rhinovirus

(from the Greek rhin-, which means "nose") is a genus of the Picornaviridae family of viruses. Rhinoviruses are the most common viral infective agents in humans, and a 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 about 7.2 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 enveloped and are icosahedral in structure.

Rhinoviruses are composed of a capsid, that contains four viral proteins VP1, VP2, VP3 and VP4.^[1][2] 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.

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 are known to be transmitted indirectly via respiratory droplets that are 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.

The primary route of entry for rhinoviruses is the upper respiratory tract. Afterwards, the virus binds to ICAM-1 (intracellular adhesion molecule -1) receptors on respiratory epithelial cells. As the virus replicates and spreads, infected cells release distress signals known as chemokines 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 ^[3].

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

There are no vaccines against these viruses as there is little-to-no cross-protection between serotypes. It would be impractical to administer 105 separate vaccines to a patient.

..stuck here at home with nothing better to do than research on some stupid rhinovirus. *sigh*

ugh. i hate having colds :(