''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 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 the class ''

Caudoviricetes ''Caudoviricetes'' is a class of viruses known as tailed viruses and head-tail viruses (''cauda'' is Latin for "tail"). It is the sole representative of its own phylum, ''Uroviricota'' (from ''ouros'' (ουρος), a Greek word for "tailed" + ...

'', in the order '' Autographivirales'', in the family '' Autotranscriptaviridae'', 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''.

Taxonomy

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. A viral envelope protein or E protein is a protein in the env ...

, 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 ''Caudoviricetes'' is a class of viruses known as tailed viruses and head-tail viruses (''cauda'' is Latin for "tail"). It is the sole representative of its own phylum, ''Uroviricota'' (from ''ouros'' (ουρος), a Greek word for "tailed" + ...

'', 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 ''Autographivirales'' is an Order (biology), order of viruses in the class ''Caudoviricetes''. Bacteria serve as natural hosts. The order has 4 families, 2 subfamilies unassigned to a family, and a large number of genera unassigned to a family. ...

'' and subfamily '' Studiervirinae''.

References

External links

Viralzone: T7likevirus

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