''Metaviridae'' is a family of

virus A virus is a wikt:submicroscopic, 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 ...

es which exist as Ty3-gypsy LTR retrotransposons in a eukaryotic host's genome. They are closely related to

retrovirus 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 ...

es: 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 i ...

, 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 ...

'' 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'' * Genus '' Errantivirus'' Families ''Metaviridae'', '' Belpaoviridae'', '' Pseudoviridae'', '' Retroviridae'', and '' Caulimoviridae'' constitute the order '' Ortervirales''.

References

External links

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