Myxoma virus

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Myxoma virus
Myxoma virus (transmission electron microscope).jpg
Electron micrograph of Myxoma virus virion
Virus classification OOjs UI icon edit-ltr.svg
(unranked): Virus
Realm: Varidnaviria
Kingdom: Bamfordvirae
Phylum: Nucleocytoviricota
Class: Pokkesviricetes
Order: Chitovirales
Family: Poxviridae
Genus: Leporipoxvirus
Species:
Myxoma virus

Myxoma virus is a poxvirus in the genus Leporipoxvirus . The two broad geographic types of myxoma virus are Californian and South American. Californian myxoma virus is found on the West Coast of the United States, the Baja Peninsula of Mexico, and the southwest coast of Canada. South American or Brazilian myxoma virus is found in South and Central America. South American myxoma virus circulates in the jungle rabbit or tapeti (Sylvilagus brasiliensis), whereas Californian myxoma virus circulates in the brush rabbit (Sylvilagus bachmani). In their native hosts, the viruses cause the formation of benign cutaneous fibromas rather than systemic disease.

Contents

Transmission

Myxoma virus is passively transmitted on the mouth parts of mosquitoes, (such as Aedes aegyptii ) or fleas, and presumably other biting arthropods. [1] [2] It can also be spread through direct contact and contaminated fomites.[ citation needed ]

Myxomatosis

Myxomatosis is the name of the lethal disseminated disease that occurs when European rabbits (Oryctolagus cuniculus) are infected with myxoma virus; both the South and North American types are capable of causing this disease. Californian myxoma virus is particularly virulent, causing 100% mortality. [3]

Structure and genome

Virions are enveloped, and have a surface membrane with lateral bodies. The envelope contains host-derived lipids and self-synthesized glycolipids. They are brick-shaped and about 250 nanometers in diameter, 300 nm in length, and 200 nm in height. The middle contains a biconcave core that appears to be characteristic to many poxviruses.[ citation needed ]

Evolution history of myxoma virus Evolutionary History of MYXV.tiff
Evolution history of myxoma virus

The genome is nonsegmented and contains a single molecule of linear, double-stranded DNA, 160,000 nucleotides in length. The genome has a G–C content around 40%, with terminally redundant sequences, which are repeated at both ends. [5]

The genome encodes 170 open reading frames, 12 of which are duplicated in the terminal inverted repetitions. [4]

Infection and pathology

During their normal lifecycles, virions produce extracellular and intracellular proteins. The extracellular proteins are used primarily for suppressing or circumventing the host immune responses, hence are nonessential. Infection is also initiated by extracellular virions. Myxoma virus matures naturally by budding through the surface membrane of the host cell. [6]

Myxoma virus has multiple methods that it uses to evade the immune system. One route of protection involves blocking the caspase activity within the host cells. The E13L viral protein is able to inhibit the caspases by binding to the CARD protein, which is part of the caspase-1-activating inflammasome complex. By binding, it is able to inhibit apoptosis, which is normally induced by the CARD protein. In addition, myxoma virus uses the Serp-2 viral gene to inhibit a variety of other caspases. The Serp-2 gene is also capable of inhibiting granzyme B, a cysteine protease. [7] :161

Myxoma virus is also capable of producing tumor necrosis factor receptor mimics to reduce the host's natural response to TNF. The M-T2 protein is a soluble receptor that mimics the TNF receptors within rabbits. [7] :157

Most rabbit and hare hosts are susceptible to the virus, which means the virus can effectively evade the host immunity, but susceptibility is not the primary indicator for symptomatic infection or pathology. A distinction must be made between susceptibility and permissibility, in which only the latter must be true before the virus is able to replicate in the cell and cause pathologies. This is the reason myxoma virus is very species-specific; it is able to circumvent a certain species of rabbit's immune response, but is unable to do so for any other species. The virus is able to get into the cells of many different species, though, including human, mouse, and monkey, which is generally useless if it is unable to replicate and avoid the immune system.[ citation needed ]

In 1993, the Australian government approved a modification of myxoma virus that would introduce genetic code into rabbit sperm and egg proteins. This mutation would induce an autoimmune response and inhibit fertility. [8] This immunocontraceptive vaccine is still[ when? ] being tested for wild release.[ citation needed ]

Research

The myxoma virus has become of interest in human medicine because some of its proteins have strong immunosuppressive effects, and several of its virus-encoded immunomodulators are being developed to treat systemic inflammatory syndromes in people such as cardiovascular disease. Myxoma virus also can infect many types of human cancer cells, which is being used to develop it as a virotherapeutic agent for virotherapy. [9]

Related Research Articles

<span class="mw-page-title-main">Myxomatosis</span> Rabbit disease caused by Myxoma virus

Myxomatosis is a disease caused by Myxoma virus, a poxvirus in the genus Leporipoxvirus. The natural hosts are tapeti in South and Central America, and brush rabbits in North America. The myxoma virus causes only a mild disease in these species, but causes a severe and usually fatal disease in European rabbits.

<i>Papillomaviridae</i> Family of viruses

Papillomaviridae is a family of non-enveloped DNA viruses whose members are known as papillomaviruses. Several hundred species of papillomaviruses, traditionally referred to as "types", have been identified infecting all carefully inspected mammals, but also other vertebrates such as birds, snakes, turtles and fish. Infection by most papillomavirus types, depending on the type, is either asymptomatic or causes small benign tumors, known as papillomas or warts. Papillomas caused by some types, however, such as human papillomaviruses 16 and 18, carry a risk of becoming cancerous.

<i>Dengue virus</i> Species of virus

Dengue virus (DENV) is the cause of dengue fever. It is a mosquito-borne, single positive-stranded RNA virus of the family Flaviviridae; genus Flavivirus. Four serotypes of the virus have been found, and a reported fifth has yet to be confirmed, all of which can cause the full spectrum of disease. Nevertheless, scientists' understanding of dengue virus may be simplistic as, rather than distinct antigenic groups, a continuum appears to exist. This same study identified 47 strains of dengue virus. Additionally, coinfection with and lack of rapid tests for Zika virus and chikungunya complicate matters in real-world infections.

<i>Measles morbillivirus</i> Species of virus

Measles morbillivirus(MeV), also called measles virus (MV), is a single-stranded, negative-sense, enveloped, non-segmented RNA virus of the genus Morbillivirus within the family Paramyxoviridae. It is the cause of measles. Humans are the natural hosts of the virus; no animal reservoirs are known to exist.

Viral pathogenesis is the study of the process and mechanisms by which viruses cause diseases in their target hosts, often at the cellular or molecular level. It is a specialized field of study in virology.

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

A polydnavirus (PDV) or more recently, polydnaviriform is a member of the family Polydnaviridae of insect viruses. 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.

<i>Gammaretrovirus</i> Genus of viruses

Gammaretrovirus is a genus in the Retroviridae family. Example species are the murine leukemia virus and the feline leukemia virus. They cause various sarcomas, leukemias and immune deficiencies in mammals, reptiles and birds.

<i>Herpesviridae</i> Family of DNA viruses

Herpesviridae is a large family of DNA viruses that cause infections and certain diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word ἕρπειν, referring to spreading cutaneous lesions, usually involving blisters, seen in flares of herpes simplex 1, herpes simplex 2 and herpes zoster (shingles). In 1971, the International Committee on the Taxonomy of Viruses (ICTV) established Herpesvirus as a genus with 23 viruses among four groups. As of 2020, 115 species are recognized, all but one of which are in one of the three subfamilies. Herpesviruses can cause both latent and lytic infections.

<span class="mw-page-title-main">Viral envelope</span> Outermost layer of many types of the infectious agent

A viral envelope is the outermost layer of many types of viruses. It protects the genetic material in their life cycle when traveling between host cells. Not all viruses have envelopes. A viral envelope protein or E protein is a protein in the envelope, which may be acquired by the capsid from an infected host cell.

<i>Molluscum contagiosum virus</i> Species of virus

Molluscum contagiosum virus (MCV) is a species of DNA poxvirus that causes the human skin infection molluscum contagiosum. Molluscum contagiosum affects about 200,000 people a year, about 1% of all diagnosed skin diseases. Diagnosis is based on the size and shape of the skin lesions and can be confirmed with a biopsy, as the virus cannot be routinely cultured. Molluscum contagiosum virus is the only species in the genus Molluscipoxvirus. MCV is a member of the subfamily Chordopoxvirinae of family Poxviridae. Other commonly known viruses that reside in the subfamily Chordopoxvirinae are variola virus and monkeypox virus.

<span class="mw-page-title-main">Mengovirus</span> Species of virus

Mengovirus, also known as Columbia SK virus, mouse Elberfield virus, and Encephalomyocarditisvirus (EMCV), belongs to the genus Cardiovirus which is a member of the Picornaviridae. Its genome is a single stranded positive-sense RNA molecule, making the Mengoviruses a class IV virus under the Baltimore classification system. The genome is approximately 8400nt in length, and has 5’ VG protein and a 3’ polyadenine tail. Mengovirus was isolated by George W. A. Dick in 1948, in the Mengo district of Entebbe in Uganda, from a captive rhesus monkey that had developed hind limb paralysis.

<span class="mw-page-title-main">Viral shedding</span> Dissemination of mature virions from host cell

Viral shedding is the expulsion and release of virus progeny following successful reproduction during a host cell infection. Once replication has been completed and the host cell is exhausted of all resources in making viral progeny, the viruses may begin to leave the cell by several methods.

<i>Ascoviridae</i> Family of viruses

Ascoviridae is a family of double strand DNA viruses that infect primarily invertebrates, mainly noctuids and spodoptera species; it contains two genera, Ascovirus, which contains three species, and Toursvirus with a single species Diadromus pulchellus toursvirus.

<i>Lagovirus</i> Genus of viruses

Lagovirus is a genus of viruses, in the family Caliciviridae. Lagomorphs serve as natural hosts. There are two species in this genus. Diseases associated with this genus include: necrotizing hepatitis leading to fatal hemorrhages.

<span class="mw-page-title-main">Necroptosis</span> Programmed form of necrosis, or inflammatory cell death

Necroptosis is a programmed form of necrosis, or inflammatory cell death. Conventionally, necrosis is associated with unprogrammed cell death resulting from cellular damage or infiltration by pathogens, in contrast to orderly, programmed cell death via apoptosis. The discovery of necroptosis showed that cells can execute necrosis in a programmed fashion and that apoptosis is not always the preferred form of cell death. Furthermore, the immunogenic nature of necroptosis favors its participation in certain circumstances, such as aiding in defence against pathogens by the immune system. Necroptosis is well defined as a viral defense mechanism, allowing the cell to undergo "cellular suicide" in a caspase-independent fashion in the presence of viral caspase inhibitors to restrict virus replication. In addition to being a response to disease, necroptosis has also been characterized as a component of inflammatory diseases such as Crohn's disease, pancreatitis, and myocardial infarction.

<i>Avibirnavirus</i> Genus of viruses

Avibirnavirus is a genus of viruses in family Birnaviridae. There is a single species in this genus: Infectious bursal disease virus, which infects chickens and other fowl. It causes severe inflammation of the bursa of Fabricius, and causes considerable morbidity and mortality.

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.

This glossary of virology is a list of definitions of terms and concepts used in virology, the study of viruses, particularly in the description of viruses and their actions. Related fields include microbiology, molecular biology, and genetics.

<i>Sepik virus</i> Mosquito transmitted virus endemic to Papua New Guinea

Sepik virus (SEPV) is an arthropod-borne virus (arbovirus) of the genus Flavivirus and family Flaviviridae. Flaviviridae is one of the most well characterized viral families, as it contains many well-known viruses that cause diseases that have become very prevalent in the world, like Dengue virus. The genus Flavivirus is one of the largest viral genera and encompasses over 50 viral species, including tick and mosquito borne viruses like Yellow fever virus and West Nile virus. Sepik virus is much less well known and has not been as well-classified as other viruses because it has not been known of for very long. Sepik virus was first isolated in 1966 from the mosquito Mansoniaseptempunctata, and it derives its name from the Sepik River area in Papua New Guinea, where it was first found. The geographic range of Sepik virus is limited to Papua New Guinea, due to its isolation.

Rio Negro virus is an alphavirus that was first isolated in Argentina in 1980. The virus was first called Ag80-663 but was renamed to Rio Negro virus in 2005. It is a former member of the Venezuelan equine encephalitis complex (VEEC), which are a group of alphaviruses in the Americas that have the potential to emerge and cause disease. Río Negro virus was recently reclassified as a distinct species. Closely related viruses include Mucambo virus and Everglades virus.

References

  1. Fenner, Frank (1952). "The mechanism of the transmission of myxomatosis in the European rabbit (Oryctolagus cuniculus) by the mosquito Aedes aegypti". Australian Journal of Experimental Biology and Medical Science. 30 (2): 139–152. doi:10.1038/icb.1952.13. PMID   14934625.
  2. Lockley, R.M. (1954). "The European rabbit flea, Spilopsyllus cuniculi, as a vector of myxomatosis in Britain". Veterinary Record. 66: 434.
  3. Silvers, L. (2006). "Virulence and pathogenesis of the MSW and MSD strains of Californian myxoma virus in European rabbits with genetic resistance to myxomatosis compared to rabbits with no genetic resistance". Virology. 348 (1): 72–83. doi: 10.1016/j.virol.2005.12.007 . PMID   16442580.
  4. 1 2 Kerr, Peter; Ghedin, Elodie; et al. (2012), "Evolutionary History and Attenuation of Myxoma Virus on Two Continents", PLOS Pathogens, 8 (10): e1002950, doi: 10.1371/journal.ppat.1002950 , PMC   3464225 , PMID   23055928
  5. Cheryl Cameron; et al. (25 November 1999). "The Complete DNA Sequence of Myxoma Virus". Virology. 264 (2): 298–318. doi: 10.1006/viro.1999.0001 . PMID   10562494.
  6. ICTVdB Management (2006). 00.058.1.05.001. Myxoma virus. In: ICTVdB—The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA.
  7. 1 2 Mahy, Brian W J; Van Regenmortel, Marc H (2008), The Encyclopedia of Virology, vol. I (3rd ed.), San Diego, CA: Academic Press
  8. Shors, Teri (2013). Understanding Viruses (Second ed.). Burlington, MA: Jones & Bartlett Learning. pp.  438. ISBN   978-1-4496-4892-3.
  9. Spiesschaert, Bart; McFadden, Grant; Hermans, Katleen; Nauwynck, Hans; Van de Walle, Gerlinde R (2011). "The current status and future directions of myxoma virus, a master in immune evasion". Veterinary Research. 42 (1): 76. doi: 10.1186/1297-9716-42-76 . PMC   3131250 . PMID   21658227.