Picornaviridae

For today’s post, I will talk about Picornaviridae. As their name suggests, pico means small. So picornaviruses are small but they have a large array of viruses of over 200 serotypes. I will talk about their taxonomy and 2 piconavirus genera.
http://aka.mylifetime.com/files/images/h-280x280-SneezingSeason.jpg

These viruses can be traced all the way back to Ancient Egyptian records of polio epidemics, but are still around and cause a menagerie of diseases today, from polio to hepatitis A to the “common cold.”

Picornaviruses contain positive sense, single-stranded RNA that is approximately 7-8 kilo bases
long. The genome is monopartite and polyadenylated at the 3’ end, but has a VPg protein at the
5’ end in place of a cap. The viral RNA is infectious and replication takes place in the cytoplasm.
The virus has an IRES (Internal Ribosomal Entry Site) which distinguishes it from many other RNA viruses. The virus is naked with an icosahedral capsid which is the smallest virus of diameter only about 27-30nm.

Enterovirus (more than 60 known serotypes)

Enteroviruses are transmitted through the fecal-oral route and are highly communicable. Generally, viral shedding persists long after symptoms cease so that transmission occurs frequently, particularly in schools, childcare centers, and with close contact. Enteroviruses cause a wide variety of syndromes that range in severity from mild and non-neurologic to neurologic, paralytic, and fatal. Some examples are assorted enteroviral exanthems (rashes), Acute hemorrhagic conjunctivitis (AHC), Poliomyelitis, Pleurodynia and Myalgia.

Rhinoviruses (more than 100 known serotypes)

Rhinoviruses are transmitted through the respiratory route and replicate in the nose (“rhino”). The many serotypes are divided into “major” and “minor” groups and all cause a similar syndrome – the “common cold.” Rhinoviruses also have a short incubation time of 2-3 days. The large number of serotypes allows many rhinovirus infections to occur in one person over time, since immunity only develops for one serotype and each newly acquired rhinovirus causes a new “cold.”

It occurs throughout the year and few serotypes can circulate simultaneously. There are no promising compounds for polio treatment and there are no treatments that can kill a rhinovirus. Therefore, treatment involves relieving symptoms as the body fights the rhinovirus infection. Some ways to reduce symptoms caused by an infection include drinking lots of water, resting in bed, taking common cold medicine and gargling with warm salt water or taking lozenges.

http://www.maine.gov/dhhs/boh/images/is%20it%20a%20cold%20or%20the%20flu.jpg