Norovirus

The genus Norovirus includes non-enveloped viruses with a single-stranded RNA of positive polarity belonging to the family Caliciviridae. Heretofore, various Norovirus species were detected in humans as well as in cattle, swine, mice, and oysters. Especially the human noroviruses have a great medical importance as the causative agent of viral gastroenteritis. The name is derived from the type species of the genus, the Norwalk virus from.

First description

The type species of the genus Norovirus, Norwalk virus, was characterized in stool samples of a viral gastroenteritis outbreak of 1968 in Norwalk, Ohio by immune electron microscopy morphologically first time in 1972. In order to prove the connection between the found virus and gastroenteritis disease, purified ultrafiltrate was chair ( isolated from human faeces of diseased patients) administered orally to volunteers, who subsequently also infected.

Morphology

Noroviruses have a diameter 35-39 nm and exhibit in electron microscopic image on a very fuzzy, round structure. They have an icosahedral (twenty -area ) capsid with a T = 3 symmetry.

Genome

The single-stranded genome of noroviruses is about 7.3 to 7.7 kb in size and consists of three partially overlapping open reading frames ( ORFs). The ORF1 encodes a non- Strukturpolyprotein, which shows the viral RNA polymerase. ORF2 corresponds to the capsid protein CP and ORF3 a virion -associated structural protein of unknown function. The genome of noroviruses can be very effective to produce new variants and subtypes in infection of different strains or variants within a cell by recombination. An influenza virus similar antigenic drift and antigenic shift is also observed in some species of noroviruses.

Taxonomy

  • Genus Norovirus
  • Species Norwalk virus

Provisionally classified:

  • Species Human Norovirus Alphatron
  • Species Human Norovirus Saitama
  • Species Bovine Norovirus CH126
  • Species bovine norovirus Jena
  • Murine Norovirus species
  • Norovirus species of the pig ( porcine norovirus )
  • Norovirus species of oyster

Human noroviruses

For information on the clinical course, transmission, epidemiology, etc. See the Humane noroviruses

Virus classification National Center for Biotechnology Information RNA-Virus Ostreidae Norwalk (Ohio) RNA-Polymerase
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