Origins and Evolution of the Global RNA Virome

Yuri I. Wolf; Darius Kazlauskas; Jaime Iranzo; Adriana LucÍa-Sanz; Jens H. Kuhn; Mart Krupovic; Valerian V. Dolja; Eugene V. Koonin

The large number and immense diversity of the viruses included in our analysis create 192 serious challenges for a systematic, phylogeny-based nomenclature of the identified evolutionary 193 lineages of RNA viruses. Many such lineages consist of viruses newly discovered by 194 metaviromics, are not yet formally classified by the International Committee on Taxonomy of 195 Viruses (ICTV), and therefore, cannot be assigned formal names. For the purpose of the present 196 work, we adopted a semi-arbitrary naming scheme using the following approach. 1) We use 197 taxon names that have been fully accepted by the ICTV as of March 2018 (47) whenever 198 possible. These names are recognizable through their capitalization and italicization and rank-199 specific suffixes (e.g., -virales for orders, -viridae for families). As is the common practice in 200 virus taxonomy, the officially classified members of each ICTV-approved taxon are referred to 201 via vernaculars (recognizable through their lack of capitalization and italicization). For instance, 202 the members of the ICTV-approved order Bunyavirales are called bunyaviruses, whereas those 203 of the family Tombusviridae are called tombusviruses. However, in this work, both taxon and 204 vernacular terms are to be understood sensu lato: if our analysis indicates certain viruses to be 205 members of or very closely related to an ICTV-established taxon, we consider them members of 206 that taxon despite the lack of current ICTV recognition. As a result, in our analysis, the order 207 All rights reserved. No reuse allowed without permission.