View source for Rhinovirus

{{Taxobox_begin | color = violet | name = ''Rhinovirus''}}
{{Taxobox_begin_placement_virus}}
{{Taxobox_group_iv_entry}}
{{Taxobox_familia_entry | taxon = ''[[Picornaviridae]]''}}
{{Taxobox_genus_entry | taxon = '''''Rhinovirus'''''}}
{{Taxobox_end_placement}}
{{Taxobox_section_subdivision | color = violet | plural_taxon = Species}}
'''''Human rhinovirus A''''' (HRV-A) <br>
'''''Human rhinovirus B''''' (HRV-B)
{{Taxobox_end}}
'''''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 the causative agent of the [[common cold]]. There are over 105 serologic virus types that cause cold symptoms, and rhinoviruses are responsible for approximately 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&prime; end of the [[genome]] is a virus-encoded protein, and like mammalian mRNA, there is a 3&prime; [[poly-A tail]]. Structural proteins are encoded in the 5&prime; region of the genome and non structural at the end. This is the same for all [[Piconaviruses]]. The viral particles themselves are not [[Viral envelope|enveloped]] and are [[icosahedral]] in structure. 

== Rhinovirus Structure ==
Rhinoviruses are composed of a [[capsid]], which contains four viral [[proteins]] VP1, VP2, VP3 and VP4. Proteins VP1, VP2 and VP3 are organised into 60 repeating protameric icosahedral units. These are thought to be the cause of [[antigen]] diversity associated with these viruses.

==Transmission and epidemiology==
Rhinoviruses have two main modes of transmission: In the past it was obvious that these viruses were transmitted directly from person-to-person via aerosols of respiratory droplets. However, now they can be transmitted indirectly via respiratory droplets that were deposited on the [[hands]] and then transported by [[fingers]] to the [[nose]] or [[eyes]]. 

Rhinoviruses occur worldwide causing [[disease]] especially at schools for example which enhance transmission during fall and winter. They show [[symptoms]] such as [[fever]], [[cough]], and [[nasal congestion]]. The frequency of colds is high in childhood and decreases during adulthood most probably because of the possession of [[immunity]].

==Pathogenesis==
Most people are infected with a rhinovirus.  The common cold occurs only when the [[immune system]] is weakened.  The most common reason for this is [[stress]]. 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).

Rhinoviruses rarely cause lower [[respiratory tract]] [[disease]] probably because they grow poorly at 37°C.

==Novel antiviral drugs==
[[Interferon]]-alpha used intranasally was shown to be protective to rhinovirus infections. However, volunteers treated with this drug experiences some side effects, such as nasal bleeding, and [[resistance]] was also developing toward the drug. Hence, all research put into this drug was ceased.

Pleconaril, which is a 3c [[protease]] [[inhibitor]] is a bioavailable [[antiviral]] drug which is taken orally for treating infections caused by [[picornaviruses]]. This antiviral agent was shown to be safe and effective in experimental models. When tested in volunteers, during the clinical trials, this drug caused a significant decrease in [[mucus]] secretions and illness-associated [[symptoms]]. It was observed ''in'' ''vitro'' that pleconaril blocks viral attachment to the host-cell receptors by integrating into the viral [[capsid]] cavities, which inhibits viral capsid uncoating. This finally results in the inhibition of viral [[replication]] required for effective rhinoviral [[pathogenesis]]. Hopefully, this antiviral agent might soon be available for treatment of rhinoviral infections, however, its efficacy in treating these infections is under further evaluation.  

==Vaccine==
There are no [[vaccines]] against this virus as there is little-to-no cross-protection between serotypes.

==References==
* Anzueto A., Niederman M. S.; Diagnosis and Treatment of Rhinovirus Respiratory Infections; ''Chest''; 2003; 1664-1672 
*[http://www.bioteach.ubc.ca/Biomedicine/Rhinovirus/index.html Rhinovirus: an unstoppable cause of the common cold?]
*[http://web.umr.edu/~microbio/BIO221_1998/rhinovirus.html Rhinovirus]

[[Category:Infectious diseases]]
[[Category:Picornaviruses]]

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