''Muvirus'' (synonyms: ''Mu-like phages'', ''Mu-like viruses'', ''Mulikevirus'') 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" + ...

''. Bacteria serve as natural hosts, with transmission achieved through passive diffusion. There are two species in this genus.

Taxonomy

The following two species are assigned to the genus: * ''Muvirus mu'' ( bacteriophage Mu) * '' Muvirus SfMu''

Structure

Muviruses 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 an icosahedral structure of about 54 nm in width. The neck is knob-like, and the tail is contractile with a base plate and six short terminal fibers.

Genome

'' Escherichia virus Mu'' has been fully sequenced and is available from ICTV. It has 36k nucleotides, with 55 proteins. Two similar, unclassified viruses are also sequenced. The complete genomes are availabl
here

Life cycle

The virus attaches to the host cell

lipopolysaccharides Lipopolysaccharide (LPS), now more commonly known as endotoxin, is a collective term for components of the outermost membrane of the cell envelope of gram-negative bacteria, such as '' E. coli'' and ''Salmonella'' with a common structural archit ...

using its terminal fibers, and ejects the viral DNA into the host cytoplasm via contraction of its tail sheath. Once in the cell, the viral DNA is protected from degradation by the host nucleases. The viral DNA is then circularized and integrated into the host chromosome. The viral genome is copied 50–100 times in the host chromosome via

replicative transposition Replicative transposition is a mechanism of transposition in molecular biology, proposed by James A. Shapiro in 1979, in which the transposable element is duplicated during the reaction, so that the transposing entity is a copy of the original elem ...

. DNA-templated transcription is the method of transcription. Translation takes place by -1 ribosomal frameshifting. 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. Bacteria serve as the natural host. Transmission routes are passive diffusion.

History

According to the ICTV's 1996 report, the genus ''Mu-like phages'' was first accepted as a new genus in the family

Myoviridae ''Myoviridae'' was a family of bacteriophages in the order '' Caudovirales''. The family ''Myoviridae'' and order '' Caudovirales'' have now been abolished, with the term myovirus now used to refer to the morphology of viruses in this former famil ...

, a year after its type species was recognized by the committee. In 1998, it 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" + ...

. The next year (1999), the name was changed to ''Mu-like viruses''. Finally, in the 2010–11 report, it was renamed again to ''Mulikevirus''. These reports (with the exception of 1998) are available online here
199619992010
The genus was later renamed to ''Muvirus''.

References

External links

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