Additional changes to taxonomy ratified in a special vote by the International Committee on Taxonomy of Viruses (October 2018)

Abstract

This article reports the changes to virus taxonomy approved and ratified by the International Committee on Taxonomy of Viruses (ICTV) in October 2018. Of note, the ICTV has approved, by an absolute majority, the creation of additional taxonomical ranks above those recognized previously. A total of 15 ranks (realm, subrealm, kingdom, subkingdom, phylum, subphylum, class, subclass, order, suborder, family, subfamily, genus, subgenus, and species) are now available to encompass the entire spectrum of virus diversity. Classification at ranks above genus is not obligatory but can be used by the authors of new taxonomic proposals when scientific justification is provided.

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 (http://ictv.global/statutes.asp), proposals submitted to the ICTV Executive Committee (EC) 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 presented for ratification to the full ICTV membership by publication on the ICTV website (http://ictv.global) followed by an electronic vote.

Nine proposals that were discussed at the EC meeting in July 2017 (Singapore) and subsequently at the EC meeting in July 2018 (Washington, DC, USA) [1,2,3,4,5,6,7,8,9] were approved by the EC and then ratified in a supplemental vote. The proposals were made publicly available on the ICTV website in August 2018, and a list of them was then emailed on August 30, 2018 to the 156 members of ICTV, i.e., EC Members, Life Members, ICTV Subcommittee Members (including the SG chairs) and ICTV National Representatives. Following this, members were requested to vote on whether to ratify the proposals, with a closing date of October 7, 2018. Since the processing of these proposals overlapped the end of the 2014–2017 EC tenure and the start of the 2017–2020 EC tenure, members of both ECs constitute the authorship of this article.

Changes to virus taxonomy: taxa and nomenclature

The 156 members of the ICTV were contacted by e-mail and asked to vote on the ratification of the nine proposals. All nine proposals [1,2,3,4,5,6,7,8,9] were ratified by ICTV members. Proposal 2017.005G, introducing the additional ranks [1], was ratified by 99 votes in favor and 6 votes against. Voting on the remaining eight proposals, each of which utilizes some of the new taxonomy ranks, was contingent on ICTV members voting in favor of proposal 2017.005G, and each of these proposals received from 83 to 86 votes. A summary of the individual proposals is provided in Table 1, and the entire revised taxonomy reflecting the approved changes is shown in Supplementary file 1, with the new taxa indicated by bold type. Each proposal is cited and listed in the References to acknowledge the authors’ efforts and to provide links to the specific proposal as coded on the ICTV website. These documents remain available for those who wish to see the full details of the proposals.

Table 1 Summary of taxonomic changes approved in October 2018

The introduction of the additional ranks permitted in virus taxonomy necessitates several changes in the ICTV Code. The proposed changes to the Code, approved by the EC, are posted at http://ictv.global/code.asp and will be submitted for ratification by ICTV in early 2019.

Conclusion

All nine proposals submitted to ratification were ratified by an absolute majority of the ICTV, and the changes proposed are now part of official ICTV taxonomy. An up-to-date list of all approved taxa can be found on the ICTV online website: http://ictv.global/msl.htm. The remaining taxonomic proposals approved at the EC meeting in July 2018 (Washington, DC, USA) will be offered to the ICTV for ratification in early 2019.