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 ICTV Statutes (http://www.ictv.global/statutes.asp) and ICTV Executive Committee (EC) procedures, proposals undergo a review process involving input from the ICTV Study Groups (SGs) and Subcommittees (SCs), other interested virologists, and the EC. Proposals may thus be considered on more than one occasion before they are submitted for ratification by the ICTV membership. Proposals are presented for ratification by publication on the ICTV website (http://www.ictv.global) followed by an electronic vote. The latest set of proposals approved by the EC was made available on the ICTV website in January 2017 (see http://ictv.global/proposals-2017 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 then emailed on January 24, 2018 to the 160 members of ICTV, namely the EC Members, Life Members, ICTV Subcommittee Members (including the SG chairs) and ICTV National Representatives. Members were then requested to vote on whether to ratify the taxonomic proposals (voting closed on February 25, 2018).

Since the processing of this year’s proposals overlapped the end of the 2014–2017 EC tenure and the start of the 2017–2020 EC tenure, members of the both ECs constitute the authorship of this article.

Changes to virus taxonomy: taxa and nomenclature

Large number of changes were ratified by ICTV members (Table 1). Increase in the number of all taxa compared to the 2017 taxonomy was within the range of 9–11%, except for the number of subfamilies, which grew by 31%.

Table 1 Summary of taxonomic changes approved in February 2018
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A summary of the individual proposals is provided in Table 2. Names of newly created taxa are in bold italic type. Names of existing taxa that have been moved or renamed are shown in plain italic type. Each proposal is cited and listed in the References, to acknowledge the authors’ efforts and to provide a link to each specific proposal on the ICTV website. These documents remain available for any who wish to see the full details of the proposals.

Table 2 Taxonomic changes approved in February 2018
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Changes to the International Code of Virus Classification and Nomenclature

ICTV has adopted one change to the Code, by ratifying Proposal 2017.003G.A.v2.ICVCN_Rule_3.11_Change. “Change ICVCN Rule 3.11 to permit, with limitations, the names of people to be recognised in names of taxa”. As with many other proposals dealing with general approaches to virus taxonomy and nomenclature, this proposed change was a subject of a lively debate in the community, and was adopted by the overwhelming majority of the ICTV. This change also allowed the creation of two new taxa in the order Caudovirales, i.e., the family Ackermannviridae, to honor Hans-Wolfgang Ackermann (1936–2017), a former Life Member of the ICTV and Professor Emeritus at Université Laval, for his foundational contributions to the biology and taxonomy of prokaryotic viruses, and the subfamily Mccleskeyvirinae, to honor Charles Shelton McCleskey (1904–1984), a former Professor Emeritus at Louisiana State University, for his pioneering work on viruses of Leuconostoc bacteria.

Conclusion

All of the taxonomic proposals listed below were approved by the 87–95 affirming votes from the 96 members who voted (a return rate of about 60%). The changes are now part of the official ICTV taxonomy. Several proposals that had been discussed at the 2017 EC meeting were not included in the ballot because they needed further development. Several other proposals were found, after completion of the ratification rate, to contain typographical errors in species’ names. According to the current ICTV procedures, these errors will need to be corrected by additional proposals to be submitted to the 2018 EC meeting. An up-to-date list of all approved taxa can be found on the ICTV website at http://ictv.global/msl.