Duplodnaviria

Duplodnaviria is a realm of viruses that includes all double-stranded DNA viruses encoding the HK97 fold major capsid protein, the main building block of the capsid that holds the viral DNA. Its viruses also share an icosahedral capsid, a portal opening, a protease that empties the capsid before DNA packaging and a terminase enzyme that packs the DNA in. The realm has three groups: the caudoviruses, which are among the most abundant organisms on Earth and infect prokaryotes; the herpesviruses, which infect animals; and the putative mirusviruses, which infect microscopic eukaryotes in sunlit oceans. It contains one kingdom, Heunggongvirae, split into two phyla, and it likely predates the last universal common ancestor of cellular life. Realms are the highest rank of virus taxonomy, and Duplodnaviria is one of ten.