Tequatrovirus

Tequatrovirus is a genus of viruses in the order Caudovirales, in the family Myoviridae, in the subfamily Tevenvirinae. Gram-negative bacteria serve as the natural host, with transmission achieved through passive diffusion. There are currently 21 species in this genus, including the type species Escherichia virus T4.[1][2][3]

Tequatrovirus
Virus classification
(unranked): Virus
Realm: Duplodnaviria
Kingdom: Heunggongvirae
Phylum: Uroviricota
Class: Caudoviricetes
Order: Caudovirales
Family: Myoviridae
Subfamily: Tevenvirinae
Genus: Tequatrovirus
Type species
Escherichia virus T4
Species

See text

Taxonomy

The following list is a map of Tequatrovirus species according to ICTV Master Species List (MSL) 2018b v2:[4][5]

Group: dsDNA

  • Genus: Tequatrovirus (formerly T4virus)
  • Escherichia virus AR1
  • Escherichia virus C40
  • Escherichia virus CF2
  • Escherichia virus E112
  • Escherichia virus ECML134
  • Escherichia virus HY01
  • Escherichia virus HY03
  • Escherichia virus Ime09
  • Escherichia virus RB3
  • Escherichia virus RB14
  • Escherichia virus slur03
  • Escherichia virus slur04
  • Escherichia virus T4 (formerly T-even phages), contains the following strains/isolates:
  • Shigella virus Pss1
  • Shigella virus Sf21
  • Shigella virus Sf22
  • Shigella virus Sf24
  • Shigella virus SHBML501
  • Shigella virus Shfl2
  • Yersinia virus D1
  • Yersinia virus PST

Structure

T4virus species are nonenveloped, with a head and tail. The head is a prolate spheroid approximately 120 nm in length and 86 nm in width, with an elongated icosahedral symmetry (T=13, Q=21) composed of 152 total capsomers. The tail has six long terminal fibers, six short spikes, and a small base plate. The tail is enclosed in a sheath, which loosens and slides around the tail core upon contraction.[1]

GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
TequatrovirusHead-TailT=13 Q=21Non-envelopedLinearMonopartite

Genome

Genomes are linear, around 169kb in length. The genome codes for 300 proteins.[1] Twelve of the fourteen species have been fully sequenced and are available from ICTV. They range between 159k and 235k nucleotides, with 242 to 292 proteins. The complete genomes are available from the National Center for Biotechnology Information, along with the complete genomes for dozens of other similar, unclassified virus strains.[3]

Life cycle

Viral replication is cytoplasmic. The virus attaches to the host cell using its terminal fibers, and uses viral exolysin to degrade the cell wall enough to eject the viral DNA into the host cytoplasm via contraction of its tail sheath. DNA-templated transcription is the method of transcription. The virus exits the host cell by lysis, and holin/endolysin/spanin proteins. Once the viral genes have been replicated, the procapsid is assembled and packed. The tail is then assembled and the mature virions are released via lysis. Gram-negative bacteria serve as the natural host. Transmission routes are passive diffusion.[1]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
TequatrovirusBacteria: gram negativeNoneInjectionLysisCytoplasmCytoplasmPassive diffusion

History

The ICTV's first report (1971) included the genus T-even phages, unassigned to an order, family, or subfamily. The genus was renamed in 1976 to T-even phage group, moved into the newly created family Myoviridae in 1981. In 1993, it was renamed again to T4-like phages, and was moved into the newly created order Caudovirales in 1998. The next year (1999), it was renamed to T4-like viruses. Once more, the genus was moved into the newly created subfamily Tevenvirinae in 2010-11, renamed to T4likevirus in 2012, and renamed again to T4virus in 2015. The proposals before 1993, and from 1998 are unavailable online. The other proposals are available here: 1993, 1999, 2010, 2012.[2]

References
  1. "Viral Zone". ExPASy. Retrieved 11 February 2015.
  2. "Virus Taxonomy: 2015 Release". International Committee on Taxonomy of Viruses. Retrieved 4 March 2017.
  3. NCBI. "T4virus Complete Genomes". Retrieved 13 February 2015.
  4. https://talk.ictvonline.org/files/master-species-lists/m/msl/7992 ICTV MSL 2018a v1]
  5. Andrew M. Kropinski et al.: To amend the membership of the genus T4likevirus, and create six (6) new genera in the subfamily Tevenvirinae, on: ICTV Online
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