Ebolavirus

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Not to be confused with Ebola virus. ‹See Tfd›
For the current outbreak, go to 2014 West Africa Ebola outbreak.
Genus Ebolavirus
Virus classification
Group: Group V ((-)ssRNA)
Order: Mononegavirales
Family: Filoviridae
Genus: Ebolavirus
Type species
Zaire ebolavirus
Species

Bundibugyo ebolavirus
Reston ebolavirus
Sudan ebolavirus
Taï Forest ebolavirus
Zaire ebolavirus

Ebolavirus is the virus responsible for Ebola virus disease, a type of hemorrhagic fever. The name Ebolavirus is derived from the Ebola River in Zaire (where Ebola virus was first discovered) and the taxonomic suffix -virus (denoting a viral genus).[1] The species in this genus are called ebolaviruses.[1] Currently five virus species are recognised: Bundibugyo ebolavirus, Reston ebolavirus, Sudan ebolavirus, Taï Forest ebolavirus (originally Côte d'Ivoire ebolavirus) and Zaire ebolavirus.[1] The genus Ebolavirus is a virological taxon included in the family Filoviridae, order Mononegavirales.[1] This genus was introduced in 1998 as the "Ebola-like viruses".[2][3] In 2002 the name was changed to Ebolavirus[4][5] and in 2010 the genus was emended.[1]

Taxonomy notes[edit]

Ebolavirus is pronounced iːˌboʊlə’vɑɪrəs (IPA) or ee-boh-luh-vahy-ruhs in English phonetic notation.[1]

According to the rules for taxon naming established by the International Committee on Taxonomy of Viruses (ICTV), the name Ebolavirus is always to be capitalized, italicized, never abbreviated, and to be preceded by the word "genus". The names of its members (ebolaviruses) are to be written in lower case, are not italicized, and used without articles.[1]

Genus inclusion criteria[edit]

A virus of the family Filoviridae is a member of the genus Ebolavirus if[1]

  • its genome has several gene overlaps
  • its fourth gene (GP) encodes four proteins (sGP, ssGP, Δ-peptide, and GP1,2) using cotranscriptional editing to express ssGP and GP1,2 and proteolytic cleavage to express sGP and Δ-peptide
  • peak infectivity of its virions is associated with particles ≈805 nm in length
  • its genome differs from that of Marburg virus by ≥50% and from that of Ebola virus by <50% at the nucleotide level
  • its virions show almost no antigenic cross reactivity with marburgvirions

Classification[edit]

Electron micrograph of an Ebola virus virion
Phylogenetic tree comparing the Ebolavirus and Marburgvirus. Numbers indicate percent confidence of branches.

The genera Ebolavirus and Marburgvirus were originally classified as the species of the now-obsolete Filovirus genus. In March, 1998, the Vertebrate Virus Subcommittee proposed in the International Committee on Taxonomy of Viruses (ICTV) to change the Filovirus genus to the Filoviridae family with two specific genera: Ebola-like viruses and Marburg-like viruses. This proposal was implemented in Washington, D.C., as of April, 2001 and in Paris as of July, 2002. In 2000, another proposal was made in Washington, D.C., to change the "-like viruses" to "-virus" resulting in today's Ebolavirus and Marburgvirus.[6]

The five characterised Ebola species are:

Zaire ebolavirus (ZEBOV) 
Also known simply as the Zaire virus, ZEBOV has the highest case-fatality rate, up to 90% in some epidemics, with an average case fatality rate of approximately 83% over 27 years. There have been more outbreaks of Zaire ebolavirus than of any other species. The first outbreak took place on 26 August 1976 in Yambuku.[7] Mabalo Lokela, a 44‑year-old schoolteacher, became the first recorded case. The symptoms resembled malaria, and subsequent patients received quinine. Transmission has been attributed to reuse of unsterilized needles and close personal contact.
Sudan ebolavirus (SEBOV) 
Like the Zaire virus, SEBOV emerged in 1976; it was at first assumed to be identical with the Zaire species.[8] SEBOV is believed to have broken out first amongst cotton factory workers in Nzara, Sudan, with the first case reported as a worker exposed to a potential natural reservoir. Scientists tested local animals and insects in response to this; however, none tested positive for the virus. The carrier is still unknown. The lack of barrier nursing (or "bedside isolation") facilitated the spread of the disease. The most recent outbreak occurred in May, 2004. Twenty confirmed cases were reported in Yambio County, Sudan, with five deaths resulting. The average fatality rates for SEBOV were 54% in 1976, 68% in 1979, and 53% in 2000 and 2001.
Reston ebolavirus (REBOV) 
This virus was discovered during an outbreak of simian hemorrhagic fever virus (SHFV) in crab-eating macaques from Hazleton Laboratories (now Covance) in 1989. Since the initial outbreak in Reston, Virginia, it has since been found in nonhuman primates in Pennsylvania, Texas, and Siena, Italy. In each case, the affected animals had been imported from a facility in the Philippines,[9] where the virus has also infected pigs.[10] Despite its status as a Level‑4 organism and its apparent pathogenicity in monkeys, REBOV did not cause disease in exposed human laboratory workers.[11]
Côte d'Ivoire ebolavirus (CIEBOV)
Also referred to as Tai ebolavirus and by the English place name, "Ivory Coast", it was first discovered among chimpanzees from the Tai Forest in Côte d'Ivoire, Africa, in 1994. Necropsies showed blood within the heart to be brown; no obvious marks were seen on the organs; and one necropsy displayed lungs filled with blood. Studies of tissues taken from the chimpanzees showed results similar to human cases during the 1976 Ebola outbreaks in Zaire and Sudan. As more dead chimpanzees were discovered, many tested positive for Ebola using molecular techniques. The source of the virus was believed to be the meat of infected western red colobus monkeys (Procolobus badius) upon which the chimpanzees preyed. One of the scientists performing the necropsies on the infected chimpanzees contracted Ebola. She developed symptoms similar to those of dengue fever approximately a week after the necropsy, and was transported to Switzerland for treatment. She was discharged from hospital after two weeks and had fully recovered six weeks after the infection.[12]
Bundibugyo ebolavirus
On November 24, 2007, the Uganda Ministry of Health confirmed an outbreak of Ebola in the Bundibugyo District. After confirmation of samples tested by the United States National Reference Laboratories and the CDC, the World Health Organization confirmed the presence of the new species. On 20 February 2008, the Uganda Ministry officially announced the end of the epidemic in Bundibugyo, with the last infected person discharged on 8 January 2008.[13] An epidemiological study conducted by WHO and Uganda Ministry of Health scientists determined there were 116 confirmed and probable cases the new Ebola species, and that the outbreak had a mortality rate of 34% (39 deaths).[14]

Evolution[edit]

Rates of genetic change are one one-hundredth as fast as influenza A in humans, but on the same magnitude as those of hepatitis B. Extrapolating backwards using these rates indicates Ebolavirus and Marburgvirus diverged several thousand years ago.[15] However, paleoviruses (genomic fossils) of filoviruses (Filoviridae) found in mammals indicate that the family itself is at least tens of millions of years old.[16]

Genus organization[edit]

Genus Ebolavirus: species and viruses
Species name Virus name (Abbreviation)
Bundibugyo ebolavirus Bundibugyo virus (BDBV; previously BEBOV)
Reston ebolavirus Reston virus (RESTV; previously REBOV)
Sudan ebolavirus Sudan virus (SUDV; previously SEBOV)
Taï Forest ebolavirus Taï Forest virus (TAFV; previously CIEBOV)
Zaire ebolavirus* Ebola virus (EBOV; previously ZEBOV)

Table legend: * denotes type species

Research[edit]

A 2013 study isolated antibodies from fruit bats in Bangladesh, against Ebola Zaire and Reston viruses, thus identifying potential virus hosts and signs of the filoviruses in Asia.[17]

References[edit]

  1. ^ a b c d e f g h Kuhn, Jens H.; Becker, Stephan; Ebihara, Hideki; Geisbert, Thomas W.; Johnson, Karl M.; Kawaoka, Yoshihiro; Lipkin, W. Ian; Negredo, Ana I et al. (2010). "Proposal for a revised taxonomy of the family Filoviridae: Classification, names of taxa and viruses, and virus abbreviations". Archives of Virology 155 (12): 2083–103. doi:10.1007/s00705-010-0814-x. PMC 3074192. PMID 21046175. 
  2. ^ Netesov, S. V.; Feldmann, H.; Jahrling, P. B.; Klenk, H. D.; Sanchez, A. (2000). "Family Filoviridae". In van Regenmortel, M. H. V.; Fauquet, C. M.; Bishop, D. H. L.; Carstens, E. B.; Estes, M. K.; Lemon, S. M.; Maniloff, J.; Mayo, M. A.; McGeoch, D. J.; Pringle, C. R.; Wickner, R. B. Virus Taxonomy—Seventh Report of the International Committee on Taxonomy of Viruses. San Diego, USA: Academic Press. pp. 539–48. ISBN 0-12-370200-3{{inconsistent citations}} 
  3. ^ Pringle, C. R. (1998). "Virus taxonomy-San Diego 1998". Archives of Virology 143 (7): 1449–59. doi:10.1007/s007050050389. PMID 9742051. 
  4. ^ Feldmann, H.; Geisbert, T. W.; Jahrling, P. B.; Klenk, H.-D.; Netesov, S. V.; Peters, C. J.; Sanchez, A.; Swanepoel, R.; Volchkov, V. E. (2005). "Family Filoviridae". In Fauquet, C. M.; Mayo, M. A.; Maniloff, J.; Desselberger, U.; Ball, L. A. Virus Taxonomy—Eighth Report of the International Committee on Taxonomy of Viruses. San Diego, USA: Elsevier/Academic Press. pp. 645–653. ISBN 0-12-370200-3{{inconsistent citations}} 
  5. ^ Mayo, M. A. (2002). "ICTV at the Paris ICV: results of the plenary session and the binomial ballot". Archives of Virology 147 (11): 2254–60. doi:10.1007/s007050200052. 
  6. ^ Büchen-Osmond, Cornelia (2006-04-25). "ICTVdB Virus Description – 01.025.0.02. Ebolavirus". International Committee on Taxonomy of Viruses. Retrieved 2009-06-02. 
  7. ^ Isaacson, M; Sureau, P; Courteille, G; Pattyn, SR;. Clinical Aspects of Ebola Virus Disease at the Ngaliema Hospital, Kinshasa, Zaire, 1976. Retrieved 2009-07-08. 
  8. ^ Feldmann, H.; Geisbert, T. W. (2011). "Ebola haemorrhagic fever". The Lancet 377 (9768): 849–862. doi:10.1016/S0140-6736(10)60667-8. PMID 21084112. 
  9. ^ Special Pathogens Branch CDC (2008-01-14). "Known Cases and Outbreaks of Ebola Hemorrhagic Fever". Center for Disease Control and Prevention. Retrieved 2008-08-02. 
  10. ^ McNeil Jr, Donald G. (2009-01-24). "Pig-to-Human Ebola Case Suspected in Philippines". New York Times. Retrieved 2009-01-26. 
  11. ^ McCormick & Fisher-Hoch 1999, p. 300
  12. ^ Waterman, Tara (1999). Ebola Cote D'Ivoire Outbreaks. Stanford University. Retrieved 2009-05-30. 
  13. ^ "End of Ebola outbreak in Uganda" (Press release). World Health Organization. 2008-02-20. 
  14. ^ Wamala, J; Lukwago, L; Malimbo, M; Nguku, P; Yoti, Z; Musenero, M; Amone, J; Mbabazi, W; Nanyunja, M; Zaramba, S; Opio, A; Lutwama, J; Talisuna, A; Okware, I; (2010). "Ebola Hemorrhagic Fever Associated with Novel Virus Strain, Uganda, 2007–2008". Emerging Infectious Disease 16 (7). Retrieved 2010-06-24. 
  15. ^ Suzuki, Y; Gojobori (1997). "The origin and evolution of Ebola and Marburg viruses". Molecular Biology and Evolution 14 (8): 800–6. PMID 9254917. 
  16. ^ Taylor, D.; Leach, R.; Bruenn, J. (2010). "Filoviruses are ancient and integrated into mammalian genomes". BMC Evolutionary Biology 10: 193. doi:10.1186/1471-2148-10-193. PMC 2906475. PMID 20569424. 
  17. ^ Kevin J. Olival, Ariful Islam, Meng Yu, Simon J. Anthony, Jonathan H. Epstein, Shahneaz Ali Khan, Salah Uddin Khan, Gary Crameri, Lin-Fa Wang, W. Ian Lipkin, Stephen P. Luby, and Peter Daszak (2013). "Ebola Virus Antibodies in Fruit Bats, Bangladesh". Emerging Infectious Disease (CDC) 19 (2). doi:10.3201/eid1902.120524. 

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