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Viruses, Volume 10, Issue 3 (March 2018)

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Cover Story (view full-size image) Studies of dipteran insects, such as fruit flies and virus-transmitting mosquitoes, have greatly [...] Read more.
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Open AccessReview Enterovirus Transmission by Secretory Autophagy
Viruses 2018, 10(3), 139; https://doi.org/10.3390/v10030139
Received: 6 February 2018 / Revised: 12 March 2018 / Accepted: 16 March 2018 / Published: 20 March 2018
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Abstract
Present in many cell types, non-degradative secretory autophagy is a newly discovered pathway in which autophagosomes fuse with the plasma membrane instead of lysosomes. Surprisingly, some viruses exploit secretory autophagy to exit cells non-lytically, shedding into the extracellular environment as particle populations contained
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Present in many cell types, non-degradative secretory autophagy is a newly discovered pathway in which autophagosomes fuse with the plasma membrane instead of lysosomes. Surprisingly, some viruses exploit secretory autophagy to exit cells non-lytically, shedding into the extracellular environment as particle populations contained within vesicles. As a result, this significantly enhances the infectivity of these viruses. In this paper, this novel cellular exit pathway is highlighted and its advantages for viral transmission discussed. Full article
(This article belongs to the Special Issue Viruses and Autophagy)
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Open AccessReview Alphavirus Nucleocapsid Packaging and Assembly
Viruses 2018, 10(3), 138; https://doi.org/10.3390/v10030138
Received: 12 December 2017 / Revised: 11 March 2018 / Accepted: 13 March 2018 / Published: 20 March 2018
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Abstract
Alphavirus nucleocapsids are assembled in the cytoplasm of infected cells from 240 copies of the capsid protein and the approximately 11 kb positive strand genomic RNA. However, the challenge of how the capsid specifically selects its RNA package and assembles around it has
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Alphavirus nucleocapsids are assembled in the cytoplasm of infected cells from 240 copies of the capsid protein and the approximately 11 kb positive strand genomic RNA. However, the challenge of how the capsid specifically selects its RNA package and assembles around it has remained an elusive one to solve. In this review, we will summarize what is known about the alphavirus capsid protein, the packaging signal, and their roles in the mechanism of packaging and assembly. We will review the discovery of the packaging signal and how there is as much evidence for, as well as against, its requirement to specify packaging of the genomic RNA. Finally, we will compare this model with those of other viral systems including particular reference to a relatively new idea of RNA packaging based on the presence of multiple minimal packaging signals throughout the genome known as the two stage mechanism. This review will provide a basis for further investigating the fundamental ways of how RNA viruses are able to select their own cargo from the relative chaos that is the cytoplasm. Full article
(This article belongs to the Special Issue Advances in Alphavirus Research)
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Open AccessArticle Beet Necrotic Yellow Vein Virus Noncoding RNA Production Depends on a 5′→3′ Xrn Exoribonuclease Activity
Viruses 2018, 10(3), 137; https://doi.org/10.3390/v10030137
Received: 17 January 2018 / Revised: 28 February 2018 / Accepted: 17 March 2018 / Published: 19 March 2018
Cited by 1 | PDF Full-text (9735 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The RNA3 species of the beet necrotic yellow vein virus (BNYVV), a multipartite positive-stranded RNA phytovirus, contains the ‘core’ nucleotide sequence required for its systemic movement in Beta macrocarpa. Within this ‘core’ sequence resides a conserved “coremin” motif of 20 nucleotides that
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The RNA3 species of the beet necrotic yellow vein virus (BNYVV), a multipartite positive-stranded RNA phytovirus, contains the ‘core’ nucleotide sequence required for its systemic movement in Beta macrocarpa. Within this ‘core’ sequence resides a conserved “coremin” motif of 20 nucleotides that is absolutely essential for long-distance movement. RNA3 undergoes processing steps to yield a noncoding RNA3 (ncRNA3) possessing “coremin” at its 5′ end, a mandatory element for ncRNA3 accumulation. Expression of wild-type (wt) or mutated RNA3 in Saccharomyces cerevisiae allows for the accumulation of ncRNA3 species. Screening of S. cerevisiae ribonuclease mutants identified the 5′-to-3′ exoribonuclease Xrn1 as a key enzyme in RNA3 processing that was recapitulated both in vitro and in insect cell extracts. Xrn1 stalled on ncRNA3-containing RNA substrates in these decay assays in a similar fashion as the flavivirus Xrn1-resistant structure (sfRNA). Substitution of the BNYVV-RNA3 ‘core’ sequence by the sfRNA sequence led to the accumulation of an ncRNA species in yeast in vitro but not in planta and no viral long distance occurred. Interestingly, XRN4 knockdown reduced BNYVV RNA accumulation suggesting a dual role for the ribonuclease in the viral cycle. Full article
(This article belongs to the Special Issue Long Non-Coding RNAs and Antiviral Immunity)
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Open AccessArticle The Incidence and Genetic Diversity of Apple Mosaic Virus (ApMV) and Prune Dwarf Virus (PDV) in Prunus Species in Australia
Viruses 2018, 10(3), 136; https://doi.org/10.3390/v10030136
Received: 23 February 2018 / Revised: 14 March 2018 / Accepted: 17 March 2018 / Published: 19 March 2018
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Abstract
Apple mosaic virus (ApMV) and prune dwarf virus (PDV) are amongst the most common viruses infecting Prunus species worldwide but their incidence and genetic diversity in Australia is not known. In a survey of 127 Prunus tree samples collected from five states in
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Apple mosaic virus (ApMV) and prune dwarf virus (PDV) are amongst the most common viruses infecting Prunus species worldwide but their incidence and genetic diversity in Australia is not known. In a survey of 127 Prunus tree samples collected from five states in Australia, ApMV and PDV occurred in 4 (3%) and 13 (10%) of the trees respectively. High-throughput sequencing (HTS) of amplicons from partial conserved regions of RNA1, RNA2, and RNA3, encoding the methyltransferase (MT), RNA-dependent RNA polymerase (RdRp), and the coat protein (CP) genes respectively, of ApMV and PDV was used to determine the genetic diversity of the Australian isolates of each virus. Phylogenetic comparison of Australian ApMV and PDV amplicon HTS variants and full length genomes of both viruses with isolates occurring in other countries identified genetic strains of each virus occurring in Australia. A single Australian Prunus infecting ApMV genetic strain was identified as all ApMV isolates sequence variants formed a single phylogenetic group in each of RNA1, RNA2, and RNA3. Two Australian PDV genetic strains were identified based on the combination of observed phylogenetic groups in each of RNA1, RNA2, and RNA3 and one Prunus tree had both strains. The accuracy of amplicon sequence variants phylogenetic analysis based on segments of each virus RNA were confirmed by phylogenetic analysis of full length genome sequences of Australian ApMV and PDV isolates and all published ApMV and PDV genomes from other countries. Full article
(This article belongs to the Special Issue Fruit Tree Viruses and Viroids)
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Open AccessArticle Transcriptome Analysis of Epithelioma Papulosum Cyprini Cells Infected by Reovirus Isolated from Allogynogenetic Silver Crucian Carp
Viruses 2018, 10(3), 135; https://doi.org/10.3390/v10030135
Received: 8 January 2018 / Revised: 7 March 2018 / Accepted: 16 March 2018 / Published: 18 March 2018
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Abstract
The present study aimed to identify differentially expressed genes (DEGs) and major signal transduction pathways that were related to the immune response of epithelioma papulosum cyprinid (EPC) cells to reoviruses isolated from allogynogenetic silver crucian carp. The study also lays a theoretical foundation
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The present study aimed to identify differentially expressed genes (DEGs) and major signal transduction pathways that were related to the immune response of epithelioma papulosum cyprinid (EPC) cells to reoviruses isolated from allogynogenetic silver crucian carp. The study also lays a theoretical foundation for the pathogenesis and immunity of the reovirus, which is helpful to the breeding of cyprinids fish. Reovirus infected and uninfected EPC cells were analyzed by using a new-generation high-throughput sequencing technology. DEGs were identified, annotated, and classified, and the signal pathways involved in the response to reovirus infection were identified by using bioinformatics tool. The data were assembled into 92,101 contigs with an average length of 835.24 bp and an N50 value of 1432 nt. Differential expression analysis of all the genes identified 3316 DEGs at a false discovery rate (FDR) of <0.01 and a fold-change of ≥3, of which 1691 were upregulated genes, 1625 were downregulated, and about 305 were immune-related genes. Gene Ontology (GO) enrichment analysis resulted in the annotation of 3941 GO terms, including 2719 biological processes (37,810 unigenes), 376 cell components (7943 unigenes), and 846 molecular functions (11,750 unigenes). KEGG metabolic pathway analysis matched the DEGs from pre-and post-infection EPC cells to 193 pathways, of which 35 were immune-related, including the Toll-like receptor, cytokine-cytokine receptor interaction, and the JAK-STAT signaling pathways. Full article
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Open AccessArticle A Novel Betabaculovirus Isolated from the Monocot Pest Mocis latipes (Lepidoptera: Noctuidae) and the Evolution of Multiple-Copy Genes
Viruses 2018, 10(3), 134; https://doi.org/10.3390/v10030134
Received: 18 December 2017 / Revised: 12 March 2018 / Accepted: 14 March 2018 / Published: 16 March 2018
Cited by 1 | PDF Full-text (1904 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this report, we described the genome of a novel baculovirus isolated from the monocot insect pest Mocis latipes, the striped grass looper. The genome has 134,272 bp in length with a G + C content of 38.3%. Based on the concatenated
[...] Read more.
In this report, we described the genome of a novel baculovirus isolated from the monocot insect pest Mocis latipes, the striped grass looper. The genome has 134,272 bp in length with a G + C content of 38.3%. Based on the concatenated sequence of the 38 baculovirus core genes, we found that the virus is a betabaculovirus closely related to the noctuid-infecting betabaculoviruses including Pseudaletia unipuncta granulovirus (PsunGV), Trichoplusia ni granulovirus (TnGV), Helicoverpa armigera granulovirus (HearGV), and Xestia c-nigrum granulovirus (XecnGV). The virus may constitute a new Betabaculovirus species tentatively named Mocis latipes granulovirus (MolaGV). After gene content analysis, five open reading frames (ORFs) were found to be unique to MolaGV and several auxiliary genes were found including iap-3, iap-5, bro-a, bro-b, and three enhancins. The virus genome lacked both chitinase and cathepsin. We then looked at the evolutionary history of the enhancin gene and found that betabaculovirus acquired this gene from an alphabaculovirus followed by several duplication events. Gene duplication also happened to an endonuclease-like gene. Genomic and gene content analyses revealed both a strict collinearity and gene expansion into the genome of the MolaGV-related species. We also characterized the granulin gene using a recombinant Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and found that occlusion bodies were produced into the nucleus of infected cells and presented a polyhedral shape and no occluded virions within. Overall, betabaculovirus genome sequencing is of importance to the field as few genomes are publicly accessible. Mocis latipes is a secondary pest of maize, rice, and wheat crops in Brazil. Certainly, both the discovery and description of novel baculoviruses may lead to development of greener and safer pesticides in order to counteract and effectively control crop damage-causing insect populations Full article
(This article belongs to the Section Insect Viruses)
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Open AccessReview Antiviral Defense and Innate Immune Memory in the Oyster
Viruses 2018, 10(3), 133; https://doi.org/10.3390/v10030133
Received: 8 February 2018 / Revised: 6 March 2018 / Accepted: 14 March 2018 / Published: 16 March 2018
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Abstract
The Pacific oyster, Crassostrea gigas, is becoming a valuable model for investigating antiviral defense in the Lophotrochozoa superphylum. In the past five years, improvements to laboratory-based experimental infection protocols using Ostreid herpesvirus I (OsHV-1) from naturally infected C. gigas combined with next-generation
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The Pacific oyster, Crassostrea gigas, is becoming a valuable model for investigating antiviral defense in the Lophotrochozoa superphylum. In the past five years, improvements to laboratory-based experimental infection protocols using Ostreid herpesvirus I (OsHV-1) from naturally infected C. gigas combined with next-generation sequencing techniques has revealed that oysters have a complex antiviral response involving the activation of all major innate immune pathways. Experimental evidence indicates C. gigas utilizes an interferon-like response to limit OsHV-1 replication and spread. Oysters injected with a viral mimic (polyI:C) develop resistance to OsHV-1. Improved survival following polyI:C injection was found later in life (within-generational immune priming) and in the next generation (multi-generational immune priming). These studies indicate that the oyster’s antiviral defense system exhibits a form of innate immune-memory. An important priority is to identify the molecular mechanisms responsible for this phenomenon. This knowledge will motivate the development of practical and cost-effective treatments for improving oyster health in aquaculture. Full article
(This article belongs to the Special Issue Antiviral Defense in Invertebrates)
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Open AccessArticle High Mobility Group Box 1 Influences HSV1716 Spread and Acts as an Adjuvant to Chemotherapy
Viruses 2018, 10(3), 132; https://doi.org/10.3390/v10030132
Received: 2 February 2018 / Revised: 6 March 2018 / Accepted: 12 March 2018 / Published: 15 March 2018
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Abstract
High Mobility Group Box 1 (HMGB1) is a multifunctional protein that plays various roles in the processes of inflammation, cancer, and other diseases. Many reports document abundant HMGB1 release following infection with oncolytic viruses (OVs). Further, other groups including previous reports from our
[...] Read more.
High Mobility Group Box 1 (HMGB1) is a multifunctional protein that plays various roles in the processes of inflammation, cancer, and other diseases. Many reports document abundant HMGB1 release following infection with oncolytic viruses (OVs). Further, other groups including previous reports from our laboratory highlight the synergistic effects of OVs with chemotherapy drugs. Here, we show that virus-free supernatants have varying cytotoxic potential, and HMGB1 is actively secreted by two established fibroblast cell lines (NIH 3T3 and 3T6-Swiss albino) following HSV1716 infection in vitro. Further, pharmacologic inhibition or genetic knock-down of HMGB1 reveals a role for HMGB1 in viral restriction, the ability to modulate bystander cell proliferation, and drug sensitivity in 3T6 cells. These data further support the multifactorial role of HMGB1, and suggest it could be a target for modulating the efficacy of oncolytic virus therapies alone or in combination with other frontline cancer treatments. Full article
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Open AccessArticle Intermolecular RNA Recombination Occurs at Different Frequencies in Alternate Forms of Brome Mosaic Virus RNA Replication Compartments
Viruses 2018, 10(3), 131; https://doi.org/10.3390/v10030131
Received: 26 February 2018 / Revised: 13 March 2018 / Accepted: 14 March 2018 / Published: 15 March 2018
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Abstract
Positive-strand RNA viruses replicate their genomes in membrane-bound replication compartments. Brome mosaic virus (BMV) replicates in vesicular invaginations of the endoplasmic reticulum membrane. BMV has served as a productive model system to study processes like virus-host interactions, RNA replication and recombination. Here we
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Positive-strand RNA viruses replicate their genomes in membrane-bound replication compartments. Brome mosaic virus (BMV) replicates in vesicular invaginations of the endoplasmic reticulum membrane. BMV has served as a productive model system to study processes like virus-host interactions, RNA replication and recombination. Here we present multiple lines of evidence showing that the structure of the viral RNA replication compartments plays a fundamental role and that recruitment of parental RNAs to a common replication compartment is a limiting step in intermolecular RNA recombination. We show that a previously defined requirement for an RNA recruitment element on both parental RNAs is not to function as a preferred crossover site, but in order for individual RNAs to be recruited into the replication compartments. Moreover, modulating the form of the replication compartments from spherular vesicles (spherules) to more expansive membrane layers increased intermolecular RNA recombination frequency by 200- to 1000-fold. We propose that intermolecular RNA recombination requires parental RNAs to be recruited into replication compartments as monomers, and that recruitment of multiple RNAs into a contiguous space is much more common for layers than for spherules. These results could explain differences in recombination frequencies between viruses that replicate in association with smaller spherules versus larger double-membrane vesicles and convoluted membranes. Full article
(This article belongs to the Special Issue Viral Recombination: Ecology, Evolution and Pathogenesis)
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Open AccessArticle Utilisation of Chimeric Lyssaviruses to Assess Vaccine Protection against Highly Divergent Lyssaviruses
Viruses 2018, 10(3), 130; https://doi.org/10.3390/v10030130
Received: 2 March 2018 / Revised: 13 March 2018 / Accepted: 13 March 2018 / Published: 15 March 2018
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Abstract
Lyssaviruses constitute a diverse range of viruses with the ability to cause fatal encephalitis known as rabies. Existing human rabies vaccines and post exposure prophylaxes (PEP) are based on inactivated preparations of, and neutralising antibody preparations directed against, classical rabies viruses, respectively. Whilst
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Lyssaviruses constitute a diverse range of viruses with the ability to cause fatal encephalitis known as rabies. Existing human rabies vaccines and post exposure prophylaxes (PEP) are based on inactivated preparations of, and neutralising antibody preparations directed against, classical rabies viruses, respectively. Whilst these prophylaxes are highly efficient at neutralising and preventing a productive infection with rabies virus, their ability to neutralise other lyssaviruses is thought to be limited. The remaining 15 virus species within the lyssavirus genus have been divided into at least three phylogroups that generally predict vaccine protection. Existing rabies vaccines afford protection against phylogroup I viruses but offer little to no protection against phylogroup II and III viruses. As such, work involving sharps with phylogroup II and III must be considered of high risk as no PEP is thought to have any effect on the prevention of a productive infection with these lyssaviruses. Whilst rabies virus itself has been characterised in a number of different animal models, data on the remaining lyssaviruses are scarce. As the lyssavirus glycoprotein is considered to be the sole target of neutralising antibodies we generated a vaccine strain of rabies using reverse genetics expressing highly divergent glycoproteins of West Caucasian Bat lyssavirus and Ikoma lyssavirus. Using these recombinants, we propose that recombinant vaccine strain derived lyssaviruses containing heterologous glycoproteins may be a suitable surrogate for wildtype viruses when assessing vaccine protection for the lyssaviruses. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle Tomato Spotted Wilt Virus NSs Protein Supports Infection and Systemic Movement of a Potyvirus and Is a Symptom Determinant
Viruses 2018, 10(3), 129; https://doi.org/10.3390/v10030129
Received: 3 February 2018 / Revised: 12 March 2018 / Accepted: 13 March 2018 / Published: 14 March 2018
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Abstract
Plant viruses are inducers and targets of antiviral RNA silencing. To condition susceptibility, most plant viruses encode silencing suppressor proteins that interfere with antiviral RNA silencing. The NSs protein is an RNA silencing suppressor in orthotospoviruses, such as the tomato spotted wilt virus
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Plant viruses are inducers and targets of antiviral RNA silencing. To condition susceptibility, most plant viruses encode silencing suppressor proteins that interfere with antiviral RNA silencing. The NSs protein is an RNA silencing suppressor in orthotospoviruses, such as the tomato spotted wilt virus (TSWV). The mechanism of RNA silencing suppression by NSs and its role in virus infection and movement are poorly understood. Here, we cloned and tagged TSWV NSs and expressed it from a GFP-tagged turnip mosaic virus (TuMV-GFP) carrying either a wild-type or suppressor-deficient (AS9) helper component proteinase (HC-Pro). When expressed in cis, NSs restored pathogenicity and promoted systemic infection of suppressor-deficient TuMV-AS9-GFP in Nicotiana benthamiana and Arabidopsis thaliana. Inactivating mutations were introduced in NSs RNA-binding domain one. A genetic analysis with active and suppressor-deficient NSs, in combination with wild-type and mutant plants lacking essential components of the RNA silencing machinery, showed that the NSs insert is stable when expressed from a potyvirus. NSs can functionally replace potyviral HC-Pro, condition virus susceptibility, and promote systemic infection and symptom development by suppressing antiviral RNA silencing through a mechanism that partially overlaps that of potyviral HC-Pro. The results presented provide new insight into the mechanism of silencing suppression by NSs and its effect on virus infection. Full article
(This article belongs to the Section Viruses of Plants, Fungi and Protozoa)
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Open AccessArticle Molecular Diagnosis of Felis catus Gammaherpesvirus 1 (FcaGHV1) Infection in Cats of Known Retrovirus Status with and without Lymphoma
Viruses 2018, 10(3), 128; https://doi.org/10.3390/v10030128
Received: 14 February 2018 / Revised: 9 March 2018 / Accepted: 12 March 2018 / Published: 14 March 2018
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Abstract
The pathogenicity of Felis catus gammaherpesvirus 1 (FcaGHV1), a common infection of domestic cats, is unknown. To explore an association between FcaGHV1 detection and feline lymphoma, a retrospective, cross-sectional, disease-association study was conducted. The infection status of all cats for feline immunodeficiency virus
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The pathogenicity of Felis catus gammaherpesvirus 1 (FcaGHV1), a common infection of domestic cats, is unknown. To explore an association between FcaGHV1 detection and feline lymphoma, a retrospective, cross-sectional, disease-association study was conducted. The infection status of all cats for feline immunodeficiency virus and feline leukaemia virus was determined. Neither a molecular diagnosis of FcaGHV1 nor whole-blood FcaGHV1 load was related to outcome in 122 lymphoma cases compared with 71 controls matched for age and sex. Molecular analysis of lymphoma-derived DNA paired with autologous uninvolved tissue did not suggest restriction of FcaGHV1 DNA to tumour tissue. FcaGHV1 DNA detection was associated with significantly shorter survival in lymphoma cases, an observation that could not be adequately explained by treatment differences. In addition, regressive feline leukaemia virus infection was identified as a risk factor for lymphoma. A history of fighting or roaming was identified as a novel epidemiological risk factor for FcaGHV1 detection, lending support to intercat aggression as a potential route of transmission. Studies investigating the cellular location and expression of FcaGHV1 are indicated to assist in ruling out a lymphomagenic role for this virus. Prospective investigation of FcaGHV1 DNA detection as a prognostic marker in feline lymphoma is warranted. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle Cellular hnRNP A1 Interacts with Nucleocapsid Protein of Porcine Epidemic Diarrhea Virus and Impairs Viral Replication
Viruses 2018, 10(3), 127; https://doi.org/10.3390/v10030127
Received: 8 February 2018 / Revised: 7 March 2018 / Accepted: 7 March 2018 / Published: 13 March 2018
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Abstract
The nucleocapsid (N) protein is a major structural component of porcine epidemic diarrhea virus (PEDV), which is predicted to be a multifunctional protein in viral replication. Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is a cellular protein participating in the splicing of pre-mRNA in
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The nucleocapsid (N) protein is a major structural component of porcine epidemic diarrhea virus (PEDV), which is predicted to be a multifunctional protein in viral replication. Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is a cellular protein participating in the splicing of pre-mRNA in the nucleus and translation regulation in the cytoplasm. According to our previous proteomic study about PEDV infection in vivo, hnRNP A1 was thought to be a cellular factor influencing PEDV replication. In this report, PEDV N protein was discovered to colocalize with cellular hnRNP A1 in perinuclear region of PEDV infected cells. Co-immunoprecipitation (CO-IP) results clearly demonstrated that PEDV N protein could bind to human hnRNP A1. Replication of PEDV was inhibited by silencing the expression of hnRNP A1 in CCL-81 cells, suggesting the positive effect of hnRNP A1 on PEDV infection. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle Development and Testing of a Method for Validating Chemical Inactivation of Ebola Virus
Viruses 2018, 10(3), 126; https://doi.org/10.3390/v10030126
Received: 1 January 2018 / Revised: 28 February 2018 / Accepted: 9 March 2018 / Published: 13 March 2018
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Abstract
Complete inactivation of infectious Ebola virus (EBOV) is required before a sample may be removed from a Biosafety Level 4 laboratory. The United States Federal Select Agent Program regulations require that procedures used to demonstrate chemical inactivation must be validated in-house to confirm
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Complete inactivation of infectious Ebola virus (EBOV) is required before a sample may be removed from a Biosafety Level 4 laboratory. The United States Federal Select Agent Program regulations require that procedures used to demonstrate chemical inactivation must be validated in-house to confirm complete inactivation. The objective of this study was to develop a method for validating chemical inactivation of EBOV and then demonstrate the effectiveness of several commonly-used inactivation methods. Samples containing infectious EBOV (Zaire ebolavirus) in different matrices were treated, and the sample was diluted to limit the cytopathic effect of the inactivant. The presence of infectious virus was determined by assessing the cytopathic effect in Vero E6 cells. Crucially, this method did not result in a loss of infectivity in control samples, and we were able to detect less than five infectious units of EBOV (Zaire ebolavirus). We found that TRIzol LS reagent and RNA-Bee inactivated EBOV in serum; TRIzol LS reagent inactivated EBOV in clarified cell culture media; TRIzol reagent inactivated EBOV in tissue and infected Vero E6 cells; 10% neutral buffered formalin inactivated EBOV in tissue; and osmium tetroxide vapors inactivated EBOV on transmission electron microscopy grids. The methods described herein are easily performed and can be adapted to validate inactivation of viruses in various matrices and by various chemical methods. Full article
(This article belongs to the collection Advances in Ebolavirus, Marburgvirus, and Cuevavirus Research)
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Open AccessArticle Human Parainfluenza Virus Type 3 Matrix Protein Reduces Viral RNA Synthesis of HPIV3 by Regulating Inclusion Body Formation
Viruses 2018, 10(3), 125; https://doi.org/10.3390/v10030125
Received: 13 January 2018 / Revised: 7 March 2018 / Accepted: 7 March 2018 / Published: 11 March 2018
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Abstract
Human parainfluenza virus type 3 is one of the main causes of lower respiratory illness in newborns and infants. The role of the matrix protein (M) in viral budding is extensively studied, but the effect of M on viral replication remains to be
[...] Read more.
Human parainfluenza virus type 3 is one of the main causes of lower respiratory illness in newborns and infants. The role of the matrix protein (M) in viral budding is extensively studied, but the effect of M on viral replication remains to be determined. Using an HPIV3 minigenome assay, we found that M reduced HPIV3 mingenome-encoded reporter activity even though it had an unspecific effect on the expression of cellular genes. Furthermore, the inhibition effect of M on viral RNA synthesis was proven to be independent of its virus-like particles (VLPs)’ release ability. A VLP’s defective mutant (ML302A) decreased the expression of minigenome reporter as wild type M did. Using an immunofluorescence assay, we found that M weakened the formation of inclusion bodies (IBs), although it did not co-localize with the IBs. Moreover, using another mutant, ML305A , which is defective in M-nucleoprotein (N) interaction, we found that ML305A had no effect on reporter activity and IB formation as the wild type of M did. Taken together, we conclude that M reduces the replication of HPIV3 and IB formation by M–N interaction. Full article
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