Group Group V ((−)ssRNA) Family Filoviridae Species Marburg marburgvirus | Order Mononegavirales Genus Marburgvirus | |
Ravn virus (RAVV) is a close relative of the much more commonly known Marburg virus (MARV). RAVV causes Marburg virus disease in humans and nonhuman primates, a form of viral hemorrhagic fever. RAVV is a Select Agent, World Health Organization Risk Group 4 Pathogen (requiring Biosafety Level 4-equivalent containment), National Institutes of Health/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen, Centers for Disease Control and Prevention Category A Bioterrorism Agent, and listed as a Biological Agent for Export Control by the Australia Group.
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Use of term
Ravn virus (today abbreviated RAVV, but then considered identical to Marburg virus) was first described in 1996. Today, the virus is classified as one of two members of the species Marburg marburgvirus, which is included into the genus Marburgvirus, family Filoviridae, order Mononegavirales. The name Ravn virus is derived from Ravn (the name of the Danish patient from whom this virus was first isolated) and the taxonomic suffix virus.
Note
Ravn virus is pronounced rævn vɑɪrəs (IPA) or ra-vuhn vahy-ruhs in English phonetic notation. According to the rules for taxon naming established by the International Committee on Taxonomy of Viruses (ICTV), the name Ravn virus is always to be capitalized, but is never italicized, and may be abbreviated (with RAVV being the official abbreviation).
Previous designations
Ravn virus was first introduced as a new "subtype" of Marburg virus in 1996. In 2006, a thorough whole-genome analysis of all marburgviruses revealed the existence of five distinct genetic lineages. The genomes of representative isolates of four of those lineages differed from each other by only 0-7.8% on the nucleotide level, whereas representatives of the fifth lineage, including the new "subtype", differed from those of the other lineages by up to 21.3%. Consequently, the fifth genetic lineage was reclassified as a virus, Ravn virus (RAVV), distinct from the virus represented by the four more closely related lineages, Marburg virus (MARV).
Virus inclusion criteria
A virus that fulfills the criteria for being a member of the species Marburg marburgvirus is a Ravn virus if it has the properties of Marburg marburgviruses and if its genome diverges from that of the prototype Marburg marburgvirus, Marburg virus variant Musoke (MARV/Mus), by ≥10% but from that of the prototype Ravn virus (variant Ravn) by <10% at the nucleotide level.
Disease
RAVV is one of two marburgviruses that causes Marburg virus disease (MVD) in humans (in the literature also often referred to as Marburg hemorrhagic fever, MHF). MVD due to RAVV infection cannot be differentiated from MVD caused by MARV by clinical observation alone, which is why the clinical presentation and pathology of infections by all marburgviruses is presented together on a separate page (see Marburg virus disease (MVD)). In the past, RAVV has caused the following MVD outbreaks:
Virology
RAVV is basically uncharacterized on a molecular level. However, its genomic sequence, and with it the genomic organization and the conservation of individual open reading frames, is similar to that of Marburg virus. It is therefore currently assumed that the knowledge obtained for MARV can be extrapolated to RAVV and that all RAVV proteins behave analogous to those of MARV.
Ecology
In 2009, the successful isolation of infectious RAVV was reported from caught healthy Egyptian rousettes (Rousettus aegyptiacus). This isolation, together with the isolation of infectious MARV, strongly suggests that Old World fruit bats are involved in the natural maintenance of marburgviruses. Further studies are necessary to establish whether Egyptian rousettes are the actual hosts of RAVV and MARV or whether they get infected via contact with another animal and therefore serve only as intermediate hosts.