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 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.

Barley Yellow Mosaic Virus VPg Is the Determinant Protein for Breaking eIF4E-Mediated Recessive Resistance in Barley Plants.

In this study, we investigated the barley yellow mosaic virus (BaYMV, genus ) factor(s) responsible for breaking eIF4E-mediated recessive resistance genes (//) in barley. Genome mapping analysis using chimeric infectious cDNA clones between -breaking (JT10) and -non-breaking (JK05) isolates indicated that genome-linked viral protein (VPg) is the determinant protein for breaking the resistance. Likewise, VPg is also responsible for overcoming the resistances of and alleles.

Association of VPg and eIF4E in the host tropism at the cellular level of Barley yellow mosaic virus and Wheat yellow mosaic virus in the genus Bymovirus.

Barley yellow mosaic virus (BaYMV) and Wheat yellow mosaic virus (WYMV) are separate species in the genus Bymovirus with bipartite plus-sense RNA genomes. In fields, BaYMV infects only barley and WYMV infects only wheat. Here, we studied the replicative capability of the two viruses in barley and wheat mesophyll protoplasts.

Biological and genetic diversity of Wheat yellow mosaic virus (Genus Bymovirus).

The biological and genetic diversity of Wheat yellow mosaic virus (WYMV) isolates in Japan was characterized. On the basis of wheat cultivar reactions, 14 WYMV isolates from various places were classified into pathotypes I, II, or III. These were distributed in central, northern, and southern areas of Japan, respectively.

Differential detection of Wheat yellow mosaic virus, Japanese soil-borne wheat mosaic virus and Chinese wheat mosaic virus by reverse transcription loop-mediated isothermal amplification reaction.

A differential detection method for three wheat viruses: Wheat yellow mosaic virus (WYMV), Japanese soil-borne mosaic virus (JSBWMV) and Chinese wheat mosaic virus (CWMV) using reverse transcription loop-mediated isothermal amplification (RT-LAMP) reaction was developed. All three primer sets, which were designed from the genome sequences of WYMV, JSBWMV and CWMV respectively, worked most efficiently at 65 °C and could detect each virus RNA within 10 min by fluorescence monitoring using an isothermal DNA amplification and fluorescence detection device. Furthermore, these primer sets showed unique annealing curves.

Influence of amino acid at position 132 in VPg on replication and systemic infection of Barley yellow mosaic virus.

A substitution of Lys with Asn or His at the amino-acid position 132 in VPg (VPg132) correlates with overcoming rym4-gene resistance by European strain 2 of Barley yellow mosaic virus (BaYMV-2). From the full-length cDNA clones for a Japanese BaYMV isolate JK05 (BaYMV-JK05) we generated virus mutants with Tyr, Lys, Asn, and Ala substituted for wild-type His at the VPg132. Only Tyr and Asn mutants replicated efficiently in protoplasts from barley varieties that are susceptible to wild-type virus.

Bymovirus reverse genetics: requirements for RNA2-encoded proteins in systemic infection.

Barley yellow mosaic virus (BaYMV), the type species of the genus Bymovirus in the family Potyviridae in the picornavirus-like superfamily, causes a yellow mosaic disease of winter barley with significant yield losses in Europe and East Asia. Until now, infectious in vitro transcripts for the bipartite plus-sense RNA genome of any bymovirus species have not been available, rendering molecular analyses of bymovirus pathogenicity and the host resistance mechanisms difficult. In this study, we constructed the first cDNA clones of BaYMV RNA1 and RNA2, from which infectious RNA can be transcribed in vitro.

Chromosomal integration of a binding domain:bait gene into yeast enhances detection in the two-hybrid system.

We have developed a modified yeast two-hybrid system using the GAL4 transcription activator by integrating a BD:bait gene (GAL4 binding domain:bait gene) into the host chromosome. Locus-specific integration by homologous recombination and use of a strong transcription promoter enabled uniform expression of the integrated BD:bait gene in all host cells. Moreover, after introduction of an AD:prey (GAL4 activation domain:prey) plasmid, false positives were nearly undetectable and false negatives were decreased significantly.

Orchid fleck virus is a rhabdovirus with an unusual bipartite genome.

Orchid fleck virus (OFV) has an unusual bipartite negative-sense RNA genome with clear sequence similarities to those of nucleorhabdoviruses. The OFV genome consists of two single-stranded RNA molecules, RNA1 and RNA2 that are 6413 and 6001 nt long, respectively, with open reading frame (ORF) information in the complementary sense. RNA1 encodes 49 (ORF1), 26 (ORF2), 38 (ORF3), 20 (ORF4) and 61 kDa (ORF5) proteins, and RNA2 encodes a single protein of 212 kDa (ORF6).

RNase E maintenance of proper FtsZ/FtsA ratio required for nonfilamentous growth of Escherichia coli cells but not for colony-forming ability.

Inactivation or deletion of the RNase E-encoding rne gene of Escherichia coli results in the growth of bacterial cells as filamentous chains in liquid culture (K. Goldblum and D. Apirion, J.

The optimal temperature for RNA replication in cells infected by Soil-borne wheat mosaic virus is 17 degrees C.

Systemic infection of wheat plants with Soil-borne wheat mosaic virus (SBWMV) requires temperatures below 20 degrees C. Here we examine the cause of the temperature sensitivity by inoculating infectious in vitro transcripts of SBWMV RNA1 and RNA2 to barley mesophyll protoplasts. After RNA inoculation, protoplasts were incubated at temperatures between 15 and 25 degrees C for up to 48 h.

Modification of the 5' terminus of Sindbis virus genomic RNA allows nsP4 RNA polymerases with nonaromatic amino acids at the N terminus to function in RNA replication.

We have previously shown that Sindbis virus RNA polymerase requires an N-terminal aromatic amino acid or histidine for wild-type or pseudo-wild-type function; mutant viruses with a nonaromatic amino acid at the N terminus of the polymerase, but which are otherwise wild type, are unable to produce progeny viruses and will not form a plaque at any temperature tested. We now show that such mutant polymerases can function to produce progeny virus sufficient to form plaques at both 30 and 40 degrees C upon addition of AU, AUA, or AUU to the 5' terminus of the genomic RNA or upon substitution of A for U as the third nucleotide of the genome. These results are consistent with the hypothesis that (i) 3'-UA-5' is required at the 3' terminus of the minus-strand RNA for initiation of plus-strand genomic RNA synthesis; (ii) in the wild-type virus this sequence is present in a secondary structure that can be opened by the wild-type polymerase but not by the mutant polymerase; (iii) the addition of AU, AUA, or AUU to the 5' end of the genomic RNA provides unpaired 3'-UA-5' at the 3' end of the minus strand that can be utilized by the mutant polymerase, and similarly, the effect of the U3A mutation is to destabilize the secondary structure, freeing 3'-terminal UA; and (iv) the N terminus of nsP4 may directly interact with the 3' terminus of the minus-strand RNA for the initiation of the plus-strand genomic RNA synthesis.

Rice grassy stunt tenuivirus nonstructural protein p5 interacts with itself to form oligomeric complexes in vitro and in vivo.

We investigated the interaction of Rice grassy stunt tenuivirus (RGSV) nonstructural protein p5, a protein of 22 kDa encoded on vRNA 5, with all 12 RGSV proteins by using a GAL4 transcription activator-based yeast two-hybrid system. The p5 protein interacted only with itself and not with any other viral protein; the interacting domains were localized within the N-terminal 96 amino acids of p5. The p5-p5 interaction was reproduced in an Sos recruitment-mediated yeast two-hybrid system as well in by far-Western blots.

Engineering of a Sagiyama alphavirus RNA-based transient expression vector.

Sagiyama virus (SAGV), a strain of Getah virus in the genus Alphavirus in the family Togaviridae, has a broad host range in vertebrates and invertebrates but is not pathogenic for humans. We engineered the SAGV genome as an efficient transient expression vector using the full-length infectious cDNA clone pSAG2 as the background. A green fluorescent protein (GFP) gene was used as a reporter gene and expressed from a subgenomic mRNA.