''Teseptimavirus'' (synonyms ''T7 phage group'', ''T7-like phages'', ''T7-like viruses'', ''T7likevirus'') 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'', in the family '' Autographiviridae'', in the subfamily '' Studiervirinae''. Bacteria serve as the natural host, with transmission achieved through passive diffusion. There are currently 17 species in this genus, including the type species ''

Escherichia virus T7 Bacteriophage T7 (or the T7 phage) is a bacteriophage, a virus that infects bacteria. It infects most strains of ''Escherichia coli'' and relies on these hosts to propagate. Bacteriophage T7 has a Lytic cycle, lytic life cycle, meaning that it ...

''.

Taxonomy

The following species are recognized: * '' Enterobacteria virus IME390'' * '' Escherichia virus 13a'' * '' Escherichia virus 64795ec1'' * '' Escherichia virus C5'' * '' Escherichia virus CICC80001'' * '' Escherichia virus Ebrios'' * '' Escherichia virus EG1'' * '' Escherichia virus HZ2R8'' * ''

Escherichia virus HZP2 ''Escherichia'' () is a genus of Gram-negative, non-spore-forming, facultatively anaerobic, rod-shaped bacteria from the family Enterobacteriaceae. In those species which are inhabitants of the gastrointestinal tracts of warm-blooded animals, '' ...

'' * '' Escherichia virus N30'' * '' Escherichia virus NCA'' * ''

'' * '' Salmonella virus 3A8767'' * '' Salmonella virus Vi06'' * '' Stenotrophomonas virus IME15'' * '' Yersinia virus YpPY'' * '' Yersinia virus YpsPG''

Structure

Sp6likeviruses 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 has icosahedral symmetry (T=7) approximately 60 nm in diameter. The tail is non-contractile and has six short subterminal fibers.

Genome

Genomes are linear, around 40-42kb in length. All three viruses' genomes have been fully sequenced and are available on NCBI's website. They range between 37k and 40k nucleotides, with 42 to 60 proteins. All three complete genomes, as well as several additional "unclassified" virus genomes, are availabl
here
ref name=NCBI>

Life cycle

Viral replication is cytoplasmic. The virus attaches to the host cell adhesion receptors using its tail fibers, and ejects the viral DNA into the host periplasm vi

Class I genes are transcribed by the host cell's RNA polymerase before the viral genome completely exits the capsid. Class II genes are then transcribed by T7 RNA polymerase and the host genome is degraded. Genomic DNA is replicated by T7 DNA polymerase and concatemers are formed before Class III genes are transcribed. Finally, the procapsid is assembled and packed, the tail is assembled and the mature virions are released via lysis. Bacteria serve as the natural host. Transmission routes are passive diffusion.

History

According to ICTV'
second report
in 1976, the genus ''T7likevirus'' was first accepted under the name ''T7 phage group'', unassigned to an order, family, or sub-family. In ICTV's third report in 1981, the genus was classified into the family '' Poloviridae''. ''T7 phage group'' was renamed to ''T7-like phages'' in th
sixth report
in 1995. In 1998, the whole family was moved into the newly created order '' Caudovirales'', and the genus was renamed again in th
seventh report
in 1999 to ''T7-like viruses''. 2009 saw the genus moved into the newly created subfamily ''Autographivirinae'', and it was renamed again i
2012
to ''T7likevirus''. The genus was later renamed to ''Teseptimavirus'' under the newly established family '' Autographiviridae'' and subfamily '' Studiervirinae''.

References

External links

Viralzone: T7likevirus

ICTV
{{Use dmy dates, date=April 2017 Caudovirales Virus genera