HCIV-1 and Other Tailless Icosahedral Internal Membrane-Containing Viruses of the Family Sphaerolipoviridae

• Published in: Viruses 2017-02, Vol.9 (2), p.32
• Main Authors: Demina, Tatiana A, Pietilä, Maija K, Svirskaitė, Julija, Ravantti, Janne J, Atanasova, Nina S, Bamford, Dennis H, Oksanen, Hanna M
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - genetics; Alphasphaerolipovirus; Archaea - virology; archaeal virus; Archaeal Viruses - classification; Archaeal Viruses - genetics; Archaeal Viruses - ultrastructure; Bacteriophages - classification; Bacteriophages - genetics; Bacteriophages - ultrastructure; Capsid Proteins - genetics; halophilic archaea; halovirus; International Committee on Taxonomy of Viruses; membrane virus; Phylogeny; Review; Sequence Analysis, DNA; Sphaerolipoviridae; structure-based viral lineage; tailless icosahedral virus; Thermus - virology; Virion - ultrastructure; virus classification
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v9020032

Members of the virus family include both archaeal viruses and bacteriophages that possess a tailless icosahedral capsid with an internal membrane. The genera and comprise viruses that infect halophilic euryarchaea, whereas viruses of thermophilic bacteria belong to the genus . Both sequence-based and structural clustering of the major capsid proteins and ATPases of sphaerolipoviruses yield three distinct clades corresponding to these three genera. Conserved virion architectural principles observed in sphaerolipoviruses suggest that these viruses belong to the PRD1-adenovirus structural lineage. Here we focus on archaeal alphasphaerolipoviruses and their related putative proviruses. The highest sequence similarities among alphasphaerolipoviruses are observed in the core structural elements of their virions: the two major capsid proteins, the major membrane protein, and a putative packaging ATPase. A recently described tailless icosahedral haloarchaeal virus, icosahedral virus 1 (HCIV-1), has a double-stranded DNA genome and an internal membrane lining the capsid. HCIV-1 shares significant similarities with the other tailless icosahedral internal membrane-containing haloarchaeal viruses of the family . The proposal to include a new virus species, , into the genus was submitted to the International Committee on Taxonomy of Viruses (ICTV) in 2016.