''Metaviridae'' is a family 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 which exist as Ty3-gypsy

LTR retrotransposon LTR retrotransposons are class I transposable element characterized by the presence of long terminal repeats (LTRs) directly flanking an internal coding region. As retrotransposons, they mobilize through reverse transcription of their mRNA and in ...

s in a

eukaryotic Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

host's genome. They are closely related to retroviruses: members of the family ''Metaviridae'' share many genomic elements with retroviruses, including length, organization, and genes themselves. This includes genes that encode reverse transcriptase,

integrase Retroviral integrase (IN) is an enzyme produced by a retrovirus (such as HIV) that integrates—forms covalent links between—its genetic information into that of the host cell it infects. Retroviral INs are not to be confused with phage int ...

, and

capsid A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may ...

proteins. The reverse transcriptase and integrase proteins are needed for the retrotransposon activity of the virus. In some cases, virus-like particles can be formed from capsid proteins. Some assembled virus-like particles of members of the family ''Metaviridae'' can penetrate and infect previously uninfected cells. An example of this is the gypsy, a retroelement found in the ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Ch ...

'' genome. The ability to infect other cells is determined by the presence of the retroviral ''env'' genes which encode coat proteins. ''Metaviridae'' is a family of retrotransposons found in all eukaryotes known and studied. Viruses of this family proliferate through intermediates called virus-like particles known for their ability to induce mutations and genome sequencing. Members of the family ''Metaviridae'' are often referred to as LTR-retrotransposons of the Ty3-gypsy family. Among the members are only species that produce intracellular particles, the collection of these particles is heterogeneous. Extracellular particles are surrounded by oval nuclei and are called virions. In many systems, virions are characterized biochemically. Genomes of retrotransposons in this family are positive strand RNAs. In addition to the RNA genome, some cellular RNAs can be randomly associated with particles, including specific tRNAs, in case of virus replication prepared by tRNAs. Particle fractions from cells are heterogeneous relative to maturation and are therefore associated with intermediate transcriptions and reverse transcription products in addition to genomic RNA. When it comes to virion producing members, it appears that the virion membrane is derived from the membrane of the host cell.

Taxonomy

The family ''Metaviridae'' is split into the following genera: * Genus ''

Metavirus ''Metavirus'' is a genus of viruses in the family ''Metaviridae''. They are retrotransposons that invade a eukaryotic host genome and may only replicate once the virus has infected the host. These genetic elements exist to infect and replicate in ...

'' * Genus '' Errantivirus'' Families ''Metaviridae'', ''

Belpaoviridae ''Semotivirus'' is the only genus of viruses in the family ''Belpaoviridae'' (formerly included in the family ''Metaviridae''). Species exist as retrotransposons in a eukaryotic host's genome. BEL/pao transposons are only found in animals. Spec ...

'', ''

Pseudoviridae ''Pseudoviridae'' is a family of viruses, which includes three genera. Viruses of the family are actually LTR retrotransposons of the Ty1-copia family. They replicate via structures called virus-like particles (VLPs). VLPs are not infectious ...

'', ''

Retroviridae A retrovirus is a type of virus that inserts a DNA copy of its RNA genome into the DNA of a host cell that it invades, thus changing the genome of that cell. Once inside the host cell's cytoplasm, the virus uses its own reverse transcriptase ...

'', and ''

Caulimoviridae ''Caulimoviridae'' is a family of viruses infecting plants. There are 94 species in this family, assigned to 11 genera. Viruses belonging to the family ''Caulimoviridae'' are termed double-stranded DNA (dsDNA) reverse-transcribing viruses (or pa ...

'' constitute the order ''

Ortervirales ''Ortervirales'' is an order that contains all accepted species of single-stranded RNA viruses that replicate through a DNA intermediate (Group VI) and all accepted species of double-stranded DNA viruses (except '' Hepadnaviridae'') that replic ...

''.

References

External links

ICTV Report: ''Metaviridae''
*
Descriptions of Plant Viruses
Ortervirales RNA reverse-transcribing viruses Virus families {{Virus-stub