About 90 percent of adults worldwide are infected with Epstein-Barr virus, or EBV. The virus infects B cells (the white blood cells that make antibodies) and can contribute to B-cell-derived cancers, but in most people it remains dormant -- a state scientists refer to as 'latent infection' -- for the rest of their lives. A new study sheds new light on why the infected person's immune system cannot eliminate EBV, or the associated cancer risk.