Bracovirus | |
---|---|
Virus classification | |
(unranked): | Viriform |
Family: | Polydnaviriformidae |
Genus: | Bracoviriform |
Synonyms | |
Bracoviriform
|
Bracovirus is a genus of viruses, in the family Polydnaviridae . Bracoviruses are an ancient symbiotic virus contained in parasitic braconid wasps that evolved from the nudivirus approximately 190 million years ago and has been evolving for at least 100 million years. [1] It is one of two genera belonging to the Polydnaviridae family, with Ichnovirus being the other genus. There are 32 species in this genus. [2] [3]
Parasitoid wasps in the subfamilies Microgastrinae, Miracinae, Cheloninae, Cardiochilinae, Khoikhoiinae, and Mendesellinae are the natural hosts for Bracoviruses, though the virus does not cause disease in these wasps. Instead, the wasps are themselves parasites of lepidoptera. The wasp injects one or more eggs into its lepidoptera host along with a quantity of virus. The virus does not replicate inside the wasp's host, but expression of viral genes prevents its immune system from killing the wasp's egg and causes other physiological alterations that ultimately cause the parasitized host to die. [2] Studies conducted on Cotesia congregata have shown that male wasps do contain proviral sequences of DNA, but the females are the ones responsible for the amplification of the viral DNA. [4]
The genus Bracovirus contained the 32 species in ICTV versions 1999a-2020 [5] The genus Bracoviriform contains the following 31 species starting ICTV version 2021 [3] The species Ichnoviriform rostralis, previously known as Tranosema rostrale bracovirus was moved to Ichnoviriform (Ichnovirus) from Bracoviriform (Bracovirus) in 2021.
Species | Previous name, Virus name | Abbreviation |
---|---|---|
Bracoviriform altitudinis | Chelonus altitudinis bracovirus | CalBV |
Bracoviriform argentifrontis | Ascogaster argentifrons bracovirus | AaBV |
Bracoviriform blackburni | Chelonus blackburni bracovirus | CbBV |
Bracoviriform canadense | Hypomicrogaster canadensis bracovirus | HcBV |
Bracoviriform congregatae | Cotesia congregata bracovirus | CcBV |
Bracoviriform crassicornis | Apanteles crassicornis bracovirus | AcBV |
Bracoviriform croceipedis | Microplitis croceipes bracovirus | McBV |
Bracoviriform curvimaculati | Chelonus nr. curvimaculatus bracovirus | CcBV |
Bracoviriform demolitoris | Microplitis demolitor bracovirus | MdBV |
Bracoviriform ectdytolophae | Hypomicrogaster ectdytolophae bracovirus | HcEV |
Bracoviriform facetosae | Diolcogaster facetosa bracovirus | DfBV |
Bracoviriform flavicoxis | Glyptapanteles flavicoxis bracovirus | GflBV |
Bracoviriform flavipedis | Cotesia flavipes bracovirus | CfBV |
Bracoviriform flavitestaceae | Phanerotoma flavitestacea bracovirus | PfBV |
Bracoviriform fumiferanae | Apanteles fumiferanae bracovirus | AfBV |
Bracoviriform glomeratae | Cotesia glomerata bracovirus | CgBV |
Bracoviriform hyphantriae | Cotesia hyphantriae bracovirus | ChBV |
Bracoviriform inaniti | Chelonus inanitus bracovirus | CinaBV |
Bracoviriform indiense | Glyptapanteles indiensis bracovirus | GiBV |
Bracoviriform insularis | Chelonus insularis bracovirus | CinsBV |
Bracoviriform kariyai | Cotesia kariyai bracovirus | CkBV |
Bracoviriform liparidis | Glyptapanteles liparidis bracovirus | GlBV |
Bracoviriform marginiventris | Cotesia marginiventris bracovirus | CmaBV |
Bracoviriform melanoscelae | Cotesia melanoscela bracovirus | CmeBV |
Bracoviriform nigricipitis | Cardiochiles nigriceps bracovirus | CnBV |
Bracoviriform ornigis | Pholetesor ornigis bracovirus | PoBV |
Bracoviriform paleacritae | Protapanteles paleacritae bracovirus | PpBV |
Bracoviriform quadridentatae | Ascogaster quadridentata bracovirus | AqBV |
Bracoviriform rubeculae | Cotesia rubecula bracovirus | CrBV |
Bracoviriform schaeferi | Cotesia schaeferi bracovirus | CsBV |
Bracoviriform texani | Chelonus texanus bracovirus | CtBV |
Viruses in Bracovirus are enveloped, with prolate ellipsoid and cylindrical geometries. Genomes are circular and segmented, around 2.0-31kb in length. The genome of the virus is enveloped with 35 double stranded DNA (dsDNA) all of which are circular. [2] [4]
Genus | Structure | Symmetry | Capsid | Genomic arrangement | Genomic segmentation |
---|---|---|---|---|---|
Bracovirus | Prolate ellipsoid | Enveloped | Circular | Segmented |
Viral replication is nuclear. DNA-templated transcription is the method of transcription. The virus exits the host cell by nuclear pore export. Transmission routes are parental. [2]
The replication of the Bracoviriform occurs within the ovaries of a parasitic wasps in calyx cells and is maintained by vertical transmission and to go into further detail the packaged genome of dsDNA is replicated inside of the wasp ovaries by development of the sequences of the virus from proviral segments in the tandem arrays in the wasp genome. The development of the sequences of Bracoviriform shows head-to-head and tail-to-tail sequences, which is unexpected, given that it has evolved from the nudivirus [4] The research conducted on Cotesia congregata shows that the viral genome contains one to three proviral segments. [4]
The virus like particle is transmitted into a lepidopteran host (a caterpillar) and infects and manipulates the physiology of the caterpillar so that it can be used as a living incubator for wasp larvae. When this happens the virus disrupts the caterpillar's immune system causing paralysis and inhibiting the pupating of the host. The arresting of the host increases the chance of success of the wasp larva developing successfully. [1]
Genus | Host details | Tissue tropism | Entry details | Release details | Replication site | Assembly site | Transmission |
---|---|---|---|---|---|---|---|
Bracoviriform | Parasitoid wasps (Braconidae) | Hemocytes; fat bodies | Unknown | Lysis; budding | Nucleus | Nucleus | Unknown |
Flaviviridae is a family of enveloped positive-strand RNA viruses which mainly infect mammals and birds. They are primarily spread through arthropod vectors. The family gets its name from the yellow fever virus; flavus is Latin for "yellow", and yellow fever in turn was named because of its propensity to cause jaundice in victims. There are 89 species in the family divided among four genera. Diseases associated with the group include: hepatitis (hepaciviruses), hemorrhagic syndromes, fatal mucosal disease (pestiviruses), hemorrhagic fever, encephalitis, and the birth defect microcephaly (flaviviruses).
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.
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Polydnaviriformidae ( PDV) is a family of insect viriforms; members are known as polydnaviruses. There are two genera in the family: Bracoform and Ichnoviriform. Polydnaviruses form a symbiotic relationship with parasitoid wasps. Ichnoviriforms (IV) occur in Ichneumonid wasps and Bracoviriforms (BV) in Braconid wasps. The larvae of wasps in both of those groups are themselves parasitic on Lepidoptera, and the polydnaviruses are important in circumventing the immune response of their parasitized hosts. Little or no sequence homology exists between BV and IV, suggesting that the two genera have been evolving independently for a long time.
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Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causing the death of these hosts. Different species specialise in hosts from different insect orders, most often Lepidoptera, though some select beetles, flies, or bugs; the spider wasps (Pompilidae) exclusively attack spiders.
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Cotesia congregata is a parasitoid wasp of the genus Cotesia. The genus is particularly noted for its use of polydnaviruses. Parasitoids are distinct from true parasites in that a parasitoid will ultimately kill its host or otherwise sterilize it.
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Aurivirus is a genus of viruses in the order Herpesvirales, and one of only two genera the family Malacoherpesviridae. Haliotid molluscs serve as natural hosts. There is only one species described in this genus, Haliotid herpesvirus 1 (AbHV-1), commonly known as abalone herpesvirus. A disease associated with this virus is acute ganglioneuritis.
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