Talk:RNA virus

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Article Grading: The following comments were left by the quality and importance raters: (edit · refresh) Sorry to bother... but where is the Retroviridae in this classification? after all it does account for AIDS - HIV virus... please fix 89.0.179.144 19:00, 2 August 2007 (UTC)

Contents 1 HBV classified as an RNA virus? 2 Factual accuracy disupted 3 Importance of RNA viruses 4 Mutation rates 5 First sentence

[edit] HBV classified as an RNA virus?

• Anyone have a source for the following claim (2nd sentence in the entry): "For example, Hepatitis B virus is classified as an RNA virus, even though its genome is double-stranded DNA, because the genome is transcribed into RNA during replication." I was under the impression that Hep B was classified as a reverse transcriptase DNA virus.[1] -- MarcoTolo 20:45, 15 April 2006 (UTC)

Thankyou for pointing that out - I also found the contrary to be true: (Sources: [2] and [3]) and will change the article accordingly -- Serephine / talk - 03:37, 11 June 2006 (UTC)

[edit] Factual accuracy disupted

Cheers, all, I'm RelentlessRouge. About standard RNA viruses and how they replicate, I'm not quite sure if that's right. What's written says the following (for negative-sense viruses):

RNA[-] ---> RNA[+](mRNA) ---> protein

How's the RNA replicate?

I might probably not know what the hell I'm talking about, but please enlighten me.

RelentlessRouge 11:27, 14 June 2006 (UTC)

No worries, virus replication is a messy thing to understand. A negative-sense virus cannot have its genome read by host ribosomes until it has been converted into positive-sense RNA - the ribosomes just won't translate it. In order:

• The negative-sense strand of RNA is read by a host protein called RNA polymerase which makes a copy of it. This copy is now positive-sense - a bit like a mirror image.
• This positive-sense strand acts as messenger RNA (mRNA) for the virus, and is read by the host ribosome
• The ribosome constructs a protein based on what the mRNA tells it
• This protein goes on in a number of different, complicated ways to direct the synthesis of new virions - such as the creation of more negative-sense RNA strands and capsid proteins.

Hopefully that helps. Thanks for pointing out that this might not be apparent at first glance, I'll update the article ☻ -- Serephine ♠ talk - 11:49, 14 June 2006 (UTC)

It would help if the definition of negative-sense is mentioned in this article, because the negative-sense article redirects to here. 87.243.196.213 08:29, 26 March 2007 (UTC)

[edit] Importance of RNA viruses

I suggest adding a line to the initial paragraph to emphasise the importance of these viruses.

Notable human RNA viruses include SARS, Influenza and HCV.

--TransControl 08:45, 28 July 2006 (UTC)

'As such, they possess ribonucleic acid (RNA) as their genetic material and do not replicate using a DNA intermediate' HIV is an RNA virus that uses a DNA intermeadiate

As described in Virus classification, retroviruses like HIV are not (usually) included among the RNA viruses precisely because they violate that rule. The RNA world hypothesis suggests that they may be evolutionarily very distinct from regular RNA viruses. Sakkura 20:56, 2 December 2007 (UTC)

There appears to be an error in classification. Flavidiridae are put under Class IV and should be Class V. Pondo1950 (talk) 12:45, 13 March 2008 (UTC)

[edit] Mutation rates

There is no reference for this suspicious statement:

Retroviruses integrate a DNA intermediate of their RNA genome into the host genome, and therefore have a higher chance of correcting any mistakes in their genome thanks to the action of proof-reading DNA polymerases belonging to the host cell.

Any support for that? If the error occurs during reverse transcription, host DNA repair mechanisms will have no effect because the DNA strands that get integrated will match. I'll edit the statement and see how it sits.Scray (talk) 11:50, 19 March 2008 (UTC)

Yes well spotted. Retroviruses have the best of both worlds. During their RNA phase they are highly mutable because of the error rate of RT. During the DNA phase their genomes are stable but errors made by the RT cannot be corrected. Favourable mutations naturally selected during the RT phase are stable in the DNA form and reproduce as DNA with the host DNA. --GrahamColm^Talk 14:27, 19 March 2008 (UTC)

[edit] First sentence

Page 97 of [4] does not say anything about classification, and papers like [5] see retroviruses as RNA viruses. Narayanese (talk) 21:27, 10 April 2008 (UTC)

I assume you're asking about RNA viruses lacking a DNA intermediate? Though I don't see where page 97 is cited in this respect (maybe I missed it), that reference does say (lines 3-4 in the second paragraph), "The absence of a DNA intermediate in the replication cycle of RNA viruses has, until recently...". More to the point, the rewording of the first sentence is meant to highlight the classification of RNA viruses specifically as lacking a DNA intermediate. The second sentence highlights this further, and the classification page reveals that the RNA viruses specifically lack a DNA intermediate. Maybe I am missing your point?Scray (talk) 04:59, 11 April 2008 (UTC)

If you think that's the classification, then add a source that says so explicitly. Because I've seen many call retroviruses RNA viruses. Narayanese (talk) 06:27, 11 April 2008 (UTC)

Here's a relevant link to ICTV that shows the reverse-transcribing viruses clearly distinct from the RNA viruses[6]. Using Google Books and the search string "virus classification characteristics fields", I was also able to find similar classification in Fields Virology (Table on page 28). I have not seen a current, reputable source that explicitly includes the retroviridae in a formal classification of RNA viruses. Can you provide one? In any event, ICTV seems to be the gold standard now. We (as a community) need to get the relevant pages in sync.Scray (talk) 11:25, 11 April 2008 (UTC)

Well if the ICTV says so then I'm fine. Narayanese (talk) 12:21, 11 April 2008 (UTC)

MeSH includes them though, so I think I'll add something about them sometimes being included. Narayanese (talk) 21:29, 12 April 2008 (UTC)