Viruses from this realm are archaeal filamentous viruses with linear A-form double-stranded DNA genomes and characteristic major capsid proteins with SIRV2-like folding, which have nothing to do with those of other known viruses .
The realm is called Adnaviria, which refers to the double-helical structures of the A-form that have been adapted from the viral genomes in the nucleocapsids.
capsid of solfataricus rod-shaped virus (SSRV1), encapsidating A-form DNA
Adnaviria: a New Realm for Archaeal Filamentous Viruses with Linear A-Form Double-Stranded DNA Genomes
Mart Krupovic, Jens H Kuhn, Fengbin Wang, Diana P Baquero, Valerian V Dolja, Edward H Egelman, David Prangishvili, Eugene V Koonin
J Virol. 2021 Jul 12;95(15):e0067321.
Structures of filamentous viruses infecting hyperthermophilic archaea explain DNA stabilization in extreme environments
Fengbin Wang, Diana P Baquero, Leticia C Beltran, Zhangli Su, Tomasz Osinski, Weili Zheng, David Prangishvili, Mart Krupovic, Edward H Egelman
Proc Natl Acad Sci U S A. 2020 Aug 18;117(33):19643-19652.
Adnaviria: a New Realm for Archaeal Filamentous Viruses with Linear A-Form Double-Stranded DNA Genomes
Mart Krupovic, Jens H Kuhn, Fengbin Wang, Diana P Baquero, Valerian V Dolja, Edward H Egelman, David Prangishvili, Eugene V Koonin
J Virol. 2021 Jul 12;95(15):e0067321.
A new proposed taxon for double-stranded DNA viruses, the order "Ligamenvirales"
David Prangishvili, Mart Krupovic
Arch Virol. 2012 Apr;157(4):791-5.