''Metavirus'' 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 family ''

Metaviridae ''Metaviridae'' is a family of viruses which exist as Ty3-gypsy LTR retrotransposons in a eukaryotic host's genome. They are closely related to retroviruses: members of the family ''Metaviridae'' share many genomic elements with retroviruses, i ...

''. They are

retrotransposon Retrotransposons (also called Class I transposable elements) are mobile elements which move in the host genome by converting their transcribed RNA into DNA through reverse transcription. Thus, they differ from Class II transposable elements, or ...

s that invade a eukaryotic host genome and may only replicate once the virus has infected the host. ''Metavirus'' may use several different hosts for transmission, and has been found to be transmissible through ovule and pollen of some plants. ''Metavirus'' contains five families of the ''Ty3/Gypsy'' element with either one or two open-reading frames (''gag3'' and/or ''pol3''); these families are ''mdg1, mdg3, blastopia,'' ''412,'' and ''micropia''. There is evidence to support that amino acid deprivation in the elements of the host genome has frequently caused a frameshift towards the ''Ty3'' element. ''Metavirus'' corresponds with the ''Ogre/Tat'' gene lineage.

Morphology

Species of ''Metavirus'' are single-stranded RNA retrotransposons. They have an icosahedral and linear conformation and are not enclosed in an envelope. Their diameter is approximately 50 nm and they are usually between 42 and 52 nm in length. These genetic elements contain a core and capsid.

Species

The genus contains the following species, listed by scientific name and followed by the exemplar virus of the species: * ''Metavirus athilai'', Arabidopsis thaliana Athila virus * ''Metavirus blastopiae'', Drosophila melanogaster Blastopia virus * ''Metavirus bombycis'', Bombyx mori Mag virus * ''Metavirus caenorhabditis'',

Caenorhabditis elegans Cer1 virus Caenorhabditis elegans Cer1 virus is a species of retroviruses in the genus '' Metavirus''. References External links * ICTVdB Index of VirusesDescriptions of Plant Viruses Metaviridae RNA reverse-transcribing viruses Caenorhabditis ...

Evolution

Because of their high mutation and recombination rate and their ability to conduct

horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the e ...

, the evolutionary history of many retroelements may be challenging to trace (Benachenhou et al., 2013). Scientists often look to the genomes of ''Metavirus'' to compare nucleic acid sequences to the sequences of other viruses, constructing lineages and proposing common ancestors. Multiple taxa of ''Metavirus'' have genomic sequence that are homologous to other genera of Metaviridae and a suggest common ancestor and/or coevolution. Scientists often look at capsid proteins for evidence of ''Metavirus'' evolution. Much of the lineage of ''Metavirus'' remains unsolved and is presently being researched.

Studies

Mascagni et al. (2017) conducted researched to find homologs and identify strands in sunflower species. In the experiment, DNA was extracted from various

helianthus ''Helianthus'' () is a genus comprising around 70 species of annual and perennial flowering plants in the daisy family Asteraceae commonly known as sunflowers. Except for three South American species, the species of ''Helianthus'' are native to ...

species and the genomes of retrotransposons were identified using BLASTX analysis. Phylogenetic trees were constructed using neighbor-joining clustering method and a bioinformatic pipeline was constructed to allow genomic analysis. Two elements, ''SURE'' and ''Helicopia,'' were identified and placed into the ''Gypsy'' and ''Copia'' superfamilies, respectively. Thus, the ''SURE'' element belongs to the ''Gypsy'' group, of the ''Ogre/Tat'' lineage, of the genus ''Metavirus''. Further analysis led Mascagni et al. (2017) to identify mutations and conclude that the ''Metavirus'' lineage evolved before ''Sirevirus.'' Mascagni et al. (2017) also found evidence that the ''SURE'' elements and ''Helicopia'' elements had hybridized, potential for new lineages. Nefedova and Kim (2009), conducted a study on ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (an insect of the Order (biology), 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", "pomace fly" ...

'' to further identify lineages of ''Metavirus''. Homologs were identified from previously extracted DNA of retrotransposons and ''

'' and phylogenetic trees were constructed. ''Metaviruses'' possess the env gene, allowing them to be infective, which Nefedova and Kim (2009) concluded was obtained from horizontal gene transfer from baculoviruses. ''Metavirus'' contains the roo element which is thought to have been obtained from gene transfer from '' Errantivirus,'' or more likely, the two genera share a

common ancestor Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonl ...

References

External links

ICTV Report: ''Metaviridae''
*
Descriptions of Plant Viruses
{{Taxonbar, from=Q18819496 Metaviridae RNA reverse-transcribing viruses Virus genera