Tibrovirus
| Tibrovirus | |
|---|---|
| Virus classification | |
| Group: | Group V ((−)ssRNA)
|
| Order: | |
| Family: | |
| Genus: | Tibrovirus
|
| Type species | |
| Tibrogargan tibrovirus | |
| Species | |
| |
Tibrovirus is a poorly characterized genus of viruses in the family Rhabdoviridae, order Mononegavirales. As of 2019, there are 8 members of the tibrovirus genus: Ekpoma virus 1, Ekpoma virus 2, Bas-Congo virus, Coastal Plains virus, Bivens Arm virus, Beatrice Hill virus, Sweetwater Branch virus, and Tibrogargan virus[1]. Tibroviruses contain the typical five open reading frames shared by all rhabdoviruses, as well as three open reading frames of unknown function. Tibroviruses have been isolated from biting midges, cattle, and humans. Only one tibrovirus, Bas-Congo virus, has been associated with disease.
Discovery
Tibrogargan virus was the first tibrovirus discovered[2]. It was isolated from a pool of biting midges (Culicoides brevitaris) collected in 1976 in Preachester, Australia.
In 1981, Coastal Plains virus was isolated from the blood of a healthy, asymptomatic steer[3].
Between 1981-1982, two tibroviruses were isolated from biting midges in Florida[4]. These midges were feeding on Water Buffalo imported from Trinidad.
In 1984, another tibrovirus from Australia was reported[5]. This tibrovirus was named Beatrice Hill virus. It is 72% identical to Tibrogargan virus and Bivens Arm virus.
In 2012, a novel tibrovirus called Bas-Congo was detected in the plasma of a patient in the Democratic Republic of Congo suffering from symptoms resembling hemorrhagic fever[6]. The patient recovered from his illness.
In 2015, two more human-associated tibroviruses were reported[7]. These viruses, called Ekpoma virus 1 and Ekpoma virus 2, were detected in plasma samples from two healthy women in Nigeria.
Transmission
Tibrogargan virus, Bivens Arm virus, Beatrice Hill virus, and Sweetwater Branch virus were all isolated from biting midges. It is therefore highly likely that biting midges are the primary insect vector for these viruses. It is not known how Bas-Congo, Ekpoma virus 1 or Ekpoma virus 2 are transmitted.
Clinical Disease
With the exception of Bas-Congo virus, none of the other tibroviruses have been associated with disease.
Antibodies that neutralize Tibrogargan virus have been found in cattle and buffalo in Australia. Some herd are 100% seropositive. However, Tibrogargan antibodies have never been detected in humans. Furthermore, no disease has been associated with Tibrogargan virus. Cattle have been experimentally inoculated with Tibrovirus, but no overt signs of illness have been observed[8].
Bas-Congo virus has been associated with a case of hemorrhagic fever. However, it is not known whether Bas-Congo virus actually caused the patient's illness.
The Ekpoma viruses are not associated with clinical symptoms in Nigeria. The two viruses were detected in two apparently healthy, asymptomatic women.
Morphology
Tibrovirus virions are enveloped, but only the morphology of Tibrogargan virus and Sweetwater branch virus have been observed by electron microscopy.
| Genus | Structure | Symmetry | Capsid | Genomic arrangement | Genomic segmentation |
|---|---|---|---|---|---|
| Tibrovirus | Bullet-shaped | Helical | Enveloped | Linear | Non-segmented |
Genome
Tibrovirus genomes are single-stranded, negative-sense RNA molecules approximately 13 kb in length. The genome encodes for the typical five proteins found in all rhabdoviruses: nucleocapsid (N), phosphoprotein (P), matrix (M), glycoprotein (G), and polymerase (L). However, there are three additional genes, U1-U3, that encode for proteins of unknown function.[9]
Life cycle
Viral replication is cytoplasmic. Entry into the host cell is achieved by attachment of the viral G glycoproteins to host receptors, which mediate clathrin-mediated endocytosis. Replication follows the negative-stranded RNA virus replication model. Negative stranded RNA virus transcription, using polymerase stuttering is the method of transcription. The virus exits the host cell by budding, and tubule-guided viral movement. Cattle and water buffalo serve as the natural host.[9]
| Genus | Host details | Tissue tropism | Entry details | Release details | Replication site | Assembly site | Transmission |
|---|---|---|---|---|---|---|---|
| Tibrovirus | Bovine | None | Clathrin-mediated endocytosis | Budding | Cytoplasm | Cytoplasm | Zoonosis; arthropod bite: midges |
Taxonomy
| Genus | Species | Virus (Abbreviation) |
| Tibrovirus | Coastal Plains tibrovirus | Coastal Plains virus (CPV) |
| Tibrogargan tibrovirus* | Bivens Arm virus (BAV) | |
| Tibrogargan virus (TIBV) |
Table legend: "*" denotes type species.
References
- ^ https://talk.ictvonline.org/ictv-reports/ictv_online_report/negative-sense-rna-viruses/mononegavirales/w/rhabdoviridae/802/genus-tibrovirus
- ^ Cybinski, D. H., St. George, T. D., Standfast, H. A. & McGregor, A. Isolation of tibrogargan virus, a new Australian rhabdovirus, from Culicoides brevitarsis. Veterinary Microbiology 5, 301–308 (1980)
- ^ Cybinski, D. H. & Gard, G. P. Isolation of a new rhabdovirus in Australia related to Tibrogargan virus. Aust. J. Biol. Sci. 39, 225–232 (1986
- ^ Gibbs, E. P. et al. Bivens arm virus: a new rhabdovirus isolated from Culicoides insignis in Florida and related to Tibrogargan virus of Australia. Vet. Microbiol. 19, 141–150 (1989)
- ^ StandJast, H. et al. Isolation of Arboviruses from Insects Collected at Beatrice Hill, Northern Territory of Australia, 1974?1976. Australian Journal of Biological Sciences 37, 351 (1984)
- ^ Grard, G. et al. A novel rhabdovirus associated with acute hemorrhagic fever in central Africa. PLoS Pathog. 8, (2012)
- ^ Stremlau, M. H. et al. Discovery of novel rhabdoviruses in the blood of healthy individuals from West Africa. PLoS Negl Trop Dis 9, e0003631 (2015)
- ^ Cybinski, D. H., St. George, T. D., Standfast, H. A. & McGregor, A. Isolation of tibrogargan virus, a new Australian rhabdovirus, from Culicoides brevitarsis. Veterinary Microbiology 5, 301–308 (1980)
- ^ a b "Viral Zone". ExPASy. Retrieved 13 August 2015.
- ^ Afonso, Claudio L.; Amarasinghe, Gaya K.; Bányai, Krisztián; Bào, Yīmíng; Basler, Christopher F.; Bavari, Sina; Bejerman, Nicolás; Blasdell, Kim R.; Briand, François-Xavier (1 August 2016). "Taxonomy of the order Mononegavirales: update 2016". Archives of Virology. 161 (8): 2351–2360. doi:10.1007/s00705-016-2880-1. ISSN 1432-8798. PMC 4947412. PMID 27216929.