Ascoviridae

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Ascoviridae
Virus classification
Group: Group I (dsDNA)
Family: Ascoviridae
Genera
  • Ascovirus

Ascoviridae is a family of double strand DNA viruses that infect primarily invertebrates;[1] mainly noctuids and spodoptera species.[2] There are currently four species in this family, divided among 1 genera (Ascovirus). The type species is Spodoptera frugiperda ascovirus 1a which infects the army worm (Spodoptera frugiperda).[3]

Taxonomy[edit]

Group: dsDNA

[4]

Genome[edit]

Genome

The genome is not segmented and contains a single molecule of circular double-stranded DNA. The genome has a guanine + cytosine content of 42-60%.

The genome of Spodoptera frugiperda ascovirus 1a has been sequenced.[5] 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 caspase, a cathepsin B, several kinases, E3 ubiquitin ligases, a fatty acid elongase, a sphingomyelinase, a phosphate acyltransferase and a patatin-like phospholipase.[citation needed]

Virology[edit]

The virions consist of an envelope, a core, and an internal lipid membrane associated with the inner particle. The virus capsid is enveloped and measures 130 nm in diameter, and 200-240 nm in length. Virions are bacilliform, ovoid, and allantoid.

Genus Structure Symmetry Capsid Genomic Arrangement Genomic Segmentation
Ascovirus Bacilliform, ovoidal or allantoid Enveloped Circular Monopartite

[2]

These viruses infect immature stages of the order Lepidoptera, in which they cause a chronic, fatal disease.[6] 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 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 wasps.[citation needed]

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

[2]

Evolution[edit]

Ascoviruses evolved from iridoviruses (family Iridoviridae) that also attack lepidopteran larvae and are likely the evolutionary source of ichnoviruses (family Polydnaviridae).[6]

References[edit]

  1. ^ ICTVdB Management (2006). 00.082.0.01. Ascovirus. In: ICTVdB - The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA[page needed]
  2. ^ a b c "Viral Zone". ExPASy. Retrieved 12 June 2015. 
  3. ^ Xue, J. -L.; Cheng, X. -W. (2011). "Comparative analysis of a highly variable region within the genomes of Spodoptera frugiperda ascovirus 1d (SfAV-1d) and SfAV-1a". Journal of General Virology 92 (12): 2797. doi:10.1099/vir.0.035733-0.  edit
  4. ^ ICTV. "Virus Taxonomy: 2014 Release". Retrieved 12 June 2015. 
  5. ^ Bideshi, D. K.; Demattei, M. -V.; Rouleux-Bonnin, F.; Stasiak, K.; Tan, Y.; Bigot, S.; Bigot, Y.; Federici, B. A. (2006). "Genomic Sequence of Spodoptera frugiperda Ascovirus 1a, an Enveloped, Double-Stranded DNA Insect Virus That Manipulates Apoptosis for Viral Reproduction". Journal of Virology 80 (23): 11791. doi:10.1128/JVI.01639-06.  edit
  6. ^ a b Federici, B. A.; Bideshi, D. K.; Tan, Y.; Spears, T.; Bigot, Y. (2009). "Ascoviruses: Superb Manipulators of Apoptosis for Viral Replication and Transmission". Lesser Known Large dsDNA Viruses. Current Topics in Microbiology and Immunology 328. pp. 171–96. doi:10.1007/978-3-540-68618-7_5. ISBN 978-3-540-68617-0. PMID 19216438.  edit

External links[edit]