It is written 'coronavirus' with no space and no capitalized 'c'. I'm not sure about it. It is the name of virus which makes it a proper noun. Plus, they should be two words like other viruses have. The list is here One of the known examples is Ebola virus.
The convention in English (and it may be different in other languages that use the Latin script) is that names of animals, plants and (by extension) viruses are not capitalised, unless part of the name comes from a proper noun.
So we have "blue tit" or "dog rose", but "Steller's sea eagle" and "African elephant" because Africa and Steller are the names of a continent and a person respectively. Ebola is capitalised as it is the name of a river in Africa (the Ebola river is a tributary of the Congo).
We also (again by convention) capitalise the scientific names of above the level of genus. So the blue tit is Cyanistes caeruleus in the family Paridae (the tit family) and the class Aves (birds).
Now "coronavirus" is not the scientific name (that is the subfamily Orthocoronavirinae). The particular one doing the rounds now is a Betacoronavirus. Instead "coronavirus" is the English name and so follows normal capitalisation for animals, plants and (by extension) viruses.
Names of viruses are often formed as single words with the suffix -virus. This is perhaps influenced by scientific use. There are rhinoviruses, noroviruses, adenovirus and so on. Again there isn't a logical rule, that is just how it is done. The virus that causes Ebola is known as ebolavirus (and note the downcasing when Ebola becomes a prefix).
It is written ['coronavirus' with no space and no capitalized 'c']. I'm not sure about it. It is the name of virus which makes it a proper noun.
No, that's not the name of the virus. The name of the virus is SARS-CoV-2, and the name of the disease that the virus causes is COVID-19.
The word "coronavirus", on the other hand, is just a common noun. There are lots of different types of coronaviruses. The word "coronavirus" is a classical compound created in the 1960s, and like all classical compounds, it's a single word, written with no space.
SARS-CoV-2 is a type of coronavirus, and as a result, the virus and the disease are often called "the coronavirus". Calling the disease "the coronavirus" is perfectly fine, although it's somewhat imprecise.
However, in any case, "coronavirus" is definitely not the name of either the virus or the disease.
As for the capitalization, coronavirus(es) is (are) actually more of a category than a single specific thing. But at any rate, we do not capitalise cold, influenza, or measles either. I'm not a biologist any more than I'm a linguist, so I apologise if this analogy is clunky - but I don't think of them as proper nouns, they are more like cat and mouse than Tom and Jerry.
(Ebola is named after the river, which is a proper noun, explaining why it is an apparent exception.)
As for the spacing, I'm not sure. I don't think there is a clear cut norm. I might suggest (with little to no evidence) that -virus is often/usually combined into a single word within scientific/medical terminology, like retrovirus, norovirus, adenovirus etc. Perhaps this is especially likely when both or all parts of the compound word are Latin in origin. (Note that corona is Latin for crown.)
Whereas two separate words is maybe more common with layman's terms / common names / mass media, and/or where the descriptive word or specific name is not Latin (as in Ebola virus - although that family, too, is called ebolaviruses in the scientific world).
A collective name for a group of viruses belonging to a higher-level taxon is neither italicized nor capitalized, even if it was derived from a proper noun. The first letter of a collective name may be capitalized if it begins a sentence.
- ourmiaviruses, ourmiavirus
- Guernseyviruses are distributed worldwide.
- The guernseyviruses are distributed worldwide.
- the aparavirus polymerase
Note that if taxa have the same stem (e.g. Flavivirus and Flaviviridae), this may lead to ambiguity because both groups of viruses could be referred to as flaviviruses. Some virologists use the terms stem + virads, stem + virids, stem + virins, and stem + virus to distinguish members of orders, families, subfamilies and genera, respectively.
Complex example sentences
- Ebola virus (species Zaire ebolavirus; genus Ebolavirus; family Filoviridae; order Mononegavirales) can cause disease in humans and nonhuman primates.
* The complete rules for naming virus taxa can be found in the ICTV Code.
** A proper noun is a name used for an individual person, place, or organization. A common noun denotes a class of objects or a concept. Host genus names are normally considered as proper nouns because they refer to a group of unique entities but some, for example "citrus", have become common nouns because they can also describe intergeneric hybrids. Virus genus names are not considered as proper nouns when used as part of a species or virus name because they refer to a subset of the genus and not the genus as a whole.
In the current case, "coronavirus" is the collective name for the members of the family Coronaviridae; thus, "Coronaviridae" is italicized and capitalized, but "coronavirus" isn't. Additionally (see e.g. this), the (official) virus name "severe acute respiratory syndrome coronavirus 2" is not italicized, but the species name (scientific name) "Severe acute respiratory syndrome-related coronavirus" is italicized.
In the case of the Ebola virus, "Ebola" is the proper name of a tributary of the Congo River near which the first case was isolated, so "Ebola" retains capitalization; for the species name "Zaire ebolavirus" however, only "Zaire" is capitalized (as a proper name), and "ebolavirus" being the species name is left uncapitalized.
Taxonomical nomenclature is straightforward if you know the rules.
(This should probably have been a question for biology.SE.)
Adding some context to the other answers about spaces... Likely because of English's diverse origins, it has an ambiguous relationship with compound words. Compound words are where smaller words are joined together into larger single words, instead of keeping them separated with a space. English is actually a Germanic language with a lot of Latin vocabulary. Both these languages naturally use compound words. While we do this in English a bit, usually with only 2 compounds, like "cannot" or "become", Germanic languages generally do this for most words. From German, there is "Abbaugerechtigkeit" with 3 parts, as well as Swedish's "parkeringsgarage".
Instead of having compound words be systematic, like in other Germanic languages, English seems to only add compound words to the language after decades of use and there are differences between American (AmE) and British English (BrE) in this respect. Thus, my experience as a native English speaker has been that it is not at all clear when two words can be used as a single word or not. Luckily, there is a nice solution.
In American English at least, usually you can combine two words with a hyphen '-', like "part-time". The rules for hyphen use extend far beyond nouns. The hyphen is also nice for English students, because it clearly identifies where the words break apart, a bit like Japanese (自殺).
As both previous answers hinted at, there is no space between "corona" and "virus" because most scientific words are in Latin.
The genus of viruses that cause "Ebola virus disease" (with spaces) is in fact called ebolavirus (no space). Likewise, coronavirus (no space) refers to members of the family of viruses that cause "corona virus disease" (with spaces). That last term, of course, gets abbreviated to CoViD.
Side note: coronavirus is a less-specific name than ebolavirus. It refers to members of the family coronaviridae (meaning crown-shaped viruses) or its sub-family Orthocoronavirinae. A family/sub-family is slightly higher up the taxonomic tree than a genus. Analogously, the genus ebolavirus is part of the family filoviridae meaning string-shaped viruses.