Talk:Virus

How many cells are killed by a virus?

I read the virus article and searched around and do not see any information on how many cells are normally killed by a typical virus during a normal infection (one, two, or more 10^x?). Now I expect there are going to be several dozen "it depends" tossed in the mix, but it would be of interest to the article to see just how many cells need to die before an immune response is initiated and the end number of cell deaths when the virus is "under control"(i.e. person not dead yet). Septagram (talk) 06:27, 26 November 2011 (UTC)

I think you have answered your own question. Yes of course "it depends". Cell deaths range from none to millions, depending on the species of virus, the host and the type of cell infected. And it depends on what is meant by a normal infection – there's probably no such thing. In the lab, millions of bacteria can shown to be killed by a bacteriophage in a few minutes. In the cells of the salivary glands of many species of mosquito, viruses such as some species of flavivirus can reproduce without causing any cell damage. This is why these insects are efficient vectors. Some viruses actually cause and increase in the cell population - think about warts and cancer. Rotaviruses can destroy all the billions of enterocytes that line the duodenum. We also need to take into account the so-called lytic and and latent cycles of virus replication. Some viruses cause latent infections, some bacteriophages do not undergo a cycle of replication immediately after infecting a bacterium. They integrate their DNA with the host bacterium and this stage is called a prophage. Retroviruses, such as HIV, also do this and, despite being RNA viruses, they can hide their genes as DNA within the host cells. This is called pro-viral DNA. This is why, at the moment, HIV infections can be controlled but not cured. To complicate this attempt at an answer further, we have to remember that many cell deaths that follow a virus infection are not caused by the viruses directly – the cells often kill themselves (see apoptosis) or are destroyed by cells of the immune system as a result of antigen presentation. In fact, in mammals and other animals, thanks to the phenomenon of antigen presentation, no cells need to die before the immune response is invoked. Lastly some virus infections (probably many more than we currently know about) are called "silent" in that there is no apparent immune response, no cell damage or death. Many humans, perhaps most, are infected with two species of papovavirus called JC and BK, and there are no overt signs of infection or an immune response. But there must be one because these otherwise harmless viruses cause problems in the immuno-compromised such as transplant recipients. Virus-host interactions are complex and there is no simple answer to your question. I have tried to explain why using only one "it depends". Graham Colm (talk) 08:55, 26 November 2011 (UTC)

Still I would like to see some numbers on the common flu and the difference flu shots make in reducing any cell deaths. Septagram (talk) 04:37, 7 December 2011 (UTC)

Definition

(pasted from my Talk Page Graham Colm (talk) 21:55, 13 December 2011 (UTC))

As you have suggested I am raising here the question of why you consider a definition of a virus at the start of an article discussing viruses to be a problem. It seems a logical place to place it. The definition is taken from a textbook of virology and seems to cover most of the known cases up to its date of publication. The virophages might create a problem for this definition as do the viroids if we include Hepatitis D as a viroid. Since you seem to have a problem with this I would be grateful if you could explain your position. DrMicro (talk) 21:24, 13 December 2011 (UTC)

Hi, I didn't mean here, I meant the Virus Discussion Page, but never mind. The problem I see with this sentence in the Lead is that it is too technical for many readers. This FA has been carefully crafted, with input from non-scientists, to introduce the readers gently into a subject that many find baffling. Having expressions such as "acellular", "nucleotide genomes", "encode at least one protein" and " transmitted horizontally" in the second sentence, will put many readers off straight away. We haven't told them yet about viral reproduction, but they need to know this to understand this definition. And, its inclusion mentioned something in the Lead that is not in the Main Article, which we do not do in FAs. You noticed that I simply moved the sentence down, rather than delete it. We must, especially in the Lead, write in the most accessible English we can on this highly technical subject. There is a similar problem with the recently added section on triangulation numbers—this is probably gobbledygook to the average reader. It's something I have been meaning to tackle but have not gotten around to yet. You say that the definition is taken from the source. How close is the wording? If it is too close this could be another issue. I do not disagree with the definition and I don't think the satellite viruses go against it, and viroids aren't viruses–that's why we call them viroids. It's it's placement at the top of the article, which is the main problem. Graham Colm (talk) 21:55, 13 December 2011 (UTC)

Sorry about the confusion re Talk page. I knew you would see it here and I wasn't sure which page you meant. An apology seems in order: I didn't see that you had moved it which is why I replaced it.

Concerning the definition: the version here is very close to the original. This is permitted under copyright: it is two sentences from an entire textbook (hence quantitatively a trivial quantity) and has been properly cited. Secondly this is as you correctly have noted a technical subject. For that reason precise definitions are important to ensure clear communication. Technical definitions resemble each other very closely for this reason.

The satellite viruses might qualify under this definition but I'm not at all sure about the virophages. They had not been described at the time this text book was published (1995)

The triangulation number probably deserves a page on its own as it it repeatedly referred to on the pages dealing with the various viruses.DrMicro (talk) 22:21, 13 December 2011 (UTC)

It is "clear communication" that is the issue. That's why I don't think it is helpful in the Lead. It is a definition aimed at virologists. I think the section on triangulation numbers would be better placed in Capsid. Graham Colm (talk) 22:30, 13 December 2011 (UTC)

PS. No apology needed :-) I think the so-called virophages are just satellites – but this is a discussion for another day. I am happy with the current placement of the definition, but still a little concerned over the similarity to the source. But no big deal. Graham Colm (talk) 22:51, 13 December 2011 (UTC)

WP:PLAGIARISM. We often only use a few sentences from any one source in any one article. That doesn't mean we are allowed to take them verbatim. Copyright and plagiarism are two separate things. In addition, multiple articles may take from one source, breaching the acceptable limit wrt copyright (for example, this is why we can't verbatim reproduce the DSM in every relevant disease article). --Colin°^Talk 13:08, 14 December 2011 (UTC)

Copyright law permits and has permitted since its creation the use of small amounts of material from a published work. These materials may be used verbatim for defined purposes including reviews and criticism. The US ruling on a publication an encyclopedia of characters and places in the Harry Potter novel hinged on the amount of material cited in the book that was taken verbatim from the Harry Potter novels. Two sentences taken from a text book and subsequently modified would pass any reasonable test of copyright.DrMicro (talk) 13:36, 15 December 2011 (UTC)

Copyright law is not the issue here. We don't write this encyclopaedia by assembling sentences taken from our sources and then passing it off as our original work. Have a read of the guideline. If the definition used by an authoratative source is brilliant and we don't want to weaken it by rephrasing, then we can attribute it, put it in quotes, etc. --Colin°^Talk 14:44, 15 December 2011 (UTC)

I have removed the troublesome edit. It is not a universally accepted definition in any case and it is not supported by the reference given [1] despite the confession that "the version here is very close to the original". Viruses are difficult to define fully in a couple of sentences and most virologists do not attempt to do this. The satellite viruses for example are not covered by this definition. Prof Nigel Dimmock (an internationally acclaimed virologist) in Introduction to Modern Virology ISBN 9781405136457 (2007) calls Chapter 1 of his book "Towards a definition of a virus", but makes no attempt at one. This book was published over ten years after the one cited. Graham Colm (talk) 19:04, 14 December 2011 (UTC)

Edit request on 20 December 2011

Please replace (A virus is a small infectious agent that can replicate only inside the living cells of organisms.) with (A virus is a small infectious agent. Viruses are obligate intracellular parasites, meaning that they must remain inside a cell in order to survive and replicate.) because I feel that it needs to be added that they are obligate intracellular parasites. This would mean a lot more to a biologist than 'they can replicate only inside the living cells of organisms'. F6ZHOST (talk) 18:25, 20 December 2011 (UTC)

• - On hold - additions require WP:RS reliable sources so that users can assess and add them - Please present one for discussion or feel free to open a new edit request that includes a reliable source that supports the desired edit. - Thanks Youreallycan (talk) 23:08, 21 December 2011 (UTC)

"obligate intracellular parasite" means "can replicate only inside the living cells of organisms". There is no need to add another term and then define it. Also "in order to" is redundant, and viruses can survive outside cells – that's how we catch colds and other viral infections. Graham Colm (talk) 07:07, 22 December 2011 (UTC)

Small request: Single virus particle - 12/30/11

As great as the article is, it was missing one small thing. This:

Viron or Virion (pronounced /ˈvaɪrɒn, ˈvɪri.ɒn/) refers to a single virus particle. "Virion" is included in there, but not "Viron".

While this information is available on Wikipedia, it really ought to be available in the actual virus article. While perhaps a trifling detail, I found myself needing to know it, and imagine there must be others who have as well. — Preceding unsigned comment added by Ramivacation (talk • contribs) 23:40, 30 December 2011 (UTC)

Hi, where is this definition from other than WP? I have never heard the word "viron" used in this context. A Google search for "viron" returns nothing about viruses, apart from our Wikipedia entry, which I have just corrected. Graham Colm (talk) 00:33, 31 December 2011 (UTC)

Too long lead

Hi,

I think the lead is much too long. Due to the lead guidelines it should have at most 4 paragraphs, but now there are 6.

At least the paragraphs are properly constructed, i.e. they consist of one thought at the time, while there are numerous examples, where simply glueing them together makes them (artificially) less.

I know the article is important, long and complicated, but look at the comparable example of how to make lead readable by strong trimming in the RNA article. I'd love to see something like that here. kocio (talk) 22:21, 17 January 2012 (UTC)

Hi, the article has undergone a rigorous review at FAC, and although some changes have taken place since its promotion, I think the Lead is of adequate length for a vital article that receives an average of 5,000 hits a day. As you know, I trimmed RNA, but I don't think similar surgery is needed here. Graham Colm (talk) 22:38, 17 January 2012 (UTC)