Filoviridae
Encyclopedia
The family
Filoviridae is the taxonomic
home of several related virus
es 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 human
s and nonhuman primates in the form of viral hemorrhagic fever
s. All accepted members of the family (all ebolaviruses
and marburgviruses
) are Select Agent
s, World Health Organization
Risk Group 4 Pathogens (requiring Biosafety Level 4-equivalent containment
), National Institutes of Health
/National Institute of Allergy and Infectious Diseases
Category A Priority Pathogens, Centers for Disease Control and Prevention
Category A Bioterrorism Agents
, and listed as Biological Agents for Export Control by the Australia Group
. It is expected that "cuevaviruses
", suggested to be additional members of the family, will be classified in a similar way in the near future.
It is a non-segmented, negative single stranded RNA virus, similar to the Paramyxoviridae. It is enveloped and has a helical structure. It contains 7 proteins.
Filoviridae is a virological taxon
(i.e. a man-made concept
) that was created in 1982 and emended in 1991, 1995, 2000, 2005, and 2010 The family currently includes the three virus
genera
"Cuevavirus
", Ebolavirus
, and Marburgvirus
and is included in the order
Mononegavirales
. The members of the family (i.e. the actual physical entities) are called filoviruses or filovirids. The name Filoviridae is derived from the Latin
noun
filum (alluding to the filamentous morphology of filovirions) and the taxonomic
suffix
-viridae (which denotes a virus family).
, the name Filoviridae is always to be capitalized
, italicized
, never abbreviated, and to be preceded by the word "family". The names of its members (filoviruses/filovirids) are to be written in lower case, are not italicized, and used without articles
.
is a member of the family Filoviridae if
Table legend: "*" denotes type species; "suggested" refers to taxa that have been suggested by individual researchers but that have not been formally proposed to the ICTV, and "accepted" refers to taxa that have been accepted by the Executive Committee of the ICTV but that have yet to be ratified.
begins with virion attachment to specific cell-surface receptors
, followed by fusion
of the virion envelope with cellular membranes and the concomitant release of the virus nucleocapsid into the cytosol
. The virus RdRp partially uncoats the nucleocapsid and transcribes
the genes
into positive-stranded mRNAs, which are then translated into structural and nonstructural proteins. Filovirus RdRps bind to a single promoter located at the 3' end of the genome. Transcription either terminates after a gene or continues to the next gene downstream. This means that genes close to the 3' end of the genome are transcribed in the greatest abundance, whereas those toward the 5' end are least likely to be transcribed. The gene order is therefore a simple but effective form of transcriptional regulation. The most abundant protein produced is the nucleoprotein
, whose concentration
in the cell determines when the RdRp switches from gene transcription to genome replication. Replication results in full-length, positive-stranded antigenomes that are in turn transcribed into negative-stranded virus progeny genome copies. Newly synthesized structural proteins and genomes self-assemble and accumulate near the inside of the cell membrane
. Virions bud
off from the cell, gaining their envelopes from the cellular membrane they bud from. The mature progeny particles then infect other cells to repeat the cycle.
s, rodent
s, shrew
s, tenrecs, tarsiers, and marsupial
s. Although most filovirus-like fossils appear to be pseudogenes, evolutionary analyses suggest that orthologs isolated from several species of the bat genus Myotis have been maintained by selection.
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...
Filoviridae is the taxonomic
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...
home of several related 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...
es that form filamentous virions. Two members of the family that are commonly known are 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,...
and Marburg virus
Marburg virus
Marburg virus disease is the name for the human disease caused by any of the two marburgviruses Marburg virus and Ravn virus...
. Both viruses, and some of their lesser known relatives, cause severe disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
in human
Human
Humans are the only living species in the Homo genus...
s and nonhuman primates in the form of viral hemorrhagic fever
Viral hemorrhagic fever
The viral hemorrhagic fevers are a diverse group of animal and human illnesses that are caused by four distinct families of RNA viruses: the families Arenaviridae, Filoviridae, Bunyaviridae, and Flaviviridae. All types of VHF are characterized by fever and bleeding disorders and all can progress...
s. All accepted members of the family (all ebolaviruses
Ebolavirus
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....
and marburgviruses
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...
) are Select Agent
Select agent
In United States law, Select Agents are pathogens or biological toxins which have been declared by the U.S. Department of Health and Human Services or by the U.S. Department of Agriculture to have the "potential to pose a severe threat to public health and safety"...
s, 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...
Risk Group 4 Pathogens (requiring Biosafety Level 4-equivalent containment
Biosafety
Biosafety: prevention of large-scale loss of biological integrity, focusing both on ecology and human health .Biosafety is related to several fields:*In ecology ,...
), National Institutes of Health
National Institutes of Health
The National Institutes of Health are an agency of the United States Department of Health and Human Services and are the primary agency of the United States government responsible for biomedical and health-related research. Its science and engineering counterpart is the National Science Foundation...
/National Institute of Allergy and Infectious Diseases
National Institute of Allergy and Infectious Diseases
The National Institute of Allergy and Infectious Diseases is one of the 27 institutes and centers that make up the National Institutes of Health , an agency of the United States Department of Health and Human Services...
Category A Priority Pathogens, Centers for Disease Control and Prevention
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...
Category A Bioterrorism Agents
Bioterrorism
Bioterrorism is terrorism involving the intentional release or dissemination of biological agents. These agents are bacteria, viruses, or toxins, and may be in a naturally occurring or a human-modified form. For the use of this method in warfare, see biological warfare.-Definition:According to the...
, and listed as Biological Agents for Export Control by the Australia Group
Australia Group
The Australia Group is an informal group of countries established in 1985 to help member countries to identify those of their exports which need to be controlled so as not to contribute to the spread of chemical and biological weapons .The group, initially consisting of 15 members, held its first...
. It is expected that "cuevaviruses
Cuevavirus
The genus "Cuevavirus" was recently suggested to be included in the family Filoviridae. It is suggested to include only one species, "Lloviu cuevavirus", as a taxonomic home for the recently discovered agent Lloviu virus . LLOV is a distant relative of the commonly known Ebola virus and Marburg...
", suggested to be additional members of the family, will be classified in a similar way in the near future.
It is a non-segmented, negative single stranded RNA virus, similar to the Paramyxoviridae. It is enveloped and has a helical structure. It contains 7 proteins.
Use of term
The familyInternational 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...
Filoviridae 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...
(i.e. a man-made concept
Concept
The word concept is used in ordinary language as well as in almost all academic disciplines. Particularly in philosophy, psychology and cognitive sciences the term is much used and much discussed. WordNet defines concept: "conception, construct ". However, the meaning of the term concept is much...
) that was created in 1982 and emended in 1991, 1995, 2000, 2005, and 2010 The family currently includes the three 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...
genera
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...
"Cuevavirus
Cuevavirus
The genus "Cuevavirus" was recently suggested to be included in the family Filoviridae. It is suggested to include only one species, "Lloviu cuevavirus", as a taxonomic home for the recently discovered agent Lloviu virus . LLOV is a distant relative of the commonly known Ebola virus and Marburg...
", Ebolavirus
Ebolavirus
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....
, 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...
and is included in the order
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...
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...
. The members of the family (i.e. the actual physical entities) are called filoviruses or filovirids. The name Filoviridae is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
noun
Noun
In linguistics, a noun is a member of a large, open lexical category whose members can occur as the main word in the subject of a clause, the object of a verb, or the object of a preposition .Lexical categories are defined in terms of how their members combine with other kinds of...
filum (alluding to the filamentous morphology of filovirions) 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...
-viridae (which denotes a virus family).
Note
Filoviridae is pronounced ˌfiːloʊ’viːrɨdɛ (IPA) or fee-loh-vee-ri-deh in English phonetic notation. According to the rules for taxon naming established by the International Committee on Taxonomy of Viruses (ICTV)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...
, the name Filoviridae 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 "family". The names of its members (filoviruses/filovirids) 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...
.
Family inclusion criteria
A virus that fulfills the criteria for being a member of the order MononegaviralesMononegavirales
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...
is a member of the family Filoviridae if
- it causes viral hemorrhagic feverViral hemorrhagic feverThe viral hemorrhagic fevers are a diverse group of animal and human illnesses that are caused by four distinct families of RNA viruses: the families Arenaviridae, Filoviridae, Bunyaviridae, and Flaviviridae. All types of VHF are characterized by fever and bleeding disorders and all can progress...
in certain primatePrimateA primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s - it infects primates, pigPigA pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...
s or batsBatsA bat is a flying mammal in the Chiroptera order.Bats may also refer to:-Films:*Bats , starring Lou Diamond Phillips and Bob Gunton*Bats: Human Harvest -Groups:...
in natureNatureNature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general... - it needs to be adaptedAdaptationAn adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
through serial passageSerial passageSerial passage is a virus attenuation technique developed originally by Louis Pasteur in the 1880s. It is similar to selective breeding, and can be used to create an attenuated strain of a virus to develop vaccines, or to increase the virulence of a viral strain in order to create epidemics.The...
to cause diseaseDiseaseA disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
in rodentRodentRodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s - it exclusively replicatesReplicationReplication may refer to:Science* Replication is one of the main principles of the scientific method, a.k.a. reproducibility** Replication , the repetition of a test or complete experiment...
in the cytoplasmCytoplasmThe cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
of a hostHost (biology)In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
cellCell (biology)The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos.... - it has a genomeGenomeIn modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
≈19 kbBase pairIn molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
in length - it has an RNARNARibonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
genome that constitutes ≈1.1% of the virion mass - its genome has a molecular weightMolecular massThe molecular mass of a substance is the mass of one molecule of that substance, in unified atomic mass unit u...
of ≈4.2 x 106 - its genome contains one or more geneGeneA gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
overlaps - its genome contains seven genes in the order 3'-UTRThree prime untranslated regionIn molecular genetics, the three prime untranslated region is a particular section of messenger RNA . It is preceeded by the coding region....
-NP-VP35-VP40-GP-VP30-VP24-L-5'-UTRFive prime untranslated regionA messenger ribonucleic acid molecule codes for a protein through translation. The mRNA also contains regions that are not translated: in eukaryotes these include the 5' untranslated region, 3' untranslated region, 5' cap and poly-A tail.... - its VP24 gene is not homologousHomology (biology)Homology forms the basis of organization for comparative biology. In 1843, Richard Owen defined homology as "the same organ in different animals under every variety of form and function". Organs as different as a bat's wing, a seal's flipper, a cat's paw and a human hand have a common underlying...
to genes of other mononegavirusesMononegaviralesThe 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... - its genome contains transcriptionTranscription (genetics)Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...
initiation and termination signals not found in genomes of other mononegaviruses - it forms nucleocapsids with a buoyant densityBuoyancyIn physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
in CsClCaesium chlorideCaesium chloride is the inorganic compound with the formula CsCl. This colorless solid is an important source of caesium ions in a variety of applications. Its crystal structure forms a major structural type where each caesium ion is coordinated by 8 chlorine ions...
of ≈1.32 g/cm3 - it forms nucleocapsids with a central axial channel (≈10-15 nm in width) surrounded by a dark layer (≈20 nm in width) and an outer helical layer (≈50 nm in width) with a cross striation (periodicity of ≈5 nm)
- it expresses a class I fusion glycoproteinGlycoproteinGlycoproteins are proteins that contain oligosaccharide chains covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...
that is highly N- and O-glycosylatedGlycosylationGlycosylation is the reaction in which a carbohydrate, i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule . In biology glycosylation refers to the enzymatic process that attaches glycans to proteins, lipids, or other organic molecules...
and acylatedAcylationIn chemistry, acylation is the process of adding an acyl group to a compound. The compound providing the acyl group is called the acylating agent....
at its cytoplasmic tail - it expressess a primary matrix protein that is not glycosylated
- it forms virions that bud from the plasma membraneCell membraneThe cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
- it forms virions that are predominantly filamentous (U- and 6-shaped) and that are ≈80 nm in width, and several hundred nm and up to 14 μm in length
- it forms virions that have surface projections ≈7 nm in length spaced ≈10 nm apart from each other
- it forms virions with a molecular massMolecular massThe molecular mass of a substance is the mass of one molecule of that substance, in unified atomic mass unit u...
of ≈3.82 x 108; an S20WSvedbergA svedberg is a non-SI physical unit used for sedimentation coefficients. It characterizes the behaviour of a particle type in sedimentation processes, notably centrifugation. The svedberg is technically a measure of time, and is defined as exactly 10-13 seconds A svedberg (symbol S, sometimes...
of at least 1.40; and a buoyant densityBuoyancyIn physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
in potassium tartratePotassium tartratePotassium tartrate, dipotassium tartrate or argol has formula K2C4H4O6. It is the potassium salt of tartaric acid. It is often confused with potassium bitartrate, also known as cream of tartar...
of ≈1.14 g/cm3 - it forms virions that are poorly neutralizedNeutralisation (immunology)Neutralisation in the immunological sense refers to the ability of antibodies to block the site on bacteria or viruses that they use to enter their target cell. One example of this within biology is a neutralizing antibody....
in vivoIn vivoIn vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
Family organization
| Genus 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... |
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... |
| "Cuevavirus Cuevavirus The genus "Cuevavirus" was recently suggested to be included in the family Filoviridae. It is suggested to include only one species, "Lloviu cuevavirus", as a taxonomic home for the recently discovered agent Lloviu virus . LLOV is a distant relative of the commonly known Ebola virus and Marburg... " (suggested) |
"Lloviu cuevavirus Lloviu cuevavirus The species "Lloviu cuevavirus" was recently suggested to be included in the genus . It is suggested to be the taxonomic home for the recently disovered agent Lloviu virus . LLOV is a distant relative of the commonly known Ebola virus and Marburg virus.-Use of term:The species "Lloviu cuevavirus"... "* (suggested) |
Lloviu virus Lloviu virus Lloviu virus is a newly discovered, uncultured virus distantly related to the well-known pathogens Ebola virus and Marburg virus.-Use of term:... (LLOV) |
| Ebolavirus Ebolavirus 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.... |
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) |
| 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) |
|
| 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) |
|
| Taï Forest ebolavirus | Taï Forest virus (TAFV) | |
| 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) |
|
| 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... |
Marburg marburgvirus Marburg marburgvirus The species Marburg marburgvirus is the taxonomic home of two related viruses that form filamentous virions, Marburg virus and Ravn virus... * (accepted) |
Marburg virus Marburg virus Marburg virus disease is the name for the human disease caused by any of the two marburgviruses Marburg virus and Ravn virus... (MARV) |
| Ravn virus Ravn virus Ravn virus is a close relative of the much more commonly known Marburg virus . RAVV causes severe disease in humans and in nonhuman primates in the form of viral hemorrhagic fever... (RAVV) |
||
Table legend: "*" denotes type species; "suggested" refers to taxa that have been suggested by individual researchers but that have not been formally proposed to the ICTV, and "accepted" refers to taxa that have been accepted by the Executive Committee of the ICTV but that have yet to be ratified.
Life cycle
The filovirus life cycleBiological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
begins with virion attachment to specific cell-surface receptors
Receptor (biochemistry)
In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...
, followed by fusion
Lipid bilayer fusion
Fusion is the process by which two initially distinct lipid bilayers merge their hydrophobic cores, resulting in one interconnected structure. If this fusion proceeds completely through both leaflets of both bilayers, an aqueous bridge is formed and the internal contents of the two structures can mix...
of the virion envelope with cellular membranes and the concomitant release of the virus nucleocapsid into the cytosol
Cytosol
The cytosol or intracellular fluid is the liquid found inside cells, that is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into compartments....
. The virus RdRp partially uncoats the nucleocapsid and transcribes
Transcription (genetics)
Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...
the genes
Gênes
Gênes is the name of a département of the First French Empire in present Italy, named after the city of Genoa. It was formed in 1805, when Napoleon Bonaparte occupied the Republic of Genoa. Its capital was Genoa, and it was divided in the arrondissements of Genoa, Bobbio, Novi Ligure, Tortona and...
into positive-stranded mRNAs, which are then translated into structural and nonstructural proteins. Filovirus RdRps bind to a single promoter located at the 3' end of the genome. Transcription either terminates after a gene or continues to the next gene downstream. This means that genes close to the 3' end of the genome are transcribed in the greatest abundance, whereas those toward the 5' end are least likely to be transcribed. The gene order is therefore a simple but effective form of transcriptional regulation. The most abundant protein produced is the nucleoprotein
Nucleoprotein
A nucleoprotein is any protein that is structurally associated with nucleic acid .Many viruses harness this protein, and they are known for being host-specific...
, whose concentration
Concentration
In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...
in the cell determines when the RdRp switches from gene transcription to genome replication. Replication results in full-length, positive-stranded antigenomes that are in turn transcribed into negative-stranded virus progeny genome copies. Newly synthesized structural proteins and genomes self-assemble and accumulate near the inside of the cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
. Virions bud
Budding
Budding is a form of asexual reproduction in which a new organism grows on another one. The new organism remains attached as it grows, separating from the parent organism only when it is mature. Since the reproduction is asexual, the newly created organism is a clone and is genetically identical...
off from the cell, gaining their envelopes from the cellular membrane they bud from. The mature progeny particles then infect other cells to repeat the cycle.
Paleovirology
Filoviruses have a history that dates back several tens of million of years. Filovirus gene "fossils" have been detected as integrated sequences in the genomes of batBat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s, rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, shrew
Shrew
A shrew or shrew mouse is a small molelike mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.Although its external appearance is generally that of...
s, tenrecs, tarsiers, and marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
s. Although most filovirus-like fossils appear to be pseudogenes, evolutionary analyses suggest that orthologs isolated from several species of the bat genus Myotis have been maintained by selection.