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1.
Virologie (Montrouge) ; 25(4): 224-235, 2021 08 01.
Artigo em Francês | MEDLINE | ID: mdl-34468319

RESUMO

Genetic recombination is a major force driving the evolution of some species of positive sense RNA viruses. Recombination events occur when at least two viruses simultaneously infect the same cell, thereby giving rise to new genomes comprised of genetic sequences originating from the parental genomes. The main mechanism by which recombination occurs involves the viral polymerase that generates a chimera as it switches templates during viral replication. Various experimental systems have alluded to the existence of recombination events that are independent of viral polymerase activity. The origins and frequency of such events remain to be elucidated to this day. Furthermore, it is not known whether non-replicative recombination yields products that are different from recombinants generated by the viral polymerase. If this is the case, then non-replicative recombination may play a unique role in the evolution of positive sense RNA viruses. Finally, the sparse data available suggest that non-replicative recombination does not necessarily involve only virus-specific sequences. It is thus possible that the non-replicative recombination observed in virus-focused studies may in fact reveal a more generalized mechanism that is non-specific to virus RNAs.


Assuntos
Vírus de RNA de Cadeia Positiva , Recombinação Genética , Sequência de Bases , RNA Viral/genética , Recombinação Genética/genética , Replicação Viral/genética
2.
Virologie (Montrouge) ; 25(4): 62-73, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-34468320

RESUMO

Genetic recombination is a major force driving the evolution of some species of positive sense RNA viruses. Recombination events occur when at least two viruses simultaneously infect the same cell, thereby giving rise to new genomes comprised of genetic sequences originating from the parental genomes. The main mechanism by which recombination occurs involves the viral polymerase that generates a chimera as it switches templates during viral replication. Various experimental systems have alluded to the existence of recombination events that are independent of viral polymerase activity. The origins and the frequency of such events remain to be elucidated to this day. Furthermore, it is not known whether non-replicative recombination yields products that are different from recombinants generated by the viral polymerase. If this is the case, then non-replicative recombination may play a unique role in the evolution of positive sense RNA viruses. Finally, the sparse data available suggest that non-replicative recombination does not necessarily involve only virus-specific sequences. It is thus possible that the non-replicative recombination observed in virus-focused studies may in fact reveal a more generalized mechanism that is non-specific to virus RNAs.


Assuntos
Vírus de RNA de Cadeia Positiva , Recombinação Genética , Sequência de Bases , RNA Viral/genética , Recombinação Genética/genética , Replicação Viral/genética
3.
J Invertebr Pathol ; 185: 107667, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34560106

RESUMO

Managed and wild bee populations are in decline around the globe due to several biotic and abiotic stressors. Pathogenic viruses associated with the Western honey bee (Apis mellifera) have been identified as key contributors to losses of managed honey bee colonies, and are known to be transmitted to wild bee populations through shared floral resources. However, little is known about the prevalence and intensity of these viruses in wild bee populations, or how bee visitation to flowers impacts viral transmission in agroecosystems. This study surveyed honey bee, bumble bee (Bombus impatiens) and wild squash bee (Eucera (Peponapis) pruinosa) populations in Cucurbita agroecosystems across Pennsylvania (USA) for the prevalence and intensity of five honey bee viruses: acute bee paralysis virus (ABPV), deformed wing virus (DWV), Israeli acute paralysis virus (IAPV), Kashmir bee virus (KBV), and slow bee paralysis virus (SBPV). We investigated the potential role of bee visitation rate to flowers on DWV intensity among species in the pollinator community, with the expectation that increased bee visitation to flowers would increase the opportunity for transmission events between host species. We found that honey bee viruses are highly prevalent but in lower titers in wild E. pruinosa and B. impatiens than in A. mellifera populations throughout Pennsylvania (USA). DWV was detected in 88% of B. impatiens, 48% of E. pruinosa, and 95% of A. mellifera. IAPV was detected in 5% of B. impatiens and 4% of E. pruinosa, compared to 9% in A. mellifera. KBV was detected in 1% of B. impatiens and 5% of E. pruinosa, compared to 32% in A. mellifera. Our results indicate that DWV titers are not correlated with bee visitation in Cucurbita fields. The potential fitness impacts of these low viral titers detected in E. pruinosa remain to be investigated.


Assuntos
Abelhas/virologia , Vírus de Insetos/fisiologia , Vírus de RNA de Cadeia Positiva/fisiologia , Animais , Produtos Agrícolas , Cucurbita , Dicistroviridae/fisiologia , Pennsylvania , Polinização , Vírus de RNA/fisiologia , Especificidade da Espécie
4.
Cells ; 10(9)2021 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-34572055

RESUMO

All intracellular pathogens critically depend on host cell organelles and metabolites for successful infection and replication. One hallmark of positive-strand RNA viruses is to induce alterations of the (endo)membrane system in order to shield their double-stranded RNA replication intermediates from detection by the host cell's surveillance systems. This spatial seclusion also allows for accruing host and viral factors and building blocks required for efficient replication of the genome and prevents access of antiviral effectors. Even though the principle is iterated by almost all positive-strand RNA viruses infecting plants and animals, the specific structure and the organellar source of membranes differs. Here, we discuss the characteristic ultrastructural features of the virus-induced membranous replication organelles in plant and animal cells and the scientific progress gained by advanced microscopy methods.


Assuntos
Interações Hospedeiro-Patógeno , Membranas Intracelulares/ultraestrutura , Organelas/ultraestrutura , Vírus de RNA de Cadeia Positiva/patogenicidade , Infecções por Vírus de RNA/patologia , RNA Viral/genética , Replicação Viral , Animais , Membranas Intracelulares/metabolismo , Membranas Intracelulares/virologia , Organelas/metabolismo , Organelas/virologia , Plantas , Infecções por Vírus de RNA/metabolismo , Infecções por Vírus de RNA/virologia
5.
Bioorg Med Chem ; 46: 116356, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34416512

RESUMO

The ongoing COVID-19 pandemic, periodic recurrence of viral infections, and the emergence of challenging variants has created an urgent need of alternative therapeutic approaches to combat the spread of viral infections, failing to which may pose a greater risk to mankind in future. Resilience against antiviral drugs or fast evolutionary rate of viruses is stressing the scientific community to identify new therapeutic approaches for timely control of disease. Host metabolic pathways are exquisite reservoir of energy to viruses and contribute a diverse array of functions for successful replication and pathogenesis of virus. Targeting the host factors rather than viral enzymes to cease viral infection, has emerged as an alternative antiviral strategy. This approach offers advantage in terms of increased threshold to viral resistance and can provide broad-spectrum antiviral action against different viruses. The article here provides substantial review of literature illuminating the host factors and molecular mechanisms involved in innate/adaptive responses to viral infection, hijacking of signalling pathways by viruses and the intracellular metabolic pathways required for viral replication. Host-targeted drugs acting on the pathways usurped by viruses are also addressed in this study. Host-directed antiviral therapeutics might prove to be a rewarding approach in controlling the unprecedented spread of viral infection, however the probability of cellular side effects or cytotoxicity on host cell should not be ignored at the time of clinical investigations.


Assuntos
Antivirais/farmacologia , Vírus de RNA de Cadeia Positiva/efeitos dos fármacos , Animais , Citocinas/metabolismo , Mudança da Fase de Leitura do Gene Ribossômico/efeitos dos fármacos , Mudança da Fase de Leitura do Gene Ribossômico/fisiologia , Glicosilação/efeitos dos fármacos , Humanos , Imunidade/efeitos dos fármacos , Imunidade/fisiologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Metabolismo dos Lipídeos/fisiologia , Redes e Vias Metabólicas/efeitos dos fármacos , Redes e Vias Metabólicas/fisiologia , Poliaminas/metabolismo , Vírus de RNA de Cadeia Positiva/fisiologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Ubiquitinação/efeitos dos fármacos , Ubiquitinação/fisiologia
6.
Viruses ; 13(8)2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-34452414

RESUMO

Nucleotidylylation is a post-transcriptional modification important for replication in the picornavirus supergroup of RNA viruses, including members of the Caliciviridae, Coronaviridae, Picornaviridae and Potyviridae virus families. This modification occurs when the RNA-dependent RNA polymerase (RdRp) attaches one or more nucleotides to a target protein through a nucleotidyl-transferase reaction. The most characterized nucleotidylylation target is VPg (viral protein genome-linked), a protein linked to the 5' end of the genome in Caliciviridae, Picornaviridae and Potyviridae. The nucleotidylylation of VPg by RdRp is a critical step for the VPg protein to act as a primer for genome replication and, in Caliciviridae and Potyviridae, for the initiation of translation. In contrast, Coronaviridae do not express a VPg protein, but the nucleotidylylation of proteins involved in replication initiation is critical for genome replication. Furthermore, the RdRp proteins of the viruses that perform nucleotidylylation are themselves nucleotidylylated, and in the case of coronavirus, this has been shown to be essential for viral replication. This review focuses on nucleotidylylation within the picornavirus supergroup of viruses, including the proteins that are modified, what is known about the nucleotidylylation process and the roles that these modifications have in the viral life cycle.


Assuntos
Nucleotídeos/metabolismo , Vírus de RNA de Cadeia Positiva/metabolismo , RNA Polimerase Dependente de RNA/metabolismo , Proteínas Virais/metabolismo , Caliciviridae/genética , Caliciviridae/metabolismo , Coronaviridae/genética , Coronaviridae/metabolismo , Genoma Viral , Nidovirales/genética , Nidovirales/metabolismo , Picornaviridae/genética , Picornaviridae/metabolismo , Vírus de RNA de Cadeia Positiva/genética , Potyviridae/genética , Potyviridae/metabolismo , RNA Viral/genética , RNA Viral/metabolismo , Replicação Viral
7.
Arch Virol ; 166(10): 2711-2722, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34313859

RESUMO

A unique capsidless virus with a positive-sense, single-stranded RNA genome (hadakavirus 1, HadV1), a member of the extended picorna-like supergroup, was isolated previously from the phytopathogenic fungus Fusarium oxysporum. Here, we describe the molecular and biological characterisation of a second hadakavirus strain from Fusarium nygamai, which has not been investigated in detail previously as a virus host. This virus, hadakavirus 1 strain 1NL (HadV1-1NL), has features similar to the first hadakavirus, HadV1-7n, despite having a different number of segments (10 for HadV1-1NL vs. 11 for HadV1-7n). The 10 genomic RNA segments of HadV1-1NL range in size from 0.9 kb to 2.5 kb. All HadV1-1NL segments show 67% to 86% local nucleotide sequence identity to their HadV1-7n counterparts, whereas HadV1-1NL has no homolog of HadV1-7n RNA8, which encodes a zinc-finger motif. Another interesting feature is the possible coding incapability of HadV1-1NL RNA10. HadV1-1NL was predicted to be capsidless based on the RNase A susceptibility of its replicative form dsRNA. Phenotypic comparison of multiple virus-infected and virus-free single-spore isolates indicated asymptomatic infection by HadV1-1NL. Less-efficient vertical transmission via spores was observed as the infected fungal colonies from which the spores were derived became older, as was observed for HadV1-7n. This study shows a second example of a hadakavirus that appears to have unusual features.


Assuntos
Fusarium/virologia , Genoma Viral/genética , Vírus de RNA de Cadeia Positiva/genética , Micovírus/classificação , Micovírus/genética , Micovírus/isolamento & purificação , Filogenia , Doenças das Plantas/microbiologia , Vírus de RNA de Cadeia Positiva/classificação , Vírus de RNA de Cadeia Positiva/isolamento & purificação , RNA de Cadeia Dupla/metabolismo , RNA Viral/genética , Ribonucleases/metabolismo , Análise de Sequência de DNA , Especificidade da Espécie , Esporos Fúngicos/virologia , Proteínas Virais/genética
8.
Arch Virol ; 166(10): 2869-2873, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34292373

RESUMO

Eriophyid mites are commonly found on the leaf surface of different plant species. In the present study, a novel virus associated with an eriophyid mite species was detected using high-throughput sequencing (HTS) of total RNA from fruit tree leaves, primarily growing under greenhouse conditions. The complete genome sequence was characterized using rapid amplification of cDNA ends followed by Sanger sequencing, revealing a genome of 8885 nucleotides in length. The single positive-stranded RNA genome was predicted to encode typical conserved domains of members of the genus Iflavirus in the family Iflaviridae. Phylogenetic analysis showed this virus to be closely related to the unclassified iflavirus tomato matilda associated virus (TMaV), with a maximum amino acid sequence identity of 59% in the RNA-dependent RNA polymerase domain. This low identity value justifies the recognition of the novel virus as a potential novel iflavirus. In addition to a lack of graft-transmissibility evidence, RT-PCR and HTS detection of this virus in the putative host plants were not consistent through different years and growing seasons, raising the possibility that rather than a plant virus, this was a virus infecting an organism associated with fruit tree leaves. Identification of Tetra pinnatifidae HTS-derived contigs in all fruit tree samples carrying the novel virus suggested this mite as the most likely host of the new virus (p-value < 1e-11), which is tentatively named "eriophyid mite-associated virus" (EMaV). This study highlights the importance of a careful biological study before assigning a new virus to a particular plant host when using metagenomics data.


Assuntos
Frutas/parasitologia , Ácaros/virologia , Vírus de RNA de Cadeia Positiva/classificação , Árvores/parasitologia , Sequência de Aminoácidos , Animais , Frutas/virologia , Genoma Viral/genética , Metagenômica , Filogenia , Extratos Vegetais , Folhas de Planta/parasitologia , Folhas de Planta/virologia , Vírus de RNA de Cadeia Positiva/genética , RNA Viral/genética , RNA Polimerase Dependente de RNA , Árvores/virologia
9.
RNA ; 27(6): 653-664, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33811147

RESUMO

Structured RNA elements are common in the genomes of RNA viruses, often playing critical roles during viral infection. Some viral RNA elements use forms of tRNA mimicry, but the diverse ways this mimicry can be achieved are poorly understood. Histidine-accepting tRNA-like structures (TLSHis) are examples found at the 3' termini of some positive-sense single-stranded RNA (+ssRNA) viruses where they interact with several host proteins, induce histidylation of the RNA genome, and facilitate processes important for infection, to include genome replication. As only five TLSHis examples had been reported, we explored the possible larger phylogenetic distribution and diversity of this TLS class using bioinformatic approaches. We identified many new examples of TLSHis, yielding a rigorous consensus sequence and secondary structure model that we validated by chemical probing of representative TLSHis RNAs. We confirmed new examples as authentic TLSHis by demonstrating their ability to be histidylated in vitro, then used mutational analyses to imply a tertiary interaction that is likely analogous to the D- and T-loop interaction found in canonical tRNAs. These results expand our understanding of how diverse RNA sequences achieve tRNA-like structure and function in the context of viral RNA genomes and lay the groundwork for high-resolution structural studies of tRNA mimicry by histidine-accepting TLSs.


Assuntos
Vírus de RNA de Cadeia Positiva/química , RNA de Transferência de Histidina/química , Aminoacilação , Conformação de Ácido Nucleico , Filogenia , Vírus de RNA de Cadeia Positiva/classificação , Vírus de RNA de Cadeia Positiva/genética , Vírus de RNA de Cadeia Positiva/metabolismo , RNA de Transferência de Histidina/genética , RNA de Transferência de Histidina/metabolismo , Saccharomyces cerevisiae
10.
PLoS One ; 16(3): e0248486, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33755700

RESUMO

Husavirus (HuV) is an unclassified virus of the order Picornavirales that has already been identified worldwide in various locations. The genetic, epidemiological, and pathogenic characteristics are, however, little understood. In children with acute gastroenteritis, this study used next-generation sequencing to recognize unknown sources of viruses. In particular, 251 fecal samples obtained from individuals were sequenced in southern, northeastern, and northern Brazil. all samples were also analyzed using culture methods and parasitological tests to classify other enteric pathogens such as bacteria, parasites, and viruses. 1.9% of the samples tested positive for HuV, for a total of 5 positive children, with a mean age of 2 year, with three males and two females. Detailed molecular characterization of full genomes showed that Brazilian HuVs' nucleotide divergence is less than 11%. The genetic gap between Brazilian sequences and the closest HuV reported previously, on the other hand, is 18%. The study showed that Brazilian sequences are closely related to the HuV defined in Viet Nam in 2013, further characterization based on phylogenetics. At least two divergent clades of HuV in South America were also seen in the phylogenetic study.


Assuntos
Genoma Viral , Infecções por Picornaviridae , Vírus de RNA de Cadeia Positiva , Brasil , Pré-Escolar , Fezes/virologia , Feminino , Variação Genética , Humanos , Lactente , Masculino , Infecções por Picornaviridae/epidemiologia , Infecções por Picornaviridae/virologia , Vírus de RNA de Cadeia Positiva/classificação , Vírus de RNA de Cadeia Positiva/isolamento & purificação
11.
Mol Omics ; 17(3): 357-364, 2021 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-33725065

RESUMO

In the era of big data and artificial intelligence, a lot of new discoveries have influenced the fields of antiviral drug design and pharmacophore identification. Viruses have always been a threat to society in terms of public health and economic stability. Viruses not only affect humans but also livestock and agriculture with a direct impact on food safety, economy and environmental imprint. Most recently, with the pandemic of COVID-19, it was made clear that a single virus can have a devastating impact on global well-being and economy. In this direction, there is an emerging need for the identification of promising pharmacological targets in viruses. Herein, an effort has been made to discuss the current knowledge, state-of-the-art applications and future implications for the main pharmacological targets of single-stranded RNA viruses.


Assuntos
Antivirais/farmacologia , Descoberta de Drogas/métodos , Vírus de RNA de Cadeia Positiva/genética , Proteínas Virais/química , Desenho de Fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Metiltransferases/química , Terapia de Alvo Molecular , Peptídeo Hidrolases/química , Vírus de RNA de Cadeia Positiva/química , SARS-CoV-2/efeitos dos fármacos , Proteínas Virais/metabolismo
12.
BMJ Case Rep ; 14(3)2021 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-33766959

RESUMO

Double filtration plasmapheresis (DFPP) is an apheretic technique that selectively removes high molecular weight substances using a plasma component filter. DFPP has been used to treat positive-sense RNA virus infections, mainly chronic hepatitis C virus (HCV) infection, because of its ability to directly eliminate viral particles from blood plasma from 2008 to about 2015, before direct-acting antiviral agents was marketed. This effect has been termed virus removal and eradication by DFPP. HCV is a positive-sense RNA virus similar to West Nile virus, dengue virus and the SARS and Middle East respiratory syndrome coronaviruses. SARS-CoV-2 is classified same viral species. These viruses are all classified in Family Flaviviridae which are family of single-stranded plus-stranded RNA viruses. Viral particles are 40-60 nm in diameter, enveloped and spherical in shape. We present a rare case of HCV removal where an RNA virus infection that copresented with virus-associated autoimmune hepatitis was eliminated using DFPP. Our results indicate that DFPP may facilitate prompt viraemia reduction and may have novel treatment applications for SARS-CoV-2, that is, use of therapeutic plasma exchange for fulminant COVID-19.


Assuntos
Coinfecção/terapia , Coinfecção/virologia , Hepatite C Crônica/terapia , Hepatite Autoimune/terapia , Plasmaferese/métodos , Antivirais/uso terapêutico , COVID-19/complicações , COVID-19/terapia , Quimioterapia Combinada , Feminino , Hepatite C Crônica/complicações , Hepatite Autoimune/complicações , Humanos , Interferon alfa-2/uso terapêutico , Pessoa de Meia-Idade , Polietilenoglicóis/uso terapêutico , Vírus de RNA de Cadeia Positiva/isolamento & purificação , Ribavirina/uso terapêutico , SARS-CoV-2 , Resultado do Tratamento , Carga Viral
13.
Sci Rep ; 11(1): 2977, 2021 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-33536558

RESUMO

Surface inactivation of human microbial pathogens has a long history. The Smith Papyrus (2600 ~ 2200 B.C.) described the use of copper surfaces to sterilize chest wounds and drinking water. Brass and bronze on doorknobs can discourage microbial spread in hospitals, and metal-base surface coatings are used in hygiene-sensitive environments, both as inactivators and modulators of cellular immunity. A limitation of these approaches is that the reactive oxygen radicals (ROS) generated at metal surfaces also damage human cells by oxidizing their proteins and lipids. Silicon nitride (Si3N4) is a non-oxide ceramic compound with known surface bacterial resistance. We show here that off-stoichiometric reactions at Si3N4 surfaces are also capable of inactivating different types of single-stranded RNA (ssRNA) viruses independent of whether their structure presents an envelop or not. The antiviral property of Si3N4 derives from a hydrolysis reaction at its surface and the subsequent formation of reactive nitrogen species (RNS) in doses that could be metabolized by mammalian cells but are lethal to pathogens. Real-time reverse transcription (RT)-polymerase chain reaction (PCR) tests of viral RNA and in situ Raman spectroscopy suggested that the products of Si3N4 hydrolysis directly react with viral proteins and RNA. Si3N4 may have a role in controlling human epidemics related to ssRNA mutant viruses.


Assuntos
Cerâmica/química , Desinfecção/instrumentação , Vírus de RNA de Sentido Negativo/química , Vírus de RNA de Cadeia Positiva/química , Compostos de Silício/química , Animais , Gatos , Cães , Hidrólise , Macaca mulatta , Células Madin Darby de Rim Canino , Teste de Materiais , Mutação , Vírus de RNA de Sentido Negativo/genética , Vírus de RNA de Cadeia Positiva/genética , Espécies Reativas de Nitrogênio/química , Propriedades de Superfície
14.
Curr Opin Virol ; 47: 25-31, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33383355

RESUMO

Positive-strand RNA virus genome replication takes place on intracellular membranes that separate the reduced cytosol from the oxidized extracellular/luminal milieu. Ongoing studies of these membrane-bounded genome replication complexes have revealed underlying common principles in their structure, assembly and functionalization, including transmembrane features and redox dependencies. Among these, members of the alphavirus, flavivirus, and picornavirus supergroups all encode membrane-permeabilizing viroporins required for efficient RNA replication. For flaviviruses and particularly alphavirus supergroup members, these viroporins are linked to activating viral RNA capping and potentially other later-stage RNA replication functions, and to local transmembrane release of oxidizing potential to trigger these changes in cytoplasmic RNA replication complexes. Further exploration of these emerging shared principles could spur development of broad-spectrum antivirals.


Assuntos
Genoma Viral/fisiologia , Membranas Intracelulares/virologia , Oxirredução , Vírus de RNA de Cadeia Positiva/fisiologia , Replicação Viral/fisiologia , Citoplasma/metabolismo , Citoplasma/virologia , Membranas Intracelulares/metabolismo , Vírus de RNA de Cadeia Positiva/classificação , Capuzes de RNA/metabolismo , RNA Viral/biossíntese , Proteínas Virais/metabolismo , Compartimentos de Replicação Viral/metabolismo
15.
Brief Bioinform ; 22(4)2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-33313676

RESUMO

The genus Culicoides includes biting midges, some of which are vectors for viruses that cause diseases in humans and animals. Knowledge of the roles of Culicoides in viral ecology is inadequate. We collected ~300 000 samples of Culicoides and mosquitoes in 15 representative regions within Yunnan, China. Using mosquitoes as reference vectors, we designed a comparative virome strategy to study the viral composition, diversity, hosts and spatiotemporal distribution of Culicoides. A map of viromes in Culicoides and mosquitoes in Yunan province, China, was constructed. At the same locations, Culicoides and mosquitoes usually share a similar viral diversity. At least 10 important pathogenic viruses were detected from Culicoides. Many novel viruses were discovered, including 21 segmented viruses of Flaviviridae, 180 viruses of Monjiviricetes and 130 viruses of Bunyavirales. The findings demonstrate that Culicoides is an important part of viral ecology and should be studied and monitored for potentially emerging viruses.


Assuntos
Ceratopogonidae/virologia , Culicidae/virologia , Vírus de RNA de Cadeia Positiva/classificação , Viroma , Animais
16.
Cell Rep ; 33(10): 108476, 2020 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-33296660

RESUMO

Dicistrovirus intergenic region internal ribosomal entry sites (IGR IRESs) do not require initiator tRNA, an AUG codon, or initiation factors and jumpstart translation from the middle of the elongation cycle via formation of IRES/80S complexes resembling the pre-translocation state. eEF2 then translocates the [codon-anticodon]-mimicking pseudoknot I (PKI) from ribosomal A sites to P sites, bringing the first sense codon into the decoding center. Halastavi árva virus (HalV) contains an IGR that is related to previously described IGR IRESs but lacks domain 2, which enables these IRESs to bind to individual 40S ribosomal subunits. By using in vitro reconstitution and cryoelectron microscopy (cryo-EM), we now report that the HalV IGR IRES functions by the simplest initiation mechanism that involves binding to 80S ribosomes such that PKI is placed in the P site, so that the A site contains the first codon that is directly accessible for decoding without prior eEF2-mediated translocation of PKI.


Assuntos
Sítios Internos de Entrada Ribossomal/genética , Iniciação Traducional da Cadeia Peptídica/genética , Vírus de RNA de Cadeia Positiva/genética , Anticódon , Códon/metabolismo , Microscopia Crioeletrônica/métodos , DNA Intergênico/metabolismo , Sítios Internos de Entrada Ribossomal/fisiologia , Iniciação Traducional da Cadeia Peptídica/fisiologia , Fator 2 de Elongação de Peptídeos/metabolismo , Fatores de Iniciação de Peptídeos/genética , Vírus de RNA de Cadeia Positiva/metabolismo , Biossíntese de Proteínas/genética , RNA Mensageiro/metabolismo , RNA Viral/genética , Ribossomos/metabolismo , Replicação Viral/genética , Replicação Viral/fisiologia , Vírus/metabolismo
17.
J Invertebr Pathol ; 177: 107494, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33115693

RESUMO

A positive, single-stranded RNA virus is identified from the transcriptome of Probopyrinella latreuticola Gissler, 1882; a bopyrid isopod parasite of the Sargassum shrimp, Latreutes fucorum Fabricius, 1789. The viral sequence is 13,098 bp in length (including polyA), encoding four open reading frames (ORF). ORF-1 encodes a polyprotein, with three computationally discernible functional domains: viral methyltransferase; viral helicase; and RNA-directed RNA polymerase. The remaining ORFs encode a transmembrane protein, a capsid protein and a protein of undetermined function. The raw transcriptomic data reveal a low level of background single nucleotide mutations within the data. Comparison of the protein sequence data and synteny with other viral isolates reveals that the greatest protein similarity (<39%) is shared with the Negevirus group, a group that exclusively infects insects. Phylogenetic assessment of the individual polyprotein domains revealed a mixed prediction of phylogenetic origins, suggesting with low confidence that the novel +ssRNA virus could be present in multiple places throughout the individual gene trees. A concatenated approach strongly suggested that this new virus is an early diverging isolate, branching before the Negevirus and Cilevirus groups. Alongside the new isolate are other marine viruses, also present toward the base of the tree. The isopod virosphere, with the addition of this novel virus, is discussed relative to viral genomics/systematics. A great diversity of nege-like viruses appears to be present in marine invertebrate hosts, which require greater efforts for discovery and identification.


Assuntos
Isópodes/virologia , Vírus de RNA de Cadeia Positiva/isolamento & purificação , Animais , Decápodes/parasitologia , Parasitos/virologia
18.
J Vet Med Sci ; 82(12): 1793-1797, 2020 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-33055455

RESUMO

Rotavirus A (RVA), bovine torovirus (BToV), bovine enterovirus (BEV) and bovine coronavirus (BCV) at a bovine farm in Ibaraki prefecture were monitored by one-step multiplex reverse transcription polymerase chain reaction (RT-PCR), with the aim of confirming the reduction of "viral pathogen indicators". A total of 960 bovine fecal samples were collected from calves less than 2 month-old within the period from October 2016 to October 2018 every 2 months at the bovine farm. In each sampling, 40 samples were taken from calves 3 week-old or less, and 40 samples from calves over 3 week-old, in principle. At the end of September 2017, the farm introduced improvement of hygiene protocols on boots by exchanging boots and appropriate usage of a footbath at the entrance of calf sheds. In the comparison of the virus detection by RT-PCR, prevalence of all 4 viruses was significantly reduced (P<0.01) in calves 3 week-old or less after the improvement. The mortality of calves less than 2 month-old was also significantly reduced after the improvement of hygiene protocols. These data suggest that the proper control of boots at calf sheds is important, perhaps even vital, for rearing hygiene measures at bovine farms so as to attain substantial decrease in the prevalence of pathogens.


Assuntos
Criação de Animais Domésticos/métodos , Doenças dos Bovinos/prevenção & controle , Doenças dos Bovinos/virologia , Vírus de RNA de Cadeia Positiva/isolamento & purificação , Sapatos , Animais , Bovinos , Fazendas , Fezes/virologia , Japão , Reação em Cadeia da Polimerase Multiplex , Infecções por Vírus de RNA/prevenção & controle , Infecções por Vírus de RNA/veterinária
19.
Adv Virus Res ; 107: 87-131, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32711736

RESUMO

Plant viruses induce a range of symptoms of varying intensity, ranging from severe systemic necrosis to mild or asymptomatic infection. Several evolutionary constraints drive virus virulence, including the dependence of viruses on host factors to complete their infection cycle, the requirement to counteract or evade plant antiviral defense responses and the mode of virus transmission. Viruses have developed an array of strategies to modulate disease severity. Accumulating evidence has highlighted not only the multifunctional role that viral proteins play in disrupting or highjacking plant factors, hormone signaling pathways and intracellular organelles, but also the interaction networks between viral proteins, subviral RNAs and/or other viral-associated RNAs that regulate disease severity. This review focusses on positive-strand RNA viruses, which constitute the majority of characterized plant viruses. Using well-characterized viruses with different genome types as examples, recent advances are discussed as well as knowledge gaps and opportunities for further research.


Assuntos
Doenças das Plantas , Vírus de Plantas , Vírus de RNA de Cadeia Positiva , Proteínas Virais , Vírus de DNA/genética , Doenças das Plantas/virologia , Vírus de Plantas/genética , Plantas/virologia , RNA , Interferência de RNA , RNA Viral/genética , Transdução de Sinais , Proteínas Virais/genética
20.
J Invertebr Pathol ; 173: 107370, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32259537

RESUMO

Virus-based biocontrol technologies represent sustainable alternatives to pesticides and insecticides. Phytoplasmas are prokaryotic plant pathogens causing severe losses to crops worldwide. Novel approaches are needed since insecticides against their insect vectors and rogueing of infected plants are the only available strategies to counteract phytoplasma diseases. A new iflavirus, named EVV-1, has been described in the leafhopper phytoplasma vector Euscelidius variegatus, raising the potential to use virus-based application strategies against phytoplasma disease. Here transmission routes of EVV-1 are characterized, and localization within the host reveals the mechanism of insect tolerance to virus infection. Both vertical and horizontal transmission of EVV-1 occur and vertical transmission was more efficient. The virus is systemic and occurs in all life-stages, with the highest loads measured in ovaries and first to third instar nymphs. The basic knowledge gained here on the biology of the virus is crucial for possible future application of iflaviruses as biocontrol agents.


Assuntos
Hemípteros/microbiologia , Insetos Vetores/microbiologia , Vírus de RNA de Cadeia Positiva/fisiologia , Animais , Controle de Insetos , Controle Biológico de Vetores , Phytoplasma/fisiologia , Doenças por Fitoplasmas/microbiologia
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