Just about wherever scientists look—deep within the earth, on grains of sand blown off of the Sahara Desert, under mile-thick layers of Antarctic ice—they find viruses. And when they look in familiar places, they find new ones. In 2009, Dana Willner, a biologist at San Diego State University, led a virus-hunting expedition into the human body. The scientists had ten people cough up sputum and spit it into a cup. Five of the people were sick with cystic fibrosis, and five were healthy. Out of that fluid, Willner and her team fished out fragments of DNA, which they compared to databases of the tens of millions of genes already known to science. Before Willner’s study, the lungs of healthy people were believed to be sterile. But Willner and her colleagues discovered that all their subjects, sick and healthy alike, carried viral menageries in their chests. On average, each person had 174 species of viruses in the lungs. But only 10 percent of those species bore any close kinship to any virus ever found before.
Carl Zimmer – A Planet of Viruses (via scipsy)
Can’t recommend reading Carl Zimmer enough. Working my way through Evolution: The Triumph of an Idea and it is fantastic.