Changes to virus taxonomy and the ICTV Statutes ratified by the International Committee on Taxonomy of Viruses (2023)

This article reports changes to virus taxonomy and taxon nomenclature that were approved and ratified by the International Committee on Taxonomy of Viruses (ICTV) in April 2023. The entire ICTV membership was invited to vote on 174 taxonomic proposals that had been approved by the ICTV Executive Committee in July 2022, as well as a proposed revision of the ICTV Statutes. All proposals and the revised ICTV Statutes were approved by a majority of the voting membership. Of note, the ICTV continued the process of renaming existing species in accordance with the recently mandated binomial format and included gene transfer agents (GTAs) in the classification framework by classifying them as viriforms. In total, one class, seven orders, 31 families, 214 genera, and 858 species were created.


Introduction
Changes to virus taxonomy (the universal scheme of virus classification of the International Committee on Taxonomy of Viruses [ICTV]) take place annually and are the result of a multi-stage process.In accordance with the ICTV Statutes (https:// ictv.global/ about/ statu tes), proposals are submitted to the ICTV Executive Committee (EC) and undergo a review process that involves input from the ICTV Study Groups (SGs) and Subcommittees (SCs), other interested virologists, and the EC.After final approval by the EC, proposals are placed on the ICTV website (https:// ictv.global) for viewing by the full ICTV membership, which ratifies them by online voting [1].
The latest set of proposals approved by the EC was made available on the ICTV website in February 2023 (see https:// ictv.global/ files/ propo sals/ appro ved for all proposals combined into a single zip file, and use the links provided in the References to access individual proposals).A list of proposals was emailed on March 8, 2023, to the 185 members of the ICTV -the EC Members, SC Members (including the SG chairs and co-chairs), ICTV Life Members, and ICTV National Representatives.Members were then requested to vote on whether to ratify the taxonomic proposals.Voting closed on April 8, 2023.

Changes to virus taxonomy and the ICTV Statutes
All proposals  were ratified by ICTV members (72% of eligible voters), in every case receiving a majority of "yes" votes (99-100%).A summary of the taxonomy changes enacted by the proposals is provided in Table 1.The new class, orders, and families ratified in 2023 are listed in Table 2.Each proposal is cited and listed in the References to acknowledge the authors' efforts and to provide links to the specific proposal on the ICTV website.These documents remain available for those who would like to see the details of the proposals.
Of note, a large number of proposals renamed existing species for compliance with the recently mandated binomial nomenclature format.As a result, 8,982 out of the current 11,273 species (80%) now have binomial names.The  process will be concluded in 2023, with the remaining 2,291 species being renamed.
Another notable taxonomic change approved in this ratification was the inclusion of gene transfer agents (GTAs) in the classification scheme as viriforms [154].

Lineage
Taxon history page

Duplodnaviria › Heunggongvirae › Uroviricota › Caudoviricetes › Fredfastierviridae
A change to the ICTV Statutes was also ratified in the vote and approved in May 2023 by the Virology Division of the International Union of Microbiological Societies (IUMS), which is the parent organization of the ICTV.The new ICTV Statutes can be found at https:// ictv.global/ about/ statu tes.The purpose of the approved change was to specify a three-year cycle for the ICTV Plenary Meeting.As stated in the new text of Article 5.1: "Plenary Meetings of the full ICTV membership shall be held every three years.In the years when it coincides with the International Congresses of Virology (ICV) organized by the IUMS, the Plenary Meeting shall be held in conjunction with the ICV.Otherwise, the Plenary Meeting shall be held online no later than one month after the Executive Committee annual meeting".

Conclusion
All proposals submitted for ratification were ratified by a majority vote of the ICTV, and the additions and changes to virus classification are now part of the official ICTV taxonomy.New ICTV Statutes are now in force as well.An up-to-date list of all approved taxa, which now includes 11,273 virus species, can be found on the ICTV website: See https:// ictv.global/ msl for the Master Species List (MSL) and https:// ictv.global/ vmr for the Virus Metadata Resource (VMR), the latter of which provides an exemplar virus isolate for each species along with the GenBank accession number of the isolate.

Table 1
Summary of taxonomic changes approved by the ICTV in 2023a Total number of taxa in the ICTV Master Species List prior to 2023 ratification b Total number of taxa now recognized, as reported in the ICTV Master Species List #38

Table 2
New classes, orders, and families ratified by the ICTV in 2023