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).
In March 2020, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. At the genus rank, 20 new genera were added, two were deleted, one was moved, and three were renamed. At the species rank, 160 species were added, four were deleted, ten were moved and renamed, and 30 species were renamed. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.
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.
Several dsRNA bands (approx. 0.6-7 kbp in size) were recovered from tissues of mosaicdiseased fig seedlings which contained the enveloped round structures known as double membrane bodies (DMBs). BLAST analysis of a 4353 and a 1120 nt sequence from the two largest RNA segments showed homology with the polymerase and the putative glycoprotein precursor genes of negative-sense single-stranded RNA viruses of the family Bunyaviridae. Negative-and positive-sense riboprobes designed from both RNA segments hybridized to two bands of approximately 7 and 2.3 kbp in Northern blots of dsRNAs. Thus, these segments were identified as putative RNA-1 and RNA-2 of a novel virus for which the name fig mosaic virus (FMV) is proposed. Identity levels of predicted amino acids of the protein encoded by FMV RNA-1 with those of species of the family Bunyaviridae and European mountain ash ringspot-associated virus (EMERaV) were 28 and 54 %, respectively. RNA-2 showed 38 % identity at the amino acid level only with EMARaV. RNA-1 segment contained five conserved motifs (A-E) and an endonucleolytic centre of comparable genes of L RNA of bunyaviruses and EMARaV RNA-1. In a phylogenetic tree constructed with RdRp sequences, EMARaV grouped with FMV in a clade distinct from those of all bunyavirus genera. The consistent association of DMBs with mosaic symptoms and the results of molecular investigations strongly indicate that DMBs are particles of FMV, the aetiological agent of fig mosaic disease.
The complete sequence of four viral RNA segments of fig mosaic virus (FMV) was determined. Each of the four RNAs comprises a single open reading frame (ORF) 7,093, 2,252, 1,490 and 1,472 nucleotides in size, respectively. These ORFs encode the following proteins in the order: RNA-dependent RNA polymerase (p1 264 kDa), a putative glycoprotein (p2 73 kDa), a putative nucleocapsid protein (p3 35 kDa) and a protein with unknown function (p4 40.5 kDa). All RNA segments possess untranslated regions containing at the 5' and 3' termini a 13-nt complementary sequence. A conserved motif denoted premotif A was found to be present in addition to the five RdRp motifs A-F in RNA-1. In phylogenetic trees constructed with the amino acid sequences of RNA-1 and RNA-2, FMV clustered consistently with European mountain ash ringspot-associated virus (EMARaV) in a clade close to those comprising members of the genera Hantavirus, Orthobunyavirus and Tospovirus. The amino acid sequence of the putative FMV nucleocapsid protein encoded by RNA-3 shared identity with comparable sequences of EMARaV and the unclassified viruses pigeonpea sterility mosaic virus (PPSMV) and maize red stripe virus (MRSV). The nucleocapsid sequences rooted the four viruses in a clade close to the genus Tospovirus. Based on molecular, morphological and epidemiological features, FMV appears to be very closely related to PPSMV and MRSV. All these viruses are phylogenetically related to EMARaV and therefore seem to be eligible for classification in the proposed genus Emaravirus, which, in turn, may find a taxonomic allocation in the family Bunyaviridae.
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