Ebolavirus
The genus Ebolavirus (- or ; - or ) is a virological taxon included in the family "Filoviridae" (filament-shaped viruses), order "Mononegavirales". The members of this genus are called ebolaviruses, and encode their genome in the form of single-stranded negative-sense RNA. The six known virus species are named for the region where each was originally identified: "Bundibugyo ebolavirus", "Reston ebolavirus", "Sudan ebolavirus", "Taï Forest ebolavirus" (originally "Côte d'Ivoire ebolavirus"), "Zaire ebolavirus", and "Bombali ebolavirus". The last is the most recent species to be named and was isolated from Angolan free-tailed bats in Sierra Leone. Each species of the genus  Ebolavirus has one member virus, and four of these cause Ebola virus disease (EVD) in humans, a type of hemorrhagic fever having a very high case fatality rate. The Reston virus has caused EVD in other primates. "Zaire ebolavirus" has the highest mortality rate of the ebolaviruses and is responsible for the largest number of outbreaks of the six known species of the genus, including the 1976 Zaire outbreak and the outbreak with the most deaths (2014). Ebolaviruses were first described after outbreaks of EVD in southern Sudan in June 1976 and in Zaire in August 1976. The name "Ebolavirus  is derived from the Ebola River in Zaire (now the Democratic Republic of the Congo), near the location of the 1976 outbreak, and the taxonomic suffix -virus" (denoting a viral genus). 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. Ebolaviruses are closely related to marburgviruses. Hosts. Researchers have found evidence of Ebola infection in three species of fruit bat. The bats show no symptoms of the disease, indicating that they may be the main natural reservoirs of the Ebolavirus. It is possible  that there are other reservoirs and vectors. Understanding where the virus incubates between outbreaks and how it is transmitted between species will help protect humans and other primates from the virus. The researchers found that bats of three species — Franquet's epauletted fruit bat ("Epomops franqueti"), the hammer-headed bat ("Hypsignathus monstrosus") and the little collared fruit bat ("Myonycteris torquata") — had either genetic material from the Ebola virus, known as RNA sequences, or evidence of an immune response to the disease. The bats showed no symptoms themselves. The Bombali ebolavirus (BOMV) was isolated from the little free-tailed bat ("Chaerephon  pumilus") and the Angolan free-tailed bat ("Mops condylurus") in Sierra Leone. Entry pathway. The entry pathway that the virus uses is a key step in its cycle. Several pathways have been suggested for Ebolavirus such as phagocytosis and clathrin and caveolin mediated endocytosis. However, Nanbo et al. (2010) and Saeed et al. (2010) independently proved that neither of these pathways is actually used. They discovered that Ebolavirus uses macropinocytosis to enter the host cells. Induction of macropinocytosis leads to the formation of macropinocytosis-specific endosomes (macropinosomes), which are large enough to accommodate Ebola virions. This discovery was proven by  the fact that Ebolavirus co-localizes with sorting nexin 5 (SNX5), which consists of a large family of peripheral membrane proteins that associate with newly formed macropinosomes. Also, blocking the macropinocytosis pathway has been proven to stop Ebolavirus from entering the cells. Four different macropinocytosis specific inhibitors were tested: cytochalasin D (depolymerizing agent), wortmannin (Wort), LY-294002 (both are inhibitors of PI3K) and EIPA (5-(N-ethyl-N-isopropyl) amiloride), an inhibitor of the Na+/H+ exchanger specific for pinocytosis. Then, internalized EBOV particles are transported to late endosomes and, there, co-localization with GTPase Rab7 (marker of late endosomes) is observed . Mutation of both Rab5 and Rab7 GTPases additionally inhibits viral entry. After trafficking to late endosomes, Ebola virus binds the intracellular receptor Neimann-Pick C1 (NPC1) and the viral membrane fuses with the endosomal membrane, allowing the virus to release its genome into the cytoplasm. Taxonomy notes. According to the rules for taxon naming established by the International Committee on Taxonomy of Viruses (ICTV), the name of the genus "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. Genus inclusion criteria. A virus of the family "Filoviridae" is a member of the genus "Ebolavirus" if Classification. The genera "Ebolavirus" and "Marburgvirus" were originally classified as the species of the now-obsolete genus "Filovirus". In March 1998, the Vertebrate Virus Subcommittee proposed in the International Committee on Taxonomy of Viruses (ICTV) to change the genus "Filovirus" to the family "Filoviridae" 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". Five characterised species of the genus "Ebolavirus" are: Evolution. Rates of genetic change are 8*10 per site per year and are thus one fourth as fast as influenza A in humans. Extrapolating backwards, Ebolavirus and Marburgvirus probably diverged several thousand years ago. A study done in 1995 and 1996 found that the genes of Ebolavirus and Marburgvirus differed by about 55% at the nucleotide level, and at least 67% at the amino acid level. The same study found that the  strains of Ebolavirus differed by about 37-41% across the nucleotide level and 34-43% across the amino acid level. The EBOV strain was found to have an almost 2% change in the nucleotide level from the original 1976 strain from the Yambuki outbreak and the strain from the 1995 Kikwit outbreak. However, paleoviruses of filoviruses found in mammals indicate that the family itself is at least tens of millions of years old. Genus organization and common names. The genus "Ebolavirus" has been organized into six species; however, the nomenclature has proven somewhat controversial, with many authors continuing to use  common names rather than species names when referring to these viruses. In particular, the generic term "Ebola virus" is widely used to refer specifically to members of the species "Zaire ebolavirus". Consequently, in 2010, a group of researchers recommended that the name "Ebola virus" be adopted for a subclassification within the species "Zaire ebolavirus" and that similar common names be formally adopted for other "Ebolavirus" species. In 2011, the International Committee on Taxonomy of Viruses (ICTV) rejected a proposal (2010.010bV) to formally recognize these names, as they do not designate names for subtypes, variants, strains, or other subspecies level groupings . As such, the widely used common names are not formally recognized as part of the taxonomic nomenclature. In particular, "Ebola virus" does not have an official meaning recognized by ICTV, and rather they continue to use and recommend only the species designation "Zaire ebolavirus". The threshold for putting isolates into different species is usually a difference of more than 30% at the nucleotide level, compared to the type strain. If a virus is in a given species but differs from the type strain by more than 10% at the nucleotide level, it is proposed that it be named as a  new virus. , none of the "Ebolavirus" species contain members divergent enough to receive more than one "virus" designation. Research. 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. A recent alignment-free analysis of Ebola virus genomes from the current outbreak reveals the presence of three short DNA sequences that appear nowhere in the human genome, suggesting that the identification of specific species sequences may prove to be useful for the development of both diagnosis and therapeutics.