Parvoviridae
Encyclopedia
The Parvoviridae family includes the smallest known virus
es, and some of the most environmentally resistant. They were discovered during the 1960s and affect vertebrate
s and insect
s. Parvoviridae have a genome
consisting of single-stranded DNA
and an icosahedral
capsid
.
Parvovirus B19
was the first human parvovirus to be discovered and is best known for causing a childhood exanthem
called "fifth disease
" (erythema infectiosum), although it is also associated with other diseases including arthritis
.
Parvovirus RA-1 had originally also been associated with rheumatoid arthritis
, but this is now thought to have been an error due to laboratory contamination.
The genome is 4-6 kilobases in length and usually encodes two 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. In the genus Bocavirus there is a third open reading frame between the non structural and structural open reading frames.
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.
The species Chipmunk parvovirus currently placed in the Erythovirus genus probably belongs in a separate genus.
Subfamily Parvovirinae:
Subfamily Densovirinae:
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es, and some of the most environmentally resistant. They were discovered during the 1960s and affect vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
s and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s. Parvoviridae have a genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
consisting of single-stranded DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
and an icosahedral
Icosahedron
In geometry, an icosahedron is a regular polyhedron with 20 identical equilateral triangular faces, 30 edges and 12 vertices. It is one of the five Platonic solids....
capsid
Capsid
A capsid is the protein shell of a virus. It consists of several oligomeric structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The capsid encloses the genetic...
.
Parvovirus B19
Parvovirus B19
The B19 virus, generally referred to as parvovirus B19 or sometimes erythrovirus B19, was the first known human virus in the family of parvoviruses, genus erythrovirus...
was the first human parvovirus to be discovered and is best known for causing a childhood exanthem
Exanthem
An exanthem is a widespread rash usually occurring in children. Exanthems can be caused by toxins or drugs, microorganisms, or can result from autoimmune disease.It can be contrasted with an enanthem.-Types:...
called "fifth disease
Fifth disease
Erythema infectiosum or fifth disease is one of several possible manifestations of infection by erythrovirus, previously called parvovirus B19. The disease is also referred to as slapped cheek syndrome, slapcheek, slap face or slapped face. In Japan the disease is called 'apple sickness' or...
" (erythema infectiosum), although it is also associated with other diseases including arthritis
Arthritis
Arthritis is a form of joint disorder that involves inflammation of one or more joints....
.
Parvovirus RA-1 had originally also been associated with rheumatoid arthritis
Rheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
, but this is now thought to have been an error due to laboratory contamination.
Virology
The viruses in this family 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 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. In the genus Bocavirus there is a third open reading frame between the non structural and structural open reading frames.
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
The family is divided into two subfamilies - Parvovirinae - which infect vertebrates and - Densovirinae - which infect invertebrates. Each subfamily has been subdivided into several genera. The classification of the subfamily Parvovirinae may need revision. The Amdovirus and Parvovirus genera are probably more closely related to one another than to the other genera in this family.The species Chipmunk parvovirus currently placed in the Erythovirus genus probably belongs in a separate genus.
Subfamily Parvovirinae:
- Genus AmdovirusAmdovirusAmdovirus is a genus of the Parvoviridae family of viruses. One well known member is Aleutian mink disease virus.-External links:* *...
; type species: Aleutian mink disease virus - Genus BocavirusBocavirusBocavirus is a genus in the family Parvoviridae, subfamily Parvovirinae.The type species is bovine bocavirus.-Genome:Like the other members of this family bocaviuses have two open reading frames - ORF1 and 2. Uniquely among parvoviruses, the bocaviruses they contain a third open reading frame...
; type species: Bovine parvovirus - Genus DependovirusDependovirusDependovirus is a genus of the Parvoviridae viruses, which are Group II viruses according to the Baltimore classification. The Dependovirus is part of the sub family of the Parvoviridae family known as the Parvovirinae...
; type species: Adeno-associated virus 2 - Genus ErythrovirusErythrovirusErythrovirus is a genus of viruses in the family Parvoviridae.The type species is parvovirus B19.-Virology:Erythroviruses are small , non-enveloped icosahedral viruses...
; type species: B19 virus - Genus Partetravirus;
- Genus ParvovirusParvovirusParvovirus, often truncated to "parvo", is both the common name in English casually applied to all the viruses in the Parvoviridae taxonomic family, and also the taxonomic name of the Parvovirus genus within the Parvoviridae family...
; type species: Murine minute virus
Subfamily Densovirinae:
- Genus Brevidensovirus; type species: Aedes aegypti densovirus
- Genus ContravirusContraVirusContraVirus is a Rogue Spyware application that poses as a legitimate anti-spyware program. The application uses a false scanner to force computer users to pay for the removal of non-existent spyware items. It may also be known as ExpertAntivirus....
- Genus DensovirusDensovirusThe virus genus Densovirus belongs to the Densovirinae subfamily which belongs to the Parvoviridae family. The viruses of this genus are single-stranded DNA viruses . The viruses of this genus are invertebrate viruses, infecting crustaceans and insects...
; type species: Junonia coenia densovirus - Genus Iteravirus; type species: Bombyx mori densovirus
- Genus Pefudensovirus; type species: Periplanta fuliginosa densovirus