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Erbovirus

Erbovirus

Group:	Group IV ((+)ssRNA)
Family:	Picornaviridae
Genus:	Erbovirus

Species

Equine rhinitis B virus

Erbovirus is a viral genus of the Picornaviridae family.^[1] Viruses belonging to the Erbovirus genus have been isolated in horses with acute upper febrile respiratory disease.^[2] The structure of the erbovirus virion is icosahedral,^[1] having a diameter of 27-30nm.^[3]

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Physical characteristics

The virion essentially is a nucleocapsid that is visible under an electron microscope and is able to infect cultured cells from a broad range of mammals including rabbit kidney (RK13), African green monkey kidney (Vero), equine foetal kidney (EFK), and is able to infect humans.^[4]

The RNA genome of the virion is inside the capsid that is composed by twelve capsomers, which are cup-shaped pentamers.

The erbovirus particles are non-enveloped and the molecular mass of the virions is around 8-9 x 10⁶ Daltons.^[3] They are resistant to inactivation by non-ionic detergent treatment.^[3]

Erbovirus, as a typical picornavirus, has a single-stranded positive-sense RNA genome. A feature of the picornavirus genome is the virus protein that is linked at the 5’ end of the genome, known as "VPg" (Virus-Protein-attached-to-the-Genome).^[1] In addition, the 3’ end of the genome has a poly-A tail.^[1] The transcription of the erbovirus genome gives rise to a polyprotein which is further more processed and cleaved to give the mature viral proteins, in order from 5' to 3' : L ("Leader"), VP4, VP2, VP3, VP1, 2A, 2B, 2C, 3A (Vpg), 3B, 3C^pro, 3D^pol.^[5]

The type (and only) species of the Erbovirus genus is Equine rhinitis B virus which was recently found to have three phylogenetically distinct types, equine rhinitis B virus (ERBV)-1, ERBV-2 and ERBV-3.^[6] One such phylogenetic group was found to mostly comprise of "acid stable" virus isolates, surviving pH 3.6 for 1 hour at room temperature.^[7]

Epidemiology

ERBV's appear to infect most foals and weanlings, eliciting a low serum antibody response in stark contrast to equine rhinitis A virus (ERAV), which is the only species of the genus Aphthovirus that is not a foot-and-mouth disease virus (FMDV), and appears to only infect horses once they begin training for racing (approx. 2 years old). ERAV enters the blood and elicits a very high serum antibody response that seems to then limit the spread of the virus by herd-immunity, given that only approximately 40% of horses have detectable ERAV antibody.^[8] The low serum antibody response of ERBV appears to allow the continual, seasonal re-infection of horses. Horses are also known to shed ERBV for up to two years, possibly more.

References

^ ^a ^b ^c ^d Notes on Genus: Erbovirus. dpvweb. Retrieved on 2007-03-16.
^ Dynon K, Black W, Ficorilli N, Hartley C, Studdert M (2007). "Detection of viruses in nasal swab samples from horses with acute, febrile, respiratory disease using virus isolation, polymerase chain reaction and serology". Aust Vet J 85 (1-2): 46-50. PMID 17300454.
^ ^a ^b ^c 'Erbovirus'. ICTVdb. Retrieved on 2007-03-16.
^ Kriegshäuser G, Deutz A, Kuechler E, Skern T, Lussy H, Nowotny N (2005). "Prevalence of neutralizing antibodies to Equine rhinitis A and B virus in horses and man". Vet Microbiol 106 (3-4): 293-6. PMID 15778036.
^ Wutz G, Auer H, Nowotny N, Grosse B, Skern T, Kuechler E (1996). "Equine rhinovirus serotypes 1 and 2: relationship to each other and to aphthoviruses and cardioviruses". J Gen Virol 77 ( Pt 8): 1719-30. PMID 8760418.
^ Black W, Studdert M (2006). "Formerly unclassified, acid-stable equine picornaviruses are a third equine rhinitis B virus serotype in the genus Erbovirus". J Gen Virol 87 (Pt 10): 3023-7. PMID 16963761.
^ Black W, Hartley C, Ficorilli N, Studdert M (2005). "Sequence variation divides Equine rhinitis B virus into three distinct phylogenetic groups that correlate with serotype and acid stability". J Gen Virol 86 (Pt 8): 2323-32. PMID 16033980.
^ Black W, Wilcox R, Stevenson R, Hartley C, Ficorilli N, Gilkerson J, Studdert M (2007). "Prevalence of serum neutralising antibody to equine rhinitis A virus (ERAV), equine rhinitis B virus 1 (ERBV1) and ERBV2". Vet Microbiol 119 (1): 65-71. PMID 17046179.

Categories: Horse diseases | Picornaviruses | Animal virology

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Erbovirus". A list of authors is available in Wikipedia.