''Tequatrovirus'' is a genus of

virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...

es in subfamily ''

Tevenvirinae ''Tevenvirinae'' is a subfamily of viruses in the family ''Straboviridae'' of class ''Caudoviricetes''. The subfamily was previously placed in the morphology-based family ''Myoviridae'', which was found to be paraphyletic in genome studies and ab ...

'' of family ''

Straboviridae ''Straboviridae'' is a family of viruses in the order '' Pantevenvirales'', class ''Caudoviricetes''. The viruses in this family were formerly place in the morphology-based family '' Myoviridae'', which was found to be paraphyletic in genome stud ...

''.

Gram-negative bacteria Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the Crystal violet, crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelo ...

serve as the natural host, with transmission achieved through passive diffusion. There are 82 species in this genus.

Taxonomy

Escherichia virus T4 Escherichia virus T4 is a species of bacteriophages that infect ''Escherichia coli'' bacteria. It is a double-stranded DNA virus in the subfamily '' Tevenvirinae'' of the family '' Straboviridae''. T4 is capable of undergoing only a lytic li ...

'') * '' Tequatrovirus T6'' * '' Tequatrovirus teqdroes'' * '' Tequatrovirus teqhad'' * '' Tequatrovirus teqskov'' * '' Tequatrovirus ufvareg1'' * '' Tequatrovirus vipecoom'' * '' Tequatrovirus vtec'' * '' Tequatrovirus yueel1'' * '' Tequatrovirus zeen18'' * '' Tequatrovirus zeezee23'' * '' Tequatrovirus zeezeesix'' * '' Tequatrovirus zeezeethirty''

Structure

''Tequatrovirus'' species are

nonenveloped A viral envelope is the outermost layer of many types of viruses. It protects the genetic material in their life cycle when traveling between host cells. Not all viruses have envelopes. A viral envelope protein or E protein is a protein in the env ...

, with a head and tail. The head is a

prolate spheroid A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a quadric surface obtained by rotating an ellipse about one of its principal axes; in other words, an ellipsoid with two equal semi-diameters. A spheroid has cir ...

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.

Genome

Genomes are linear, around 169kb in length. The genome codes for 300 proteins. Some 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 The National Center for Biotechnology Information (NCBI) is part of the National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The NCBI is lo ...

, along with the complete genomes for dozens of other similar, unclassified virus strains.

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 Holins are a diverse group of small proteins produced by dsDNA bacteriophages in order to trigger and control the degradation of the host's cell wall at the end of the lytic cycle. Holins form pores in the host's cell membrane, allowing lysins t ...

endolysin Lysins, also known as endolysins or murein hydrolases, are hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the final stage of the lytic cycle. Lysins are highly evolved enzymes that are able to target ...

/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.

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. In 2021, the subfamily ''Tevenvirinae'' was moved to the new family ''

''.

References

External links

History of ''Tequatrovirus'' classification
(with links to all reports) ** Selected reports
1993199920102012

ICTV
{{Taxonbar, from1=Q69866765, from2=Q4348591 Tevenvirinae Virus genera