Introduction

Changes to virus taxonomy (the Universal Scheme of Virus Classification of the International Committee on Taxonomy of Viruses [ICTV]) now take place annually and are the result of a multi-stage process. In accordance with the ICTV Statutes (http://www.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 then presented for ratification to the full ICTV membership 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 by January 2017. A list of these proposals was then emailed on 9 February 2017 to the 149 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 10 March 2017).

Changes to virus taxonomy: taxa and nomenclature

A large number of changes were ratified by ICTV members (Table 1). A summary of the individual proposals, listed by the ICTV Subcommittee responsible for managing them, is provided in Tables 2, 3, 4, 5, 6, 7. Some proposals concern more than one Subcommittee and appropriate cross-references are then provided. Names of newly created taxa are in bold italic type. Names of existing taxa that have been moved or renamed are shown in plain italics. 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 any who wish to see the full details of the proposals.

Table 1 Summary of taxonomic changes approved in March 2017
Table 2 Taxonomic changes from the Subcommitee for Bacterial and Archaeal Viruses (new taxa are in bold typeface)
Table 3 Taxonomic changes from the Subcommitee for Animal Viruses with DNA or Reverse-Transcribing Genomes (new taxa are in bold typeface)
Table 4 Taxonomic changes from the Subcommitee for Fungal and Protist Viruses (changes listed here for convenience; the natural hosts are for the most part unknown; new taxa are in bold typeface)
Table 5 Taxonomic changes from the Subcommitee for Animal Viruses with dsRNA or ssRNA genomes (new taxa are in bold typeface)
Table 6 Taxonomic changes from the Subcommitee for Plant Viruses (new taxa are in bold typeface; plant-infecting viruses are also affected by changes listed in Table 5 to the genera Emaravirus [105], Tenuivirus [113], Tospovirus [114] and Cytorhabdovirus [122] and the creation of the order Bunyavirales [114])
Table 7 Taxonomic changes from the Subcommitee for Animal Viruses with ssRNA+ Genomes (new taxa are in bold typeface)

Changes to the International Code of Virus Classification and Nomenclature

Additions to the Code Rule 3.32 and a new Rule 3.34 were proposed [176] to enable the classification of satellite nucleic acids (see Plant Virus proposal to create the family Tolecusatellitidae [153]). The additions are shown in bold, below:

Viroids and satellite nucleic acids

3.32

Rules concerned with the classification of viruses shall also apply to the classification of viroids and satellite nucleic acids.

3.34

The formal endings for taxa of satellite nucleic acids are the suffix "-satellite” for genera, the suffix “-satellitinae” for sub-families (should this taxon be needed) and “-satellitidae” for families.

Conclusion

All of the taxonomic proposals listed were unanimously (or almost unanimously) approved by the 90 members who voted (a return rate of about 60%). The changes are now part of the official ICTV taxonomy. An up-to-date list of all approved taxa can be found on the ICTV online website: http://www.ictv.global/msl.htm.