Structure and replication cycle of a virus infecting climate-modulating alga .

The globally distributed marine alga has cooling effect on the Earth's climate. The population density of is restricted by viruses, including virus 201 (EhV-201). Despite the impact of viruses on the climate, there is limited information about their structure and replication. Here, we show that the dsDNA genome inside the EhV-201 virion is protected by an inner membrane, capsid, and outer membrane. EhV-201 virions infect by using fivefold vertices to bind to and fuse the virus' inner membrane with the cell plasma membrane. Progeny virions assemble in the cytoplasm at the surface of endoplasmic reticulum-derived membrane segments. Genome packaging initiates synchronously with the capsid assembly and completes through an aperture in the forming capsid. The genome-filled capsids acquire an outer membrane by budding into intracellular vesicles. EhV-201 infection induces a loss of surface protective layers from cells, which enables the continuous release of virions by exocytosis.