Neuromyelitis Optica May be Linked with Epstein-Barr Virus

By Scott Baltic

NEW YORK (Reuters Health) - Persistent, active replication of Epstein-Barr virus might play a role in neuromyelitis optica (NMO) and also might contribute to the immunological alterations that play a role in the disorder, Japanese researchers say.

Compared both to patients with multiple sclerosis and to healthy control subjects, patients with NMO had significantly elevated levels of the anti-early antigen (EA) IgG antibody. (EA IgG is an EBV-specific antigen.) Further, this antibody remained elevated both during clinical relapse and during remission of NMO, the researchers reported online November 28 in the Journal of Neurology, Neurosurgery & Psychiatry.

The estimated incidence of NMO is three per 100,000 per year worldwide, in contrast to an MS incidence of about 10 per 100,000 in Japan and 100 to 200 per 100,000 in the Western world, Dr. Satoshi Kuwabara of the Graduate School of Medicine, Chiba University, told Reuters Health in an email.

The paper noted that although Epstein-Barr virus (EBV) has long been considered a key environmental factor in multiple sclerosis, associations between NMO and various infectious agents have not been firmly established.

If it could eventually be established that EBV does indeed play a role in NMO, Kuwabara said, treatment with anti-EBV agents could perhaps reduce the severity of NMO or delay, or even suppress, its onset.

The study involved 50 patients (median age 50; 48 females) with NMO (38 with definite NMO and 12 with partial NMO, defined as anti-AQP4 antibody-positive optic neuritis and/or transverse myelitis) and 51 patients (median age 35; 40 females) with MS. Fifty-two volunteers (median age 32; 41 females) participated as healthy controls.

The researchers evaluated serum antibodies against five EBV-specific antigens: anti-viral capsid antigen (VCA) IgM, anti-VCA IgG, anti-early antigen (EA) IgM, anti-EA IgG and anti-EBV nuclear antigen (EBNA)-1 IgG.

They found elevated serum anti-EA IgG antibodies in 52.0% of patients with NMO, 25.5% of patients with MS, and 25.0% of healthy controls (p=0.005 for both comparisons).

Dr. Bruce Bebo, executive vice president of research at the National Multiple Sclerosis Society, told Reuters Health by email that this paper is the first he's heard of this possible connection between EBV and NMO, although he added, "It's biologically plausible."

Based in part on the small study cohort, Dr. Bebo said, "I would call the paper quite preliminary."

A pathogenic virus makes a lot of different proteins during different phases of an infection, Dr. Bebo explained, and the novel aspect of the current findings is that EA is made during active infection. "It's a hint that there may be a link between active EBV infection and NMO," he said, and so the finding deserves further work and a larger study.

He agreed with Dr. Kuwabara that if this line of research pans out, it might be possible some day to intervene in NMO with antiviral therapy.

SOURCE: https://bmj.co/1HN1FMz

J Neurol Neurosurg Psychiatry 2014.

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