A new tale for oceanic viruses

Double-stranded DNA (dsDNA) viruses that infect bacteria and archaea are thought to be the most abundant viruses in the oceans. Electron microscopy analyses have indicated that most oceanic viruses are non-tailed; however, tailed dsDNA viruses dominate sequence and culture collections, suggesting that we have a limited understanding of the diversity of oceanic viruses and their effects on marine ecosystems. Kauffman et al. now report the discovery of a major lineage of non-tailed dsDNA viruses with capsids that have a double jelly roll (DJR) fold — a fold that was previously associated with non-tailed viruses but, owing to biochemical and physical features of DJR viruses, they had been systematically lost in previous surveys. This new family, named the Autolykiviridae, was found to have a broad host range, and DJR viruses were also found in the genomes of diverse bacterial and archaeal phyla. These findings suggest that the ecological importance of non-tailed dsDNA viruses is far greater than previously thought.