United Arab Emirates scientists have found active Epstein-Barr virus in many multiple sclerosis patients’ brain cells, supporting the notion that it plays a role in the disease.
The team found it in two types of brain cells — astrocytes and microglia. The virus can be active or lie dormant in the body.
Researchers’ study, “Epstein-Barr virus is present in the brain of most cases of multiple sclerosis and may engage more than just B cells,” appeared in the journal PLoS ONE. A team at United Arab Emirates University led the work.
Epstein-Barr, a member of the herpes family, is one of the most common human viruses.
The researchers had already found it in the three membranes covering the brain and spinal cord of MS patients. In fact, they found it in 35 percent of MS cases, they reported.
They wanted to know if they could find the virus in MS patients’ brain cells and, if so, what role it played.
Their study involved examining brain tissue samples and DNA of two sets of people who had died: 101 with MS and 21 with other neurodegenerative disorders.
Altogether, they looked at 1,055 specimens — 615 of brain tissue and 440 of DNA.
They found the Epstein-Barr virus in 90 percent of the MS cases, versus 24 percent of the non-MS cases.
The team discovered low to moderate amounts of the virus in most of the MS patients. But in 18 percent of the cases, “widespread but scattered presence of EBV-infected [Epstein-Barr-virus-infected] cells was noted in the affected tissues,” they wrote.
Gene expression studies on the 18 heavily infected MS cases confirmed that the genes had been producing EBNA1, a protein that plays a key role in the virus’s life cycle.
Researchers also detected BZLF1, a protein involved in the virus shifting from a dormant to an active stage. But there was less BZLF1 than EBNA1 production.
The team found no other herpus viruses in the samples.
“The fact that we did not find any evidence for the presence of other common human herpes viruses — namely HSV-1, CMV and HHV-6 — in any of the cases indicates that the presence of EBV in MS is likely to be selective and specific,” the researchers wrote.
Immune B-cells are the Epstein-Barr virus’s major target in humans. The Emirates study showed for the first time that the virus can be found in MS patients’ astrocytes and microglia as well.
“We show for the first time that astrocytes and microglia, in addition to B-cells, can also be infected,” the team wrote. “To the best of our knowledge, this is the most comprehensive study demonstrating that EBV is present and transcriptionally active in the brain of most cases of MS and supports a role for the virus in MS pathogenesis.”
The team called for studies that could shed light on how the virus is involved in the development of MS.