This perspective highlights that giant viruses arose from smaller viruses by taking up host genes. They remain typical viruses despite genomes that can reach 5 Mb and virions larger than many bacterial and archaeal cells. The virus-cell boundary to is put between replicators, which use host ribosomes, and reproducers, which build their own. This is a distinction no currently discovered giant virus appears to have crossed. One of the open questions that remains is what drives some lineages to a K strategy, accumulating virus-host interaction genes, while others stay compact. doi.org/10.1073/pnas.2610442…

Giant virus genomes carry discrete genomic islands that concentrate sequence variation and mosaic gene content. These regions, rather than the conserved core, account for much of what separates closely related Nucleocytoviricota genomes. doi.org/10.1038/s41467-026-7…