Talk:Baltimore classification

Baltimore classification has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Review: September 12, 2025. (Reviewed version).

Diploid

Although there is some sense in calling class vi viruses 'diploid' it wrongly implies that all the trappings of diploidy (e.g. homozygosity, etc.) apply.Bendž |Ť 16:29, 14 May 2007 (UTC)[reply]

Retroviruses and Pararetroviruses

Current information tells that Retroviruses are a sample for Group VI viruses. So are there other viruses in Group VI that are no Retroviruses? If not, so 'Retroviruses' and 'Group VI viruses' are synomyms and text here as in 'Baltomore groups' template should be modified accordingly. Please nore, that in contrast to the written information, SsRNA-RT virus redirects to Retrovirus as if this was a synonym.

Similar problem for Gruop VII: Current information does not mention the term Pararetrovirus. So is Pararetrovirus a synonym or a sample for Group VII viruses? And is Hepadnaviruses as synony or a sample for Pararetroviruses? Kind regards

--Ernsts (talk) 07:25, 29 August 2017 (UTC)[reply]

Basic definition is misleading

I am not going to edit anything because I am just beginning to study this subject.

The first paragraph vs. the caption of the first graphic say two different things. Is the Baltimore classification based primarily on method of replication (main text) or mRNA synthesis (essentially, transcription) (caption of first graphic)? My textbook breaks it down in terms of the latter. — Preceding unsigned comment added by 2603:9000:AC08:A600:799C:E57B:B62C:99E2 (talk) 02:54, 25 April 2020 (UTC)[reply]

August 2020 rewrite, expansion, and reorganization of Baltimore articles

I've rewritten and significantly expanded this article, along with Orthornavirae and Negarnaviricota as part of an effort to update articles related to the Baltimore groups. As part of this, the articles "DNA virus", "RNA virus", as well as the individual group articles (excluding ssRNA-RT) have all been redirected to this article. I've tried to include a lot of the information in the expansions rather than simply removing it.

DNA virus article was outdated and had become a collection of miscellaneous information. Now, information about DNA viruses can be found here and on the three realm articles.
RNA virus and the RNA virus Baltimore groups were similar. Outdated and generally lacking information, except for -ssRNA virus, which now = Negarnaviricota, so two articles aren't needed.
Excluding the dsDNA-RT article, the reverse transcribing articles have not been reorganized yet because Retrovirus needs a rewrite in conjunction with significant expansion of Revtraviricetes, which I have not done (yet).

I decided that redirecting the articles would be better than keeping them for several reasons: The main Baltimore article is now highly detailed, as are most of the taxa related to them. Baltimore classification has been partially merged with virus taxonomy and since the ICTV has "official" priority over Baltimore classification, I view it as beneficial to focus efforts on improving the taxa articles that relate to Baltimore groups. Retaining and expanding the other articles would almost certainly be duplicating information from taxa articles. And lastly, the reorganization may make maintaining and updating these articles easier. I do feel like this reorganization may be controversial (and the redirects can always be undone if need be), so comments are appreciated. Velayinosu (talk) 04:11, 7 August 2020 (UTC)[reply]

RNA virus, DNA virus, and retrovirus should have their own stand alone articles. A redirect to this article is not satisfactory. When you hover over any of these terms having a blurp for the intro to the Baltimore classification article come up is not useful. It is fine to redirect for the lower category -ssRNA, +ssRNA , dsRNA, ssDNA, and dsDNA to either this article or the RNA virus or DNA virus articles. There is the possibility of doing a merge of Orthornavirae with RNA virus, and of Revtraviricetes with retrovirus, although this might be complicated. I'm fine with a redirect from the DNA virus article at the moment because that article was really in bad shape, but eventually a new and rewritten version of that article should be restored. However, I'm not hard fixed on anything and completely flexible for any improvements. --Guest2625 (talk) 22:22, 10 August 2020 (UTC)[reply]

1) I feel like the meaningful information on RNA virus is already included in Orthornavirae, so rather than a merge a simple redirect would be fine (though should it redirect to Ortho or to here? or should Ortho be the redirect?)

2) I might update/expand the retrovirus group of articles later.

3) DNA virus is the only one of the three overarching groups that lacks a taxonomic synonym so it may warrant an article. That discussion can be held on its talk page if we want to talk about what a rewrite would look like.

4) Much of the unmerged content on -ssRNA was written as part of an education assignment that I felt that was too technical or detailed to be included in whole. Some of it is included in Negarnaviricota, just condensed (e.g. the encapsidation section's most important contents are in "Characteristics"). There are for example 8 paragraphs about -ssRNA interactions with host immune responses, which in my opinion is too much detail for that specific subject for a taxon article.

5) I added introductory paragraphs for the three overarching groups as suggested.

6) About the two subphyla, I understand why you undid the redirect. My reasoning was that in general sub- taxa articles are likely to be highly repetitive of their parent taxon. This is why I wrote Negarnaviricota in a way that covers the subphyla as well, that way separate articles wouldn't be needed for them. Velayinosu (talk) 01:50, 12 August 2020 (UTC)[reply]

You're doing great work in reorganizing these different articles. However, it is important to be thorough in merging the material. The reason for this is that alot of previous editors did alot of work in creating those articles. If you want to do complete rewrites, it's better just to do the ICTV articles (orthornavirae, negarnaviricota, revtraviricetes, and the DNA ones), as you're doing now, and let the old articles remain during a gradual merge. There is no rush. I also think the Baltimore article looks great. The reason the old articles cannot be removed is because of navigation purposes. When someone hovers over the -ssRNA virus, +ssRNA virus, dsRNA virus, RNA virus, and DNA virus links in different articles, you want them to get a brief blurb that gives them a couple sentences about the topic. The Baltimore article redirects do not accomplish this. Also you have to think about google searches and what shows up in the infobox on the side of the search. Without the old articles, wikipedia will lose alot of reader traffic from google.

The mergers I'm thinking that should be done are orthornavirae/RNA viruses, negarnaviricota/-ssRNA, and revtraviricetes/retrovirus. The +ssRNA virus article would become an article which summarized postive stranded RNA viruses and directed towards the three articles Kitrinoviricota, Lenarviricota, Pisuviricota. This would be an expanded version of your baltimore article +ssRNA virus section merged with the current +ssRNA virus article. Similarly, the dsRNA virus article would become an article which summarized double stranded RNA viruses and directed towards the two articles duplornaviricota and pisuviricota. This again would be an expanded version of your baltimore article dsRNA section merged with the current dsRNA article. I'm not yet focused on the DNA virus articles but the same would be done for them.

All the above merging, however, takes alot of time, and it's important to try and preserve previous editors old work. The merging can be done slowly into the ICTV articles that you have created. And also slowly from your baltimore sections into the old +ssRNA and dsRNA articles. Below there is an example of merging your negarnaviricota article lead with the -ssRNA article lead. This could be used as a format template for the other leads. I think the title of the article should remain negarnaviricota, but it could also be negative stranded RNA viruses. Let me know what you think of this negarnaviricota/-ssRNA lead merge. --Guest2625 (talk) 07:09, 12 August 2020 (UTC)[reply]

Yes the changes to -ssRNA thus far are fine and you can try that for RNA virus + Orthornavirae too if you want. I'll update dsRNA and +ssRNA and add sections for the phyla as you suggest. Velayinosu (talk) 23:36, 13 August 2020 (UTC)[reply]

I altered around the Orthornavirae lead, so that now it is about the group members, i.e. RNA viruses. At some point, an administrative merger can be done with the RNA virus article and the new title RNA virus can go with the Orthornavirae article. --Guest2625 (talk) 11:13, 16 August 2020 (UTC)[reply]

RNA virus

Does this edit by Velayinosu align with WP:COMMONNAME? I am very familiar with ICTV but scientific nomenclature does not always dominate WP page names. — soupvector (talk) 04:41, 8 September 2020 (UTC)[reply]

"RNA virus" is not a name, common or otherwise. Graham Beards (talk) 06:50, 8 September 2020 (UTC)[reply]

We do keep articles on historically recognized taxa and classification systems, because they and their terminology remain in the literature and are likely to be used in non-specialist publications for years. (See e.g. Category:Historically recognized plant taxa.) So whatever changes are made to accommodate current views should not remove such useful information. Peter coxhead (talk) 08:09, 8 September 2020 (UTC)[reply]
I agree with this, that taxa are seen as deprecated does not justify deletion, historical taxa are an important part of the history of science. Also I would note that on Google Scholar "RNA virus" brings up about 3,010,000 results, while Orthornavirae only brings up 16 results. Despite the best efforts of the ICTV their classification is not commonly employed by workers in the field. Outside of academia their efforts have had even less sway. ----Jules (Mrjulesd) 11:31, 8 September 2020 (UTC)[reply]

The title is supposed to be "RNA virus" but the content of the article is supposed to be what is currently the content of "Orthornavirae". I'm not sure what the appropriate way to address this is. Velayinosu (talk) 01:32, 9 September 2020 (UTC)[reply]

The content should match the title, i.e. it should be about the ICTV taxon Orthornavirae. The term "RNA virus" should be explained elsewhere. Peter coxhead (talk) 10:08, 9 September 2020 (UTC)[reply]

The best way to deal with these two articles, which are essentially on the same thing, (RNA virus being the object and Orthornavirae being the taxon container) is to do a merger. The merger would be of the content of the Orthornavirae article into the RNA virus article. The final title of the article would be RNA virus and would have the structure of all other virus group articles. --Guest2625 (talk) 05:58, 10 September 2020 (UTC)[reply]

I disagree. We have used the ICTV taxa for article titles and taxoboxes. As I noted above, the Baltimore system and names like "RNA virus" should be discussed, but should not replace the use of the ICTV classification. Peter coxhead (talk) 09:47, 10 September 2020 (UTC)[reply]

I'm fine with the two articles as they are named now. However, having two articles "RNA virus" and "Orthornaviriae" which cover essentially the same material is not ideal. How do you feel about the current structure of the Astrovirus article? Currently the article has the common name "Astrovirus" the lead discusses the group of viruses called "Astroviruses", and the virusbox has the heading "Astroviridae". --Guest2625 (talk) 13:08, 10 September 2020 (UTC)[reply]

Negarnaviricota

Negative stranded RNA viruses (-ssRNA viruses) are a group of related viruses that have negative-sense, single-stranded genomes made of ribonucleic acid. They have genomes that act as complementary strands from which messenger RNA (mRNA) is synthesized by the viral enzyme RNA-dependent RNA polymerase (RdRp). During replication of the viral genome, RdRp synthesizes a positive sense antigenome that it uses as a template to create genomic -ssRNA. -ssRNA viruses also share a number of other characteristics: most contain a viral envelope that surrounds the capsid, which encases the viral genome, -ssRNA virus genomes are usually linear, and it is common for their genome to be segmented.

Negative stranded RNA viruses constitute the phylum Negarnaviricota, in the kingdom Orthornavirae and realm Riboviria. They are descended from a common ancestor that was a double-stranded RNA (dsRNA) virus, and they are considered to be a sister clade of reoviruses, which are dsRNA viruses. Within the phylum, there are two major branches that form two subphyla: Haploviricotina, whose members are mostly non-segmented and which encode an RdRp that synthesizes caps on mRNA, and Polyploviricotina, whose members are segmented and which encode an RdRp that snatches caps from host mRNAs. A total of six classes in the phylum are recognized.

-ssRNA viruses are closely associated with arthropods and can be informally divided between those that are reliant on arthropods for transmission and those that are descended from arthropod viruses but can now replicate in vertebrates without the aid of arthropods. Prominent arthropod-borne -ssRNA viruses include the Rift Valley fever virus and the tomato spotted wilt virus. Notable vertebrate -ssRNA viruses include the ebola virus, hantaviruses, influenza viruses, the Lassa fever virus, and the rabies virus. — Preceding unsigned comment added by Guest2625 (talk • contribs) 07:08, 12 August 2020 (UTC)[reply]

What's wrong with WP:MERGE discussions?

The current situation is:

There has been an attempt to merge Orthornavirae to RNA virus
There has been an attempt to merge DNA virus to this page

Now neither of these took place with a WP:MERGE discussion, just ad hoc declarations that they should be merged. Now my question is: why is process being abandoned? There is nothing very obvious about either of these. To get rid of the Orthornavirae article seems a very retrograde approach. Also, in my mind, we should have some sort of article discussing the meaning of "DNA virus", it could be much reduced, but its needed as a vast number of sources and textbooks divide viruses on the basis of their genome. Even the ICTV divide viruses on the basis of their genomes, see [1]

Now I don't mind these articles being merged if proper process is carried out, and there is consensus for these changes. The current redirect wars are getting us nowhere, and process being abandoned is really not helping. Process is important. Jules (Mrjulesd) 08:14, 23 September 2020 (UTC)[reply]

Are the megavirales missing?

The megavirales seem to be missing. It contains humdingers like Pandoravirus and Pithovirus.

There is a T101 in your kitchen (talk) — Preceding undated comment added 14:18, 4 December 2021 (UTC)[reply]

I evaluated the article titled "Baltimore Classification". A link to the evaluation can be found here: <https://en.wikipedia.org/wiki/User:Slolamingsnailmail/Evaluate_an_Article>. How do the "pathways" that each Baltimore group takes differ? In what ways are the pathways to synthesize mRNA different for each group? Slolamingsnailmail (talk) 19:43, 21 September 2022 (UTC) Slolamingsnailmail[reply]

GA review

This review is transcluded from Talk:Baltimore classification/GA1. The edit link for this section can be used to add comments to the review.

Nominator: Velayinosu (talk · contribs) 02:16, 25 August 2025 (UTC)[reply]

Reviewer: Esculenta (talk · contribs) 17:21, 8 September 2025 (UTC)[reply]

Hello, I'll review this article. Will have my comments here within a few days. Esculenta (talk) 17:21, 8 September 2025 (UTC)[reply]

Spot checks

I spot checked all of the 31 claims cited to Koonin 2021, the main source used in this article. In most I didn't find any issue with source-text integrity or with close paraphrasing. The following five instances may need some correcting/prose tweaking:

article text: "By Baltimore group, dsDNA and RT viruses are non-segmented, ssDNA viruses are mostly non-segmented, dsRNA and +ssRNA viruses are mostly segmented, and around half of –ssRNA viruses are segmented." In the source, Table 1 summarises segmentation patterns (and the surrounding text on pages 5–6). It shows: dsDNA (none), ssDNA (mostly non‑segmented), dsRNA (mostly segmented), +ssRNA "mostly non‑segmented, but many segmented', −ssRNA "roughly half segmented", ssRNA‑RT (non‑segmented), dsDNA‑RT (non‑segmented). Pages 5–6. The statement that +ssRNA viruses are mostly segmented contradicts Table 1 (they are "mostly non‑segmented").
article text: "As such, dsDNA seems to be the only genomic organization that allows for maintenance and efficient replication of genomes that exceed about 50 kb." Source: "Thus, it appears that dsDNA that is replicated and expressed according to the classical scheme of genetic information flow is the only type of nucleic acid that provides for the maintenance and efficient replication of genomes in excess of about 50 kb." perhaps restructure phrasing to avoid WP:CLOP
article text: "Excluding anelloviruses and bidnaviruses, which encode their own replication proteins, ssDNA viruses encode an endonuclease that initiates RCR/RHR and otherwise rely on host machinery." Koonin 2021 says Bidnaviridae encode their own protein‑primed DNA polymerase; Anelloviridae encode proteins with no detectable homologs (not necessarily "replication proteins"). Suggest a tweak to fix the overreach on anelloviruses.
article text: "RNA replication and reverse transcription of RNA into DNA are generally shunned by cells," source: "RNA replication and reverse transcription of RNA into DNA are usually discouraged by cells," (WP:CLOP)
~~article text: "In the expanded system, there are 25 classes, 17 superclasses, and six types of genetic information transfer." The source says 35 classes~~

Images

all images have licenses that are compatible with their use on Wikipedia.
~~suggest to link Parvovirus in its image caption (to be consistent with others)~~
in the "Hepatitis D virus" image, the lay reader isn't going to know what the multiple "...Ags" are; perhaps mention that the coloured circles are viral surface proteins, and that inside is the ribonucleoprotein core, consisting of the viral single-stranded RNA genome (ssRNA) bound by hepatitis D antigens (blue).

Prose and content

Generally, the article is very well-written and organized. I found a few things to nitpick about:

~~possibly useful links for the lead: viral genome, DNA replication~~
~~other possible useful links (later in article): concatemer, monophyletic~~
Incorrect statement in the "sense" note for DNA. It currently says the positive‑sense DNA strand is noncoding and the negative‑sense strand is used as template. That reverses the standard convention and will mislead non‑specialists. Suggest a clarification something like "For DNA, the positive‑sense (coding, non‑template) strand has the same sequence as the mRNA (with T in place of U), whereas the negative‑sense (antisense, template) strand is used by RNA polymerase to synthesise mRNA."
~~both "nonsegmented" and "non-segmented" are used (MOS:HYPHEN prefers the hyphenated form)~~
~~"According Koonin et al." missing word, and, the phrasing "and colleagues" may be a better prose choice than "et al."~~
"First, a transcription preinitiation complex binds to the DNA upstream of the site where transcription begins, which allows for the recruitment of a host RNA polymerase enzyme." suggest simpler "First, a transcription preinitiation complex binds to the DNA upstream of the transcription site, recruiting host RNA polymerase."
~~In the history section, it might be useful to briefly explain how viruses were classified before Baltimore.~~
I found it odd that there are no links/mentions between this article and International Committee on Taxonomy of Viruses. Does this organization not explicitly recommend and use the Baltimore classification?

The History section mentions the ICTV quite a bit. The ICTV incorporates Baltimore classification into the definition of many higher taxa. For example, Duplornaviricota is a phylum of dsRNA viruses, indicated by its name duplo + rna, same for the class Duplornaviricetes. The ICTV's article isn't as developed as this one.

are there any criticisms or limitations of this classification system? This source (doi:10.1007/s00705-018-3938-z), for example, discusses limitations with classification of environmental DNA-obtained sequences that lack info about replication mechanisms.

I don't know of any criticisms of Baltimore classification specifically but the limitations are mentioned, for example it doesn't necessarily show evolutionary relationships, so Baltimore classification is a complementary system used in conjunction with the ICTV's system. I'm not sure the source you linked is relevant to this article since it is discussing issues with the ICTV's system before they started reforming it from ~2018 onwards to address the issues raised in the source (and other issues). Maybe it would be more appropriate on the ICTV's article than here.

(not GA) FYI, I found the image "Figure 1. Baltimore classification of viruses based on mRNA synthesis" in doi:10.11648/j.ajls.20231102.11 {{doi}}: unflagged free DOI (link) (available here to be a layperson reader-friendly way of illustrating the replication mechanisms of the Baltimore groups.

I didn't see this source because it's not on PubMed but I can't download the image and it's flagged as a predatory source, so I'll just leave it alone.

Assessment of criterion 3(a): pass. Articles explains the organising principle; describes each group; treats edge cases (ambisense, ambiviruses, multi‑group viruses like pleolipoviruses); surveys correlations (segmentation, genome structure/size, host range, packaged machinery, translation strategies); places the system in evolutionary and historical context; and explains how ICTV incorporated Baltimore groupings at higher ranks. Scope seems right to me. One might argue that there's a bit too much detail in mechanistic depth (polymerase stuttering in detail, cap‑snatching steps, replication forks, etc.) and taxonomic enumerations, which might be more appropriately situated in articles like Viral replication, RNA virus/DNA virus, and the relevant ICTV taxonomy ... but it seems ok to me. Might be a topic for further investigation if you intend to take this to FAC. I'll now put this on hold to give nominator time to address the above suggestions. Esculenta (talk) 18:31, 11 September 2025 (UTC)[reply]

Okay Esculenta I have addressed everything I think. I crossed out the things that I changed with the article and replied to others. Velayinosu (talk) 02:16, 12 September 2025 (UTC)[reply]

All outstanding issues resolved; the article now meets the Good Article criteria. Promoting to GA. Esculenta (talk) 02:43, 12 September 2025 (UTC)[reply]

Did you know nomination

(

Comment or view
Article history

)

... that for almost fifty years the Baltimore classification, which classifies viruses by how they transfer genetic information, was used alongside standard evolutionary taxonomy?

Source: See many in article.

ALT1: ... that some viruses can be catalogued into two groups of the Baltimore classification? Source: See "Multi-group viruses" section.
Reviewed: Template:Did you know nominations/Shaktikanta Das
Comment: One longer hook which attempts to communicate more information, and one shorter hook which is simpler and (to my mind) less interesting.

Improved to Good Article status by Velayinosu (talk). Number of QPQs required: 1. Nominator has 81 past nominations.

~~ AirshipJungleman29 (talk) 14:20, 16 September 2025 (UTC).[reply]