View source for Biology:Ascoviridae

{{Short description|Family of viruses}}
{{Virusbox
| image = Ascoviridae virion.jpg
| taxon              = Ascoviridae
| subdivision_ranks  = Genera
| subdivision        =
* ''[[Biology:Ascovirus|Ascovirus]]''
* ''Toursvirus'' 
}}

'''''Ascoviridae''''' is a family of double strand DNA viruses that infect primarily invertebrates, mainly noctuids and spodoptera species; it contains two genera, '''''Ascovirus''''', which contains three species, and '''''Toursvirus''''' with a single species ''Diadromus pulchellus toursvirus''.<ref name=ICTVProfile>{{cite journal | vauthors = Asgari S, Bideshi DK, Bigot Y, Federici BA, Cheng XW | title = ICTV Virus Taxonomy Profile: Ascoviridae | journal = The Journal of General Virology | volume = 98 | issue = 1 | pages = 4–5 | date = January 2017 | pmid = 28218573 | pmc = 5370392 | doi = 10.1099/jgv.0.000677 }}</ref><ref name=ICTVReport>{{cite web|title=Ascoviridae|url=http://www.ictv.global/report/ascoviridae|website=ICTV Online (10th) Report|language=en}}</ref><ref name=ViralZone>{{cite web|title=Viral Zone|url=http://viralzone.expasy.org/all_by_species/139.html|publisher=ExPASy|access-date=12 June 2015}}</ref>

==Taxonomy==
The family contains the following genera and species:<ref>{{cite web |title=Virus Taxonomy: 2020 Release |url=https://ictv.global/taxonomy |publisher=International Committee on Taxonomy of Viruses (ICTV) |date=March 2021 |access-date=22 May 2021}}</ref>
* ''[[Biology:Ascovirus|Ascovirus]]''
** ''Heliothis virescens ascovirus 3a''
** ''Spodoptera frugiperda ascovirus 1a''
** ''Trichoplusia ni ascovirus 2a''
* ''Toursvirus''
** ''Diadromus pulchellus toursvirus''

==Genome==
[[File:Ascoviridae genome.svg|thumb|500px|Genome]]
The genome is not segmented and contains a single molecule of circular double-stranded [[Biology:DNA|DNA]]. The genome has a [[Chemistry:Guanine|guanine]] + [[Chemistry:Cytosine|cytosine]] content of 42-60%.{{cn|date=November 2022}}

The genome of Spodoptera frugiperda ascovirus 1a has been sequenced.<ref name=Bideshi2006>{{cite journal | vauthors = Bideshi DK, Demattei MV, Rouleux-Bonnin F, Stasiak K, Tan Y, Bigot S, Bigot Y, Federici BA | display-authors = 6 | title = Genomic sequence of Spodoptera frugiperda Ascovirus 1a, an enveloped, double-stranded DNA insect virus that manipulates apoptosis for viral reproduction | journal = Journal of Virology | volume = 80 | issue = 23 | pages = 11791–805 | date = December 2006 | pmid = 16987980 | pmc = 1642580 | doi = 10.1128/JVI.01639-06 | citeseerx = 10.1.1.332.7512 }}</ref> It is 156,922 bases in length and encodes 123 putative open reading frames. The G+C ratio is 49.2%. Among the encoded proteins are a [[Biology:Caspase|caspase]], a [[Biology:Cathepsin B|cathepsin B]], several [[Biology:Kinase|kinase]]s, E3 ubiquitin ligases, a fatty acid elongase, a sphingomyelinase, a phosphate [[Biology:Acyltransferase|acyltransferase]] and a [[Biology:Patatin|patatin]]-like [[Biology:Phospholipase|phospholipase]].<ref name=Bideshi2006/>

==Virology==
The virions consist of an envelope, a core, and an internal lipid membrane associated with the inner particle. The virus [[Biology:Capsid|capsid]] is [[Biology:Viral envelope|enveloped]] and measures 130&nbsp;nm in diameter, and 200-240&nbsp;nm in length. Virions are bacilliform, ovoid, and allantoid.

{| class="wikitable sortable" style="text-align:center"
|-
! Genus !! Structure || Symmetry !! Capsid !! Genomic arrangement !! Genomic segmentation
|-
|''Ascovirus''||Bacilliform, ovoidal or allantoid||||Enveloped||Circular||Monopartite
|}<ref name=ICTVProfile/><ref name=ICTVReport/><ref name=ViralZone />

These viruses infect immature stages of the order ''[[Biology:Lepidoptera|Lepidoptera]]'', in which they cause a chronic, fatal disease.<ref name=Federici2009>{{Cite book | doi = 10.1007/978-3-540-68618-7_5| chapter = Ascoviruses: Superb Manipulators of Apoptosis for Viral Replication and Transmission| title = Lesser Known Large dsDNA Viruses| volume = 328| pages = 171–96| series = Current Topics in Microbiology and Immunology| year = 2009| vauthors = Federici BA, Bideshi DK, Tan Y, Spears T, Bigot Y | isbn = 978-3-540-68617-0 | pmid=19216438}}</ref> They are transmissed by endoparasitic wasps and the host develops a unique cytopathology that resembles apoptosis. Cell infection induces apoptosis and in some species is associated with synthesis of a virus-encoded executioner [[Biology:Caspase|caspase]] and several lipid-metabolizing enzymes. After infection the host cell DNA is degraded, the nucleus fragments and the cell then cleaves into large virion-containing vesicles. Synthesis of viral proteins results in the rescue of developing apoptotic bodies that are converted into large vesicles in which virions accumulate and continue to assemble. In infected larvae, millions of these virion-containing vesicles begin to disperse from infected tissues 48–72 hours after infection into the haemolymph, making it milky white, a characteristic of this disease.  The circulation of virions and vesicles in the blood facilitates mechanical transmission by parasitic [[Biology:Wasp|wasp]]s.<ref name=Federici2009/>

{| class="wikitable sortable" style="text-align:center"
|-
! Genus !! Host details !! Tissue tropism !! Entry details !! Release details !! Replication site !! Assembly site !! Transmission
|-
|''Ascovirus''||Insects: Noctuids||Most||Cell receptor endocytosis||Cleavage||Nucleus||Cytoplasm||Mechanical
|}
<ref name=ICTVProfile/><ref name=ICTVReport/><ref name=ViralZone />

==Evolution==
Ascoviruses evolved from iridoviruses (family ''[[Biology:Iridoviridae|Iridoviridae]]'') that also attack lepidopteran larvae.<ref name="Federici2009"/> Furthermore, ascoviruses have been suggested as the evolutionary source of [[Biology:Ichnovirus|ichnovirus]]es (family ''[[Biology:Polydnaviridae|Polydnaviridae]]''),<ref name="Federici2009"/><ref name="Bigot2008">{{cite journal | vauthors = Bigot Y, Samain S, Augé-Gouillou C, Federici BA | title = Molecular evidence for the evolution of ichnoviruses from ascoviruses by symbiogenesis | journal = BMC Evolutionary Biology | volume = 8 | issue = 1 | pages = 253 | date = September 2008 | pmid = 18801176 | pmc = 2567993 | doi = 10.1186/1471-2148-8-253 | url =  | doi-access = free }}</ref> although other studies have not been able to confirm this link.<ref>{{cite journal | vauthors = Volkoff AN, Jouan V, Urbach S, Samain S, Bergoin M, Wincker P, Demettre E, Cousserans F, Provost B, Coulibaly F, Legeai F, Béliveau C, Cusson M, Gyapay G, Drezen JM | display-authors = 6 | title = Analysis of virion structural components reveals vestiges of the ancestral ichnovirus genome | journal = PLOS Pathogens | volume = 6 | issue = 5 | pages = e1000923 | date = May 2010 | pmid = 20523890 | pmc = 2877734 | doi = 10.1371/journal.ppat.1000923 | veditors = Asgari S | doi-access = free }}</ref>

== References ==
{{Reflist}}

== External links ==
{{Commons}}
* [http://www.ictv.global/report/ascoviridae '''ICTV Online (10th) Report: Ascoviridae/''']
* [http://www.expasy.org/viralzone/all_by_species/139.html Viralzone: Ascoviridae/]
* {{MeshName|Ascoviridae}}

{{Baltimore classification}}
{{Taxonbar|from=Q6836}}

[[Category:Ascoviridae| ]]
[[Category:Nucleocytoplasmic large DNA viruses]]
[[Category:Virus families]]

{{Sourceattribution|Ascoviridae}}