Rhinovirus
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2008-06-26T15:35:47Z
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{{Taxobox
| name = ''Rhinovirus''
| image = Rhinovirus.PNG
| image_caption = [[Molecular surface]] of a rhinovirus, showing protein spikes
| image_width = 185px
| virus_group = iv
| familia = ''[[Picornaviridae]]''
| genus = ''Rhinovirus''
| subdivision_ranks = Species
| subdivision =
''[[Human rhinovirus A]]''<br>
''[[Human rhinovirus B]]''
}}
'''''Rhinovirus''''' (from the Greek ''rhin''-, which means "nose") is a genus of the ''[[Picornaviridae]]'' family of [[virus]]es.
Rhinoviruses are the most common viral infective agents in humans, and a causative agent of the [[common cold]]. There are over 110 [[serologic]] virus types that cause cold symptoms, and rhinoviruses are responsible for approximately 30% to 50% of all cases.
Rhinoviruses have single-stranded positive sense [[RNA]] genomes of between 7.2 and 8.5[[Base pair|kb]] in length. At the 5′ end of the [[genome]] is a virus-encoded protein, and like mammalian mRNA, there is a 3′ [[poly-A tail]]. Structural proteins are encoded in the 5′ region of the genome and non structural at the end. This is the same for all [[picornaviruses]]. The viral particles themselves are not [[Viral envelope|enveloped]] and are [[icosahedral]] in structure.
== Structure ==
<!-- Image with unknown copyright status removed: [[Image:Rossmann.virus.jpeg|right|thumb|Picture of the Rhinovirus 16, computer-generated-model.]] -->
Rhinoviruses are composed of a [[capsid]], that contains four viral [[proteins]] VP1, VP2, VP3 and VP4.<ref name=Rossmann_1985>{{cite journal | author = Rossmann M, Arnold E, Erickson J, Frankenberger E, Griffith J, Hecht H, Johnson J, Kamer G, Luo M, Mosser A | title = Structure of a human common cold virus and functional relationship to other picornaviruses. | journal = Nature | volume = 317 | issue = 6033 | pages = 145–53 | year = 1985 | pmid = 2993920 | doi = 10.1038/317145a0}}</ref><ref name=Smith_1986>{{cite journal | author = Smith T, Kremer M, Luo M, Vriend G, Arnold E, Kamer G, Rossmann M, McKinlay M, Diana G, Otto M | title = The site of attachment in human rhinovirus 14 for antiviral agents that inhibit uncoating. | journal = Science | volume = 233 | issue = 4770 | pages = 1286–93 | year = 1986 | pmid = 3018924 | doi = 10.1126/science.3018924}}</ref> VP1, VP2, and VP3 form the major part of the protein capsid. The much smaller VP4 protein has a more extended structure and lies at interface between the capsid and the RNA genome. There are 60 copies of each of these proteins assembled as an [[icosahedron]]. Antibodies are a major defense against infection with the [[epitopes]] lying on the exterior regions of VP1-VP3.
==Transmission and epidemiology==
There are two modes of transmission: via aerosols of respiratory droplets and from contaminated surfaces, including direct person-to-person contact.
Rhinoviruses occur worldwide and are the primary cause of [[common cold]]s. [[Symptom]]s include [[Pharyngitis|sore throat]], [[rhinitis|runny nose]], [[nasal congestion]], [[sneeze|sneezing]] and [[cough]]; sometimes accompanied by [[myalgia|muscle aches]], [[fatigue (medical)|fatigue]], [[malaise]], [[headache]], [[muscle weakness]], or [[Anorexia (symptom)|loss of appetite]]. [[Fever]] and extreme [[fatigue (medical)|exhaustion]] are more usual in [[influenza]]. Children may have six to twelve colds a year. In the United States, the incidence of colds is higher in the fall and winter, with most infections occurring between September to April. The seasonality may be due to the start of the school year, or due to people spending more time indoors (thus in closer proximity with each other) increasing the chance of transmission of the virus.
{{main|Common Cold}}
==Pathogenesis==
The primary route of entry for rhinoviruses is the upper [[respiratory tract]]. Afterwards, the virus binds to [[ICAM-1]] (intracellular adhesion molecule -1) [[receptor (biochemistry)|receptor]]s on respiratory epithelial cells. As the virus replicates and spreads, infected cells release distress signals known as [[chemokine]]s and [[cytokines]] (which in turn activate inflammatory mediators).
Infection occurs rapidly, with the virus adhering to surface receptors within 15 minutes of entering the respiratory tract. The [[incubation period]] is generally 8-10 hours before symptoms begin to occur.<ref>{{cite web|url=http://www.scq.ubc.ca/?p=438|author=McCoy, Lori|title=Rhinovirus: An Unstoppable Cause of the Common Cold|publisher=The Science Creative Quarterly}}</ref>
Rhinoviruses rarely cause lower [[respiratory tract]] disease probably because they grow poorly at 37°C.<!-- Can anyone add information as to why this temperature is here? Is the lower respiratory tract's temperature 37°Celcius? The page does not explain this very well, as it has no reference for this information, and no explanation. -->
==Novel antiviral drugs==
[[Interferon]]-alpha used intranasally was shown to be protective to rhinovirus infections. However, volunteers treated with this drug experienced some side effects, such as nasal bleeding, and [[Resistance to antiviral drugs|resistance]] was also developing toward the drug. Hence, all research put into this drug was ceased.
[[Pleconaril]] is an orally bioavailable [[antiviral]] drug being developed for the treatment of infections caused by [[picornaviruses]].<ref name=Pevear_1999>{{cite journal | author = Pevear D, Tull T, Seipel M, Groarke J | title = Activity of pleconaril against enteroviruses. | journal = Antimicrob Agents Chemother | volume = 43 | issue = 9 | pages = 2109–15 | year = 1999 | pmid = 10471549}}</ref> This drug acts by binding to a hydrophobic pocket in VP1 and stabilizes the protein capsid to such an extent that the virus cannot release its RNA genome into the target cell. When tested in volunteers, during the clinical trials, this drug caused a significant decrease in [[mucus]] secretions and illness-associated [[symptoms]]. Pleconaril is not currently available for treatment of rhinoviral infections, as its efficacy in treating these infections is under further evaluation.<ref name=Fleisher_2003>{{cite journal | author = Fleischer R, Laessig K | title = Safety and efficacy evaluation of pleconaril for treatment of the common cold. | journal = Clin Infect Dis | volume = 37 | issue = 12 | pages = 1722 | year = 2003 | pmid = 14689362 | doi = 10.1086/379830}}</ref>
==Vaccine==
There are no [[vaccines]] against these viruses as there is little-to-no cross-protection between [[serotype]]s.
==References==
{{reflist}}
* Smith, T. J., Chase, E. S., Schmidt, T. J., Olson, N. H. & Baker, T. S. (1996). Neutralizing antibody to human rhinovirus 14 penetrates the receptor-binding canyon. Nature 383, 350-354.
* Abraham, G. & Colonno, R. J. (1984). Many rhinovirus serotypes share the same cellular receptor. J. Virol. 51: 340-345.
==External links==
*[http://videos.med.wisc.edu/videoInfo.php?videoid=1691 VIDEO: Rhinoviruses, the Old, the New and the UW]James E. Gern, MD, speaks at the University of Wisconsin School of Medicine and Public Health, 2008.
*[http://www.cellsalive.com/howbig.htm How Big is a Rhinovirus? (animation)]
{{Common Cold}}
[[Category:Viral diseases]]
[[Category:Picornaviruses]]
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