Epstein-barr virus is one of the most common viruses in the world, with around 95% of us infected, but scientists now have strong evidence that it can play a role in multiple sclerosis.    

So how does a virus that causes little or no illness in most people go on to trigger a serious autoimmune disease in some, and could targeting the virus help us prevent MS?   

Luke O'Neill, Professor of Biochemistry in the School of Biochemistry and Immunology at Trinity College Dublin joined Ciara to explain.