Densovirinae

Densovirinae[1] is a subfamily of single-stranded DNA viruses in the family Parvoviridae.[2][3] The subfamily currently has 8 recognized genera and 17 species.[4] Densoviruses are known to infect members of insect orders Blattodea, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera, while some viruses infect and multiply in crustaceans such as shrimp or crayfish, or sea stars from phylum Echinodermata.[3]

Densovirinae
Virus classification
(unranked): Virus
Realm: Monodnaviria
Kingdom: Shotokuvirae
Phylum: Cossaviricota
Class: Quintoviricetes
Order: Piccovirales
Family: Parvoviridae
Subfamily: Densovirinae
Genera

See text

Virology

Densoviruses are small (18–26 nanometers in diameter) and non enveloped. Virions are icosahedral in shape with triangulation number (T) = 1. There are 60 copies of the coat protein in the virion. Each copy has a shape described as a "quadrilateral 'kite-shaped' wedge", and the appearance of the surface is rough with many small projections. Virions do not appear to contain lipids.[5][6]

Genomes are non-segmented, about 4–6 kilobases in length and usually contain two or three open reading frames. The 5' open reading frame encodes two nonstructural proteins (NS-1 and NS-2) and the 3' open reading frame encodes two or three capsid proteins (VP1, VP2, VP3). Both the 5' and 3' termini have hairpin loops. If a third open reading frame is present (depends on the genus) it encodes a second non structural protein. The genome is anmbisense, encoding proteins on both the positive sense and negative sense directions. Transcriptional regulation and post-transcriptional modification are used to produce different nonstructural proteins and structural proteins.[7][8][9][6]

Virions enter the host cell is achieved by attachment to host receptors, which may be mediated by clathrin-mediated endocytosis[10] or clathrin-independent dynamin-dependent endocytosis.[11] The NS-1 protein has a superfamily 3 DNA helicase and an HuH endonuclease motif. These motifs are common in small DNA viruses. The proteins that contain these motifs bind to the viral origins of replication and unwind and nick these origins, allowing access by the host's proteins to the viral genome for replication and transcription. The genome is replicated by a unique rolling hairpin mechanism. DNA-templated transcription, with some alternative splicing mechanism is the manner of transcription.[3][10]

Taxonomy

Eight genera are currently recognized, containing a combined 17 species:

  • Aquambidensovirus
  • Blattambidensovirus
  • Hemiambidensovirus
  • Iteradensovirus
  • Miniambidensovirus
  • Pefuambidensovirus
  • Protoambidensovirus
  • Scindoambidensovirus

Ambidensovirus was previously recognized as a genus, but in 2019 it was split into the six genera prefixed with Aqu-, Blatt-, Hemi-, Pefu-, Proto-, and Scindo-.[12]

References
  1. "Subfamily: Densovirinae". ICTV Report on Virus Taxonomy (10th Report). ICTV. Retrieved 13 May 2020.
  2. Cotmore, SF; Agbandje-McKenna, M; Canuti, M; Chiorini, JA; Eis-Hubinger, A; Hughes, J; Mietzsch, M; Modha, S; Ogliastro, M; Pénzes, JJ; Pintel, DJ; Qiu, J; Soderlund-Venermo, M; Tattersall, P; Tijssen, P; and the ICTV Report Consortium (2019). "ICTV Virus Taxonomy Profile: Parvoviridae". Journal of General Virology. 100 (3): 367–368. doi:10.1099/jgv.0.001212. PMC 6537627. PMID 30672729.
  3. "ICTV 10th Report (2018) Parvoviridae".
  4. "Virus Taxonomy: 2019 Release". talk.ictvonline.org. International Committee on Taxonomy of Viruses. Retrieved 8 May 2020.
  5. "Densovirinae". ICTVdB—The Universal Virus Database, version 4. Retrieved 12 May 2020.
  6. Simpson AA, Chipman PR, Baker TS, Tijssen P, Rossmann MG (November 1998). "The structure of an insect parvovirus (Galleria mellonella densovirus) at 3.7 A resolution". Structure. 6 (11): 1355–67. doi:10.1016/S0969-2126(98)00136-1. PMC 4167665. PMID 9817847.
  7. Pham HT, Huynh OT, Jousset FX, Bergoin M, Tijssen P (August 2013). "Junonia coenia Densovirus (JcDNV) Genome Structure". Genome Announcements. 1 (4). doi:10.1128/genomeA.00591-13. PMC 3738899. PMID 23929483.
  8. Dumas B, Jourdan M, Pascaud AM, Bergoin M (November 1992). "Complete nucleotide sequence of the cloned infectious genome of Junonia coenia densovirus reveals an organization unique among parvoviruses". Virology. 191 (1): 202–22. doi:10.1016/0042-6822(92)90182-O. PMID 1413502.
  9. Bruemmer A, Scholari F, Lopez-Ferber M, Conway JF, Hewat EA (April 2005). "Structure of an insect parvovirus (Junonia coenia Densovirus) determined by cryo-electron microscopy". Journal of Molecular Biology. 347 (4): 791–801. doi:10.1016/j.jmb.2005.02.009. PMID 15769470.
  10. "Viral Zone". ExPASy. Retrieved 12 May 2020.
  11. Wang Y, Gosselin Grenet AS, Castelli I, Cermenati G, Ravallec M, Fiandra L, Debaisieux S, Multeau C, Lautredou N, Dupressoir T, Li Y, Casartelli M, Ogliastro M (November 2013). "Densovirus crosses the insect midgut by transcytosis and disturbs the epithelial barrier function". Journal of Virology. 87 (22): 12380–91. doi:10.1128/JVI.01396-13. PMC 3807927. PMID 24027326.
  12. "ICTV Taxonomy history: Ambidensovirus". talk.ictvonline.org. International Committee on Taxonomy of Viruses. Retrieved 12 May 2020.
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