Densovirinae

Densovirinae is a subfamily of single-stranded DNA viruses in the family Parvoviridae. It currently contains 5 genera and 21 recognized species.^[1]The host range includes members of insect orders Blattodea, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera, while some viruses infect and multiply in crustceans such as shrimp or crayfish, or sea stars from phylum Echinodermata.

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.

Genomes are 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 NS-1 protein has a superfamily 3 DNA helicase motif. These motifs are common in DNA viruses. The proteins that contain these motifs bind to the origin of replication and unwind the viral genome 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.

Taxonomy

Five genera are currently recognized, containing a combined twenty species:

Ambidensovirus; type species: Lepidopteran ambidensovirus 1

Brevidensovirus; type species: Dipteran brevidensovirus 1

Hepandensovirus; type species: Decapod hepandensovirus 1

Iteradensovirus; type species: Lepidopteran iteradensovirus 1

Penstyldensovirus; type species: Decapod penstyldensovirus 1

and there is one recognized but unclassified species:

Orthopteran densovirus 1; virus name: Acheta domestica mini ambidensovirus

References