Scientists can now work out all the viruses you've been exposed to over your lifetime.
The resulting 'viral CV' could be used to show how infections interact and be linked to specific diseases, or protect us from other diseases like cancer or asthma.
Dr Chris Smith of The Naked Scientists told This Way Up's Simon Morton that humans can succumb to many viral infections during their lives. Although the majority of these viruses are transient and cleared by the immune system, they could still have a lasting health legacy and alter the risk that a person will develop certain diseases later in life.
Harvard scientist Stephen Elledge and his colleagues, writing in the journal Science, have devised a test that can 'read' the immune memory to reveal all of the viral infections a person has encountered.