Portogloboviridae

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Portogloboviridae
Portoglobovirus virion.png
Portoglobovirus virion
Virus classification e
(unranked): Virus
Realm: Varidnaviria

Portogloboviridae is a family of DNA viruses that infect archaea. It is a proposed family of the realm Varidnaviria. Viruses in the family are related to Halopanivirales.[note 1] The capsid proteins of these viruses and their characteristics are of evolutionary importance for the origin of the other Varidnaviria viruses since they seem to retain primordial characters.[1]

Description[]

The virions in this family have a capsid with icosahedral geometry and a viral envelope that protects the genetic material. The diameter is 83 to 87 nanometers. The genome is circular and of double-stranded DNA with a length of 20,222 base pairs. The genome contains 45 open reading frames (ORFs), which are closely arranged and occupy 89.1% of the genome. ORFs are generally short, with an average length of 103 codons. Virions have 10 proteins ranging from 20 to 32 kDa. Of these proteins, 8 code for the capsid and two for the viral envelope, including one that is a vertical single jelly roll (SJR) capsid protein. Entry into the host cell is by penetration. Viral replication occurs by chronic infection without a lytic cycle.[2]

The Portogloboviridae viruses together with Halopanivirales have evolutionary importance in the evolution of the other Varidnaviria viruses since they appear to be relics of how the first viruses of this realm were. Portogloboviridae together with Halopanivirales may have infected the last universal common ancestor (LUCA) and originated before that organism.[1]

It has been proposed that it may be related to the origin of Varidnaviria in the following way.[1]

Varidnaviria
 

Portogloboviridae

 
 
 

Halopanivirales

 
 

Bamfordvirae

 
 
 

Taxonomy[]

The family has one genus which has two species:[3]

  • Alphaportoglobovirus

Notes[]

  1. ^ The references cited in this article refer to Sphaerolipoviridae. In 2020, this family was split into three families within the order Halopanivirales, so "Halopanivirales" is used throughout this article where sources state "Sphaerolipoviridae".

References[]

  1. ^ a b c Krupovic M, Dolja VV, Koonin EV (14 July 2020). "The LUCA and its complex virome". Nat Rev Microbiol. 18 (11): 661–670. doi:10.1038/s41579-020-0408-x. PMID 32665595. S2CID 220516514. Retrieved 22 October 2020.
  2. ^ Liu Y, Ishino S, Ishino Y, Pehau-Arnaudet G, Krupovic M, Prangishvili D (9 July 2017). "A Novel Type of Polyhedral Viruses Infecting Hyperthermophilic Archaea". J Virol. 91 (13): e00589-17. doi:10.1128/JVI.00589-17. PMC 5469268. PMID 28424284.
  3. ^ "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Retrieved 24 May 2021.
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