| Densovirinae | |
|---|---|
Virus classification | |
| (unranked): | Virus |
| Realm: | Monodnaviria |
| Kingdom: | Shotokuvirae |
| Phylum: | Cossaviricota |
| Class: | Quintoviricetes |
| Order: | Piccovirales |
| Family: | Parvoviridae |
| Subfamily: | Densovirinae |
| Genera | |
Densovirinae[1] is a subfamily of single-strandedDNA viruses in the familyParvoviridae.[2][3] The subfamily has 11 recognized genera.[4] Densoviruses are known to infect members of insect ordersBlattodea,Diptera,Hemiptera,Hymenoptera,Lepidoptera, andOrthoptera, while some viruses infect and multiply in crustaceans such asshrimp orcrayfish, orsea stars from phylumEchinodermata.[3]
Densoviruses are small (18–26 nanometers in diameter) and non enveloped. Virions are icosahedral in shape with triangulation number (T) = 1. There are 60copies 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 containlipids.[5][6]
Genomes are non-segmented, about 4–6 kilobases in length and usually contain two or threeopen 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 ambisense, encoding proteins on both the positive sense and negative sense directions.Transcriptional regulation andpost-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 byclathrin-mediated endocytosis[10] orclathrin-independentdynamin-dependentendocytosis.[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 forreplication andtranscription. 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]
Eleven genera are currently recognized:[4]
Ambidensovirus was previously recognized as a genus, but in 2019 it was split into the six genera prefixed withAqu-,Blatt-,Hemi-,Pefu-,Proto-, andScindo-.[12]