Cystoviridae

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Cystovirus
Systematics
Classification : Viruses
Area : Riboviria
Empire : Orthornavirae
Phylum : Duplornaviricota
Class : Vidaverviricetes
Order : Mindivirales
Family : Cystoviridae
Genre : Cystovirus
Taxonomic characteristics
Genome : dsRNA
Baltimore : Group 3
Symmetry : icosahedral
Cover : available
Left


The Cystoviridae are a virus family of enveloped RNA viruses with a segmented double-stranded genome . The family so far only includes the genus Cystovirus . As a bacteriophage , it uses various gram-negative bacteria as host .

Cystoviruses are the only bacteriophage family with a complete virus envelope and the only one with an RNA -based genome. The families of the Tectiviridae and the Corticoviridae have enclosed lipids in their capsids , but no outer virus envelope.

The cystovirus family appears to be most closely related to the Reoviridae , but they also have homologies to the Totiviridae . This makes cystoviruses the only bacteriophage family that are more closely related to eukaryotic viruses than to other phages.

Genome

The cystoviruses have three genome segments of 2.9 kilobases (S segment), 4 kilobases (M segment) and 6.4 kilobases (L segment). The genome codes for 12 proteins . Most of the identified cystoviruses infect Pseudomonas species, although this may also be due to the investigation and enrichment method. The Pseudomonas phages Phi6 , Phi7, Phi8, Phi9, Phi10, Phi11, Phi12 and Phi13 have been characterized and named, others have only been isolated so far.

While the tropism of some cystoviruses such as Phi6 is determined by the binding of the multimeric protein P3 to type IV pili as a receptor , Phi8, Phi12 and Phi13 use a heterodimeric protein that binds to lipopolysaccharides .

The protein P6 mediates the fusion with the cell membrane of the host cell and the subsequent introduction of the nucleocapsid without unpacking the RNA. P5 is a hydrolytic enzyme that dissolves the bacterial proteoglycan layer. As an RNA-dependent RNA polymerase, P2 ensures the replication of the genome within the nucleocapsid. P4 transports the single-stranded viral RNA segments of positive polarity with consumption of ATP into the newly produced capsid proteins, where they are completed by P2 to double-stranded RNA. The cell is then left by lysis .

External system

With the Master Species List # 35 of March 2020, the ICTV assigned the Cystoviridae to the newly created Phylum Duplornaviricota . A cladogram can be found at Picornavirales §ICTV Master Species List # 35 .

literature

  • H.-W. Ackermann, MS DuBow: Cystoviridae . In: Viruses of Prokaryotes, Vol II. (1987), CRC Press, Boca Raton Florida, pp 171-218.
  • DH Bamford, RB Wickner: Assembly of double-stranded RNA viruses: bacteriophage f6 and yeast virus LA. “Sem. ViroI ” . (1994), Vol. 5, pp. 61-69.
  • S. Onodera, X. Qiao, J. Qiao, L. Mindich: Directed changes in the number of double-stranded RNA genomic segments in bacteriophage phi6 . Proc. Acad. Nall. Sci. USA (1998), Vol. 95, pp. 3920-3924.
  • Index of Viruses - Cystoviridae (2009). In: ICTVdB - The Universal Virus Database, version 4 . Büchen-Osmond, C. (Ed), Columbia University, New York, USA. [1]

Web links

Individual evidence

  1. ICTV Master Species List 2018b.v2 . MSL # 34, March 2019
  2. a b c d ICTV: ICTV Taxonomy history: Human alphaherpesvirus 1 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  3. Butcher SJ, Dokland T, Ojala PM, Bamford DH, Fuller SD: Intermediates in the assembly pathway of the double-stranded RNA virus Phi 6 . In: EMBO J. . 16, No. 14, July 1997, pp. 4477-87. doi : 10.1093 / emboj / 16.14.4477 . PMID 9250692 . PMC 1170074 (free full text).
  4. a b Silander OK, Weinreich DM, Wright KM, et al. : Widespread genetic exchange among terrestrial bacteriophages . In: Proc. Natl. Acad. Sci. USA . 102, No. 52, December 2005, pp. 19009-14. doi : 10.1073 / pnas.0503074102 . PMID 16365305 . PMC 1323146 (free full text).
  5. Mindich L, Qiao X, Qiao J, Onodera S, Romantschuk M, Hoogstraten D: Isolation of additional bacteriophages with genomes of segmented double-stranded RNA . In: J. Bacteriol. . 181, No. 15, August 1999, pp. 4505-8. PMID 10419946 . PMC 103579 (free full text).
  6. ICTV: ICTV Master Species List 2019.v1 , New MSL including all taxa updates since the 2018b release, March 2020 (MSL # 35)