| Parvoviruses | |
|---|---|
| Virus classification | |
| Group: | Group II (ssDNA) |
| Family: | Parvoviridae |
| Subfamily: | Densovirinae |
| Genera | |
|
Brevidensovirus |
|
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.
The viruses in this subfamily are small (18-26 nanometers in diameter) and non enveloped. The viron is isosahedral with triangulation number (T) = 1. There are 60 copies of the coat protein in the viron.
The genome is 4-6 kilobases in length and usually encodes 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.
There are four genera currently recognised: Brevidensovirus, Densovirus, Iteravirus and Pefudensovirus.
This subfamily also includes a number of unclassified viruses.