The virion consists of the genome encased in capsid proteins to form a helical nucleoprotein complex.

Adnaviria was established in 2020 after cryogenic electron microscopy showed that the viruses in the realm were related due to a shared MCP, A-DNA, and general virion structure.

Viruses in Adnaviria have potentially existed for a long time, as it is thought that they may have infected the last archaeal common ancestor.

Adnaviria takes the first part of its name, Adna-, from A-DNA, which refers to the A-form genomic DNA of all viruses in the realm.

[2] Viruses in Adnaviria infect hyperthermophilic and acidophilic archaea and have linear, double-stranded DNA (dsDNA) genomes that range from about 16 to 56 kilobase pairs in length.

For lipothrixviruses and tristromaviruses,[8] it is heterodimer, a molecule formed by the bonding of two different MCPs that are paralogous, i.e. the result of a gene duplication event.

[3][5][10][12] Viruses in Adnaviria have potentially existed for a long time, as it is thought that they may have infected the last archaeal common ancestor.

Adnaviruses are morphologically similar to non-archaeal filamentous viruses but their virions are built from different capsid proteins.

[20][21] Cryogenic electron microscopy would later show in 2020 that the MCPs of tristromaviruses contained a SIRV2-like fold like ligamenviruses, which provided justification for establishing Adnaviria in the same year.