News

The cause of multiple sclerosis is not yet known, but it appears to be triggered by a combination of genetic and environmental factors. Over the years, many viruses and bacteria – including human herpes virus-6 (HHV-6) and Epstein-Barr virus (EBV) – have been or are being investigated to determine if they are involved in the development of MS. Both of these common herpes viruses, to which most adults have been exposed, can reside in cells in the brain.
 
EBV, which causes mononucleosis, has received significant attention, with a growing number of research findings indicating that previous infection with EBV contributes to the risk of developing MS. HHV-6 has also been explored, but conclusions have been difficult to draw because up to now, it has not been possible to distinguish between infection by the two main strains of this virus – HHV-6A and HHV-6B.
 
Now researchers at Sweden’s Karolinska Institute and collaborators have developed a lab test that can distinguish between immune responses to HHV-6A and HHV-6B, and they searched for differences in these responses between thousands of people with MS compared to people who do not have MS. In a new paper, the researchers report that people with MS had a 55 percent higher risk of carrying antibodies against the HHV-6A protein than those without MS. People with MS had higher immune responses to HHV-6A, but not to HHV-6B, even before symptoms began. The researchers also report evidence of a possible interaction between HHV-6A and EBV, and interactions of HHV-6A with specific immune response genes linked to MS risk.
                                                                                                                          
This study does not prove that HHV-6A causes MS, but adds important evidence around the question of what triggers MS and how to stop it and prevent it.
 
Read a feature article/view video on the Karolinska Institute’s website
Read the Paper published in Frontiers in Immunology on November 26, 2019