Introduction

Changes and updates 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 review and ratification to the full ICTV membership by publication on the ICTV website (http://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 2019 (see http://ictv.global/proposals-2018/ 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 12, 2019 to the 162 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 15, 2019.

Changes to virus taxonomy, the International Code of Virus Classification and Nomenclature (ICTV Code), and the appointment of a new ICTV Life Member

All proposals [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216] were ratified by ICTV members, in every case receiving an absolute majority of votes, between 60 and 64% of eligible voters. A summary of the taxonomy changes enacted by the ratified proposals is provided in Table 1. Each proposal is cited and listed in the References to acknowledge the authors’ efforts and to provide links to the specific document source on the ICTV website. These documents remain available for those who wish to see the full details.

Table 1 Summary of taxonomic changes approved in February 2019
Full size table

The introduction, in late 2018, of additional ranks in virus taxonomy has necessitated several changes in the ICTV Code. The amended Code had been approved by the EC and has been ratified by ICTV voting on an additional ballot question. The Code can be found at http://ictv.global/code.asp.

Finally, Dr. Michael J. Adams has been elected as a Life Member, following nomination by the President, recommendation by the Executive Committee, and ratification by the ICTV membership [217]. Dr. Adams served the EC and ICTV in various capacities from 2001 till 2017, most recently as EC Business Secretary.

Perhaps the most notable taxonomic change approved in this ratification is the establishment of the realm Riboviria, a likely monophyletic clade of viruses with positive-strand, double-strand or negative-strand genomic RNA that use cognate RNA-directed RNA polymerases (RdRPs) for replication [2]. The realm Riboviria is placed at the highest taxonomic rank permitted by the ICTV Code. The evidence for monophyly of RNA viruses and for various clades within Riboviria has been accumulating over the years from phylogenetic analyses of the universal marker, RdRP, supplemented by comparison of additional molecular traits shared by subsets of RNA viruses [2, 218,219,220].

Conclusion

All 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.