2022.012P.A-Tymoviridae 3nsp

Sep 8, 2026

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This proposal describes three novel viruses from naranjilla and sorghum that are related yet distinct from existing members of the family Tymoviridae. It requests the creation of three new species, two within the genus Tymovirus and one within the genus Marafivirus. Species demarcation is supported using established genus criteria, including overall genome nucleotide identity below 80%, capsid protein sequence identity below 90%, differential host range, divergence in 3’-terminal structure, and serological specificity.

LanguageEnglish

CategoryGeneral

FormatDOCX

Pages10

Reading Time4 min

AccessFree to download

Part 1: Title, Authors, Approvals, etc

Part 3: Taxonomic Proposal

Abstract

Text of proposal

Criteria for species demarcation in Tymovirus

1. Naranjilla chlorotic mosaic virus (NarCMV)

2. Naranjilla mild mosaic virus (NarMMV)

Part 1: TITLE, AUTHORS, APPROVALS, etc Code assigned: 2022.012P Short title: Create two new species in the genus Tymovirus and one new species in the genus Marafivirus (Tymovirales:Tymoviridae) Author(s) and email address(es) Hammond, RW (chair), Abrahamian P, Haenni A-L, Mollov D, Nagata T, Sabanadzovic S Rose.hammond@usda.gov; peter.abrahamian@usda.gov; anne-lise.haenni@ijm.fr; Dimitre.mollov@usda.gov; tatsuya@unb.br; ssabanadzovic@entomology.msstate.edu Author(s) institutional address(es) (optional) USDA [RWH, PA, DM], University of Brazil [TN], Institut Jacques Monod emeritus [A-LH], Mississippi State University [SS] Corresponding author Rosemarie Hammond, rose.hammond@usda.gov List the ICTV Study Group(s) that have seen this proposal Tymoviridae Study Group, Plant Viruses Subcommittee ICTV Study Group comments and response of proposer ICTV Study Group votes on proposal Study Group Number of members Votes support Votes against No vote Tymoviridae 4 2 Authority to use the name of a living person Is any taxon name used here derived from that of a living person (Y/N) Taxon name Person from whom the name is derived Permission attached (Y/N) Submission dates Date first submitted to SC Chair May 26, 2022 Date of this revision (if different to above) ICTV-EC comments and response of the proposer Part 3: TAXONOMIC PROPOSAL Name of accompanying Excel module 2022.012P.A.v2.Tymoviridae_3nsp.xlxs Abstract This proposal describes three novel viruses from naranjilla and sorghum that are related but distinct from current members of the family Tymoviridae. Accordingly, we propose creation of three new species, two in the genus Tymovirus and one in the genus Marafivirus, to classify these viruses. Text of proposal Proposal to create 2 new species in the genus Tymovirus and 1 new species in the genus Marafivirus A. Currently applied criteria for species demarcation in the genus Tymovirus (Dreher et al., 2012) re: Overall genome sequence identity of less than 80%. Capsid protein sequences less than 90% identical. Differential host range. Differences in the 3′-terminal structure. Serological specificity. 1. Naranjilla chlorotic mosaic virus (NarCMV; Tymovirus; Green et al., 2018; MG323924) Naranjilla chlorotic mosaic virus (NarCMV) was isolated and characterized by Green et al. (2018) from naranjilla (Solanum quitoense Lam.), a perennial shrub species cultivated in subtropical areas of Ecuador and Colombia. In 2015, a plant exhibiting symptoms of stunting, mosaic and chlorotic spots was sampled from the Pastaza province of Ecuador and spherical particles, composed of a single 20 kDa capsid protein, were observed under electron microscopy upon mechanical transmission to Nicotiana benthamiana indicator plants. High-throughput sequencing (HTS) was conducted from nucleic acids extracted from the indicator plant, and a single sequence contig was obtained that shared close relationships with tymoviruses. The complete 6,245 nucleotide sequence of the genome (MG323924) revealed a genome organization of three open reading frames (ORFs), a conserved tymobox typical of tymoviruses, a 3’ terminal 150 nt segment with a t-RNA-like secondary structure, and shared 71% sequence identity with the closest tymovirus, eggplant mosaic virus (EMV; KJ690172). This is below the 80% threshold for species demarcation in the genus Tymovirus in the family Tymoviridae (Dreher et al., 2012). The longest ORF encodes a 200 kDa protein containing replication-related domains, which shares 73% aa sequence identity with its closest relative, EMV. A smaller ORF which almost completely overlaps the 200 kDa protein, encodes a 69 kDa protein, and the 3’ proximal ORF, encodes the 188 aa coat protein (CP) of 20 kDa. The amino acid sequence of the CP was 83% identity to its closest match, chiltepin yellow mosaic virus (ChiYMV; FN563124), below the 90% threshold for species demarcation in the Tymoviridae Dreher et al., 2012). Phylogenetic analysis of the replicase and CP amino acids

FAQs

What new species are proposed in this document?

The proposal requests creation of three new species: two in the genus Tymovirus and one in the genus Marafivirus.

Which criteria are used to demarcate species within the genus Tymovirus?

The document applies criteria including overall genome sequence identity below 80%, capsid protein identity below 90%, differential host range, differences in the 3′-terminal structure, and serological specificity.

What evidence supports NarCMV as a distinct Tymovirus species?

NarCMV has complete genome identity below the 80% threshold for nucleotide demarcation, capsid protein identity below the 90% threshold, and a differential host range compared with the closest relatives.

Sep 8, 2026

Upload by Angel