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Wikipedia says Caliciviridae Family. My notes say that Norovirus includes the following

Noroviruses

  • Norwalk-like viruses
  • Caliciviruses
  • Astroviruses and some small gastroenteroviruses

which is a larger definition including at least two families than the Wikipedia definition. I think

  • Caliciviruses $\subset$ Caliciviridae
  • Astroviruses and some small gastroenteroviruses $\subset$ astroviridae

so the note is taking subsets among different families and classifying them into abstract class called Noroviruses.

Extension based by Chris' excellent answer.

Criteria of Noroviruses

  • (+)sense ssRNA viruses
  • Structure and replication:
    • 1) only (+)sense ssRNA,
    • 2) simple nucleocapsid viruses,
    • 3) only viruses transmitted by fecal-oral route,
    • 4) size about 30 nm in diameter.

and then final classification of Noroviruses by these criteria

Noroviruses

  • Noroviruses $\subset$ Norwalk-like viruses ($\subset$ F. Caliciviruses)
  • Some Astroviruses ($\subset$ F. astroviridae) and some small gastroenteroviruses (what?)

which, however, does not make sense since Caliciviridae $\not\subset$ Astroviridae. I do not understand what is the point of referring to the viruses by the sentence

Astroviruses and some other round/small gastroenteris viruses

which are not part of Astroviridae.

Which viruses of Caliciviridae are similar to Astroviruses that are apparently round and small gastroenteritis viruses?

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Léo Léopold Hertz 준영
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2 Answers2

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You are mixing different things here: Virus are grouped based on their genetic material (dsDNA, ssDNA ssRNA and so on) into several groups (see here for details), then grouped into families, subgrouped into a genus and then into species.

So it is: Group > Family > Genus > Species.

What you have here are are different positions in this classification. The names you mention belong all to the same tree:

Group: IV ((+)ssRNA-Viruses) > Family (Caliciviridae) > Genus (Norovirus) > Species (Norwalk Virus).

The Astrovirus belongs into the same group, but then form an own family. To answer your question: No, since the Norovirus forms its own genus in the caliciviridae family.

Chris
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  • Last sentence - do you mean genus (not family)? – Alan Boyd May 29 '14 at 18:23
  • Thank you, Chris, for your excellent answer! I have been completely confused by different naming systems that have been used. Besides those two systems, there seems to be also some conventions. I am trying to understand what is the initial point of making a abstract entity "Noroviruses" and including some viruses from different families into it. – Léo Léopold Hertz 준영 May 29 '14 at 20:59
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I take NCBI's taxonomy any day over what wikipedia says. According to NCBI Caliciviridae includes Lagovirus, Nebovirus, Norovirus, Recovirus, Sapovirus, Vesivirus, Secalivirus, etc. For example:

Viruses; ssRNA viruses; ssRNA positive-strand viruses, no DNA stage; Caliciviridae; Norovirus; Norwalk virus; Chiba virus

Anyway, due to the absence of universal phylogenetic marker genes, viral taxonomy is mostly based on capsid shape and isn't thus very accurate..

5heikki
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