Picornaviruses are viruses that belong to the family Picornaviridae. The name picornavirus means small RNA virus.
Picornaviruses are non-enveloped, positive-stranded RNA viruses with an icosahedral capsid. The genome RNA is
unusual because it has a protein on the 5' end that is used as a primer for transcription by RNA polymerase.
According to a study at the Mayo Clinic, picornaviruses can "cross over" into the brain, causing memory
loss and other neurological symptoms.
Picornaviruses include two main categories: the enteroviruses and the rhinoviruses. Some important enteroviruses are
poliovirus and Hepatitis A virus. Enteroviruses infect the enteric tract as it is visible from its name. On the other hand,
Rhinoviruses infect primarily the nose and the throat. Enteroviruses replicate at 37°C, whereas Rhinoviruses grow
better at 33°C, as this is the lower temperature of the nose. Enteroviruses are stable under acid conditions and thus
they are able to survive exposure to gastric acid. In contrast, Rhinoviruses are acid-labile and that is the reason why
Rhinoviruses are restricted to the nose and throat.
They include the following genera:
Genus Enterovirus; type species: Poliovirus
Genus Rhinovirus; type species: Human rhinovirus A (common cold)
Genus Hepatovirus; type species: Hepatitis A virus
Genus Cardiovirus; type species: Encephalomyocarditis virus
Genus Aphthovirus; type species: Foot-and-mouth disease virus
Genus Parechovirus; type species: Human parechovirus, Ljungan virus
Genus Erbovirus; type species: Equine rhinitis B virus
Genus Kobuvirus; type species: Aichi virus
Genus Teschovirus; type species: Porcine teschovirus
The name is derived from pico meaning small (10-12m), and RNA referring to the ribonucleic acid genome.
Jul 29, 2011
Hand, foot, mouth disease kills 70 in Vietnam
HANOI - A SURGING outbreak of hand, foot and mouth disease has killed 70 people so far this year in Vietnam and
infected more than 23,000, mostly children under 5, state-controlled media reported on Thursday.
Most of the cases have been reported in the country's south, and enterovirus 71, or EV-71, is the dominant strain
circulating in Vietnam, Nguyen Van Binh, head of the Ministry of Health's Department of Preventive Medicine, was
quoted by Thanh Nien newspaper as saying.
EV-71 can result in a more serious form of the common childhood disease leading to paralysis, brain swelling or death.
This year's outbreak is a sharp uptick from recent years. Since 2008, about 10,000 to 15,000 cases were reported per
year with about 20 to 30 children dying annually.
Mr Binh said the virus has appeared to slow in recent weeks, but the rate remains high with up to 1,900 new cases
reported each week.
He warned there could be more new cases when children return to school in early September. The virus is easily
spread by sneezing and coughing. -- AP