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Epstein-Barr virus linked to multiple sclerosis relapses

14 Jun 2013, 09:13
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nerve damage due to sclerosis

Researchers from Santa Lucia Foundation in Rome, Italy published a study on April 11 that links immune reaction of human body to the Epstein-Barr Virus (EBV) to the relapse periods of relapsing-remitting multiple sclerosis (RRMS).

 

For the purposes of the study, scientists followed 113 patients with diagnosed multiple sclerosis and 49 healthy control individuals over the course of four years.

 

They analysed patients' blood as means to track the levels of CD8+ T-cell activity and map it to their multiple sclerosis disease cycles. Cytotoxic CD8+ T-cells are cells that destroy abnormal or infected cells in the body.

 

79 patients from first group were on no disease modifying therapy, whereas 20 were on Interferon Beta 1a, and 34 were on natalizumab, also labelled as Tysabri.

 

Patients experiencing a relapse of their MS, verified by magnetic resonance imaging (MRI) scans of the brain, also showed elevated EBV activity as measured by the presence of the CD8+ T-cells.

 

Investigators found greater response to the antigens produced by active Epstein-Barr Virus in the blood of multiple sclerosis patients during relapses, as compared with samples taken during periods of remission.

 

Antigens are substances that the body sees as foreign or harmful — including toxins from viruses like Epstein-Barr—and deploys an immune response to find and kill.

 

Epstein-Barr Virus is a virus from the herpesvirus family and, according to the National Institutes of Health (NIH), nearly 95 percent of all people between the ages of 35 and 40 have been infected by it.

 

EBV is responsible for the chronic viral infection known as infectious mononucleosis. It's symptoms usually are swollen lymph nodes, sore throat and fever. After the symptoms go away the virus can stay dormant in some parts of the body, for instance, in some cells of immune system for decades.

 

Infection with Epstein-Barr Virus only results in mononucleosis in 35 to 50 percent of patients, while others never show any outward signs that they've been infected. 

 

Relapsing-remitting multiple sclerosis, instead, comes and goes in irregular cycles and can produce diverse symptoms. It is considered and autoimmune disorder that can damage central nervous tissues including the spinal cord and brain. The immune response affects nerve cells' protective covering, the myelin, leading electrical “shorts” in the signalling pathways.

 

This can result in symptoms ranging from mild numbness to blindness or complete paralysis. In the relapsing-remitting form of MS, these attacks can last from a few days to several months. The flare-ups are followed by periods of remission where there is a lessening of disease activity. 
 

The role of EBV as a potential trigger for multiple sclerosis has long been debated. Whether it — or any virus — directly causes the disease or creates a “perfect storm” situation whereby the immune system, in trying to eradicate the virus, goes haywire and mistakes myelin proteins as the enemy, is unclear. 

 

According to Dr. Steven Jacobson, Chief of the Viral Immunology Section at the National Institute of Neurological Disorders and Stroke, it's important to note that "While EBV may be one of the triggers in MS...what triggers reactivation in one person may not in another".

 

He told Healthline that MS is not a disease with a single, defined, viral trigger like AIDS, for example, which is triggered by the HIV virus.

“The results [of this study] do not answer the question of whether EBV dysregulation is a consequence or cause of MS," said Dr. Tom Ech, Program Officer of the Autoimmunity and Mucosal Immunology branch of the NIH in an interview with Healthline, "but suggest a link between EBV reactivation, antiviral immune response and disease activity during the relapsing-remitting stage of MS”.

The results of this study suggest that the ebb and flow of EBV as it cycles between dormant and active phases could set the stage for the reactivation of MS. This has led to the hypothesis that multiple sclerosis could be controlled with antiviral drugs that keep Epstein-Barr virus asleep.

 

"What this group [of researchers] has shown is that further studies need to be done with antiviral drugs," said Jacobson, who has been studying viruses and multiple sclerosis for more than 30 years at the NIH.

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