Promotion of order Bunyavirales to class Bunyaviricetes to accommodate a rapidly increasing number of related polyploviricotine viruses.

Prior to 2017, the family Bunyaviridae included five genera of arthropod and rodent viruses with tri-segmented negative-sense RNA genomes related to the Bunyamwera virus. In 2017, the International Committee on Taxonomy of Viruses (ICTV) promoted the family to order Bunyavirales and subsequently greatly expanded its composition by adding multiple families for non-segmented to polysegmented viruses of animals, fungi, plants, and protists. The continued and accelerated discovery of bunyavirals highlighted that an order would not suffice to depict the evolutionary relationships of these viruses. Thus, in April 2024, the order was promoted to class Bunyaviricetes. This class currently includes two major orders, Elliovirales (Cruliviridae, Fimoviridae, Hantaviridae, Peribunyaviridae, Phasmaviridae, Tospoviridae, and Tulasviridae) and Hareavirales (Arenaviridae, Discoviridae, Konkoviridae, Leishbuviridae, Mypoviridae, Nairoviridae, Phenuiviridae, and Wupedeviridae), for hundreds of viruses, many of which are pathogenic for humans and other animals, plants, and fungi.

ICTV Virus Taxonomy Profile: Fimoviridae 2024.

Members of the family Fimoviridae are plant viruses with a multipartite negative-sense enveloped RNA genome (-ssRNA), composed of 4-10 segments comprising 12.3-18.5 kb in total, within quasi-spherical virions. Fimoviruses are transmitted to plants by eriophyid mites and induce characteristic cytopathologies in their host plants, including double membrane-bound bodies in the cytoplasm of virus-infected cells. Most fimoviruses infect dicotyledonous plants, and many cause serious disease epidemics. This is a summary of the ICTV Report on the family Fimoviridae, which is available at ictv.global/report/fimoviridae.

ICTV Virus Taxonomy Profile: Discoviridae 2023.

Discoviridae is a family of negative-sense RNA viruses with genomes of 6.2-9.7 kb that have been associated with fungi and stramenopiles. The discovirid genome consists of three monocistronic RNA segments with open reading frames (ORFs) that encode a nucleoprotein (NP), a nonstructural protein (Ns), and a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Discoviridae, which is available at ictv.global/report/discoviridae.

ICTV Virus Taxonomy Profile: Mypoviridae 2023.

Mypoviridae is a family of negative-sense RNA viruses with genomes of about 16.0 kb that have been found in myriapods. The mypovirid genome consists of three monocistronic RNA segments that encode a nucleoprotein (NP), a glycoprotein (GP), and a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Mypoviridae, which is available at: ictv.global/report/mypoviridae.

ICTV Virus Taxonomy Profile: Tulasviridae 2023.

Tulasviridae is a family of ambisense RNA viruses with genomes of about 12.2 kb that have been found in fungi. The tulasvirid genome is nonsegmented and contains three open reading frames (ORFs) that encode a nucleoprotein (NP), a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain, and a protein of unknown function (X). This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Tulasviridae, which is available at ictv.global/report/tulasviridae.

ICTV Virus Taxonomy Profile: Wupedeviridae 2023.

Wupedeviridae is a family of negative-sense RNA viruses with genomes of about 20.5 kb that have been found in myriapods. The wupedevirid genome consists of three monocistronic RNA segments with open reading frames (ORFs) that encode a nucleoprotein (NP), a glycoprotein (GP), and a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Wupedeviridae, which is available at ictv.global/report/wupedeviridae.

ICTV Virus Taxonomy Profile: Cruliviridae 2023.

Cruliviridae is a family of negative-sense RNA viruses with genomes of 10.8-11.5 kb that have been found in crustaceans. The crulivirid genome consists of three RNA segments with ORFs that encode a nucleoprotein (NP), a glycoprotein (GP), a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain, and in some family members, a zinc-finger (Z) protein of unknown function. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Cruliviridae, which is available at ictv.global/report/cruliviridae.

ICTV Virus Taxonomy Profile: Leishbuviridae 2023.

Leishbuviridae is a family of negative-sense RNA viruses with genomes of about 8.0 kb that have been found in protists. The leishbuvirid genome consists of three monocistronic RNA segments with open reading frames (ORFs) that encode a nucleoprotein (NP), a glycoprotein (GP), and a large (L) protein containing an RNA-directed RNA polymerase (RdRP) domain. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Leishbuviridae, which is available at ictv.global/report/leishbuviridae.

Annual (2023) taxonomic update of RNA-directed RNA polymerase-encoding negative-sense RNA viruses (realm Riboviria: kingdom Orthornavirae: phylum Negarnaviricota).

In April 2023, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by one new family, 14 new genera, and 140 new species. Two genera and 538 species were renamed. One species was moved, and four were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.

2022 taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.

In March 2022, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by two new families (bunyaviral Discoviridae and Tulasviridae), 41 new genera, and 98 new species. Three hundred forty-nine species were renamed and/or moved. The accidentally misspelled names of seven species were corrected. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.

Taxonomy of the order Bunyavirales: second update 2018.

In October 2018, the order Bunyavirales was amended by inclusion of the family Arenaviridae, abolishment of three families, creation of three new families, 19 new genera, and 14 new species, and renaming of three genera and 22 species. This article presents the updated taxonomy of the order Bunyavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV).

Taxonomy of the order Bunyavirales: update 2019.

In February 2019, following the annual taxon ratification vote, the order Bunyavirales was amended by creation of two new families, four new subfamilies, 11 new genera and 77 new species, merging of two species, and deletion of one species. This article presents the updated taxonomy of the order Bunyavirales now accepted by the International Committee on Taxonomy of Viruses (ICTV).

ICTV Virus Taxonomy Profile: Fimoviridae.

Members of the family Fimoviridae, order Bunyavirales are plant viruses with segmented, linear, single-stranded, negative-sense RNA genomes. They are distantly related to orthotospoviruses and orthobunyaviruses of the families Tospoviridae and Peribunyaviridae, respectively. The family Fimoviridae includes the genus Emaravirus, which comprises several species with European mountain ash ringspot-associated emaravirus as the type species. Fimoviruses are transmitted to plants by eriophyid mite vectors and induce similar characteristic cytopathologies in their host plants, including the presence of double membrane-bound bodies in the cytoplasm of the virus-infected cells. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Fimoviridae, which is available at www.ictv.global/report/fimoviridae.

Taxonomy of the family Arenaviridae and the order Bunyavirales: update 2018.

In 2018, the family Arenaviridae was expanded by inclusion of 1 new genus and 5 novel species. At the same time, the recently established order Bunyavirales was expanded by 3 species. This article presents the updated taxonomy of the family Arenaviridae and the order Bunyavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV) and summarizes additional taxonomic proposals that may affect the order in the near future.

Next generation sequencing and molecular analysis of artichoke Italian latent virus.

Next-generation sequencing (NGS) allowed the assembly of the complete RNA-1 and RNA-2 sequences of a grapevine isolate of artichoke Italian latent virus (AILV). RNA-1 and RNA-2 are 7,338 and 4,630 nucleotides in length excluding the 3' terminal poly(A) tail, and encode two putative polyproteins of 255.8 kDa (p1) and 149.6 kDa (p2), respectively. All conserved motifs and predicted cleavage sites, typical for nepovirus polyproteins, were found in p1 and p2. AILV p1 and p2 share high amino acid identity with their homologues in beet ringspot virus (p1, 81% and p2, 71%), tomato black ring virus (p1, 79% and p2, 63%), grapevine Anatolian ringspot virus (p1, 65% and p2, 63%), and grapevine chrome mosaic virus (p1, 60% and p2, 54%), and to a lesser extent with other grapevine nepoviruses of subgroup A and C. Phylogenetic and sequence analyses, all confirmed the strict relationship of AILV with members classified in subgroup B of genus Nepovirus.

Pittosporum cryptic virus 1: genome sequence completion using next-generation sequencing.

Next-generation sequencing (NGS) was applied to dsRNAs extracted from an Italian pittosporum plant infected with pittosporum cryptic virus 1 (PiCV1). NGS allowed assembly of the full genome sequence of PiCV1, comprising dsRNA1 (1.9 kbp) and dsRNA2 (1.5 kbp), which encode the RNA-dependent RNA polymerase and capsid protein genes, respectively. Phylogenetic and sequence analyses confirmed that PiCV1 is a new member of the genus Deltapartitivirus, family Partiviridae. From the same plant, NSG also permitted assembly of the complete genome sequence of eggplant mottled dwarf virus (EMDV), which shared 86 % to 98 % nucleotide sequence identity with complete and partial sequences (ca 6750 nt) of other known EMDV isolates with sequences available in the GenBank database.

Deep sequencing of dsRNAs recovered from mosaic-diseased pigeonpea reveals the presence of a novel emaravirus: pigeonpea sterility mosaic virus 2.

Deep-sequencing analysis of double-stranded RNA extracted from a mosaic-diseased pigeonpea plant (Cajanus cajan L., family Fabaceae) revealed the complete sequence of six emaravirus-like negative-sense RNA segments of 7009, 2229, 1335, 1491, 1833 and 1194 nucleotides in size. In the order from RNA1 to RNA6, these genomic RNAs contained ORFs coding for the RNA-dependent RNA polymerase (RdRp, p1 of 266 kDa), the glycoprotein precursor (GP, p2 of 74.5 kDa), the nucleocapsid (NC, p3 of 34.9 kDa), and the putative movement protein (MP, p4 of 40.7 kDa), while p5 (55 kDa) and p6 (27 kDa) had unknown functions. All RNA segments showed distant relationships to viruses of the genus Emaravirus, and in particular to pigeonpea sterility mosaic virus (PPSMV), with which they shared nucleotide sequence identity ranging from 48.5 % (RNA3) to 62.5 % (RNA1). In phylogenetic trees constructed from the sequences of the proteins encoded by RNA1, RNA2 and RNA3 (p1, p2 and p3), this new viral entity showed a consistent grouping with fig mosaic virus (FMV) and rose rosette virus (RRV), which formed a cluster of their own, clearly distinct from PPSMV-1. In experimental greenhouse trials, this novel virus was successfully transmitted to pigeonpea and French bean seedlings by the eriophyid mite Aceria cajani. Preliminary surveys conducted in the Hyderabad region (India) showed that the virus in question is widespread in pigeonpea plants affected by sterility mosaic disease (86.4 %) but is absent in symptomless plants. Based on molecular, biological and epidemiological features, this novel virus is the second emaravirus infecting pigeonpea, for which the provisional name pigeonpea sterility mosaic virus 2 (PPSMV-2) is proposed.

Phylogenetic and recombination analysis of the homing protein domain of grapevine fanleaf virus (GFLV) isolates associated with 'yellow mosaic' and 'infectious malformation' syndromes in grapevine.

The RNA2 of seven grapevine fanleaf virus (GFLV) isolates from vines with yellow mosaic (YM) symptoms from different origin were sequenced. These sequences showed a high variability in the homing protein (2A(HP)) and, in five of them, a putative recombination with arabis mosaic virus (ArMV) was detected. To investigate recombination frequency, the partial sequences of the 2A(HP) of 28 additional GFLV isolates from nine different countries, showing either YM or infectious malformations (MF) symptoms, were obtained and compared with those of GFLV isolates from GenBank. The analysis confirmed the high level of sequence variability (up to 41 % at the nucleotide level) among isolates. In phylogenetic trees constructed using different approaches, the sequenced isolates always clustered in four conserved groups, three of which comprised YM strains (groups 1, 2 and 3), and one (group 4) the MF strains. Potential interspecific recombination sites between GFLV and ArMV were predicted in the 2A(HP) gene of several isolates, all of which were associated with YM symptoms.

Identification, Sequencing, and Molecular Analysis of RNA2 of Artichoke Italian Latent Virus Isolates from Known Hosts and a New Host Plant Species.

Despite its first description in 1977 and numerous reports of its presence in various plant species in many countries, the molecular information available in GenBank for artichoke Italian latent virus (AILV) is still limited to a single complete genome sequence (RNA1 and 2) of a grapevine isolate (AILV-V) and a partial portion of the RNA2 sequence from an isolate of unknown origin and host. Here, we report the results of molecular analyses conducted on the RNA2 of some AILV isolates, sequenced for the first time in this study, together with the first-time identification of AILV in a new host plant species, namely chard (Beta vulgaris subsp. vulgaris), associated with vein clearing and mottling symptoms on leaves. The different AILV isolates sequenced were from artichoke (AILV-C), gladiolus (AILV-G), Sonchus (AILV-S), and chard (AILV-B). At the molecular level, the sequencing results of the RNA2 segments showed that AILV-C, AILV-G, AILV-S, and AILV-B had a length of 4629 nt (excluding the 3' terminal polyA tail), which is one nt shorter than that of the AILV-V reported in GenBank. A comparison of the RNA2 coding region sequences of all the isolates showed that AILV-V was the most divergent isolate, with the lowest sequence identities of 83.2% at the nucleotide level and 84.7% at the amino acid level. Putative intra-species sequence recombination sites were predicted among the AILV isolates, mainly involving the genomes of AILV-V, AILV-C, and AILV-B. This study adds insights into the variability of AILV and the occurrence of recombination that may condition plant infection.