How to find, understand, and use the Master Species List (MSL), the checklist of all virus species in the world
The International Committee on Taxonomy of Viruses (ICTV) keeps a comprehensive collection of resources on its website, https://ictv.global
One of them is the Master Species List. The MSL is a checklist of all virus species in the world. And everybody can access it, download and use it! This is simple: go to Taxonomy – Master Species Lists.
Here you will see a table which contains links to the spreadsheet versions of the list, and what is more, you can download previous versions as well - from the year 2005 to the most recent. You can simply click on any of these links and download the spreadsheet file. Then open it in any spreadsheet software which is capable to open MS Excel formats (extensions “.xls” and “.xlsx”'), and you will see the content.
There are three sheets within the file. The first provides version information. For example, this one (ICTV_Master_Species_List_2021_v2.xls) says that this is “ICTV 2021 -- Master Species List (MSL37)”. This means that this list was accepted by ICTV Executive Committee in 2021, and this is the 37th list.
These lists can have versions. For example, the current one is “Version 2” and the first sheet contains the summary of changes from the previous version (“Version 1”).
The second sheet contains a glossary that describes the meaning of the data terms that appear in the column headings on the third sheet.
Finally, the third sheet is the data itself. At the first glance, most of the table is filled with similar words but this is natural: the table is about species, and each species belongs to a genus; each genus belongs to a family; and so on. There are many species in one family so all of them will bear that same family name. The only column which contains unique names is (very naturally again) “Species”. So this third data sheet contains the names of every species recognized by the ICTV.
It also contains the immediate past history of taxonomic changes, which is very important because past taxonomic assignments and names will change as science progresses, but this process can be hard (and sometimes painful) to follow. Here ICTV is one of the leading scientific organizations in the world because you can monitor every single change of the virus taxonomy! The last four columns provide the last change associated with each species, the number of the master species list detailing that change, and the name of the proposal file that justifies the change (they can be found on the ICTV web site). A link to the complete taxonomic history is provided in the last column. This link takes you to an ICTV web page that shows every change that was ever made to that species (or other taxon).
Now you see why the MSL table is so important. For sporadic queries, the taxonomy browser of the ICTV website is more appropriate but for a complete list of virus names, the Master Species List is indispensable.