Did you know that about 50 to 75 percent of the population live with a virus dwelling in their guts?! This is the startling revelation made by researcher Rob Edwards, a professor of bioinformatics at San Diego State University. But ‘why have I never heard of it?’ you ask. The reason is that most people haven’t, not even scientists! Although extremely common in humans, it was only discovered recently when researchers studying bacteria unwittingly came across the virus, known as crAssphage . The virus is a bacteriophage, or ‘’phage’’ which means that it infects bacteria. CrAssphage infects bacteria which live inside the human gut, called Bacteroides, but it’s unclear whether the virus is harmful to humans, or responsible for any health problems. The next stage for scientists is to grow the virus in a laboratory in order to work out exactly what effect, if any, crAssphage has on the human body. In the meantime, researchers are being praised for the sophisticated technique they employed to identify the virus. David Pride, associate director of microbiology at the University of California, claimed “The biggest contribution of this work is the method they used’ which could ‘provide a blueprint for further viral discovery’. Dr Martha Clokie of the University of Leicester, was most excited by the news that ‘’scientists have produced new techniques and powerful tools to help identify previously unknown viruses’’. Given the important role bacteria plays in chronic diseases such as obesity and diabetes, Clokie hoped that “If we can pin down these viral controllers, we could perhaps one day use them to modify any harmful bacteria, rendering them less powerful.” While the discovery of the bacteria should be of interest to Medics and Biologists, all Science applicants should take heed of the methodology on display here that could prove transferrable to a variety of disciplines.