Talk:Viroid

Taxonomy

Viroid
Scientific classification
Superdomain:	Biota
Domain:	Aphanobionta
Superkingdom:	Acytota
Kingdom:	Virus

I find that there are references to domain virus, and aphanobionta to categorize these things (the domains covering the same content) ; and there's the superkingdom Acytota 132.205.15.43 20:20, 25 Nov 2004 (UTC)

WikiProject

• Wikipedia:WikiProject Viruses
• We need more people to join and help out, please consider having a look at our project page if you're interested in helping out -- Serephine ♠ talk - 12:16, 19 June 2006 (UTC)

detecting viroids

I reluctantly reverted the addition of To determine whether an infectious agent is a viroid, culture the substance by itself on a nutritive medium, away from plant cells.

While this would certainly distinguish viroids (which wouldn't grow) from bacteria (which would grow on the media), this does nothing to distinguish between (RNA) viroids and DNA viruses -- right?

So how does one determine whether an infectious agent is a viroid? Or, in practice, do we not bother -- we just use the "culture" test to decide whether to use an antibacterial treatment, or instead the other treatment that generically applies to virus, viroid, virusoid, etc. ?

The virus page mentions RNA viruses and DNA viruses. What is the difference between a "viroid" and a "RNA virus"? Or are they the same thing?

--DavidCary 14:08, 13 December 2005 (UTC)

The edit you reverted was really a nonsense. However, there is a big difference between viruses and viroids - viroids do not code their own proteins but are autocatalytic RNAs. RNA viruses code proteins. There are also virusoids, which do not code proteins, but are dependent (paraziting) on a virus. There is no general antivirus treatment (nor antiviroid etc.), there is even no general antibacterial treatment. --Kyknos 19:33, 13 December 2005 (UTC)

I'd even be cautious to suggest a close evolutionary relationship between viri and viroids. Viroids really seem to be "escaped introns" or more specifically, autocatalytic transgenes. While a virus during its lysogenic phase has something like a rudimentary sort of "life" (i.e., it causes proteins to be produced which otherwise wouldn't, and thus does have a non-autonomous metabolism - note that the infectious virus particle itself is definitely non-living), viroids seem to be "genome detritus" so to speak.

How to detect them? Tough, very tough. At first, somebody has to suspect that there is something odd going on, which is quite tough as these things are often enough symptomless. Then, you need to do RT-PCR, reversely transcribing the RNA prsent in a cell into DNA. Then, you have to note that there is a large quantity of RNA present in the original sample which does not come from the host (i.e. does not map onto the host genome in DNA sequence). And having thus determined the viroid sequence (hopefully), one could use molecular probes to fish for denaturated viroid DNA (heated, so that it does not align in double strands). IONO whether it is done that way, but it would work.

It might be added (ref?) that the mode how viroids cause pathogenic effects is unknown, but possibly has something to do with them interfering in host DNA directly (i.e., physically), compare Antisense DNA (which is single-strand however) - viroids might do it by "edging" their way into the DNA transcription/replication apparatus. Molecular monkeywrenching might be a quite appropriate expression - IF that hypothesis is correct. Dysmorodrepanis 18:26, 22 October 2006 (UTC)

List of currently existing viroids

This is a list of unique viroids including their assigned abbreviations (via ICTVdB Index of Viruses):

(ADFVd)		Apple dimple fruit viroid
(AFCVd)		Apple fruit crinkle viroids
(ASSVd)		Apple scar skin viroid
(AGVd)		Australian grapevine viroid
(ASBVd)		Avocado sunblotch viroid
(BluMVd-RNA)	Blueberry mosaic viroid
(BuSVd)		Burdock stunt viroid
(CChMVd)	Chrysanthemum chlorotic mottle viroid
(CSVd)		Chrysanthemum stunt viroid
(CBLVd)		Citrus bent leaf viroid
(CEVd)		Citrus exocortis viroid
(CbVd)		Citrus viroid III
(CVd-IV)	Citrus viroid IV
(CVd-OS)	Citrus viroid original source
(CCCVd)		Coconut cadang-cadang viroid
(CTiVd)		Coconut tinangaja viroid
(CbVd-1)	Coleus blumei viroid 1
(CbVd-2)	Coleus blumei viroid 2
(CbVd-3)	Coleus blumei viroid 3
(CLVd)		Columnea latent viroid
(ELVd)		Eggplant latent viroid
(GYSVd-1)	Grapevine yellow speckle viroid 1
(GYSVd-2)	Grapevine yellow speckle viroid 2
(HpLVd)		Hop latent viroid
(HpSVd)		Hop stunt viroid
(IrVd-1)	Iresine viroid 1
(MPVd)		Mexican papita viroid
(NGSVd)		Nicotiana glutinosa stunt viroid
(PLMVd)		Peach latent mosaic viroid
(PBCVd)		Pear blister canker viroid
(PPMMoVd)	Pigeon pea mosaic mottle viroid
(PSTVd)		Potato spindle tuber viroid
(TASVd)		Tomato apical stunt viroid
(ToBTVd)	Tomato bunchy top viroid
(TCDVd)/(TPMVd)	Tomato planta macho viroid

Van der Hoorn 15:43, 13 June 2007 (UTC)

Initial Explanation of Viroids

I realise this is a rather specialised article, but for a non-expert in biology it's relatively easy to find oneself here when looking at the most primitive forms of life/pseudo-life, as the article on virus links to this. However, on reading the intro, it's very difficult to discern what exactly a viroid is. If you assume that anyone getting here has a reasonable knowledge of what a virus is, and (roughly) what it does and how it is composed, then a short starter section comparing and contrasting viroids to traditional virii would be a lot of help to a passing reader.

Unfortunately, this is not a very active article, but if anyone reading this understands the basics of this subject, even if you don't consider yourself an expert, I urge you to take a few minutes to add some intro-level description to the opening paragraph. Every little change helps. Jovial Air (talk) 15:58, 7 March 2008 (UTC)

Inconsistencies regarding inclusion of Hepatitis Delta

This article begins by saying, "Viroids are plant pathogens...", and then under "Pathology" it describes Hepatitis D, a human pathogen. In the ICTV (the virus database), Hepatitis D is listed as a ssRNA virus, though there are publications that list hepatitis delta in parallel with viroids. Clearly, this article needs work. I'm not a viroid expert, so I'm going to add a reference in the first paragraph to hepatitis delta having similar properties, link to the hepatitis D article, and delete the Pathology section. Perhaps there should be some content on Pathology of viroids, but I don't know what that would be.Scray (talk) 09:39, 10 March 2008 (UTC)

Isn't it a virusoid or satellite virus rather than a viroid?--Miguelferig (talk) 17:41, 26 May 2012 (UTC)

removal of "without the protein coat that is typical for viruses.[1]" sentense

The sentense "without the protein coat that is typical for viruses.[1]" is wrong, There are indeed at least three virus families that do not encode for any capsid or coat proteins: Hypoviridae, Endornaviridae and Narnaviridae. The fact that viroids do not encode a capsid is not linked to their non-classification in viruses. Reference: Capsid-Less RNA Viruses Philippe Le Mercier (talk) 11:29, 29 November 2012 (UTC)