A chemical arms race at sea mediates algal host-virus interactions

► We discuss the current understanding of algal host-virus interactions. ► We discuss influence of lateral gene transfer in mediating viral infection. ► We highlight the role of viral glycosphingolipids (vGSLs) in marine coccolithoviruses as part of their lytic replication strategy. ► We discuss the use of vGSLs as novel biomarkers of infection in natural populations. ► We examine how new insight into algal host-virus interactions has empowered our thinking on resistance to virus infection in fundamentally new way.