Ebolavirus
Encyclopedia
The genus
Ebolavirus is a virological taxon
included in the family Filoviridae
, order Mononegavirales
.
This genus was introduced in 1998 as the "Ebola-like viruses".
In 2002 the name was changed to Ebolavirus
and in 2010 the genus was emended.
The name Ebolavirus is derived from the Ebola River
in Zaire
(where Ebola virus
was first disovered) and the taxonomic
suffix
-virus (denoting a viral genus). The species in this genus are called ebolaviruses. Currently includes five virus
species
are recognised: Bundibugyo ebolavirus
, Reston ebolavirus, Sudan ebolavirus
, Taï Forest ebolavirus (originally Côte d'Ivoire ebolavirus) and Zaire ebolavirus
.
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
.
is a member of the genus Ebolavirus if
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.
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
. 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. 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, where the virus has also infected pigs. Despite its status as a Level‑4 organism and its apparent pathogen
icity in monkeys, REBOV did not cause disease in exposed human laboratory workers.
Côte d'Ivoire ebolavirus (CIEBOV): Also referred to as Tai ebolavirus and by the English place name, "Ivory Coast", it was first discovered among chimpanzee
s 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.
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. 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).
using these rates indicates Ebolavirus and Marburgvirus diverged several thousand years ago. However, paleoviruses (genomic fossils) of filoviruses (Filoviridae) found in mammals indicate that the family itself is at least tens of millions of years old.
Table legend: "*" denotes type species and "accepted" refers to taxa that have been accepted by the Executive Committee of the ICTV but that have yet to be ratified.
International Committee on Taxonomy of Viruses
The International Committee on Taxonomy of Viruses is a committee which authorizes and organizes the taxonomic classification of viruses. They have developed a universal taxonomic scheme for viruses and aim to describe all the viruses of living organisms. Members of the committee are considered to...
Ebolavirus is a virological taxon
International Committee on Taxonomy of Viruses
The International Committee on Taxonomy of Viruses is a committee which authorizes and organizes the taxonomic classification of viruses. They have developed a universal taxonomic scheme for viruses and aim to describe all the viruses of living organisms. Members of the committee are considered to...
included in the family Filoviridae
Filoviridae
The family Filoviridae is the taxonomic home of several related viruses that form filamentous virions. Two members of the family that are commonly known are Ebola virus and Marburg virus. Both viruses, and some of their lesser known relatives, cause severe disease in humans and nonhuman primates in...
, order Mononegavirales
Mononegavirales
The order Mononegavirales is the taxonomic home of numerous related viruses. Members of the order that are commonly known are, for instance, Ebola virus, human respiratory syncytial virus, measles virus, mumps virus, Nipah virus, and rabies virus. All of these viruses cause significant disease in...
.
This genus was introduced in 1998 as the "Ebola-like viruses".
In 2002 the name was changed to Ebolavirus
and in 2010 the genus was emended.
The name Ebolavirus is derived from the Ebola River
Ebola River
The Ebola River in northern Democratic Republic of the Congo is the headstream of the Mongala River, a tributary of the Congo River.Ebola virus and the taxonomic ranks associated with it and its relatives are named...
in Zaire
Zaire
The Republic of Zaire was the name of the present Democratic Republic of the Congo between 27 October 1971 and 17 May 1997. The name of Zaire derives from the , itself an adaptation of the Kongo word nzere or nzadi, or "the river that swallows all rivers".-Self-proclaimed Father of the Nation:In...
(where Ebola virus
Ebola virus
Ebola virus causes severe disease in humans and in nonhuman primates in the form of viral hemorrhagic fever. EBOV is a Select Agent, World Health Organization Risk Group 4 Pathogen , National Institutes of Health/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen,...
was first disovered) and the taxonomic
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
suffix
Suffix
In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns or adjectives, and verb endings, which form the conjugation of verbs...
-virus (denoting a viral genus). The species in this genus are called ebolaviruses. Currently includes five virus
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...
species
International Committee on Taxonomy of Viruses
The International Committee on Taxonomy of Viruses is a committee which authorizes and organizes the taxonomic classification of viruses. They have developed a universal taxonomic scheme for viruses and aim to describe all the viruses of living organisms. Members of the committee are considered to...
are recognised: Bundibugyo ebolavirus
Bundibugyo ebolavirus
- Introduction and use of term :The species Bundibugyo ebolavirus is a virological taxon that was suggested in 2008 to be included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Bundibugyo virus . The members of the species are called...
, Reston ebolavirus, Sudan ebolavirus
Sudan ebolavirus
- Introduction and Use of Term :The species Sudan ebolavirus is a virological taxon included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Sudan virus . The members of the species are called Sudan ebolaviruses...
, Taï Forest ebolavirus (originally Côte d'Ivoire ebolavirus) and Zaire ebolavirus
Zaire ebolavirus
- Introduction and Use of Term :Zaire ebolavirus is a virological taxon included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Ebola virus . The members of the species are called Zaire ebolaviruses...
.
Taxonomy notes
Ebolavirus is pronounced iːˌboʊlə’vɑɪrəs (IPA) or ee-boh-luh-vahy-ruhs in English phonetic notation.According to the rules for taxon naming established by the International Committee on Taxonomy of Viruses
International Committee on Taxonomy of Viruses
The International Committee on Taxonomy of Viruses is a committee which authorizes and organizes the taxonomic classification of viruses. They have developed a universal taxonomic scheme for viruses and aim to describe all the viruses of living organisms. Members of the committee are considered to...
(ICTV), the name Ebolavirus is always to be capitalized
Capitalization
Capitalization is writing a word with its first letter as a majuscule and the remaining letters in minuscules . This of course only applies to those writing systems which have a case distinction...
, italicized
Italic type
In typography, italic type is a cursive typeface based on a stylized form of calligraphic handwriting. Owing to the influence from calligraphy, such typefaces often slant slightly to the right. Different glyph shapes from roman type are also usually used—another influence from calligraphy...
, 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
Article (grammar)
An article is a word that combines with a noun to indicate the type of reference being made by the noun. Articles specify the grammatical definiteness of the noun, in some languages extending to volume or numerical scope. The articles in the English language are the and a/an, and some...
.
Genus inclusion criteria
A virus of the family FiloviridaeFiloviridae
The family Filoviridae is the taxonomic home of several related viruses that form filamentous virions. Two members of the family that are commonly known are Ebola virus and Marburg virus. Both viruses, and some of their lesser known relatives, cause severe disease in humans and nonhuman primates in...
is a member of the genus Ebolavirus if
- 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 proteloytic 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 virusMarburg virusMarburg virus disease is the name for the human disease caused by any of the two marburgviruses Marburg virus and Ravn virus...
by ≥50% and from that of Ebola virusEbola virusEbola virus causes severe disease in humans and in nonhuman primates in the form of viral hemorrhagic fever. EBOV is a Select Agent, World Health Organization Risk Group 4 Pathogen , National Institutes of Health/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen,...
by <50% at the nucleotide level - its virions show almost no antigenic cross reactivity with marburgvirions
Classification
The genera Ebolavirus and Marburgvirus
Marburgvirus
The genus Marburgvirus is the taxonomic home of one species whose members are two related viruses that form filamentous virions, Marburg virus and Ravn virus...
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
International Committee on Taxonomy of Viruses
The International Committee on Taxonomy of Viruses is a committee which authorizes and organizes the taxonomic classification of viruses. They have developed a universal taxonomic scheme for viruses and aim to describe all the viruses of living organisms. Members of the committee are considered to...
(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.
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
Yambuku
Yambuku is a small village in Mongala District in northern Democratic Republic of the Congo and was the site of the first known outbreak of the Ebola Zaire strain of the Ebola hemorrhagic fever virus...
. Mabalo Lokela, a 44‑year-old schoolteacher, became the first recorded case. The symptoms resembled malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
, and subsequent patients received quinine
Quinine
Quinine is a natural white crystalline alkaloid having antipyretic , antimalarial, analgesic , anti-inflammatory properties and a bitter taste. It is a stereoisomer of quinidine which, unlike quinine, is an anti-arrhythmic...
. 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. SEBOV is believed to have broken out first amongst cotton factory workers in Nzara, Sudan
Sudan
Sudan , officially the Republic of the Sudan , is a country in North Africa, sometimes considered part of the Middle East politically. It is bordered by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the...
, 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
Simian hemorrhagic fever virus
Simian hemorrhagic fever virus or simian haemorrhagic fever virus or SHFV is a highly pathogenic virus in monkeys. It is a positive-stranded RNA virus classified in the family Arteriviridae.- Hosts :...
(SHFV) in crab-eating macaques
Crab-eating Macaque
The Crab-eating macaque is a cercopithecine primate native to Southeast Asia. It is also called the "long-tailed macaque", and is referred to as the "cynomolgus monkey" in laboratories.-Etymology:...
from Hazleton Laboratories
Covance
Covance, Inc. , formerly Corning Incorporated, with headquarters in Princeton, New Jersey, USA, is a contract research organization , providing drug development and animal testing services...
(now Covance) in 1989. Since the initial outbreak in Reston, Virginia
Reston, Virginia
Reston is a census-designated place in Fairfax County, Virginia, United States, within the Washington, D.C. metropolitan area. The population was 58,404, at the 2010 Census and 56,407 at the 2000 census...
, it has since been found in nonhuman primates in Pennsylvania, Texas and Siena
Siena
Siena is a city in Tuscany, Italy. It is the capital of the province of Siena.The historic centre of Siena has been declared by UNESCO a World Heritage Site. It is one of the nation's most visited tourist attractions, with over 163,000 international arrivals in 2008...
, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
. In each case, the affected animals had been imported from a facility in the Philippines, where the virus has also infected pigs. Despite its status as a Level‑4 organism and its apparent pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
icity in monkeys, REBOV did not cause disease in exposed human laboratory workers.
Côte d'Ivoire ebolavirus (CIEBOV): Also referred to as Tai ebolavirus and by the English place name, "Ivory Coast", it was first discovered among chimpanzee
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
s from the Tai Forest
Taï National Park
Taï National Park is a national park in Côte d'Ivoire containing one of the last areas of primary rainforest in West Africa. It was inscribed as a World Heritage Site in 1982 due to the breadth of its flora and fauna...
in Côte d'Ivoire
Côte d'Ivoire
The Republic of Côte d'Ivoire or Ivory Coast is a country in West Africa. It has an area of , and borders the countries Liberia, Guinea, Mali, Burkina Faso and Ghana; its southern boundary is along the Gulf of Guinea. The country's population was 15,366,672 in 1998 and was estimated to be...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, 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
Dengue fever
Dengue fever , also known as breakbone fever, is an infectious tropical disease caused by the dengue virus. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles...
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.
Bundibugyo ebolavirus: On November 24, 2007, the Uganda Ministry of Health confirmed an outbreak of Ebola in the Bundibugyo District
Bundibugyo District
Bundibugyo District is a district in Western Uganda, bordering the Democratic Republic of the Congo. Like other Ugandan districts, it is named after its 'chief town', Bundibugyo, where the district headquarters are located.-Location:...
. After confirmation of samples tested by the United States National Reference Laboratories and the CDC
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
, the World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
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. 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).
Evolution
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 backwardsMolecular clock
The molecular clock is a technique in molecular evolution that uses fossil constraints and rates of molecular change to deduce the time in geologic history when two species or other taxa diverged. It is used to estimate the time of occurrence of events called speciation or radiation...
using these rates indicates Ebolavirus and Marburgvirus diverged several thousand years ago. However, paleoviruses (genomic fossils) of filoviruses (Filoviridae) found in mammals indicate that the family itself is at least tens of millions of years old.
Genus organization
| Species name International Committee on Taxonomy of Viruses The International Committee on Taxonomy of Viruses is a committee which authorizes and organizes the taxonomic classification of viruses. They have developed a universal taxonomic scheme for viruses and aim to describe all the viruses of living organisms. Members of the committee are considered to... |
Virus name (Abbreviation) International Committee on Taxonomy of Viruses The International Committee on Taxonomy of Viruses is a committee which authorizes and organizes the taxonomic classification of viruses. They have developed a universal taxonomic scheme for viruses and aim to describe all the viruses of living organisms. Members of the committee are considered to... |
| Bundibugyo ebolavirus Bundibugyo ebolavirus - Introduction and use of term :The species Bundibugyo ebolavirus is a virological taxon that was suggested in 2008 to be included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Bundibugyo virus . The members of the species are called... (accepted) |
Bundibugyo virus Bundibugyo virus Bundibugyo virus is a close relative of the much more commonly known Ebola virus . BDBV causes severe disease in humans and in nonhuman primates in the form of viral hemorrhagic fevers... (BDBV; previously BEBOV) |
| Reston ebolavirus | Reston virus Reston virus - Introduction and Use of Term :Reston virus was first described in 1990 as a new "strain" of Ebola virus, a result of mutation from Ebola virus. It is the single member of the species Reston ebolavirus, which is included into the genus Ebolavirus, family Filoviridae, order Mononegavirales... (RESTV; previously REBOV) |
| Sudan ebolavirus Sudan ebolavirus - Introduction and Use of Term :The species Sudan ebolavirus is a virological taxon included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Sudan virus . The members of the species are called Sudan ebolaviruses... |
Sudan virus Sudan virus Sudan virus is a close relative of the much more commonly known Ebola virus . SUDV causes severe disease in humans and in nonhuman primates in the form of viral hemorrhagic fevers... (SUDV; previously SEBOV) |
| Taï Forest ebolavirus | Taï Forest virus (TAFV; previously CIEBOV) |
| Zaire ebolavirus Zaire ebolavirus - Introduction and Use of Term :Zaire ebolavirus is a virological taxon included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Ebola virus . The members of the species are called Zaire ebolaviruses... * |
Ebola virus Ebola virus Ebola virus causes severe disease in humans and in nonhuman primates in the form of viral hemorrhagic fever. EBOV is a Select Agent, World Health Organization Risk Group 4 Pathogen , National Institutes of Health/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen,... (EBOV; previously ZEBOV) |
Table legend: "*" denotes type species and "accepted" refers to taxa that have been accepted by the Executive Committee of the ICTV but that have yet to be ratified.