Giant viruses have weaponised CRISPR against their bacterial hosts

EYE OF SCIENCE/SCIENCE PHOTO LIBRARY

By Michael Le Page

Hundreds of huge, bacteria-killing viruses have been newly discovered lurking in all kinds of environments, including our guts. Their massive genomes code for many proteins not found in smaller viruses, including CRISPR systems used to attack both their bacterial hosts and rival viruses.

The massive viruses have long gone unnoticed because the standard methods used to look for bacteria-killing viruses, or bacteriophages, literally filter them out. Instead, a team has found them by looking at all the DNA present in a variety of samples …