Iridoviridae

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Iridoviridae
Iridovirus 2.jpg
TEM micrograph showing a cluster of Iridovirus virions
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(unranked): Virus
Realm: Varidnaviria
Kingdom: Bamfordvirae
Phylum: Nucleocytoviricota
Class: Megaviricetes
Order: Pimascovirales
Family:Iridoviridae
Subfamilies and genera

See text

Iridoviridae is a family of viruses with double-stranded DNA genomes. [1] Amphibians, fish, and invertebrates such as arthropods serve as natural hosts. There are currently 22 species in this family, divided among two subfamilies and seven genera. [1] [2]

Contents

Nomenclature

The name is derived from Iris, the Greek goddess of the rainbow. This name was chosen because of the "rainbow-like" iridescence observed in heavily infected insects and pelleted samples of invertebrate iridoviruses. It may refer to any member of the Iridoviridae family or a particular genus within Iridoviridae.[ citation needed ]

Taxonomy

The following subfamilies and genera are recognized (-virinae denotes subfamily and -virus denotes genus):[ citation needed ]

Structure

The virions are icosahedral with triangulation number (T) = 189–217, 120–350 nm in diameter and made up of three domains: an outer proteinaceous capsid, an intermediate lipid membrane, and a central core containing DNA-protein complexes. Some of the viruses also have an outer envelope. The presence or absence of an envelope depends on whether they budded from the cell membrane (enveloped viruses) or were arranged in paracrystalline arrays within the host cell cytoplasm and then were released by cell lysis (unenveloped viruses).[ citation needed ]

The linear genome varies between 150 and 303 kilobases in length. It contains terminal and redundant sequences and is circularly permuted.[ citation needed ]

Members of this family differ in their degree of genome methylation. The genera Chloriridovirus and Iridovirus lack a highly methylated genome. Members of Lymphocystivirus, Megalocytivirus, and Ranavirus have genomes with about 25% of their cytosine residues methylated by a virally encoded DNA methyltransferase.[ citation needed ]

GenusStructureSymmetryGenomic arrangementGenomic segmentation
LymphocystivirusPolyhedralT=189–217LinearMonopartite
MegalocytivirusPolyhedralT=189–217LinearMonopartite
RanavirusPolyhedralT=133 or 147LinearMonopartite
IridovirusPolyhedralT=147LinearMonopartite
ChloriridovirusPolyhedralT=189–217LinearMonopartite

Gene expression

Similar to the herpes viruses, transcription occurs in three stages: immediate-early, delayed-early, and late. Positive induction and negative feedback mechanisms exist in each stage, mediated by products of the other stages.[ citation needed ]

Replication

Virus particles enter the cell and uncoating occurs. The viral DNA is transported to the host cell nucleus, where it is transcribed by host RNA polymerase II modified by the virus. Meanwhile, host macromolecular synthesis ceases.

Parental DNA produces a genome which is then the template for replication in the cytoplasm. Large concatemers of viral DNA are formed by recombination in the cytoplasm. Packaging of the new genomes into virions occurs in the cytoplasm and the virus is released either by budding from the cell membrane or cell lysis.

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
Lymphocystivirus FishNoneCell receptor endocytosisLysis; buddingNucleusCytoplasmUnknown
Megalocytivirus FishNoneCell receptor endocytosisLysis; buddingNucleusCytoplasmUnknown
Ranavirus Frogs; snakesNoneCell receptor endocytosisLysis; buddingNucleusCytoplasmContact
Iridovirus InsectsNoneCell receptor endocytosisLysis; buddingNucleusCytoplasmContact
Chloriridovirus Diptera with aquatic larval stage, mainly mosquitoesNoneCell receptor endocytosisBuddingNucleusCytoplasmUnknown

DNA repair

Members of the Iridoviridae appear to have the capability to repair DNA damages. [3]

Pathogenesis

Little is known about the pathogenesis of iridoviruses. The pathogenesis is, however, temperature dependent and iridoviruses are thus confined to poikilothermic hosts.[ citation needed ]

Host range

Members of the Iridoviridae family infect mainly invertebrates, but also some vertebrate species such as fish, amphibians and reptiles.[ citation needed ]

Related Research Articles

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<i>Hepadnaviridae</i> Family of viruses

Hepadnaviridae is a family of viruses. Humans, apes, and birds serve as natural hosts. There are currently 18 species in this family, divided among 5 genera. Its best-known member is hepatitis B virus. Diseases associated with this family include: liver infections, such as hepatitis, hepatocellular carcinomas, and cirrhosis. It is the sole accepted family in the order Blubervirales.

<i>Poxviridae</i> Family of viruses

Poxviridae is a family of double-stranded DNA viruses. Vertebrates and arthropods serve as natural hosts. There are currently 83 species in this family, divided among 22 genera, which are divided into two subfamilies. Diseases associated with this family include smallpox.

<i>Parapoxvirus</i> Genus of viruses

Parapoxvirus is a genus of viruses, in the family Poxviridae, in the subfamily Chordopoxvirinae. Like all members of the family Poxviridae, they are oval, relatively large, double-stranded DNA viruses. Parapoxviruses have a unique spiral coat that distinguishes them from other poxviruses. Parapoxviruses infect vertebrates, including a wide selection of mammals, and humans.

<span class="mw-page-title-main">Tectivirus</span> Family of viruses

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<i>Ascoviridae</i> Family of viruses

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<i>Ranavirus</i> Genus of viruses

Ranavirus is a genus of viruses in the family Iridoviridae. There are six other genera of viruses within the family Iridoviridae, but Ranavirus is the only one that includes viruses that are infectious to amphibians and reptiles. Additionally, it is one of the three genera within this family which infect teleost fishes, along with Lymphocystivirus and Megalocytivirus.

Yatapoxvirus is a genus of viruses, in the family Poxviridae, in the subfamily Chordopoxvirinae. Monkeys and baboons serve as natural hosts. There are two species in this genus. Diseases associated with this genus include: histiocytomas, tumor-like mass of mononuclear cells.

Lymphocystivirus is a genus of viruses, in the family Iridoviridae. Fish serve as natural hosts. There are four species in this genus. Diseases associated with this genus include: tumor-like growths on the skin.

Chordopoxvirinae is a subfamily of viruses in the family Poxviridae. Vertebrates and arthropods serve as natural hosts. Currently, 52 species are placed in this subfamily, divided among 18 genera. Diseases associated with this subfamily include smallpox.

Entomopoxvirinae is a subfamily of viruses, in the family Poxviridae. Insects, human, vertebrates, and arthropods serve as natural hosts. There are currently 31 species in this subfamily, divided among 4 genera with one species unassigned to a genus. Diseases associated with this subfamily include: impairment of motility and development.

Chloriridovirus is a genus of viruses, in the family Iridoviridae. Diptera with aquatic larval stage, mainly mosquitoes, lepidoptera, and orthoptera insects serve as natural hosts. There are five species in this genus. Diseases associated with this genus include: yellow-green iridescence beneath the epidermis. Death rates are highest in the fourth instar. Viruses within this genus have been found to infect mosquito larvae, in which they produce various iridescent colors.

Alphaentomopoxvirus is a genus of viruses, in the family Poxviridae, in the subfamily Entomopoxvirinae. Coleoptera insects serve as natural hosts. There are seven species in this genus.

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Betaentomopoxvirus is a genus of viruses, in the family Poxviridae, in the subfamily Entomopoxvirinae. Lepidoptera and orthoptera insects serve as natural hosts. There are 16 species in this genus.

Cervidpoxvirus is a genus of viruses in the family Poxviridae in the subfamily Chordopoxvirinae. Deer serve as natural hosts. Only one species is in this genus: Mule deerpox virus.

Gammaentomopoxvirus is a genus of viruses, in the family Poxviridae, in the subfamily Entomopoxvirinae. Lepidoptera and orthoptera insects serve as natural hosts. There are six species in this genus.

Leporipoxvirus is a genus of viruses, in the family Poxviridae, in the subfamily Chordopoxvirinae. Lagomorphs and squirrels serve as natural hosts. There are four species in this genus. Diseases associated with this genus include: myxomatosis.

Crocodylidpoxvirus is a genus of viruses, in the family Poxviridae, in the subfamily Chordopoxvirinae. Crocodiles serve as natural hosts. There is only one species in this genus: Nile crocodilepox virus. Diseases associated with this genus include: nodular skin lesions in young animals. Symptoms vary from a nonfatal dermatitis to more severe disease characterized by ophthalmia, rhinitis resulting in asphyxia, and debilitating illness with stunting and high mortality.

<i>Red deerpox virus</i> Species of virus

Red deerpox virus (RDPV) is a species of virus in the genus Parapoxvirus. It has been reported in deer in New Zealand, and in wild ruminants in Italy.

References

  1. 1 2 "Iridoviridae". ICTV Online (10th) Report.
  2. ↑ "Viral Zone". ExPASy. Retrieved 15 June 2015.
  3. ↑ Ke F, Zhang QY. ADRV 12L: A Ranaviral Putative Rad2 Family Protein Involved in DNA Recombination and Repair. Viruses. 2022 Apr 27;14(5):908. doi: 10.3390/v14050908. PMID 35632650; PMCID: PMC9146916

MicrobiologyBytes: Iridoviruses, archived from the original on February 24, 2007, retrieved 2007-03-06 Viral Bioinformatics Resource Center & Viral Bioinformatics – Canada, University of Victoria, archived from the original on August 17, 2007, retrieved 2007-03-06

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