''Totivirus'' is a genus of

double-stranded RNA viruses Double-stranded RNA viruses (dsRNA viruses) are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid. The double-stranded genome is used as a template by the viral RNA dependent RNA polymerase (RdRp) to ...

in the family '' Orthototiviridae''. Fungi serve as natural hosts. The name of the group derives from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''toti'' which means undivided or whole. There are 32 species in this genus.

Structure

Viruses in the genus ''Totivirus'' are non-enveloped, with

icosahedral In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes . The plural can be either "icosahedra" () or "icosahedrons". There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrical tha ...

symmetry, and T=2 architecture. The diameter is around 40 nm.

Genome

Totiviruses have a

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

of 4700–6700

nucleotides Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...

in length and only a single copy of the genome is present in the particle. The

nucleic acid Nucleic acids are large biomolecules that are crucial in all cells and viruses. They are composed of nucleotides, which are the monomer components: a pentose, 5-carbon sugar, a phosphate group and a nitrogenous base. The two main classes of nuclei ...

content of a totivirus capsid is usually of one segment but can also contain three or four segments of linear double stranded RNA. The

contains two large overlapping

open reading frame In molecular biology, reading frames are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames ...

s (ORFs). These

open reading frames In molecular biology, reading frames are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames wil ...

(ORFs) code for a capsid protein (CP) and an

RNA-dependent RNA polymerase RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the self-replication, replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand Complementarity (molecular biology), compleme ...

(RdRp). The 5' end of the positive strand of the dsRNA genome has no cap and is very structured. Totiviruses contain a long 5' untranslated region (5' UTR) which functions as an

internal ribosome entry site An internal ribosome entry site, abbreviated IRES, is an RNA element that allows for translation initiation in a cap-independent manner, as part of the greater process of protein synthesis. Initiation of eukaryotic translation nearly always occur ...

(IRES). Totiviruses can have satellite RNAs encoding a

toxin A toxin is a naturally occurring poison produced by metabolic activities of living cells or organisms. They occur especially as proteins, often conjugated. The term was first used by organic chemist Ludwig Brieger (1849–1919), derived ...

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by virus remains intracellular. Replication follows the double-stranded RNA virus replication model. Double-stranded RNA virus transcription is the method of transcription. Translation takes place by -1 ribosomal frameshifting. The virus exits the host cell by cell-to-cell movement. Fungi ''

Saccharomyces cerevisiae ''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungal microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have be ...

'' and smut serve as the natural host. The virus is transmitted during cell division, sporogenesis, and cell fusion.

Taxonomy

The genus ''Totivirus'' contains the following species: * ''

Totivirus go ''Totivirus'' is a genus of double-stranded RNA viruses in the family '' Orthototiviridae''. Fungi serve as natural hosts. The name of the group derives from Latin ''toti'' which means undivided or whole. There are 32 species in this genus. Str ...

'' * '' Totivirus hachi'' * '' Totivirus ichi'' (

L-A helper virus ''Saccharomyces cerevisiae virus L-A'', also called L-A helper virus, is a member of the ''Totivirus'' genus of viruses found primarily in ''Saccharomyces cerevisiae''. Its discovery in the 1970s was the main starting point of research on yeast v ...

) * '' Totivirus jyu'' * '' Totivirus jyugo'' * '' Totivirus jyuhachi'' * '' Totivirus jyuichi'' * '' Totivirus jyukyu'' * '' Totivirus jyuni'' * '' Totivirus jyuroku'' * '' Totivirus jyusani'' * ''

Totivirus jyushi ''Totivirus'' is a genus of double-stranded RNA viruses in the family '' Orthototiviridae''. Fungi serve as natural hosts. The name of the group derives from Latin ''toti'' which means undivided or whole. There are 32 species in this genus. Str ...

'' * ''

Totivirus jyushichi ''Totivirus'' is a genus of double-stranded RNA viruses in the family '' Orthototiviridae''. Fungi serve as natural hosts. The name of the group derives from Latin ''toti'' which means undivided or whole. There are 32 species in this genus. Str ...

'' * ''

Totivirus kyu ''Totivirus'' is a genus of double-stranded RNA viruses in the family ''Orthototiviridae''. Fungi serve as natural hosts. The name of the group derives from Latin ''toti'' which means undivided or whole. There are 32 species in this genus. Stru ...

'' * '' Totivirus ni'' * '' Totivirus nijyu'' * '' Totivirus nijyugo'' * '' Totivirus nijyuhachi'' * '' Totivirus nijyuichi'' * '' Totivirus nijyukyu'' * '' Totivirus nijyuni'' * '' Totivirus nijyuroku'' * '' Totivirus nijyusani'' * '' Totivirus nijyushi'' * '' Totivirus nijyushichi'' * '' Totivirus roku'' * '' Totivirus sani'' * '' Totivirus sanjyu'' * '' Totivirus sanjyuichi'' * '' Totivirus sanjyuni'' * '' Totivirus shi'' * '' Totivirus shichi''

References

External links

ICTV Totivirus Page

ICTV
{{Taxonbar, from=Q7828339 Totiviridae Mycoviruses Virus genera