Bornaviridae
| Family Bornaviridae | |
|---|---|
| Virus classification | |
| Group: | Group V ((−)ssRNA) |
| Order: | Mononegavirales |
| Family: | Bornaviridae |
| Genus: | Bornavirus |
| Species | |
| |
Bornaviridae is a family of viruses in the order Mononegavirales. Horses, sheep, cattle, rodents, birds, reptiles, and humans serve as natural hosts. Currently, 16 viruses are assigned to eight species included in one genus in this family. Diseases associated with bornaviruses include Borna disease, a fatal neurologic disease of mammals restricted to central Europe; and proventricular dilatation disease in birds.[1][2]
History
Borna disease was first identified in 1926 and its genome was isolated in 1990. The viral family is named after the city of Borna in Saxony, Germany, which is where a large number of animals were lost to the sporadic encephalopathy caused by the viral disease. [3]
Taxonomy
| Genus | Species | Virus (Abbreviation) |
| Bornavirus | Elapid 1 bornavirus | Loveridge’s garter snake virus 1 (LGSV-1) |
| Mammalian 1 bornavirus* | Borna disease virus 1 (BoDV-1) | |
| Borna disease virus 2 (BoDV-2) | ||
| Mammalian 2 bornavirus | variegated squirrel bornavirus 1 (VSBV-1) | |
| Passeriform 1 bornavirus | canary bornavirus 1 (CnBV-1) | |
| canary bornavirus 2 (CnBV-2) | ||
| canary bornavirus 3 (CnBV-3)) | ||
| Passeriform 2 bornavirus | estrildid finch bornavirus 1 (EsBV-1) | |
| Psittaciform 1 bornavirus | parrot bornavirus 1 (PaBV-1) | |
| parrot bornavirus 2 (PaBV-2) | ||
| parrot bornavirus 3 (PaBV-3) | ||
| parrot bornavirus 4 (PaBV-4) | ||
| parrot bornavirus 7 (PaBV-7) | ||
| Psittaciform 2 bornavirus | parrot bornavirus 5 (PaBV-5) | |
| Waterbird 1 bornavirus | aquatic bird bornavirus 1 (ABBV-1) | |
| aquatic bird bornavirus 2 (ABBV-2) | ||
Table legend: "*" denotes type species.
Structure
Bornavirions are enveloped, with spherical geometries. The diameter is around 70 to 130 nm. Genomes are linear, around 8.9kb in length. The genome codes for 9 proteins. [1]
Below are a few of the essential proteins of Bornaviridae that have been characterized.
| Protein | Function |
|---|---|
| N | Helical nucleoside protein |
| G | Envelope glycoprotein |
| L | Viral polymerase |
| P | Phosphoprotein involved in replication |
| M | Matrix protein |
| X | Hasn't been fully characterized—perhaps nuclear transport |
| Genus | Structure | Symmetry | Capsid | Genomic arrangement | Genomic segmentation |
|---|---|---|---|---|---|
| Bornavirus | Spherical | Enveloped | Linear | Monopartite |
Life cycle
Viral replication is nuclear. Entry into the host cell is achieved by attachment of the viral GP glycoproteins to host receptors, which mediates clathrin-mediated endocytosis. Replication follows the negative stranded RNA virus replication model. Negative stranded RNA virus transcription, using polymerase stuttering, with some alternative splicing mechanism, is the method of transcription. The virus exits the host cell by nuclear pore export. Horses, sheep, cattle, rodents, birds, and humans serve as the natural hosts. Transmission routes are fomite, contact, urine, feces, and saliva.[1]
| Genus | Host details | Tissue tropism | Entry details | Release details | Replication site | Assembly site | Transmission |
|---|---|---|---|---|---|---|---|
| Bornavirus | Horses; sheep; cattle; rodents; birds; humans | Neurons; astrocytes; oligodendrocytes; ependymal cells | Clathrin-mediated endocytosis | Budding | Nucleus[4] | Cytoplasm | Fomites; contact: saliva; contact: urine; contact: feces |
Pathogenicity
Between 2011 and 2013, three German breeders of variegated squirrels (Sciurus variegatoides) had encephalitis with similar clinical signs and died 2 to 4 months after onset of the clinical symptoms. Genomic analysis found a previously unknown bornavirus in a contact squirrel and in brain tissue from the three men, the researchers reported, and it is the "likely causative agent" in their deaths. Prior to this, Bornavirus species were not thought to be responsible for human diseases.[5][6]
References
- 1 2 3 "Viral Zone". ExPASy. Retrieved 12 June 2015.
- 1 2 Amarasinghe, Gaya K.; Bào, Yīmíng; Basler, Christopher F.; Bavari, Sina; Beer, Martin; Bejerman, Nicolás; Blasdell, Kim R.; Bochnowski, Alisa; Briese, Thomas (2017-04-07). "Taxonomy of the order Mononegavirales: update 2017". Archives of Virology. ISSN 1432-8798. PMID 28389807. doi:10.1007/s00705-017-3311-7.
- ↑ "Borna".
- ↑ Veterinary Microbiology and microbial disease, 2nd edition, P J Quinn et al. Wiley-Blackwell
- ↑ Hoffmann, Bernd; Tappe, Dennis; Höper, Dirk; Herden, Christiane; Boldt, Annemarie; Mawrin, Christian; Niederstraßer, Olaf; Müller, Tobias; Jenckel, Maria; van der Grinten, Elisabeth; Lutter, Christian; Abendroth, Björn; Teifke, Jens P.; Cadar, Daniel; Schmidt-Chanasit, Jonas; Ulrich, Rainer G.; Beer, Martin (9 July 2015). "A Variegated Squirrel Bornavirus Associated with Fatal Human Encephalitis". New England Journal of Medicine. 373 (2): 154–162. PMID 26154788. doi:10.1056/NEJMoa1415627 – via Taylor and Francis+NEJM.
- ↑ "Is There a Killer Squirrel Virus?". 9 July 2015.