Jingchuvirales: a New Taxonomical Framework for a Rapidly Expanding Order of Unusual Monjiviricete Viruses Broadly Distributed among Arthropod Subphyla

Abstract

Technical advances in metagenomics and metatranscriptomics have dramatically accelerated virus discovery in recent years. "Chuviruses" were first described in 2015 as obscure negative-sense RNA viruses of diverse arthropods. Although "chuviruses" first appeared to be members of the negarnaviricot order Mononegavirales in phylogenetic analyses using RNA-directed RNA polymerase sequences, further characterization revealed unusual gene orders in genomes that are nonsegmented, segmented, and/or possibly circular. Consequently, a separate order, Jingchuvirales, was established to include a monospecific family, Chuviridae. Recently, it has become apparent that jingchuvirals are broadly distributed and are therefore likely of ecological and economic importance. Here, we describe recent and ongoing efforts to create the necessary taxonomic framework to accommodate the expected flood of novel viruses belonging to the order.

Keywords: Chuviridae; Jingchuvirales; chuvirus; mivirus; virus classification; virus nomenclature; virus taxonomy.

FIG 1

Genome organization of representatives of each of the established five jingchuviral families. Genomes are drawn to scale (3′→5′). L, large protein gene; HP, hypothetical protein gene; N, nucleoprotein gene; G, glycoprotein gene.

FIG 2

The distribution of L protein percent identities guides the taxonomical demarcation of jingchuvirals. New jingchuviral families, genera, and species should be established when the amino acid identities of two complete L sequences are <21%, <31%, and <90%, respectively. Demarcations were originally established on the basis of all available coding-complete “chu-like” RdRp sequences in GenBank on 3 March 2020 (57). Jingchuviral classification strategies follow previous taxonomical classification efforts that used pairwise sequencing comparison methods (59–64).

FIG 3

Maximum likelihood phylogenetic tree estimated using 53 complete jingchuviral L protein sequences. Tree branches are scaled by substitutions per site. Support values are shown as decimal values and were calculated from 500 replicates.