Genus Orbivirus

Type Species	Bluetongue virus	(BTV)

Distinguishing Features

Virions have relatively featureless outer capsid as viewed by negative staining and electron microscopy and a genome composed of 10 segments of dsRNA. Core particles have characteristic ring shaped capsomers. Replication is accompanied by production of viral “tubules” and viral inclusion bodies (VIB) and may be accompanied by formation of flat hexagonal crystals of the major outer core protein (VP7 (T13)) in the cytoplasm of infected cells. Viruses are transmitted between vertebrate hosts by a variety of hematophagous arthropods.

Virion Properties

Morphology

Virions of BTV are about 80  nm in diameter, core particles have a maximum diameter of 73  nm, sub cores have a maximum diameter of 59  nm and an internal diameter of 46  nm (Fig. 4). The virion is spherical in appearance but has icosahedral symmetry. Although no lipid envelope is present on mature virions, they can leave the host cell by budding through the cell plasma membrane. During this process they transiently acquire an unstable membrane envelope. Unpurified virus is often associated with cellular membranes. By conventional electron microscopy, the surface of intact virions is indistinct (Fig. 4). However, the outer capsid does have an ordered structure, with icosahedral symmetry and ‘sail’ shaped surface projections that can be observed on virions where the particle structure is maintained (e.g., using cryoelectron microscopy: Fig. 5). When the outer capsid layer is removed, it is possible to view the surface layer of the core particle, which is composed entirely of capsomeres of VP7 (T13) arranged as hexameric rings (pentameric at the 5-fold axes: Fig. 4 and 5). These rings, which are readily observed by conventional electron microscopy, give rise to the name of this genus. The core particle also contains a complete inner capsid shell (the subcore layer), which surrounds the 10 dsRNA genome segments. The minor core proteins (the transcriptase complexes) are attached to the inner surface of the subcore at the 5-fold symmetry axes (Fig. 5). Assembly of the subcore layer appears to control the overall size and symmetry of the particle.

Physicochemical and Physical Properties

The virion Mr is about 10.8 10⁷, the core Mr is about 6.7 10⁷. Their buoyant densities in CsCl are 1.36  g/cm³ (virions) and 1.40  g/cm³ (cores). The S_20W is 550S (virions) and 470S (cores). Virus infectivity is stable at pH 8-9 but virions exhibit a marked decrease in infectivity outside the pH range 6.5-10.2. In part, this may be related to the loss of outer coat proteins, particularly at the lower pH range. The sensitivity of the outer CPs and their removal by cation treatment (e.g. by treatment with MgCl₂, or CsCl) varies markedly with both pH and virus strain. At low pH values (less than 5.0), virions and cores are both disrupted. Unlike orthoreoviruses, at pH 3.0 virus infectivity is abolished. In blood samples, serum, or albumin, viruses held in vitro at less than 15°C may remain infectious for decades. Purified BTV virions held at 4°C in 0.1  M tris/HCl pH 8.0, showed no significant reduction in infectivity after 1 year. Crystals of core particles are very stable when kept at 29°C. Virus infectivity is rapidly inactivated on heating to 60°C. In general, orbiviruses are considered to be relatively resistant to treatment with solvents, or detergents, although the sensitivity to specific detergents varies with virus species. However, sodium dodecyl sulphate will disrupt the particle and destroy its infectivity. Freezing reduces virus infectivity by about 90%, possibly due to particle disruption. However, once frozen and held at -70°C, virus infectivity remains stable.

Nucleic Acid

The genomic RNA represents 12% and 19.5% of the total molecular mass of virus particles or cores, respectively. The genome is composed of 10 linear dsRNA segments that are packaged in exactly equimolar ratios, one of each segment per particle. The genomic RNA is packaged as a series of ordered concentric shells within the VP3 (T2) layer of the subcore (Fig. 5). Four layers of RNA, each of which has elements of icosahedral symmetry, can be detected by X-ray crystallography of the BTV core. Within the central space of the subcore, there appears to be an association between the dsRNA molecules and the protein density at the 5-fold axes of symmetry (vertices of the icosahedron), which is thought to represent the transcriptase complexes (TCs). From the 5-fold axis, the RNA, in the outmost layer, appears to spiral away from the 5 fold axes outward around the TC for two turns until it clashes with an icosahedrally related neighbor. At this point it is thought to move inward forming the next concentric shell of RNA. The genomic RNA contains 5-terminal Cap 1 structures (7mGpppG^(2-Om) . . . ).

For bluetongue viruses, the genome segments range in size from 3,954 to 822  bp (total size is 19.2  kbp, total Mr of 13.1 10⁶). There is no evidence for short ssRNA oligonucleotides in intact virions. The genomic RNAs are named “segment 1 to 10”, in order of increasing electrophoretic mobility in 1% agarose gels and in order of reducing molecular weight. For bluetongue viruses, the segments migrate as three size classes 3 large (segment 1-3: 3.9-2.8  kbp), 3 medium (segments 4-6: 2.0-1.6  kbp) and 4 small segments (segments 6-10: 1.2-0.8  kbp). For other members of the genus, different sizes and size classes exist. For an individual virus species the dsRNA sizes from different isolates, or different serotypes, are comparable such that a uniform segment migration pattern is observed when the genomic RNAs of ‘normal’ isolates are analysed by agarose gel electrophoresis. However, variations in primary sequence cause significant variations in rate and order of migration of genome segments during polyacrylamide gel electrophoresis (PAGE), particularly in high percentage gels (> 5% polyacrylamide). Earlier BTV genome segment nomenclature based on PAGE is inconsistent and the migration of segments 5 and 6 is usually reversed. In the genome segments that have been analyzed to date, there is only a single major ORF, which is always on the same strand (see conserved terminal sequences below). However, the ORF may have more than one functional initiation site near to the 5-end of the RNA, resulting in production of two related proteins.

For BTV-10, the 5-NTR range from 8 to 34  bp, while for the 3-ends they are 31 to 116  bp in length. For other serotypes and other viruses the lengths differ. In general, however, the 5-NTRs are shorter than the 3-NTRs. The NTRs of all the orbivirus genome segments that have been sequenced (Table 3) contain two conserved bp at either terminus (+ve 5-GU.......AC-3). The NTRs of BTV include terminal sequences of 6  bp that are identical for all 10 dsRNA segments and which are conserved between different BTV isolates. Other orbiviruses have terminal sequences comparable to those of BTVs, but which are not always identical and which may not be conserved in all 10 segments (Table 3).

Proteins

There are 7 virus structural proteins (VP1-7: Fig. 4). Proteins constitute 88% and 80.5% of the dry weight of virions and cores, respectively. In BTV, the outer capsid consists of 180 copies of the Mr 111 10³ ‘sail-shaped’ VP2 protein arranged as ‘triskellion’ structures, and 360 copies of an interdispersed and underlying VP5 protein (Mr 59 10³), which may be arranged as 120 trimers (Fig. 4 and 5). The electrophoretic migration order and nomenclature of proteins may vary in other orbivirus species. Both VP2 and VP5 of BTV are attached to VP7 (T13). The surface of the core particle consists entirely of 780 copies of VP7, which are arranged with T = 13l symmetry, as a network of hexameric and pentameric rings (in a near perfect example of quasi-equivalence: Fig. 5). Beneath the VP7 (T13) layer, the subcore capsid shell is composed of 120 copies of VP3 arranged with T = 2 symmetry, displaying “geometrical-quasi-equivalence” (Grimes, Burroughs, Gouet, Diprose, Malby, Zeintara, Mertens and Stuart, 1998: Fig. 5). The VP3 (T2) capsid shell encloses the 10 dsRNA segments of the genome (Fig. 5), as well as the three minor structural proteins. These include: the Mr 150 10³ VP1 (Pol), which is the RNA polymerase; the Mr 76 10³ VP4 (Cap), which forms functional dimers and is both the guanylyl transferase, as well as transmethylase 1 (forming the 7-methyl guanosine of the cap structure) and transmethylase 2 (forming the 2-0 methyl guanosine, as the terminal nucleotide of the RNA chain); and the Mr 36 10³ VP6/VP6a (Hel), which binds ss or dsRNA and has both helicase and NTPase activities.

X-ray diffraction studies indicate that the minor proteins are attached as a transcriptase complex (TC), to the inner surface of the subcore layer [VP3 (T2)] at the 5-fold symmetry axes (at the vertices of the icosahedron). However, because there is only a single TC at each position they do not have full icosahedral symmetry and it has not yet been possible to determine their organisation at the atomic level.

The VP7 (T13) protein of some viruses (AHSV) can also form flat hexagonal crystals, typically up to 5  m in diameter, within the cytoplasm of the infected cell. These are composed of flat sheets of hexameric rings, similar to the rings of trimers seen in the outer core surface layer.

There are three distinct non-structural viral proteins produced in cells infected with BTV or other orbiviruses. The Mr 64 10³ NS1 (TuP) protein forms tubules that vary in length, up to 4  m, which are of unknown function but regarded as a characteristic feature of orbivirus replication. These tubules may have a ladder like structure, as observed in those of BTV and EHDV (68 and 52  nm in diameter) or may be finer (23  nm in diameter) with a reticular cross weave pattern, like those produced by AHSV.

The Mr 41 10³ NS2 (ViP) protein can be phosphorylated and is an important component of the matrix of VIB, which are the site of virus replication and assembly. VIBs also contain relatively large amounts of the virus core proteins. NS2 (ViP) has ssRNA binding activity, suggesting it has an active role in replication. In conjunction with other virus proteins it is believed to be involved in the recruitment of viral mRNA for encapsidation. The NS3/NS3a proteins are two small non-structural membrane proteins (Mr 25 and 24 10³), translated from different frame initiation sites on a single ORF, which are involved in the release of virus particles from cells. This function may be essential for dissemination of progeny virus, particularly from insect vector cells, which can become persistently infected and do not show CPE or high levels of cell death. In the process of particle release, the NS3 proteins are also released from the cell.

Carbohydrates

The BTV/VP5 protein may be glycosylated. NS3 and NS3a synthesized in mammalian cells can become glycosylated, forming high molecular weight products.

Genome Organization and Replication

The BTV genome segment coding assignments, based on the dsRNA migration in 1% agarose are: Segment 1-VP1 (Pol); Segment 2-VP2; Segment 3-VP3 (T2); Segment 4-VP4 (Cap); Segment 5-NS1 (TuP); Segment 6-VP5; Segment 7-VP7 (T13); Segment 8-NS2 (ViP); Segment 9-VP6/VP6a (Hel); Segment 10-NS3/NS3a. Cognate genes of different BTV strains are similar. The S9 and S10 mRNAs are translated from either of 2 in-frame AUG codons. The significance of the 2 forms of the S9 and S10 gene products (NS3, NS3A; VP6, VP6A) is not known. In some cases other virus proteins form morphologically defined structures in infected cells [e.g. the flat hexagonal crystals formed of VP7 (T13) of AHSVs] but these are of unknown functional significance (Table 4).

Virus adsorption involves components of the outer capsid, although cell entry may also involve VP7 (T13). VP2 (possibly also VP5) is involved in determination of virulence. The outer capsid layer is lost during the early stages of replication. The transcription frequency of mRNA from individual genome segments varies, with more copies produced from the smaller segments. Details of the process of virus replication are lacking. The viral inclusion bodies (VIB) are considered to be the sites of morphogenesis of transcriptionally active virus cores containing dsRNA. The smallest particles containing RNA that are observed in VIBs appear to represent progeny subcore particles. The outer core protein [VP7 (T13)] is added within the VIB and the outer capsid proteins at the periphery of the VIB.

Virus particles are transported within the cell by specific interaction with the cellular cytoskeleton and can be released from the cell prior to lysis through interaction with membrane-associated NS3 proteins. There is also evidence of specific association between NS1 tubules and intact virions in the cell cytoplasm. In mammalian cells, replication of orbiviruses leads to shut-off of host protein synthesis and usually results in cell lysis and the release of virus particles. In persistently infected insect cells, there is no evidence for shut-off of host protein synthesis, extensive cell lysis or CPE. In some species (AHSV), NS3 is involved in determination of virulence. Virus particles can leave viable mammalian cells by two distinct mechanisms, extrusion (involving cell membrane damage) and budding. Only budding has been observed in cells of the BTV vector Culicoides variipennis, resulting in particles which have a membrane envelope, although this is unstable and is rapidly lost. Continuous release of virus particles from infected cells and reinfection appears to be a feature of orbivirus replication.

Antigenic Properties

The main virus serogroup (species) specific antigen is the immunodominant outer core protein VP7 (T13). Monoclonal or polyclonal antibodies against VP7 (T13) can neutralize core particle infectivity, but do not appear to attach to, or neutralize intact virus particles or ISVP in aqueous suspension. Other viral proteins are also conserved between virus species (in particular core and most NS proteins). However, some of these antigens may also show cross-reactions with viruses in other species, particularly those regarded as closely related. These cross-reactions are usually at a significantly lower level than with other viruses from the same virus species and may be ‘one way’. Such relationships between species are also demonstrated by comparisons of the RNA sequences of conserved segments (for example those of genome segment 3, coding for VP3 (T2), Fig. 6). These data indicate that the different orbivirus species may be divided into at least four ‘groups’. The first group (A) contains: AHSV, BTV, EHDV, Equine encephalosis virus (EEV), Eubenangee virus (EUBV), Palyam virus (PALV), Wallal virus (WALV) and Warrego virus (WARV). The second group (B) contains : Chenuda virus (CNUV), Ieri virus (IERIV), Wad Medani virus (WMV) and Great Island virus (GIV). The third group (C) contains Corriparta virus (CORV). The fourth group (D) contains Wongorr virus (WGRV). However insufficient comparisons have been made to conclusively assign all of the orbivirus species to such groups.

Each orbivirus species includes a number of serotypes that can be identified and distinguished by serum neutralization assays of intact virus particles (primarily via interactions of antibodies with the outer CPs). VP2 is the main neutralization antigen of BTV, while VP5 is also involved in determination of virus serotype, possibly by imposing conformational constraints on VP2. The VP2 and VP5 proteins of BTV exhibit the greatest antigenic and sequence variation (Fig. 6). In other viruses (GIV) the relative sizes of the outer CPs (VP4 and VP5) are very different and their individual roles may also be different. There is evidence that VP2 of BTV (particularly in association with VP5) and VP7 (T13) can be protective antigens.

In AHSV, the small nonstructural proteins, NS3 and NS3a are also ‘variable’ and may be divided into three groups (, and ) based on sequence analysis. Preliminary serological evidence suggests that NS3 crossreacts poorly between these groups. NS3 can also be involved in determination of virulence (AHSV), possibly as a result of its involvement in release of virus particles from cells (budding) and its consequent effect on virus dissemination.

Biological Properties

The specific infectivity of BTV cores varies from 1000 fold less than that of intact virions, to uninfectious, depending on the mammalian cell line used. However, in some insect cells, and adult vector insects, core particles are only slightly less infectious than intact virions. Treatment of virus with chymotrypsin or trypsin results in production of infectious subviral particles (ISVPs), in which VP2 is cleaved. BTV ISVPs have lost hemaglutinating activity, as well as the tendency to aggregate but have a significantly elevated infectivity for adults of insect vectors and for some insect cell lines (a particle infectivity ratio of approximately 13:1).

Different orbiviruses infect a wide range of vertebrate hosts including ruminants (domesticated and wild), equids (domesticated and wild), rodents, bats, marsupials, birds, sloths, and primates, including humans. Orbiviruses replicate in, and are primarily transmitted by arthropod vectors (gnats, mosquitoes, phlebotomines, or ticks, depending on the virus). Trans-stadial transmission in ticks has been demonstrated for some viruses. Infection of vertebrates in utero may also occur. Orbiviruses, particularly those transmitted by short-lived vectors (gnats, mosquitoes, phlebotomines), are only enzootic in areas where adults of the competent vector species persist and are present all, or most of the year. There is no evidence of trans-ovarial transmission of orbiviruses in Culicoides, although orbiviruses have been detected in cell lines derived from tick eggs. BTV and EHDV are distributed worldwide between about 50° North and about 30° South in the Americas and between 40° North and 35° South in the rest of the world. However, there is evidence for persistence of these viruses over winter in the absence of overt disease. Mechanisms for persistence in the vertebrate host species even at low levels may be of particular importance. Virus distribution also depends on the initial introduction into areas containing susceptible vertebrate hosts and competent vector species. For this reason not all serotypes of each species (e.g., BTV) are present at locations where some serotypes are endemic.

Orbivirus infection of arthropods has little or no evident effect. Infection in vertebrates, can vary from inapparent to fatal, depending on both the virus and the host. Some BTV strains cause death in sheep, others cause a variety of pathologies, including hemorrhagic conditions, lameness, oedema, a transitory cyanotic appearance of the tongue (giving rise to the species name), nasal and mouth lesions, etc.; still others cause no overt pathology. BTV infection of cattle may show no signs of disease but involve long-lived viraemias. AHSV, EHDV and EEV can cause severe pathology in their respective vertebrate hosts. Mortality rates in serologically naive populations can be over 98% (AHSV).

List of Species Demarcation Criteria in the Genus

In common with the other genera within the family Reoviridae, the prime determinant for inclusion of virus isolates within an orbivirus species is compatibility for reassortment of genome segments during co-infection, thereby exchanging genetic information and generating viable progeny virus strains. However, data providing direct evidence of segment reassortment between isolates is limited and serological comparisons (primarily involving the immunodominant serogroup/species specific antigen VP7 (T13)), form the usual basis of diagnostic assays for each of the virus species (serogroups).

Members of an orbivirus species may be identified by:

1.	The ability to exchange genetic material by genome segment reassortment during dual infections, thereby producing viable progeny virus strains.
2.	High levels of serological cross reaction by ELISA, or assays such as complement fixation (CF), or agar gel immunodiffusion (AGID), using either polyclonal sera, or monoclonal antibodies against conserved antigens such as VP7 (T13). For example in competition ELISA, at a test serum dilution of 1/5, a positive serum will show >50% inhibition of colour formation, while a negative control serum, or serum that is specific for a different species will normally produce <25% inhibition of colour compared to a no antibody control. Distinct but related species may show low level serological crossreaction, which may be only ‘one way’.
3.	High levels of RNA sequence similarities in “conserved” genome segments. Viruses within the same species will normally show <24% sequence variation in genome Segment 3 (encoding the major subcore structural protein, VP3 (T2)). Viruses in different species will normally contain >26% sequence variation in genome Segment 3 (see 9); these differences are also reflected in the amino acid sequences of the viral proteins.
4.	Relatively efficient cross hybridization of “conserved” genome segments (those not encoding outer capsid components, or other variable proteins) under high stringency conditions (>85% homology) (Northern or dot blots, with probes made from viral RNA or cDNA).
5.	PCR using primers to conserved genome regions or segments such as Segment 3 or Segment 7. Can be coupled with cross hybridization analysis (Northern or dot blots).
6.	Identification by virus serotype with a virus type already classified within a specific orbivirus species. None of the serotypes from different species will cross neutralize.
7.	Analysis of “electropherotype” by agarose gel electrophoresis but not by PAGE. Viruses within a single species will show a relatively uniform electropherotype. However, a major deletion / insertion event may result in two distinct electropherotypes within a single species (for example EHDV) and some similarities can exist between more closely related species.
8.	Identical conserved terminal regions of the genome segments (some closely related species can have identical terminal sequences on at least some segments).
9.	Identification of common vector or host species and the clinical signs produced. For example BTV is transmitted only by certain Culicoides species and will infect cattle and sheep producing clinical signs of varying severity but is not thought to infect horses. The reverse is true of AHSV.

List of Species in the Genus

Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus names, arthropod vector and host names { }, genome sequence accession numbers [ ], and assigned abbreviations ( ) are:

Species in the Genus

African horse sickness virus (9 serotypes)		(AHSV)
African horse sickness virus 1 to 9 {Culicoides: Equids, dogs, elephants, camels, cattle, sheep goats, predatory carnivores and (in special circumstances) humans}	Seg 1: [U94887], Seg 2: [AF021235, U01832, M94680], Seg 3: [M94681], Seg 4: [D14402], Seg 5: [D11390], Seg 6: [M94682], Seg 7: [D12533], Seg 8: [M69090], Seg 9: [U33000], Seg 10: [D12479]	(AHSV-1 to 9)
Bluetongue virus (24 serotypes)		(BTV)
Bluetongue virus 1 to 24 {Culicoides: Cattle, sheep, goats, camels. elephants, ruminants (domestic and wild), predatory carnivores}	Seg 1: [X12819], Seg 2: [M11787], Seg 3: [M22096], Seg 4: [Y00421], Seg 5: [D12532], Seg 6: [Y00422], Seg 7: [X06463], Seg 8: [D00500], Seg 9: [D00509], Seg 10: [M28981]	(BTV-1 to 24)
Changuinola virus (12 serotypes)		(CGLV)
Almeirim virus		(ALMV)
Altamira virus		(ALTV)
Caninde virus		(CANV)
Changuinola virus		(CGLV)
Gurupi virus		(GURV)
Irituia virus		(IRIV)
Jamanxi virus		(JAMV)
Jari virus		(JARIV)
Monte Dourado virus		(MDOV)
Ourem virus		(OURV)
Purus virus		(PURV)
Saraca virus {phlebotomines, culicine mosquitoes:humans, rodents, sloths}		(SRAV)
Chenuda virus (7 serotypes)		(CNUV)
Baku virus		(BAKUV)
Chenuda virus		(CNUV)
Essaouira virus		(ESSV)
Huncho virus		(HUAV)
Kala Iris virus		(KIRV)
Mono Lake virus		(MLV)
Sixgun city virus {ticks: seabirds}		(SCV)
Chobar Gorge virus (2 serotypes)		(CGV)
Chobar Gorge virus		(CGV)
Fomede virus {ticks: bats}		(FV)
Corriparta virus (5 serotypes/strains)		(CORV)
Acado virus		(ACDV)
Corriparta virus (CS109)		(CORV-CS109)
Corriparta virus (V654)		(CORV-V654)
Corriparta virus (V370)		(CORV-V370)
Jacareacanga virus {culicine mosquitoes: humans, rodents}		(JACV)
Epizootic hemorrhagic disease virus (8 serotypes)		(EHDV)
Epizootic hemorrhagic disease virus 1 to 8	Seg 2: [D10767], Seg 3: [M76616], Seg 5: [X55782], Seg 6: [X59000], Seg 7: [D10766], Seg 8: [M69091]
Ibaraki virus		(EHDV-1 to 8)
isolate 318		(IBAV)
{Culicoides: cattle, sheep, deer, camels, llamas, wild ruminants, marsupials}		(EHDV-318)
Equine encephalosis virus		(EEV)
Equine encephalosis virus 1 to 7 {Culicoides: equids}		(EEV-1 to 7)
Eubenangee virus (4 serotypes)		(EUBV)
Eubenangee virus		(EUBV)
Ngoupe virus		(NGOV)
Pata virus		(PATAV)
Tilligerry virus {Culicoides, anopheline and Culicine mosquitoes: unknown hosts}		(TILV)
Ieri virus (3 serotypes)		(IERIV)
Ieri virus		(IERIV)
Gomoka virus		GMKV)
Arkonam virus {mosquitoes: birds}		(ARKV)
Great Island virus (36 serotypes)		(GIV)
Above Maiden virus		(ABMV)
Arbroath virus
Bauline virus		(ABRV)
Broadhaven virus	Seg 2: [M87875], Seg 5: [M36394], Seg 7: [M87876], Seg 10: [M83197]	(BAUV)
		(BRDV)
		(CWV)
Colony virus		(COYV)
Colony B North virus		(CBNV)
Ellidaey virus		(ELLV)
Foula virus		(FOUV)
Great Island virus		(GIV)
Great Saltee Island virus		(GSIV)
Grimsey virus		(GSYV)
Inner Farne virus		(INFV)
Kemerovo virus		(KEMV)
Kenai virus		(KENV)
Kharagysh virus		(KHAV)
Lipovnik virus		(LIPV)
Lundy virus		(LUNV)
Maiden virus		(MDNV)
Mill Door virus		(MDRV)
Mykines virus		(MYKV)
North Clett virus		(NCLV)
North End virus		(NEDV)
Nugget virus		(NUGV)
Okhotskiy virus		(OKHV)
Poovoot virus		(POOV)
Rost Island virus		(RSTV)
St Abb’s Head virus		(SAHV)
Shiant Islands virus		(SHIV)
Thormodseyjarlettur virus		(THRV)
Tillamook virus		(TLMV)
Tindholmur virus		(TDMV)
Tribec virus		(TRBV)
Vearoy virus		(VAEV)
Wexford virus		(WEXV)
Yaquina Head virus {Argas, Ornithodoros,Ixodes ticks: seabirds, rodents, humans}		(YHV)
Lebombo virus (1 serotype)		(LEBV)
Lebombo virus 1 {culicine mosquitoes: humans, rodents}		(LEBV-1)
Orungo virus (4 serotypes)		(ORUV)
Orungo virus 1 to 4 {culicine mosquitoes: humans, camels, cattle, goats, sheep, monkeys}		(ORUV-1 to 4)
Palyam virus (11 serotypes)		(PALV)
Abadina virus		(ABAV)
Bunyip creek virus		(BCV)
CSIRO village virus		(CVGV)
D’Aguilar virus	Seg 2 [AB014725], Seg 3 [AB014728] Seg 6 [AB014726], Seg 7 [AB014727]	(DAGV)
Kasba virus		(KASV)
(Chuzan virus)		(CHUV)
Kindia virus		(KINV)
Marrakai virus		(MARV)
Nyabira virus		(NYAV)
Palyam virus		(PALV)
Petevo virus		(PETV)
Vellore virus {Culicoides, culicine mosquitoes: Cattle, sheep}		(VELV)
Umatilla virus (4 serotypes)		(UMAV)
Llano Seco virus		(LLSV)
Minnal virus		(MINV)
Netivot virus		(NETV)
Umatilla virus {culicine mosquitoes: birds}		(UMAV)
Wad Medani virus (2 serotypes)		(WMV)
Seletar virus		(SELV)
Wad Medani virus {Boophilus, Rhipicephalus, Hyalomma, Argas ticks: domesticated animals}		(WMV)
Wallal virus (3 serotypes/strains)		(WALV)
Mudjinbarry virus		(MUDV)
Wallal virus		(WALV)
Wallal K virus {Culicoides: marsupials}		(WALKV)
Warrego virus (3 serotypes/strains)		(WARV)
Mitchell river virus		(MRV)
Warrego virus		(WARV)
Warrego K virus {Culicoides, anopheline and culicine mosquitoes: marsupials}		(WARKV)
Wongorr virus (8 serotypes)		(WGRV)
Paroo river virus		(PRV)
Picola virus		(PIAV)
Wongorr virus: MRM13443		(WGRV)
Wongorr virus CS131		(WGRV-CS131)
Wongorr virus V195		(WGRV-V195)
Wongorr virus V199		(WGRV-V199)
Wongorr virus V595		(WGRV-V595)
Wongorr virus V1447 {Culicoides, mosquitoes: Cattle, macropods}		(WGRV)

Tentative Species in the Genus

Andasibe virus	{mosquitoes: unknown hosts}	(ANDV)
Codajas virus	{mosquitoes: rodents}	(COV)
Ife virus	{mosquitoes: rodents, birds, ruminants}	(IFEV)
Itupiranga virus	{mosquitoes: unknown hosts}	(ITUV)
Japanaut virus	{mosquitoes: unknown hosts}	(JAPV)
Kammavanpettai virus	{unknown vectors: birds}	(KMPV)
Lake Clarendon virus	{ticks: birds}	(LCV)
Matucare virus	{ticks: unknown hosts}	(MATV)
Peruvian horse virus	{Culicoides: horses}	(PHV)
Peruvian rodent virus (PC21)	{unknown: rodents}	(PRV)
St Croix River virus	{ticks: onknown hosts}	(SCRV)
Tembe virus	{mosquitoes: unknown hosts}	(TMEV)
Tracambe virus	{mosquitoes: unknown hosts}	(TRV)

Phylogenetic Relationships within the Genus

See Fig. 6.