your early 20s,” Imitola said.
Epstein-Barr is not only associated with MS. There are indications that it is connected with the development of certain types of cancer and the diagnosis might happen decades after the first illness.
“It doesn't happen immediately,” Imitola said. “It's not like you have mono today and then tomorrow you develop the cancer. It takes some time — takes years.”
Iwasaki said Epstein-Barr is one predictive factor for what is referred to as “long COVID,” patients who are experiencing coronavirus symptoms for months, and for some people, even years.
“One of the four predictive factors for long COVID was the EBV reactivation,” she said.
Imitola said it is leading researchers to wonder if patients with COVID who previously contracted EBV might also eventually develop an autoimmune disorder.
“Is COVID going to trigger MS in some patients? We don't know the answer,” he said. “We don't know what will be the long-term repercussions.”
“We don't know whether COVID will worsen the progression of existing patients, or whether COVID will generate a new cadre of patients that will have MS,” he said.
Robert S. Fujinami, a researcher at the University of Utah School of Medicine, wrote the link between MS and EBV is not the only known connection between a virus and an autoimmune disorder.
“In diabetes, another autoimmune disease, a Coxsackie virus has been isolated from the pancreas of a patient who died of acute diabetes,” he wrote. “When mice were infected with this virus, they developed diabetes. Clearly, in this case, the virus was the causative agent of disease.”
“Similarly, congenital rubella virus infection is also associated with the occurrence of diabetes,” Fujinami wrote, but he said since many children get a rubella vaccine, there must be other factors associated with type 1 diabetes.
For Scott Roberts, associate medical director of infection prevention at Yale New Haven Hospital, it should force a closer look at the value of vaccinations.
“This MS/EBV thing was very striking, and I think that really lends credence to the fact that yeah, maybe we should be targeting EBV vaccination or immunity to EBV to prevent decades later development of MS,” he said. “I'm sure there are other diseases out there that are viral-induced that we just have no idea about, and the fact is this may change vaccination and how we treat vaccination going forward.”