''Tequatrovirus'' is a genus of

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1 ...

es in the order ''

Caudovirales ''Caudovirales'' is an order of viruses known as the tailed bacteriophages (''cauda'' is Latin for "tail"). Under the Baltimore classification scheme, the ''Caudovirales'' are group I viruses as they have double stranded DNA (dsDNA) genomes, ...

'', in the family ''

Myoviridae ''Myoviridae'' is a family of bacteriophages in the order ''Caudovirales''. Bacteria and archaea serve as natural hosts. There are 625 species in this family, assigned to eight subfamilies and 217 genera. Subdivisions The subfamily ''Tevenvirinae ...

'', in the subfamily ''

Tevenvirinae ''Tevenvirinae'' is a subfamily of viruses in the order ''Caudovirales'', in the family ''Myoviridae''. Bacteria and archaea serve as natural hosts. There are 135 species in this subfamily, most included in 12 genera. Taxonomy The following gene ...

''.

Gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

serve as the natural host, with transmission achieved through passive diffusion. There are 75 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'' from the family Myoviridae. T4 is capable of undergoing only a lytic lifecycle ...

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. Numerous human pathogenic viruses in circulation are encase ...

, 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 circu ...

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 United States 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 ...

, 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 to ...

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. The proposals before 1993, and from 1998 are unavailable online. The other proposals are available here
1993199920102012

References

External links

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