Varidnaviria

Varidnaviria is a realm of viruses that includes all DNA viruses that encode major capsid proteins that contain two vertical jelly roll folds. The major capsid proteins (MCP) form into pseudohexameric subunits of the viral capsid, which stores the viral deoxyribonucleic acid (DNA). The jelly roll folds are vertical, or perpendicular, to the surface of the capsid. Apart from the double jelly roll fold MCP (DJR-MCP), most viruses in the realm share many other characteristics, such as minor capsid proteins (mCP) that has one vertical jelly roll fold, an ATPase that packages viral DNA into the capsid, a DNA polymerase that replicates the viral genome, and capsids that are icosahedral in shape.

Varidnaviria was established in 2019 based on the shared characteristics of the viruses in the realm. There are two kingdoms in the realm: Abadenavirae, which contains all prokaryotic DJR-MCP viruses except tectiviruses, and Bamfordvirae which contains tectiviruses and all eukaryotic DJR-MCP viruses. The DJR-MCP of Varidnaviria is believed to share common ancestry with the DUF2961 family of proteins, which are widespread in cellular life and which are mainly involved in carbohydrate metabolism and binding. Up to 2025, the realm included viruses that have a vertical single jelly roll (SJR) fold in the MCP, but these viruses were moved to a separate realm, Singelaviria, after it was shown that the vertical SJR and DJR folds have separate evolutionary origins.