Assaf Vardi - The “virocell” metabolism – Metabolic innovations during host-virus interactions in the ocean

Marine viruses that infect marine microorganisms are recognized as major ecological and evolutionary driving forces, shaping community structure and nutrient and energy cycling in the marine environment. Nevertheless, the cellular mechanisms that govern these host-virus dynamics are largely underexplored. Recent reports highlighted a novel genomic inventory found in marine viruses which can encode auxiliary metabolic genes previously thought to be restricted to their host genomes. Thus, these genes can expand viral metabolic capabilities and energy transfer between host cells and their environment. A major challenge in our current understanding of host-virus interactions in the marine environment is to decode the wealth of genomic and metagenomic data and translate it into cellular mechanisms that mediate host susceptibility and resistance to viral infection. Emiliania huxleyi is a globally important coccolithophore forming massive algal blooms in the North Atlantic Ocean that are routinely infected and terminated by large DNA viruses, coccolithoviruses (EhVs). We explore the molecular and metabolic basis for these host-virus dynamics and the signal transduction pathways that mediate host-virus interactions. By combining genome-enabled technologies and analytical chemistry approaches, we were able to identify several fundamental metabolic pathways that mediate these host-virus interactions. We revealed the role of viral-encoded sphingolipid, redox and DMS metabolism and their function in determining host cell fate (e.g. PCD and autophagy) and viral replication strategies. We currently examine the transcriptomic remodeling of host-virus interactions at a single cell resolution in order to provide novel insights into the cellular mechanisms that govern the “arms race” of the virocell during algal blooms dynamics in the ocean.