Viruses in the gut protect from infection : Nature News & Comment.
Barr and his colleagues, who are based at San Diego State University in California, show that animal mucus — whether from humans, fish or corals — is loaded with bacteria-killing viruses called phages. These protect their hosts from infection by destroying incoming bacteria. In return, the phages are exposed to a steady torrent of microbes in which to reproduce. “It’s a unique form of symbiosis, between animals and viruses,” says Rotem Sorek, a microbial geneticist at the Weizmann Institute of Science in Rehovot, Israel, who was not involved in the research.