Densovirinae

Densovirinae is a subfamily of single-stranded DNA viruses in the family Parvoviridae. The host range includes members of Dictyoptera, Diptera, Lepidoptera, Odonata and Orthoptera. Densovirus-like viruses also infect and multiply in crabs and shrimp.

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

There are five genera currently recognised, of which a combined fifteen species belong to:

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

References