scholarly journals ICTV Virus Taxonomy Profile: Pospiviroidae

2020 ◽  
Author(s):  
Francesco Di Serio ◽  
Robert A. Owens ◽  
Shi-Fang Li ◽  
Jaroslav Matoušek ◽  
Vicente Pallás ◽  
...  
Keyword(s):  
Circular Rna ◽  
Virus Taxonomy ◽  
Hammerhead Ribozymes ◽  
Rolling Circle ◽  
Link Type ◽  
The Family ◽  
Rolling Circle Mechanism ◽  
Conserved Region

Members of the family Pospiviroidae have single-stranded circular RNA genomes that adopt a rod-like or a quasi-rod-like conformation. These genomes contain a central conserved region that is involved in replication in the nucleus through an asymmetric RNA–RNA rolling-circle mechanism. Members of the family Pospiviroidae lack the hammerhead ribozymes that are typical of viroids classified in the family Avsunviroidae. The family Pospiviroidae includes the genera Apscaviroid, Cocadviroid, Coleviroid, Hostuviroid and Pospiviroid, with >25 species. This is a summary of the ICTV Report on the family Pospiviroidae, which is available at ictv.global/report/pospiviroidae.

scholarly journals ICTV Virus Taxonomy Profile: Plectroviridae

2021 ◽  
Vol 102 (5) ◽  
Author(s):  
Petar Knezevic ◽  
Evelien M. Adriaenssens ◽  
Keyword(s):  
Cell Wall ◽  
International Committee ◽  
Virus Taxonomy ◽  
Single Stranded Dna ◽  
Rolling Circle ◽  
Bacterial Surface ◽  
Link Type ◽  
Rigid Rods ◽  
The Family ◽  
Rolling Circle Mechanism

Members of the family Plectroviridae produce particles that are non-enveloped rigid rods (70–280×10–16 nm). The supercoiled, circular, single-stranded DNA genome of about 4.5–8.3 kb, encodes 4–13 proteins. Viruses of this family infect cell wall-less bacteria, adsorbing to the bacterial surface, replicating their DNA by a rolling-circle mechanism or transposition, and releasing progeny from cells by extrusion, without killing the host. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Plectroviridae which is available at ictv.global/report/plectroviridae.

Viroids with Hammerhead Ribozymes: Some Unique Structural and Functional Aspects with Respect to Other Members of the Group

1999 ◽  
Vol 380 (7-8) ◽  
pp. 849-854 ◽  
Author(s):  
R. Flores ◽  
J.-A. Navarro ◽  
M. de la Peña ◽  
B. Navarro ◽  
S. Ambrós ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Rna Polymerase ◽  
Circular Rna ◽  
Hammerhead Ribozymes ◽  
Rolling Circle ◽  
Rna Ligase ◽  
Functional Aspects ◽  
Chlorotic Mottle ◽  
Pathogenicity Determinant ◽  
Rolling Circle Mechanism

AbstractViroids, subviral pathogens of plants, are composed of a single-stranded circular RNA of 246–399 nucleotides. Within the 27 viroids sequenced, avocado sunblotch, peach latent mosaic and chrysanthemum chlorotic mottle viroids (ASBVd, PLMVd and CChMVd, respectively) can form hammerhead structures in both of their polarity strands. These ribozymes mediate self-cleavage of the oligomeric RNAs generated in the replication through a rolling circle mechanism, whose two other steps are catalyzed by an RNA polymerase and an RNA ligase. ASBVd, and presumably PLMVd and CChMVd, replicate and accumulate in the chloroplast, whereas typical viroids replicate and accumulate in the nucleus. PLMVd and CChMVd do not adopt a rod-like or quasi rod-like secondary structure as typical viroids do but have a highly branched conformation. A pathogenicity determinant has been mapped in a defined region of the CChMVd molecule.

scholarly journals Processing of RNAs of the Family Avsunviroidae in Chlamydomonas reinhardtii Chloroplasts

2007 ◽  
Vol 81 (8) ◽  
pp. 4363-4366 ◽  
Author(s):  
Diego Molina-Serrano ◽  
Loreto Suay ◽  
María L. Salvador ◽  
Ricardo Flores ◽  
José-Antonio Daròs
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Rna Processing ◽  
Hammerhead Ribozymes ◽  
Closely Related Species ◽  
Rna Transcription ◽  
Rolling Circle ◽  
Mechanism Research ◽  
Cellular Factors ◽  
The Family ◽  
Rolling Circle Mechanism

ABSTRACT The family Avsunviroidae comprises four viroid species with the ability to form hammerhead ribozymes that mediate self-cleavage of the multimeric plus and minus strands resulting from replication in the chloroplast through a symmetric rolling-circle mechanism. Research on these RNAs is restricted by their host range, which is limited to the plants wherein they were initially identified and some closely related species. Here we report cleavage and ligation in transplastomic Chlamydomonas reinhardtii expressing plus- and minus-strand dimeric transcripts of representative members of the family Avsunviroidae. Despite the absence of viroid RNA-RNA transcription, the C. reinhardtii-based system can be used to address intriguing questions about viroid RNA processing and, in particular, about the cellular factors involved in cleavage and ligation.

scholarly journals ICTV Virus Taxonomy Profile: Inoviridae

2021 ◽  
Vol 102 (7) ◽  
Author(s):  
Petar Knezevic ◽  
Evelien M. Adriaenssens ◽  
Keyword(s):  
Bacterial Genome ◽  
International Committee ◽  
Gram Negative Bacteria ◽  
Virus Taxonomy ◽  
Rolling Circle ◽  
The Family ◽  
Phage Dna ◽  
Positive Sense ◽  
Filamentous Bacteriophages ◽  
Rolling Circle Mechanism

Members of the family Inoviridae are non-enveloped flexible filamentous bacteriophages (600–2500×6–10 nm) with supercoiled, circular, positive-sense, single-stranded DNA genomes of 5.5–10.6 kb, encoding 7–15 proteins. They absorb to the pili of Gram-negative bacteria and replicate their DNA by a rolling-circle mechanism with progeny released from cells by extrusion without killing the host. Phage DNA can persist extra-chromosomally or integrate into the bacterial genome. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Inoviridae, which is available at ictv.global/report/inoviridae.

scholarly journals Natural 2′,5′-Phosphodiester Bonds Found at the Ligation Sites of Peach Latent Mosaic Viroid

2001 ◽  
Vol 75 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Fabien Côté ◽  
Dominique Lévesque ◽  
Jean-Pierre Perreault
Keyword(s):  
Circular Rna ◽  
Rolling Circle ◽  
Phosphodiester Bonds ◽  
Biological Importance ◽  
Rolling Circle Mechanism ◽  
Ligation Site

ABSTRACT Peach latent mosaic viroid (PLMVd) is a circular RNA pathogen that replicates in a DNA-independent fashion via a rolling circle mechanism. PLMVd has been shown to self-ligate in vitro primarily via the formation of 2′,5′-phosphodiester bonds; however, in vivo the occurrence and necessity of this nonenzymatic mechanism are not evident. Here, we unequivocally report the presence of 2′,5′-phosphodiester bonds at the ligation site of circular PLMVd strands isolated from infected peach leaves. These bonds serve to close the linear conformers (i.e., intermediates), yielding circular ones. Furthermore, these bonds are shown to stabilize the replicational circular templates, resulting in a significant advantage in terms of viroid viability. Although the mechanism responsible for the formation of these 2′,5′-phosphodiester bonds remains to be elucidated, a hypothesis describing in vivo nonenzymatic self-ligation is proposed. Most significantly, our results clearly show that 2′,5′-phosphodiester bonds are still present in nature and that they are of biological importance.

scholarly journals ICTV Virus Taxonomy Profile: Nanoviridae

2021 ◽  
Author(s):  
John E. Thomas ◽  
Bruno Gronenborn ◽  
Robert M. Harding ◽  
Bikash Mandal ◽  
Ioana Grigoras ◽  
...  
Keyword(s):  
Plant Viruses ◽  
Virus Taxonomy ◽  
Link Type ◽  
The Family ◽  
Genomic Dnas ◽  
Helper Factor

Nanoviridae is a family of plant viruses (nanovirids) whose members have small isometric virions and multipartite, circular, single-stranded (css) DNA genomes. Each of the six (genus Babuvirus) or eight (genus Nanovirus) genomic DNAs is 0.9–1.1 kb and is separately encapsidated. Many isolates are associated with satellite-like cssDNAs (alphasatellites) of 1.0–1.1 kb. Hosts are eudicots, predominantly legumes (genus Nanovirus), and monocotyledons, predominantly in the order Zingiberales (genus Babuvirus). Nanovirids require a virus-encoded helper factor for transmission by aphids in a circulative, non-propagative manner. This is a summary of the ICTV Report on the family Nanoviridae, which is available at ictv.global/report/nanoviridae.

scholarly journals ICTV Virus Taxonomy Profile: Ovaliviridae

2020 ◽  
Author(s):  
Li Huang ◽  
Haina Wang ◽  
Keyword(s):  
Viral Genome ◽  
International Committee ◽  
Virus Taxonomy ◽  
Enveloped Viruses ◽  
Content Type ◽  
Link Type ◽  
The Family ◽  
Virus Progeny ◽  
Linear Dsdna ◽  
Infected Cells

Ovaliviridae is a family of enveloped viruses with a linear dsDNA genome. The virions are ellipsoidal, and contain a multi-layered spool-like capsid. The viral genome is presumably replicated through protein priming by a putative DNA polymerase encoded by the virus. Progeny virions are released through hexagonal openings resulting from the rupture of virus-associated pyramids formed on the surface of infected cells. The only known host is a hyperthermophilic archaeon of the genus Sulfolobus . This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Ovaliviridae, which is available at ictv.global/report/ovaliviridae.

scholarly journals ICTV Virus Taxonomy Profile: Bornaviridae

2021 ◽  
Vol 102 (7) ◽  
Author(s):  
Dennis Rubbenstroth ◽  
Thomas Briese ◽  
Ralf Dürrwald ◽  
Masayuki Horie (堀江真行) ◽  
Timothy H. Hyndman ◽  
...  
Keyword(s):  
Public Health ◽  
Disease Virus ◽  
International Committee ◽  
Virus Taxonomy ◽  
Borna Disease Virus ◽  
Link Type ◽  
The Family ◽  
Rna Genome ◽  
Negative Sense ◽  
Borna Disease

Members of the family Bornaviridae produce enveloped virions containing a linear negative-sense non-segmented RNA genome of about 9 kb. Bornaviruses are found in mammals, birds, reptiles and fish. The most-studied viruses with public health and veterinary impact are Borna disease virus 1 and variegated squirrel bornavirus 1, both of which cause fatal encephalitis in humans. Several orthobornaviruses cause neurological and intestinal disorders in birds, mostly parrots. Endogenous bornavirus-like sequences occur in the genomes of various animals. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Bornaviridae, which is available at ictv.global/report/bornaviridae.

ICTV Virus Taxonomy Profile: Nyamiviridae 2021

2021 ◽  
Vol 102 (11) ◽  
Author(s):  
Ralf G. Dietzgen ◽  
Andrew E. Firth ◽  
Dàohóng Jiāng ◽  
Sandra Junglen ◽  
Hideki Kondo ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Rna Polymerase ◽  
International Committee ◽  
Genome Organisation ◽  
Virus Taxonomy ◽  
Link Type ◽  
A Genome ◽  
The Family ◽  
Negative Sense

Nyamiviridae is a family of viruses in the order Mononegavirales, with unsegmented (except for members of the genus Tapwovirus), negative-sense RNA genomes of 10–13 kb. Nyamviruses have a genome organisation and content similar to that of other mononegaviruses. Nyamiviridae includes several genera that form monophyletic clades on phylogenetic analysis of the RNA polymerase. Nyamiviruses have been found associated with diverse invertebrates as well as land- and seabirds. Members of the genera Nyavirus and Socyvirus produce enveloped, spherical virions. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Nyamiviridae, which is available at ictv.global/report/nyamiviridae.

scholarly journals ICTV Virus Taxonomy Profile: Metaviridae

2020 ◽  
Vol 101 (11) ◽  
pp. 1131-1132
Author(s):  
Carlos Llorens ◽  
Beatriz Soriano ◽  
Mart Krupovic ◽  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
International Committee ◽  
Virus Taxonomy ◽  
Long Terminal Repeats ◽  
Link Type ◽  
The Family ◽  
Terminal Repeats

Metaviridae is a family of retrotransposons and reverse-transcribing viruses with long terminal repeats belonging to the order Ortervirales. Members of the genera Errantivirus and Metavirus include, respectively, Saccharomyces cerevisiae Ty3 virus and its Gypsy-like relatives in drosophilids. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Metaviridae, which is available at ictv.global/report/metaviridae.

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