Aphthovirus
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Aphthovirus | ||||||||||||||||
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The genus Aphthovirus comprises four species of non-enveloped viruses from the Picornaviridae family (as of November 2018). Were named the aphthoviruses of the disease that the foot-and-mouth disease virus (s. Foot-and-mouth disease virus , FMDV) as the main representative of the genus causes ( Greek. Αφθαι ( aphthai ) for small bubbles of the oral mucosa) .
morphology
The virions (virus particles) of the aphthoviruses are about 27 to 30 nm in diameter and are composed of 60 capsomeres ( T = 1 ). Characteristic is the very smooth surface structure compared to other picornaviruses and the thin walls of the capsid , the thickness of which is only about 3 nm on average. At the capsid corners with five-pointed symmetry one finds pores that are formed by the penton proteins . A flexible protein loop (GH loop) of the capsid protein 1D consisting of 17 to 23 amino acids protrudes from the surface. At its tip is the conserved RGD recognition motif for binding to integrins on the cell surface and uptake of the virions in the host cell .
The virions of the FMDV are unstable below a pH value of 6.8, those of the equine rhinitis A virus (ERAV) only below 5.5. Some FMDV serotypes produce an excess of empty, RNA-free and therefore non-infectious capsids.
Genome
The aphthovirus genome is between 7.5 and 8.7 kb long. The translation to a single polyprotein , which is then cleaved into the individual viral proteins by means of viral proteases , can begin at two alternative starting points within the same reading frame . This creates two forms of L-protein (Lab and Lb) of different lengths, which have proteolytic activity as cysteine proteases . The L-proteins are also able to cleave the cellular initiation factor eIF-4G , thereby preventing all cellular, cap-dependent translation. Since aphthoviruses, like all picornaviruses, have an IRES at the 5 'end of the genome for translation initiation , viral protein synthesis remains unaffected by this inhibition.
Systematics
The internal systematics of the genus Aphthovirus is as follows:
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- Genus aphthovirus
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- Species Equine rhinitis A virus (en. Equine rhinitis A virus , ERAV-A)
- Serotype: ERV-1
- Species Bovine rhinitis A virus ( en.Bovine rhinitis A virus , BRAV-A)
- Serotypes: BRV-1, BRV-3
- Species Bovine rhinitis B virus (en. Bovine rhinitis B virus , BRAV-B)
- Serotype: BRV-2
- Species foot-and-mouth disease virus (s. Foot-and-mouth disease virus , FMDV)
- 7 serotypes
A cladogram of the genus with all serotypes can be found on the 'Picornavirus Pages' of the Pirbright Institute.
Individual evidence
- ↑ ICTV Master Species List 2018b.v2 . MSL # 34, March 2019
- ↑ a b c d ICTV: ICTV Taxonomy history: Enterovirus C , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
- ↑ ICTV 2016 Master Species List # 31 with Acronyms, (Excel XLSX) , on ViralZone , Swiss Institute of Bioinformatics (SIB)
- ↑ ICTV : Master Species List 2018a v1 , MSL including all taxa updates since the 2017 release. Fall 2018 (MSL # 33)
- ↑ a b Details: Aphthovirus , The Picornavirus Pages 2006–2019, The Pirbright Institute, UK. Retrieved February 17, 2019
literature
- G. Stanway, F. Brown et al. : Genus aphthovirus . In: CM Fauquet, MA Mayo et al. : Eighth Report of the International Committee on Taxonomy of Viruses . London, San Diego 2005, pp. 768ff, ISBN 0-12-249951-4