SARS-CoV-2/Taxonomy

Taxonomy of SARS-CoV-2

Viruses are named by the International Committee on Taxonomy of Viruses (ICTV).

The ICTV

The first internationally organized attempts to introduce order into the bewildering variety of viruses took place at the International Congress of Microbiology held in Moscow in 1966. A committee was created, later called the International Committee on Taxonomy of Viruses (ICTV), and was given the task of developing a single, universal taxonomic scheme for all the viruses infecting animals (vertebrates, invertebrates and protozoa), plants (higher plants and algae), fungi, bacteria and archaea. The ICTV was created as a committee of the Virology Division of the International Union of Microbiological Societies (IUMS) and is governed by Statutes approved by the Virology Division. The Statutes define the objectives of ICTV:

• (i) to develop an internationally agreed taxonomy for viruses (the term “viruses” for this purpose is taken to include viroids and some important groups of satellite viruses);
• (ii) to develop internationally agreed names for these taxa;
• (iii) to communicate taxonomic decisions to the international community of virologists; and
• (iv) to maintain an index of virus names.

The Statutes also state that classification and nomenclature of viruses will be subject to rules set out in an International Code. Virus taxonomy differs from other types of biological classification because the ICTV not only regulates a Code of Nomenclature but also considers and approves the creation of virus taxa. Priority of publication is not the determining factor.

Source: ICTV Introduction to Virus Taxonomy

Virus Taxonomy

The current virus taxonomy is presented by the ICTV on this page: https://talk.ictvonline.org/taxonomy/

As at March 2021, the taxonomy included 6 realms, 10 kingdoms, 17 phyla, 2 subphyla, 39 classes, 59 orders, 8 suborders, 189 families, 136 subfamilies, 2224 genera, 70 subgenera, 9110 species.

Naming SARS-CoV-2

The International Committee on Taxonomy of Viruses (ICTV) is concerned with the designation and naming of virus taxa (i.e. species, genus, family, etc.) rather than the designation of virus common names or disease names. For an outbreak of a new viral disease, there are three names to be decided: the disease, the virus and the species. The World Health Organization (WHO) is responsible for the first, expert virologists for the second, the ICTV for the third.

WHO guidelines for naming of new human diseases can be found at "WHO issues best practices for naming new human infectious diseases" and "WHO Best Practices for the Naming of New Human Infectious Diseases" The following article may also be of interest: "Naming diseases: First do no harm"

As experts on coronaviruses, the ICTV Coronaviridae Study Group has studied the classification (taxonomy) of the new virus. And given that they are experts on this family of viruses, they have also contributed their expertise to the naming of the virus. The virus name is "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2). And the species to which the virus SARS-CoV-2 belongs is Severe acute respiratory syndrome-related coronavirus.

The disease name (which in many cases is different from the virus name) has been designated as COVID-19 by the WHO. The '19' in COVID-19 stands for the year, 2019, that the virus was first seen. The number '19' has nothing whatsoever to do with virus strains, genotypes, or anything else related to the virus' genetics. The virus name was announced by the World Health Organization on February 11, 2020. See the February 11 World Health Organization Situation Report. This clearly states that "WHO has named the disease COVID-19, short for 'coronavirus disease 2019'.”

Source: ICTV News 2020

The news statement about the naming of SARS-CoV-2 included an image which illustrates the relationship of SARS-CoV-2 to the SARS-CoV and MERS-CoV. This image and content from ICTV is Copyright © 2021, International Committee on Taxonomy of Viruses (ICTV) and licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Naming the 2019 Coronavirus

The virus causing the current outbreak of coronavirus disease has been named "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2). The manuscript describing the name also reports the work of the ICTV Coronaviridae Study Group (ICTV-CSG) that determined the virus belongs to the existing species, Severe acute respiratory syndrome-related coronavirus.

Taxonomy of SARS-CoV-2

The full lineage of SARS-CoV-2 is:

Viruses; Riboviria; Orthornavirae; Pisuviricota; Pisoniviricetes; Nidovirales; Cornidovirineae; Coronaviridae; Orthocoronavirinae; Betacoronavirus; Sarbecovirus; Severe acute respiratory syndrome-related coronavirus

Source: National Center for Biotechnology Information (NCBI)

See also: Nature Microbiology The species Severe acute respiratory syndrome-related coronavirus: classifying 2019-nCoV and naming it SARS-CoV-2 2 March 2020

It is an interesting exercise to see where SARS-CoV-2 fits in the current virus taxonomy. Open the ICTV page at https://talk.ictvonline.org/taxonomy/ and scroll through the taxonomy using the above list as a guide. You may need to expand some sections.

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References