Viral metabolic reprogramming in marine ecosystems

Marine viruses often contain host-derived metabolic genes (i.e., auxiliary metabolic genes; AMGs), which are hypothesized to increase viral replication by augmenting key steps in host metabolism. Currently described AMGs encompass a wide variety of metabolic functions, including amino acid and carbohydrate metabolism, energy production, and iron-sulfur cluster assembly and modification, and their community-wide gene content and abundance vary as a function of environmental conditions. Here, we describe different AMGs classes, their hypothesized role in redirecting host carbon metabolism, and their ecological importance. Focusing on metagenomic ocean surveys, we propose a new model where a suite of phage-encoded genes activate host pathways that respond rapidly to environmental cues, presumably resulting in rapid changes to host metabolic flux for phage production.