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Viruses, Volume 7, Issue 12 (December 2015), Pages 6108-6754

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Open AccessArticle Activation of the Mitochondrial Apoptotic Signaling Platform during Rubella Virus Infection
Viruses 2015, 7(12), 6108-6126; doi:10.3390/v7122928
Received: 3 August 2015 / Revised: 16 November 2015 / Accepted: 17 November 2015 / Published: 26 November 2015
Cited by 1 | PDF Full-text (2610 KB) | HTML Full-text | XML Full-text
Abstract
Mitochondria- as well as p53-based signaling pathways are central for the execution of the intrinsic apoptotic cascade. Their contribution to rubella virus (RV)-induced apoptosis was addressed through time-specific evaluation of characteristic parameters such as permeabilization of the mitochondrial membrane and subsequent release of
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Mitochondria- as well as p53-based signaling pathways are central for the execution of the intrinsic apoptotic cascade. Their contribution to rubella virus (RV)-induced apoptosis was addressed through time-specific evaluation of characteristic parameters such as permeabilization of the mitochondrial membrane and subsequent release of the pro-apoptotic proteins apoptosis-inducing factor (AIF) and cytochrome c from mitochondria. Additionally, expression and localization pattern of p53 and selected members of the multifunctional and stress-inducible cyclophilin family were examined. The application of pifithrin μ as an inhibitor of p53 shuttling to mitochondria reduced RV-induced cell death to an extent similar to that of the broad spectrum caspase inhibitor z-VAD-fmk (benzyloxycarbonyl-V-A-D-(OMe)-fmk). However, RV progeny generation was not altered. This indicates that, despite an increased survival rate of its cellular host, induction of apoptosis neither supports nor restricts RV replication. Moreover, some of the examined apoptotic markers were affected in a strain-specific manner and differed between the cell culture-adapted strains: Therien and the HPV77 vaccine on the one hand, and a clinical isolate on the other. In summary, the results presented indicate that the transcription-independent mitochondrial p53 program contributes to RV-induced apoptosis. Full article
(This article belongs to the Section Antivirals & Vaccines)
Open AccessArticle Multiple Poliovirus Proteins Repress Cytoplasmic RNA Granules
Viruses 2015, 7(12), 6127-6140; doi:10.3390/v7122922
Received: 13 October 2015 / Revised: 13 November 2015 / Accepted: 17 November 2015 / Published: 25 November 2015
Cited by 8 | PDF Full-text (3364 KB) | HTML Full-text | XML Full-text
Abstract
We have previously shown that poliovirus (PV) infection induces stress granule (SG) formation early in infection and then inhibits the formation of SG and disperses processing bodies (PBs) by the mid-phase of infection. Loss of SG was linked to cleavage of G3BP1 by
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We have previously shown that poliovirus (PV) infection induces stress granule (SG) formation early in infection and then inhibits the formation of SG and disperses processing bodies (PBs) by the mid-phase of infection. Loss of SG was linked to cleavage of G3BP1 by viral 3C proteinase (3Cpro), however dispersal of PBs was not strongly linked to cleavage of specific factors by viral proteinases, suggesting other viral proteins may play roles in inhibition of SG or PB formation. Here we have screened all viral proteins for roles in inducing or inhibiting the formation of RNA granules by creating fusions with mCherry and expressing them individually in cells. Expression of viral proteins separately revealed that the capsid region P1, 2Apro, 3A, 3Cpro, the protease precursor 3CD and 3D polymerase all affect RNA granules to varying extents, whereas 2BC does not. 2Apro, which cleaves eIF4GI, induced SGs as expected, and entered novel foci containing the SG nucleating protein G3BP1. Of the two forms of G3BP, only G3BP1 is cleaved by a virus proteinase, 3Cpro, whereas G3BP2 is not cleaved by 3Cpro or 2Apro. Surprisingly, 3CD, which contains proteinase activity, differentially repressed PBs but not SGs. Further, both 2Apro and 3Cpro expression dispersed PBs, however molecular targets were different since PB dispersal due to 2Apro and heat shock protein (Hsp)90 inhibition but not 3Cpro, could be rescued by application of oxidative stress to cells. The data indicate that PV repression of SGs and PBs is multifactorial, though protease function is dominant. Full article
(This article belongs to the Special Issue Recent Progress in Enterovirus Research)
Open AccessArticle Silencing of a Germin-Like Protein Gene (CchGLP) in Geminivirus-Resistant Pepper (Capsicum chinense Jacq.) BG-3821 Increases Susceptibility to Single and Mixed Infections by Geminiviruses PHYVV and PepGMV
Viruses 2015, 7(12), 6141-6151; doi:10.3390/v7122930
Received: 11 September 2015 / Revised: 11 November 2015 / Accepted: 12 November 2015 / Published: 25 November 2015
Cited by 2 | PDF Full-text (2196 KB) | HTML Full-text | XML Full-text
Abstract
Germin-like proteins (GLPs) are encoded by a family of genes found in all plants, and in terms of function, the GLPs are implicated in the response of plants to biotic and abiotic stresses. CchGLP is a gene encoding a GLP identified in a
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Germin-like proteins (GLPs) are encoded by a family of genes found in all plants, and in terms of function, the GLPs are implicated in the response of plants to biotic and abiotic stresses. CchGLP is a gene encoding a GLP identified in a geminivirus-resistant Capsicum chinense Jacq accession named BG-3821, and it is important in geminivirus resistance when transferred to susceptible tobacco in transgenic experiments. To characterize the role of this GLP in geminivirus resistance in the original accession from which this gene was identified, this work aimed at demonstrating the possible role of CchGLP in resistance to geminiviruses in Capsicum chinense Jacq. BG-3821. Virus-induced gene silencing studies using a geminiviral vector based in PHYVV component A, displaying that silencing of CchGLP in accession BG-3821, increased susceptibility to geminivirus single and mixed infections. These results suggested that CchGLP is an important factor for geminivirus resistance in C. chinense BG-3821 accession. Full article
(This article belongs to the Section Viruses of Plants, Fungi and Protozoa)
Open AccessArticle Inhibition Profiling of Retroviral Protease Inhibitors Using an HIV-2 Modular System
Viruses 2015, 7(12), 6152-6162; doi:10.3390/v7122931
Received: 22 July 2015 / Revised: 11 November 2015 / Accepted: 13 November 2015 / Published: 27 November 2015
Cited by 1 | PDF Full-text (583 KB) | HTML Full-text | XML Full-text
Abstract
Retroviral protease inhibitors (PIs) are fundamental pillars in the treatment of HIV infection and acquired immunodeficiency syndrome (AIDS). Currently used PIs are designed against HIV-1, and their effect on HIV-2 is understudied. Using a modular HIV-2 protease cassette system, inhibition profiling assays were
[...] Read more.
Retroviral protease inhibitors (PIs) are fundamental pillars in the treatment of HIV infection and acquired immunodeficiency syndrome (AIDS). Currently used PIs are designed against HIV-1, and their effect on HIV-2 is understudied. Using a modular HIV-2 protease cassette system, inhibition profiling assays were carried out for protease inhibitors both in enzymatic and cell culture assays. Moreover, the treatment-associated resistance mutations (I54M, L90M) were introduced into the modular system, and comparative inhibition assays were performed to determine their effect on the susceptibility of the protease. Our results indicate that darunavir, saquinavir, indinavir and lopinavir were very effective HIV-2 protease inhibitors, while tipranavir, nelfinavir and amprenavir showed a decreased efficacy. I54M, L90M double mutation resulted in a significant reduction in the susceptibility to most of the inhibitors with the exception of tipranavir. To our knowledge, this modular system constitutes a novel approach in the field of HIV-2 protease characterization and susceptibility testing. Full article
(This article belongs to the Section Antivirals & Vaccines)
Open AccessArticle Incomplete LPS Core-Specific Felix01-Like Virus vB_EcoM_VpaE1
Viruses 2015, 7(12), 6163-6181; doi:10.3390/v7122932
Received: 8 October 2015 / Revised: 10 November 2015 / Accepted: 18 November 2015 / Published: 27 November 2015
Cited by 1 | PDF Full-text (9913 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Bacteriophages represent a valuable source for studying the mechanisms underlying virus-host interactions. A better understanding of the host-specificity of viruses at the molecular level can promote various phage applications, including bacterial diagnostics, antimicrobial therapeutics, and improve methods in molecular biology. In this study,
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Bacteriophages represent a valuable source for studying the mechanisms underlying virus-host interactions. A better understanding of the host-specificity of viruses at the molecular level can promote various phage applications, including bacterial diagnostics, antimicrobial therapeutics, and improve methods in molecular biology. In this study, we describe the isolation and characterization of a novel coliphage, vB_EcoM_VpaE1, which has different host specificity than its relatives. Morphology studies, coupled with the results of genomic and proteomic analyses, indicate that vB_EcoM_VpaE1 belongs to the newly proposed genus Felix01likevirus in the family Myoviridae. The genus Felix01likevirus comprises a group of highly similar phages that infect O-antigen-expressing Salmonella and Escherichia coli (E. coli) strains. Phage vB_EcoM_VpaE1 differs from the rest of Felix01-like viruses, since it infects O-antigen-deficient E. coli strains with an incomplete core lipopolysaccharide (LPS). We show that vB_EcoM_VpaE1 can infect mutants of E. coli that contain various truncations in their LPS, and can even recognize LPS that is truncated down to the inner-core oligosaccharide, showing potential for the control of rough E. coli strains, which usually emerge as resistant mutants upon infection by O-Ag-specific phages. Furthermore, VpaE1 can replicate in a wide temperature range from 9 to 49 °C, suggesting that this virus is well adapted to harsh environmental conditions. Since the structural proteins of such phages tend to be rather robust, the receptor-recognizing proteins of VpaE1 are an attractive tool for application in glycan analysis, bacterial diagnostics and antimicrobial therapeutics. Full article
(This article belongs to the Section Bacterial Viruses)
Open AccessArticle Fluorescent Protein-Tagged Sindbis Virus E2 Glycoprotein Allows Single Particle Analysis of Virus Budding from Live Cells
Viruses 2015, 7(12), 6182-6199; doi:10.3390/v7122926
Received: 27 August 2015 / Revised: 7 November 2015 / Accepted: 13 November 2015 / Published: 27 November 2015
Cited by 5 | PDF Full-text (10733 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Sindbis virus (SINV) is an enveloped, mosquito-borne alphavirus. Here we generated and characterized a fluorescent protein-tagged (FP-tagged) SINV and found that the presence of the FP-tag (mCherry) affected glycoprotein transport to the plasma membrane whereas the specific infectivity of the virus was not
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Sindbis virus (SINV) is an enveloped, mosquito-borne alphavirus. Here we generated and characterized a fluorescent protein-tagged (FP-tagged) SINV and found that the presence of the FP-tag (mCherry) affected glycoprotein transport to the plasma membrane whereas the specific infectivity of the virus was not affected. We examined the virions by transmission electron cryo-microscopy and determined the arrangement of the FP-tag on the surface of the virion. The fluorescent proteins are arranged icosahedrally on the virus surface in a stable manner that did not adversely affect receptor binding or fusion functions of E2 and E1, respectively. The delay in surface expression of the viral glycoproteins, as demonstrated by flow cytometry analysis, contributed to a 10-fold reduction in mCherry-E2 virus titer. There is a 1:1 ratio of mCherry to E2 incorporated into the virion, which leads to a strong fluorescence signal and thus facilitates single-particle tracking experiments. We used the FP-tagged virus for high-resolution live-cell imaging to study the spatial and temporal aspects of alphavirus assembly and budding from mammalian cells. These processes were further analyzed by thin section microscopy. The results demonstrate that SINV buds from the plasma membrane of infected cells and is dispersed into the surrounding media or spread to neighboring cells facilitated by its close association with filopodial extensions. Full article
Open AccessCommunication Rapid Construction of Stable Infectious Full-Length cDNA Clone of Papaya Leaf Distortion Mosaic Virus Using In-Fusion Cloning
Viruses 2015, 7(12), 6241-6250; doi:10.3390/v7122935
Received: 7 July 2015 / Revised: 18 November 2015 / Accepted: 19 November 2015 / Published: 1 December 2015
Cited by 1 | PDF Full-text (1822 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Papaya leaf distortion mosaic virus (PLDMV) is becoming a threat to papaya and transgenic papaya resistant to the related pathogen, papaya ringspot virus (PRSV). The generation of infectious viral clones is an essential step for reverse-genetics studies of viral gene function and cross-protection.
[...] Read more.
Papaya leaf distortion mosaic virus (PLDMV) is becoming a threat to papaya and transgenic papaya resistant to the related pathogen, papaya ringspot virus (PRSV). The generation of infectious viral clones is an essential step for reverse-genetics studies of viral gene function and cross-protection. In this study, a sequence- and ligation-independent cloning system, the In-Fusion® Cloning Kit (Clontech, Mountain View, CA, USA), was used to construct intron-less or intron-containing full-length cDNA clones of the isolate PLDMV-DF, with the simultaneous scarless assembly of multiple viral and intron fragments into a plasmid vector in a single reaction. The intron-containing full-length cDNA clone of PLDMV-DF was stably propagated in Escherichia coli. In vitro intron-containing transcripts were processed and spliced into biologically active intron-less transcripts following mechanical inoculation and then initiated systemic infections in Carica papaya L. seedlings, which developed similar symptoms to those caused by the wild-type virus. However, no infectivity was detected when the plants were inoculated with RNA transcripts from the intron-less construct because the instability of the viral cDNA clone in bacterial cells caused a non-sense or deletion mutation of the genomic sequence of PLDMV-DF. To our knowledge, this is the first report of the construction of an infectious full-length cDNA clone of PLDMV and the splicing of intron-containing transcripts following mechanical inoculation. In-Fusion cloning shortens the construction time from months to days. Therefore, it is a faster, more flexible, and more efficient method than the traditional multistep restriction enzyme-mediated subcloning procedure. Full article
(This article belongs to the Section Viruses of Plants, Fungi and Protozoa)
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Open AccessArticle Alphacoronaviruses Detected in French Bats Are Phylogeographically Linked to Coronaviruses of European Bats
Viruses 2015, 7(12), 6279-6290; doi:10.3390/v7122937
Received: 14 September 2015 / Revised: 17 November 2015 / Accepted: 23 November 2015 / Published: 2 December 2015
Cited by 1 | PDF Full-text (547 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Bats are a reservoir for a diverse range of viruses, including coronaviruses (CoVs). To determine the presence of CoVs in French bats, fecal samples were collected between July and August of 2014 from four bat species in seven different locations around the city
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Bats are a reservoir for a diverse range of viruses, including coronaviruses (CoVs). To determine the presence of CoVs in French bats, fecal samples were collected between July and August of 2014 from four bat species in seven different locations around the city of Bourges in France. We present for the first time the presence of alpha-CoVs in French Pipistrellus pipistrellus bat species with an estimated prevalence of 4.2%. Based on the analysis of a fragment of the RNA-dependent RNA polymerase (RdRp) gene, phylogenetic analyses show that alpha-CoVs sequences detected in French bats are closely related to other European bat alpha-CoVs. Phylogeographic analyses of RdRp sequences show that several CoVs strains circulate in European bats: (i) old strains detected that have probably diverged a long time ago and are detected in different bat subspecies; (ii) strains detected in Myotis and Pipistrellus bat species that have more recently diverged. Our findings support previous observations describing the complexity of the detected CoVs in bats worldwide. Full article
(This article belongs to the Section Animal Viruses)
Open AccessArticle Emergent HIV-1 Drug Resistance Mutations Were Not Present at Low-Frequency at Baseline in Non-Nucleoside Reverse Transcriptase Inhibitor-Treated Subjects in the STaR Study
Viruses 2015, 7(12), 6360-6370; doi:10.3390/v7122943
Received: 29 September 2015 / Revised: 19 November 2015 / Accepted: 20 November 2015 / Published: 7 December 2015
Cited by 2 | PDF Full-text (202 KB) | HTML Full-text | XML Full-text
Abstract
At Week 96 of the Single-Tablet Regimen (STaR) study, more treatment-naïve subjects that received rilpivirine/emtricitabine/tenofovir DF (RPV/FTC/TDF) developed resistance mutations compared to those treated with efavirenz (EFV)/FTC/TDF by population sequencing. Furthermore, more RPV/FTC/TDF-treated subjects with baseline HIV-1 RNA >100,000 copies/mL developed resistance compared
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At Week 96 of the Single-Tablet Regimen (STaR) study, more treatment-naïve subjects that received rilpivirine/emtricitabine/tenofovir DF (RPV/FTC/TDF) developed resistance mutations compared to those treated with efavirenz (EFV)/FTC/TDF by population sequencing. Furthermore, more RPV/FTC/TDF-treated subjects with baseline HIV-1 RNA >100,000 copies/mL developed resistance compared to subjects with baseline HIV-1 RNA ≤100,000 copies/mL. Here, deep sequencing was utilized to assess the presence of pre-existing low-frequency variants in subjects with and without resistance development in the STaR study. Deep sequencing (Illumina MiSeq) was performed on baseline and virologic failure samples for all subjects analyzed for resistance by population sequencing during the clinical study (n = 33), as well as baseline samples from control subjects with virologic response (n = 118). Primary NRTI or NNRTI drug resistance mutations present at low frequency (≥2% to 20%) were detected in 6.6% of baseline samples by deep sequencing, all of which occurred in control subjects. Deep sequencing results were generally consistent with population sequencing but detected additional primary NNRTI and NRTI resistance mutations at virologic failure in seven samples. HIV-1 drug resistance mutations emerging while on RPV/FTC/TDF or EFV/FTC/TDF treatment were not present at low frequency at baseline in the STaR study. Full article
Open AccessArticle Molecular Epidemiology of Human Rhinoviruses and Enteroviruses Highlights Their Diversity in Sub-Saharan Africa
Viruses 2015, 7(12), 6412-6423; doi:10.3390/v7122948
Received: 25 September 2015 / Revised: 16 November 2015 / Accepted: 19 November 2015 / Published: 8 December 2015
Cited by 1 | PDF Full-text (3603 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Human rhinoviruses (HRVs) and enteroviruses (HEVs) belong to the Enterovirus genus and are the most frequent cause of infection worldwide, but data on their molecular epidemiology in Africa are scarce. To understand HRV and HEV molecular epidemiology in this setting, we enrolled febrile
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Human rhinoviruses (HRVs) and enteroviruses (HEVs) belong to the Enterovirus genus and are the most frequent cause of infection worldwide, but data on their molecular epidemiology in Africa are scarce. To understand HRV and HEV molecular epidemiology in this setting, we enrolled febrile pediatric patients participating in a large prospective cohort assessing the causes of fever in Tanzanian children. Naso/oropharyngeal swabs were systematically collected and tested by real-time RT-PCR for HRV and HEV. Viruses from positive samples were sequenced and phylogenetic analyses were then applied to highlight the HRV and HEV types as well as recombinant or divergent strains. Thirty-eight percent (378/1005) of the enrolled children harboured an HRV or HEV infection. Although some types were predominant, many distinct types were co-circulating, including a vaccinal poliovirus, HEV-A71 and HEV-D68. Three HRV-A recombinants were identified: HRV-A36/HRV-A67, HRV-A12/HRV-A67 and HRV-A96/HRV-A61. Four divergent HRV strains were also identified: one HRV-B strain and three HRV-C strains. This is the first prospective study focused on HRV and HEV molecular epidemiology in sub-Saharan Africa. This systematic and thorough large screening with careful clinical data management confirms the wide genomic diversity of these viruses, brings new insights about their evolution and provides data about associated symptoms. Full article
(This article belongs to the Special Issue Recent Progress in Enterovirus Research)
Open AccessArticle Structure of the Receptor-Binding Carboxy-Terminal Domain of the Bacteriophage T5 L-Shaped Tail Fibre with and without Its Intra-Molecular Chaperone
Viruses 2015, 7(12), 6424-6440; doi:10.3390/v7122946
Received: 29 September 2015 / Revised: 20 November 2015 / Accepted: 27 November 2015 / Published: 8 December 2015
Cited by 1 | PDF Full-text (4760 KB) | HTML Full-text | XML Full-text
Abstract
Bacteriophage T5, a Siphovirus belonging to the order Caudovirales, has a flexible, three-fold symmetric tail, to which three L-shaped fibres are attached. These fibres recognize oligo-mannose units on the bacterial cell surface prior to infection and are composed of homotrimers of the
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Bacteriophage T5, a Siphovirus belonging to the order Caudovirales, has a flexible, three-fold symmetric tail, to which three L-shaped fibres are attached. These fibres recognize oligo-mannose units on the bacterial cell surface prior to infection and are composed of homotrimers of the pb1 protein. Pb1 has 1396 amino acids, of which the carboxy-terminal 133 residues form a trimeric intra-molecular chaperone that is auto-proteolyzed after correct folding. The structure of a trimer of residues 970–1263 was determined by single anomalous dispersion phasing using incorporated selenomethionine residues and refined at 2.3 Å resolution using crystals grown from native, methionine-containing, protein. The protein inhibits phage infection by competition. The phage-distal receptor-binding domain resembles a bullet, with the walls formed by partially intertwined beta-sheets, conferring stability to the structure. The fold of the domain is novel and the topology unique to the pb1 structure. A site-directed mutant (Ser1264 to Ala), in which auto-proteolysis is impeded, was also produced, crystallized and its 2.5 Å structure solved by molecular replacement. The additional chaperone domain (residues 1263–1396) consists of a central trimeric alpha-helical coiled-coil flanked by a mixed alpha-beta domain. Three long beta-hairpin tentacles, one from each chaperone monomer, extend into long curved grooves of the bullet-shaped domain. The chaperone-containing mutant did not inhibit infection by competition. Full article
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Open AccessArticle Two Cytoplasmic Acylation Sites and an Adjacent Hydrophobic Residue, but No Other Conserved Amino Acids in the Cytoplasmic Tail of HA from Influenza A Virus Are Crucial for Virus Replication
Viruses 2015, 7(12), 6458-6475; doi:10.3390/v7122950
Received: 11 October 2015 / Revised: 24 November 2015 / Accepted: 3 December 2015 / Published: 8 December 2015
Cited by 2 | PDF Full-text (3135 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Recruitment of the matrix protein M1 to the assembly site of the influenza virus is thought to be mediated by interactions with the cytoplasmic tail of hemagglutinin (HA). Based on a comprehensive sequence comparison of all sequences present in the database, we analyzed
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Recruitment of the matrix protein M1 to the assembly site of the influenza virus is thought to be mediated by interactions with the cytoplasmic tail of hemagglutinin (HA). Based on a comprehensive sequence comparison of all sequences present in the database, we analyzed the effect of mutating conserved residues in the cytosol-facing part of the transmembrane region and cytoplasmic tail of HA (A/WSN/33 (H1N1) strain) on virus replication and morphology of virions. Removal of the two cytoplasmic acylation sites and substitution of a neighboring isoleucine by glutamine prevented rescue of infectious virions. In contrast, a conservative exchange of the same isoleucine, non-conservative exchanges of glycine and glutamine, deletion of the acylation site at the end of the transmembrane region and shifting it into the tail did not affect virus morphology and had only subtle effects on virus growth and on the incorporation of M1 and Ribo-Nucleoprotein Particles (RNPs). Thus, assuming that essential amino acids are conserved between HA subtypes we suggest that, besides the two cytoplasmic acylation sites (including adjacent hydrophobic residues), no other amino acids in the cytoplasmic tail of HA are indispensable for virus assembly and budding. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle Bacteriophage Mediates Efficient Gene Transfer in Combination with Conventional Transfection Reagents
Viruses 2015, 7(12), 6476-6489; doi:10.3390/v7122951
Received: 19 August 2015 / Revised: 26 November 2015 / Accepted: 1 December 2015 / Published: 8 December 2015
Cited by 1 | PDF Full-text (2835 KB) | HTML Full-text | XML Full-text
Abstract
The development of commercially available transfection reagents for gene transfer applications has revolutionized the field of molecular biology and scientific research. However, the challenge remains in ensuring that they are efficient, safe, reproducible and cost effective. Bacteriophage (phage)-based viral vectors have the potential
[...] Read more.
The development of commercially available transfection reagents for gene transfer applications has revolutionized the field of molecular biology and scientific research. However, the challenge remains in ensuring that they are efficient, safe, reproducible and cost effective. Bacteriophage (phage)-based viral vectors have the potential to be utilized for general gene transfer applications within research and industry. Yet, they require adaptations in order to enable them to efficiently enter cells and overcome mammalian cellular barriers, as they infect bacteria only; furthermore, limited progress has been made at increasing their efficiency. The production of a novel hybrid nanocomplex system consisting of two different nanomaterial systems, phage vectors and conventional transfection reagents, could overcome these limitations. Here we demonstrate that the combination of cationic lipids, cationic polymers or calcium phosphate with M13 bacteriophage-derived vectors, engineered to carry a mammalian transgene cassette, resulted in increased cellular attachment, entry and improved transgene expression in human cells. Moreover, addition of a targeting ligand into the nanocomplex system, through genetic engineering of the phage capsid further increased gene expression and was effective in a stable cell line generation application. Overall, this new hybrid nanocomplex system (i) provides enhanced phage-mediated gene transfer; (ii) is applicable for laboratory transfection processes and (iii) shows promise within industry for large-scale gene transfer applications. Full article
Open AccessArticle Role of gga-miR-221 and gga-miR-222 during Tumour Formation in Chickens Infected by Subgroup J Avian Leukosis Virus
Viruses 2015, 7(12), 6538-6551; doi:10.3390/v7122956
Received: 13 October 2015 / Revised: 18 November 2015 / Accepted: 2 December 2015 / Published: 11 December 2015
Cited by 3 | PDF Full-text (4458 KB) | HTML Full-text | XML Full-text
Abstract
Subgroup J avian leukosis virus (ALV-J) causes a neoplastic disease in infected chickens. Differential expression patterns of microRNAs (miRNAs) are closely related to the formation and growth of tumors. (1) Background: This study was undertaken to understand how miRNAs might be related to
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Subgroup J avian leukosis virus (ALV-J) causes a neoplastic disease in infected chickens. Differential expression patterns of microRNAs (miRNAs) are closely related to the formation and growth of tumors. (1) Background: This study was undertaken to understand how miRNAs might be related to tumor growth during ALV-J infection. We chose to characterize the effects of miR-221 and miR-222 on cell proliferation, migration, and apoptosis based on previous microarray data. (2) Methods: In vivo, the expression levels of miR-221 and miR-222 were significantly increased in the liver of ALV-J infected chickens (p < 0.01). Over-expression of gga-miR-221 and gga-miR-222 promoted the proliferation, migration, and growth of DF-1 cells, and decreased the expression of BCL-2 modifying factor (BMF) making cells more resistant to apoptosis. (3) Results: Our results suggest that gga-miR-221 and gga-miR-222 may be tumour formation relevant gene in chicken that promote proliferation, migration, and growth of cancer cells, and inhibit apoptosis. BMF expression was significantly reduced in vivo 70 days after ALV-J infection. They may also play a pivotal role in tumorigenesis during ALV-J infection. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle What Can We Learn from a Metagenomic Analysis of a Georgian Bacteriophage Cocktail?
Viruses 2015, 7(12), 6570-6589; doi:10.3390/v7122958
Received: 30 September 2015 / Revised: 19 November 2015 / Accepted: 30 November 2015 / Published: 12 December 2015
Cited by 5 | PDF Full-text (714 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Phage therapy, a practice widespread in Eastern Europe, has untapped potential in the combat against antibiotic-resistant bacterial infections. However, technology transfer to Western medicine is proving challenging. Bioinformatics analysis could help to facilitate this endeavor. In the present study, the Intesti phage cocktail,
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Phage therapy, a practice widespread in Eastern Europe, has untapped potential in the combat against antibiotic-resistant bacterial infections. However, technology transfer to Western medicine is proving challenging. Bioinformatics analysis could help to facilitate this endeavor. In the present study, the Intesti phage cocktail, a key commercial product of the Eliava Institute, Georgia, has been tested on a selection of bacterial strains, sequenced as a metagenomic sample, de novo assembled and analyzed by bioinformatics methods. Furthermore, eight bacterial host strains were infected with the cocktail and the resulting lysates sequenced and compared to the unamplified cocktail. The analysis identified 23 major phage clusters in different abundances in the cocktail, among those clusters related to the ICTV genera T4likevirus, T5likevirus, T7likevirus, Chilikevirus and Twortlikevirus, as well as a cluster that was quite distant to the database sequences and a novel Proteus phage cluster. Examination of the depth of coverage showed the clusters to have different abundances within the cocktail. The cocktail was found to be composed primarily of Myoviridae (35%) and Siphoviridae (32%), with Podoviridae being a minority (15%). No undesirable genes were found. Full article
Open AccessCommunication HIV-1-Induced Small T Cell Syncytia Can Transfer Virus Particles to Target Cells through Transient Contacts
Viruses 2015, 7(12), 6590-6603; doi:10.3390/v7122959
Received: 30 July 2015 / Revised: 27 November 2015 / Accepted: 2 December 2015 / Published: 12 December 2015
Cited by 4 | PDF Full-text (8376 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
HIV-1 Env mediates fusion of viral and target cell membranes, but it can also mediate fusion of infected (producer) and target cells, thus triggering the formation of multinucleated cells, so-called syncytia. Large, round, immobile syncytia are readily observable in cultures of HIV-1-infected T
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HIV-1 Env mediates fusion of viral and target cell membranes, but it can also mediate fusion of infected (producer) and target cells, thus triggering the formation of multinucleated cells, so-called syncytia. Large, round, immobile syncytia are readily observable in cultures of HIV-1-infected T cells, but these fast growing “fusion sinks” are largely regarded as cell culture artifacts. In contrast, small HIV-1-induced syncytia were seen in the paracortex of peripheral lymph nodes and other secondary lymphoid tissue of HIV-1-positive individuals. Further, recent intravital imaging of lymph nodes in humanized mice early after their infection with HIV-1 demonstrated that a significant fraction of infected cells were highly mobile, small syncytia, suggesting that these entities contribute to virus dissemination. Here, we report that the formation of small, migratory syncytia, for which we provide further quantification in humanized mice, can be recapitulated in vitro if HIV-1-infected T cells are placed into 3D extracellular matrix (ECM) hydrogels rather than being kept in traditional suspension culture systems. Intriguingly, live-cell imaging in hydrogels revealed that these syncytia, similar to individual infected cells, can transiently interact with uninfected cells, leading to rapid virus transfer without cell-cell fusion. Infected cells were also observed to deposit large amounts of viral particles into the extracellular space. Altogether, these observations suggest the need to further evaluate the biological significance of small, T cell-based syncytia and to consider the possibility that these entities do indeed contribute to virus spread and pathogenesis. Full article
(This article belongs to the Section Animal Viruses)
Open AccessArticle Rapid Detection of Listeria by Bacteriophage Amplification and SERS-Lateral Flow Immunochromatography
Viruses 2015, 7(12), 6631-6641; doi:10.3390/v7122962
Received: 28 August 2015 / Revised: 2 November 2015 / Accepted: 10 December 2015 / Published: 14 December 2015
Cited by 1 | PDF Full-text (4552 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A rapid Listeria detection method was developed utilizing A511 bacteriophage amplification combined with surface-enhanced Raman spectroscopy (SERS) and lateral flow immunochromatography (LFI). Anti-A511 antibodies were covalently linked to SERS nanoparticles and printed onto nitrocellulose membranes. Antibody-conjugated SERS nanoparticles were used as quantifiable reporters.
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A rapid Listeria detection method was developed utilizing A511 bacteriophage amplification combined with surface-enhanced Raman spectroscopy (SERS) and lateral flow immunochromatography (LFI). Anti-A511 antibodies were covalently linked to SERS nanoparticles and printed onto nitrocellulose membranes. Antibody-conjugated SERS nanoparticles were used as quantifiable reporters. In the presence of A511, phage-SERS nanoparticle complexes were arrested and concentrated as a visible test line, which was interrogated quantitatively by Raman spectroscopy. An increase in SERS intensity correlated to an increase in captured phage-reporter complexes. SERS limit of detection was 6 × 106 pfu·mL−1, offering detection below that obtainable by the naked eye (LOD 6 × 107 pfu·mL−1). Phage amplification experiments were carried out at a multiplicity of infection (MOI) of 0.1 with 4 different starting phage concentrations monitored over time using SERS-LFI and validated by spot titer assay. Detection of L. monocytogenes concentrations of 1 × 107 colony forming units (cfu)·mL−1, 5 × 106 cfu·mL−1, 5 × 105 cfu·mL−1 and 5 × 104 cfu·mL−1 was achieved in 2, 2, 6, and 8 h, respectively. Similar experiments were conducted at a constant starting phage concentration (5 × 105 pfu·mL−1) with MOIs of 1, 2.5, and 5 and were detected in 2, 4, and 5 h, respectively. Full article
Open AccessArticle Potential Broad Spectrum Inhibitors of the Coronavirus 3CLpro: A Virtual Screening and Structure-Based Drug Design Study
Viruses 2015, 7(12), 6642-6660; doi:10.3390/v7122963
Received: 1 July 2015 / Revised: 16 November 2015 / Accepted: 30 November 2015 / Published: 15 December 2015
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Abstract
Human coronaviruses represent a significant disease burden; however, there is currently no antiviral strategy to combat infection. The outbreak of severe acute respiratory syndrome (SARS) in 2003 and Middle East respiratory syndrome (MERS) less than 10 years later demonstrates the potential of coronaviruses
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Human coronaviruses represent a significant disease burden; however, there is currently no antiviral strategy to combat infection. The outbreak of severe acute respiratory syndrome (SARS) in 2003 and Middle East respiratory syndrome (MERS) less than 10 years later demonstrates the potential of coronaviruses to cross species boundaries and further highlights the importance of identifying novel lead compounds with broad spectrum activity. The coronavirus 3CLpro provides a highly validated drug target and as there is a high degree of sequence homology and conservation in main chain architecture the design of broad spectrum inhibitors is viable. The ZINC drugs-now library was screened in a consensus high-throughput pharmacophore modeling and molecular docking approach by Vina, Glide, GOLD and MM-GBSA. Molecular dynamics further confirmed results obtained from structure-based techniques. A highly defined hit-list of 19 compounds was identified by the structure-based drug design methodologies. As these compounds were extensively validated by a consensus approach and by molecular dynamics, the likelihood that at least one of these compounds is bioactive is excellent. Additionally, the compounds segregate into 15 significantly dissimilar (p < 0.05) clusters based on shape and features, which represent valuable scaffolds that can be used as a basis for future anti-coronaviral inhibitor discovery experiments. Importantly though, the enriched subset of 19 compounds identified from the larger library has to be validated experimentally. Full article
(This article belongs to the Special Issue Bioinformatics and Computational Biology of Viruses)
Open AccessArticle A Flagellar Glycan-Specific Protein Encoded by Campylobacter Phages Inhibits Host Cell Growth
Viruses 2015, 7(12), 6661-6674; doi:10.3390/v7122964
Received: 1 October 2015 / Revised: 24 November 2015 / Accepted: 8 December 2015 / Published: 16 December 2015
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Abstract
We previously characterized a carbohydrate binding protein, Gp047, derived from lytic Campylobacter phage NCTC 12673, as a promising diagnostic tool for the identification of Campylobacter jejuni and Campylobacter coli. We also demonstrated that this protein binds specifically to acetamidino-modified pseudaminic acid residues
[...] Read more.
We previously characterized a carbohydrate binding protein, Gp047, derived from lytic Campylobacter phage NCTC 12673, as a promising diagnostic tool for the identification of Campylobacter jejuni and Campylobacter coli. We also demonstrated that this protein binds specifically to acetamidino-modified pseudaminic acid residues on host flagella, but the role of this protein in the phage lifecycle remains unknown. Here, we report that Gp047 is capable of inhibiting C. jejuni growth both on solid and liquid media, an activity, which we found to be bacteriostatic. The Gp047 domain responsible for bacterial growth inhibition is localized to the C-terminal quarter of the protein, and this activity is both contact- and dose-dependent. Gp047 gene homologues are present in all Campylobacter phages sequenced to date, and the resulting protein is not part of the phage particle. Therefore, these results suggest that either phages of this pathogen have evolved an effector protein capable of host-specific growth inhibition, or that Campylobacter cells have developed a mechanism of regulating their growth upon sensing an impending phage threat. Full article
Open AccessCommunication Development of Phage Lysin LysA2 for Use in Improved Purity Assays for Live Biotherapeutic Products
Viruses 2015, 7(12), 6675-6688; doi:10.3390/v7122965
Received: 29 September 2015 / Revised: 30 November 2015 / Accepted: 10 December 2015 / Published: 16 December 2015
PDF Full-text (9041 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Live biotherapeutic products (LBPs), commonly referred to as probiotics, are typically preparations of live bacteria, such as Lactobacillus and Bifidobacterium species that are considered normal human commensals. Popular interest in probiotics has been increasing with general health benefits being attributed to their consumption,
[...] Read more.
Live biotherapeutic products (LBPs), commonly referred to as probiotics, are typically preparations of live bacteria, such as Lactobacillus and Bifidobacterium species that are considered normal human commensals. Popular interest in probiotics has been increasing with general health benefits being attributed to their consumption, but there is also growing interest in evaluating such products for treatment of specific diseases. While over-the-counter probiotics are generally viewed as very safe, at least in healthy individuals, it must be remembered that clinical studies to assess these products may be done in individuals whose defenses are compromised, such as through a disease process, immunosuppressive clinical treatment, or an immature or aging immune system. One of the major safety criteria for LBPs used in clinical studies is microbial purity, i.e., the absence of extraneous, undesirable microorganisms. The main goal of this project is to develop recombinant phage lysins as reagents for improved purity assays for LBPs. Phage lysins are hydrolytic enzymes containing a cell binding domain that provides specificity and a catalytic domain responsible for lysis and killing. Our approach is to use recombinant phage lysins to selectively kill target product bacteria, which when used for purity assays will allow for outgrowth of potential contaminants under non-selective conditions, thus allowing an unbiased assessment of the presence of contaminants. To develop our approach, we used LysA2, a phage lysin with reported activity against a broad range of Lactobacillus species. We report the lytic profile of a non-tagged recombinant LysA2 against Lactobacillus strains in our collection. We also present a proof-of-concept experiment, showing that addition of partially purified LysA2 to a culture of Lactobacillus jensenii (L. jensenii) spiked with low numbers of Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus ) effectively eliminates or knocks down L. jensenii, allowing for clear detection of the contaminating strains. With continued identification and characterization of phage lysins, we hope that the use of recombinant phage lysins in purity assays for products containing live microbials may offer additional tools to help advance product development of LBPs. Full article
Open AccessArticle Glucose-6-Phosphate Dehydrogenase Enhances Antiviral Response through Downregulation of NADPH Sensor HSCARG and Upregulation of NF-κB Signaling
Viruses 2015, 7(12), 6689-6706; doi:10.3390/v7122966
Received: 7 October 2015 / Revised: 7 December 2015 / Accepted: 10 December 2015 / Published: 17 December 2015
Cited by 2 | PDF Full-text (3441 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Glucose-6-phosphate dehydrogenase (G6PD)-deficient cells are highly susceptible to viral infection. This study examined the mechanism underlying this phenomenon by measuring the expression of antiviral genes—tumor necrosis factor alpha (TNF-α) and GTPase myxovirus resistance 1 (MX1)—in G6PD-knockdown cells
[...] Read more.
Glucose-6-phosphate dehydrogenase (G6PD)-deficient cells are highly susceptible to viral infection. This study examined the mechanism underlying this phenomenon by measuring the expression of antiviral genes—tumor necrosis factor alpha (TNF-α) and GTPase myxovirus resistance 1 (MX1)—in G6PD-knockdown cells upon human coronavirus 229E (HCoV-229E) and enterovirus 71 (EV71) infection. Molecular analysis revealed that the promoter activities of TNF-α and MX1 were downregulated in G6PD-knockdown cells, and that the IκB degradation and DNA binding activity of NF-κB were decreased. The HSCARG protein, a nicotinamide adenine dinucleotide phosphate (NADPH) sensor and negative regulator of NF-κB, was upregulated in G6PD-knockdown cells with decreased NADPH/NADP+ ratio. Treatment of G6PD-knockdown cells with siRNA against HSCARG enhanced the DNA binding activity of NF-κB and the expression of TNF-α and MX1, but suppressed the expression of viral genes; however, the overexpression of HSCARG inhibited the antiviral response. Exogenous G6PD or IDH1 expression inhibited the expression of HSCARG, resulting in increased expression of TNF-α and MX1 and reduced viral gene expression upon virus infection. Our findings suggest that the increased susceptibility of the G6PD-knockdown cells to viral infection was due to impaired NF-κB signaling and antiviral response mediated by HSCARG. Full article
(This article belongs to the Section Antivirals & Vaccines)
Open AccessArticle Ebola Virus Infections in Nonhuman Primates Are Temporally Influenced by Glycoprotein Poly-U Editing Site Populations in the Exposure Material
Viruses 2015, 7(12), 6739-6754; doi:10.3390/v7122969
Received: 20 July 2015 / Revised: 3 December 2015 / Accepted: 7 December 2015 / Published: 19 December 2015
Cited by 5 | PDF Full-text (1481 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Recent experimentation with the variants of the Ebola virus that differ in the glycoprotein’s poly-uridine site, which dictates the form of glycoprotein produced through a transcriptional stutter, has resulted in questions regarding the pathogenicity and lethality of the stocks used to develop products
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Recent experimentation with the variants of the Ebola virus that differ in the glycoprotein’s poly-uridine site, which dictates the form of glycoprotein produced through a transcriptional stutter, has resulted in questions regarding the pathogenicity and lethality of the stocks used to develop products currently undergoing human clinical trials to combat the disease. In order to address these concerns and prevent the delay of these critical research programs, we designed an experiment that permitted us to intramuscularly challenge statistically significant numbers of naïve and vaccinated cynomolgus macaques with either a 7U or 8U variant of the Ebola virus, Kikwit isolate. In naïve animals, no difference in survivorship was observed; however, there was a significant delay in the disease course between the two groups. Significant differences were also observed in time-of-fever, serum chemistry, and hematology. In vaccinated animals, there was no statistical difference in survivorship between either challenge groups, with two succumbing in the 7U group compared to 1 in the 8U challenge group. In summary, survivorship was not affected, but the Ebola virus disease course in nonhuman primates is temporally influenced by glycoprotein poly-U editing site populations. Full article
(This article belongs to the collection Advances in Ebolavirus, Marburgvirus, and Cuevavirus Research)
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Open AccessReview Stem Cell-Based Cell Carrier for Targeted Oncolytic Virotherapy: Translational Opportunity and Open Questions
Viruses 2015, 7(12), 6200-6217; doi:10.3390/v7122921
Received: 14 September 2015 / Revised: 28 October 2015 / Accepted: 3 November 2015 / Published: 27 November 2015
Cited by 4 | PDF Full-text (999 KB) | HTML Full-text | XML Full-text
Abstract
Oncolytic virotherapy for cancer is an innovative therapeutic option where the ability of a virus to promote cell lysis is harnessed and reprogrammed to selectively destroy cancer cells. Such treatment modalities exhibited antitumor activity in preclinical and clinical settings and appear to be
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Oncolytic virotherapy for cancer is an innovative therapeutic option where the ability of a virus to promote cell lysis is harnessed and reprogrammed to selectively destroy cancer cells. Such treatment modalities exhibited antitumor activity in preclinical and clinical settings and appear to be well tolerated when tested in clinical trials. However, the clinical success of oncolytic virotherapy has been significantly hampered due to the inability to target systematic metastasis. This is partly due to the inability of the therapeutic virus to survive in the patient circulation, in order to target tumors at distant sites. An early study from various laboratories demonstrated that cells infected with oncolytic virus can protect the therapeutic payload form the host immune system as well as function as factories for virus production and enhance the therapeutic efficacy of oncolytic virus. While a variety of cell lineages possessed potential as cell carriers, copious investigation has established stem cells as a very attractive cell carrier system in oncolytic virotherapy. The ideal cell carrier desire to be susceptible to viral infection as well as support viral infection, maintain immunosuppressive properties to shield the loaded viruses from the host immune system, and most importantly possess an intrinsic tumor homing ability to deliver loaded viruses directly to the site of the metastasis—all qualities stem cells exhibit. In this review, we summarize the recent work in the development of stem cell-based carrier for oncolytic virotherapy, discuss the advantages and disadvantages of a variety of cell carriers, especially focusing on why stem cells have emerged as the leading candidate, and finally propose a future direction for stem cell-based targeted oncolytic virotherapy that involves its establishment as a viable treatment option for cancer patients in the clinical setting. Full article
(This article belongs to the Special Issue Oncolytic Viruses)
Open AccessReview Natural Products as Tools for Defining How Cellular Metabolism Influences Cellular Immune and Inflammatory Function during Chronic Infection
Viruses 2015, 7(12), 6218-6232; doi:10.3390/v7122933
Received: 2 October 2015 / Revised: 13 November 2015 / Accepted: 19 November 2015 / Published: 30 November 2015
Cited by 3 | PDF Full-text (5607 KB) | HTML Full-text | XML Full-text
Abstract
Chronic viral infections like those caused by hepatitis C virus (HCV) and human immunodeficiency virus (HIV) cause disease that establishes an ongoing state of chronic inflammation. While there have been tremendous improvements towards curing HCV with directly acting antiviral agents (DAA) and keeping
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Chronic viral infections like those caused by hepatitis C virus (HCV) and human immunodeficiency virus (HIV) cause disease that establishes an ongoing state of chronic inflammation. While there have been tremendous improvements towards curing HCV with directly acting antiviral agents (DAA) and keeping HIV viral loads below detection with antiretroviral therapy (ART), there is still a need to control inflammation in these diseases. Recent studies indicate that many natural products like curcumin, resveratrol and silymarin alter cellular metabolism and signal transduction pathways via enzymes such as adenosine monophosphate kinase (AMPK) and mechanistic target of rapamycin (mTOR), and these pathways directly influence cellular inflammatory status (such as NF-κB) and immune function. Natural products represent a vast toolkit to dissect and define how cellular metabolism controls cellular immune and inflammatory function. Full article
(This article belongs to the Special Issue HCV Drug Resistance)
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Open AccessReview Potential for Improving Potency and Specificity of Reovirus Oncolysis with Next-Generation Reovirus Variants
Viruses 2015, 7(12), 6251-6278; doi:10.3390/v7122936
Received: 19 September 2015 / Revised: 10 November 2015 / Accepted: 18 November 2015 / Published: 1 December 2015
Cited by 2 | PDF Full-text (4161 KB) | HTML Full-text | XML Full-text
Abstract
Viruses that specifically replicate in tumor over normal cells offer promising cancer therapies. Oncolytic viruses (OV) not only kill the tumor cells directly; they also promote anti-tumor immunotherapeutic responses. Other major advantages of OVs are that they dose-escalate in tumors and can be
[...] Read more.
Viruses that specifically replicate in tumor over normal cells offer promising cancer therapies. Oncolytic viruses (OV) not only kill the tumor cells directly; they also promote anti-tumor immunotherapeutic responses. Other major advantages of OVs are that they dose-escalate in tumors and can be genetically engineered to enhance potency and specificity. Unmodified wild type reovirus is a propitious OV currently in phase I–III clinical trials. This review summarizes modifications to reovirus that may improve potency and/or specificity during oncolysis. Classical genetics approaches have revealed reovirus variants with improved adaptation towards tumors or with enhanced ability to establish specific steps of virus replication and cell killing among transformed cells. The recent emergence of a reverse genetics system for reovirus has provided novel strategies to fine-tune reovirus proteins or introduce exogenous genes that could promote oncolytic activity. Over the next decade, these findings are likely to generate better-optimized second-generation reovirus vectors and improve the efficacy of oncolytic reotherapy. Full article
(This article belongs to the Special Issue Oncolytic Viruses)
Open AccessReview Evidence for Oncolytic Virotherapy: Where Have We Got to and Where Are We Going?
Viruses 2015, 7(12), 6291-6312; doi:10.3390/v7122938
Received: 24 September 2015 / Revised: 20 November 2015 / Accepted: 25 November 2015 / Published: 2 December 2015
Cited by 13 | PDF Full-text (263 KB) | HTML Full-text | XML Full-text
Abstract
The last few years have seen an increased interest in immunotherapy in the treatment of malignant disease. In particular, there has been significant enthusiasm for oncolytic virotherapy, with a large amount of pre-clinical data showing promise in animal models in a wide range
[...] Read more.
The last few years have seen an increased interest in immunotherapy in the treatment of malignant disease. In particular, there has been significant enthusiasm for oncolytic virotherapy, with a large amount of pre-clinical data showing promise in animal models in a wide range of tumour types. How do we move forward into the clinical setting and translate something which has such potential into meaningful clinical outcomes? Here, we review how the field of oncolytic virotherapy has developed thus far and what the future may hold. Full article
(This article belongs to the Special Issue Oncolytic Viruses)
Open AccessReview Viral Infection at High Magnification: 3D Electron Microscopy Methods to Analyze the Architecture of Infected Cells
Viruses 2015, 7(12), 6316-6345; doi:10.3390/v7122940
Received: 28 July 2015 / Revised: 16 October 2015 / Accepted: 16 November 2015 / Published: 3 December 2015
Cited by 5 | PDF Full-text (5082 KB) | HTML Full-text | XML Full-text
Abstract
As obligate intracellular parasites, viruses need to hijack their cellular hosts and reprogram their machineries in order to replicate their genomes and produce new virions. For the direct visualization of the different steps of a viral life cycle (attachment, entry, replication, assembly and
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As obligate intracellular parasites, viruses need to hijack their cellular hosts and reprogram their machineries in order to replicate their genomes and produce new virions. For the direct visualization of the different steps of a viral life cycle (attachment, entry, replication, assembly and egress) electron microscopy (EM) methods are extremely helpful. While conventional EM has given important information about virus-host cell interactions, the development of three-dimensional EM (3D-EM) approaches provides unprecedented insights into how viruses remodel the intracellular architecture of the host cell. During the last years several 3D-EM methods have been developed. Here we will provide a description of the main approaches and examples of innovative applications. Full article
(This article belongs to the Special Issue Electron Microscopy in Virus Diagnostics and Research)
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Open AccessReview Virologic Tools for HCV Drug Resistance Testing
Viruses 2015, 7(12), 6346-6359; doi:10.3390/v7122941
Received: 18 September 2015 / Revised: 28 November 2015 / Accepted: 30 November 2015 / Published: 4 December 2015
Cited by 9 | PDF Full-text (208 KB) | HTML Full-text | XML Full-text
Abstract
Recent advances in molecular biology have led to the development of new antiviral drugs that target specific steps of the Hepatitis C Virus (HCV) lifecycle. These drugs, collectively termed direct-acting antivirals (DAAs), include non-structural (NS) HCV protein inhibitors, NS3/4A protease inhibitors, NS5B RNA-dependent
[...] Read more.
Recent advances in molecular biology have led to the development of new antiviral drugs that target specific steps of the Hepatitis C Virus (HCV) lifecycle. These drugs, collectively termed direct-acting antivirals (DAAs), include non-structural (NS) HCV protein inhibitors, NS3/4A protease inhibitors, NS5B RNA-dependent RNA polymerase inhibitors (nucleotide analogues and non-nucleoside inhibitors), and NS5A inhibitors. Due to the high genetic variability of HCV, the outcome of DAA-based therapies may be altered by the selection of amino-acid substitutions located within the targeted proteins, which affect viral susceptibility to the administered compounds. At the drug developmental stage, preclinical and clinical characterization of HCV resistance to new drugs in development is mandatory. In the clinical setting, accurate diagnostic tools have become available to monitor drug resistance in patients who receive treatment with DAAs. In this review, we describe tools available to investigate drug resistance in preclinical studies, clinical trials and clinical practice. Full article
(This article belongs to the Special Issue HCV Drug Resistance)
Open AccessReview From Immunodeficiency to Humanization: The Contribution of Mouse Models to Explore HTLV-1 Leukemogenesis
Viruses 2015, 7(12), 6371-6386; doi:10.3390/v7122944
Received: 30 September 2015 / Revised: 16 November 2015 / Accepted: 30 November 2015 / Published: 7 December 2015
Cited by 1 | PDF Full-text (3035 KB) | HTML Full-text | XML Full-text
Abstract
The first discovered human retrovirus, Human T-Lymphotropic Virus type 1 (HTLV-1), is responsible for an aggressive form of T cell leukemia/lymphoma. Mouse models recapitulating the leukemogenesis process have been helpful for understanding the mechanisms underlying the pathogenesis of this retroviral-induced disease. This review
[...] Read more.
The first discovered human retrovirus, Human T-Lymphotropic Virus type 1 (HTLV-1), is responsible for an aggressive form of T cell leukemia/lymphoma. Mouse models recapitulating the leukemogenesis process have been helpful for understanding the mechanisms underlying the pathogenesis of this retroviral-induced disease. This review will focus on the recent advances in the generation of immunodeficient and human hemato-lymphoid system mice with a particular emphasis on the development of mouse models for HTLV-1-mediated pathogenesis, their present limitations and the challenges yet to be addressed. Full article
(This article belongs to the Special Issue Recent Advances in HTLV Research 2015) Printed Edition available
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Open AccessReview Infectious Entry Pathway of Enterovirus B Species
Viruses 2015, 7(12), 6387-6399; doi:10.3390/v7122945
Received: 9 October 2015 / Revised: 17 November 2015 / Accepted: 25 November 2015 / Published: 7 December 2015
Cited by 5 | PDF Full-text (1095 KB) | HTML Full-text | XML Full-text
Abstract
Enterovirus B species (EV-B) are responsible for a vast number of mild and serious acute infections. They are also suspected of remaining in the body, where they cause persistent infections contributing to chronic diseases such as type I diabetes. Recent studies of the
[...] Read more.
Enterovirus B species (EV-B) are responsible for a vast number of mild and serious acute infections. They are also suspected of remaining in the body, where they cause persistent infections contributing to chronic diseases such as type I diabetes. Recent studies of the infectious entry pathway of these viruses revealed remarkable similarities, including non-clathrin entry of large endosomes originating from the plasma membrane invaginations. Many cellular factors regulating the efficient entry have recently been associated with macropinocytic uptake, such as Rac1, serine/threonine p21-activated kinase (Pak1), actin, Na/H exchanger, phospholipace C (PLC) and protein kinase Cα (PKCα). Another characteristic feature is the entry of these viruses to neutral endosomes, independence of endosomal acidification and low association with acidic lysosomes. The biogenesis of neutral multivesicular bodies is crucial for their infection, at least for echovirus 1 (E1) and coxsackievirus A9 (CVA9). These pathways are triggered by the virus binding to their receptors on the plasma membrane, and they are not efficiently recycled like other cellular pathways used by circulating receptors. Therefore, the best “markers” of these pathways may be the viruses and often their receptors. A deeper understanding of this pathway and associated endosomes is crucial in elucidating the mechanisms of enterovirus uncoating and genome release from the endosomes to start efficient replication. Full article
(This article belongs to the Special Issue Recent Progress in Enterovirus Research)
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Open AccessReview Epidemiological Research on Hand, Foot, and Mouth Disease in Mainland China
Viruses 2015, 7(12), 6400-6411; doi:10.3390/v7122947
Received: 21 September 2015 / Revised: 27 November 2015 / Accepted: 1 December 2015 / Published: 7 December 2015
Cited by 6 | PDF Full-text (1360 KB) | HTML Full-text | XML Full-text
Abstract
Hand, foot, and mouth disease (HFMD), which has led to millions of attacks and several outbreaks across the world and become more predominant in Asia-Pacific Region, especially in Mainland China, is caused by several Human Enteroviruses including new enterovirus, coxsakievirus and echovirus. In
[...] Read more.
Hand, foot, and mouth disease (HFMD), which has led to millions of attacks and several outbreaks across the world and become more predominant in Asia-Pacific Region, especially in Mainland China, is caused by several Human Enteroviruses including new enterovirus, coxsakievirus and echovirus. In recent years, much research has focused on the epidemiological characteristics of HFMD. In this article, multiple characteristics of HFMD such as basic epidemiology, etiology and molecular epidemiology; influencing factors; detection; and surveillance are reviewed, as these can be help protect high risks groups, prevalence prediction and policy making for disease prevention. Full article
(This article belongs to the Special Issue Recent Progress in Enterovirus Research)
Open AccessReview Recent Progress towards Novel EV71 Anti-Therapeutics and Vaccines
Viruses 2015, 7(12), 6441-6457; doi:10.3390/v7122949
Received: 29 September 2015 / Revised: 30 November 2015 / Accepted: 1 December 2015 / Published: 8 December 2015
Cited by 8 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text
Abstract
Enterovirus 71 (EV71) is a group of viruses that belongs to the Picornaviridae family, which also includes viruses such as polioviruses. EV71, together with coxsackieviruses, is widely known for its association with Hand Foot Mouth Disease (HFMD), which generally affects children age five
[...] Read more.
Enterovirus 71 (EV71) is a group of viruses that belongs to the Picornaviridae family, which also includes viruses such as polioviruses. EV71, together with coxsackieviruses, is widely known for its association with Hand Foot Mouth Disease (HFMD), which generally affects children age five and below. Besides HFMD, EV71 can also trigger more severe and life-threatening neurological conditions such as encephalitis. Considering the lack of a vaccine and antiviral drug against EV71, together with the increasing spread of these viruses, the development of such drugs and vaccines becomes the top priority in protecting our younger generations. This article, hence, reviews some of the recent progress in the formulations of anti-therapeutics and vaccine generation for EV71, covering (i) inactivated vaccines; (ii) baculovirus-expressed vaccines against EV71; (iii) human intravenous immunoglobulin (IVIg) treatment; and (iv) the use of monoclonal antibody therapy as a prevention and treatment for EV71 infections. Full article
(This article belongs to the Special Issue Recent Progress in Enterovirus Research)
Open AccessReview Roles of HTLV-1 basic Zip Factor (HBZ) in Viral Chronicity and Leukemic Transformation. Potential New Therapeutic Approaches to Prevent and Treat HTLV-1-Related Diseases
Viruses 2015, 7(12), 6490-6505; doi:10.3390/v7122952
Received: 15 October 2015 / Revised: 24 November 2015 / Accepted: 1 December 2015 / Published: 9 December 2015
Cited by 5 | PDF Full-text (560 KB) | HTML Full-text | XML Full-text
Abstract
More than thirty years have passed since human T-cell leukemia virus type 1 (HTLV-1) was described as the first retrovirus to be the causative agent of a human cancer, adult T-cell leukemia (ATL), but the precise mechanism behind HTLV-1 pathogenesis still remains elusive.
[...] Read more.
More than thirty years have passed since human T-cell leukemia virus type 1 (HTLV-1) was described as the first retrovirus to be the causative agent of a human cancer, adult T-cell leukemia (ATL), but the precise mechanism behind HTLV-1 pathogenesis still remains elusive. For more than two decades, the transforming ability of HTLV-1 has been exclusively associated to the viral transactivator Tax. Thirteen year ago, we first reported that the minus strand of HTLV-1 encoded for a basic Zip factor factor (HBZ), and since then several teams have underscored the importance of this antisense viral protein for the maintenance of a chronic infection and the proliferation of infected cells. More recently, we as well as others have demonstrated that HBZ has the potential to transform cells both in vitro and in vivo. In this review, we focus on the latest progress in our understanding of HBZ functions in chronicity and cellular transformation. We will discuss the involvement of this paradigm shift of HTLV-1 research on new therapeutic approaches to treat HTLV-1-related human diseases. Full article
(This article belongs to the Special Issue Recent Advances in HTLV Research 2015) Printed Edition available
Open AccessReview Dendritic Cells in Oncolytic Virus-Based Anti-Cancer Therapy
Viruses 2015, 7(12), 6506-6525; doi:10.3390/v7122953
Received: 9 September 2015 / Revised: 10 November 2015 / Accepted: 27 November 2015 / Published: 9 December 2015
Cited by 1 | PDF Full-text (951 KB) | HTML Full-text | XML Full-text
Abstract
Dendritic cells (DCs) are specialized antigen-presenting cells that have a notable role in the initiation and regulation of innate and adaptive immune responses. In the context of cancer, appropriately activated DCs can induce anti-tumor immunity by activating innate immune cells and tumor-specific lymphocytes
[...] Read more.
Dendritic cells (DCs) are specialized antigen-presenting cells that have a notable role in the initiation and regulation of innate and adaptive immune responses. In the context of cancer, appropriately activated DCs can induce anti-tumor immunity by activating innate immune cells and tumor-specific lymphocytes that target cancer cells. However, the tumor microenvironment (TME) imposes different mechanisms that facilitate the impairment of DC functions, such as inefficient antigen presentation or polarization into immunosuppressive DCs. These tumor-associated DCs thus fail to initiate tumor-specific immunity, and indirectly support tumor progression. Hence, there is increasing interest in identifying interventions that can overturn DC impairment within the TME. Many reports thus far have studied oncolytic viruses (OVs), viruses that preferentially target and kill cancer cells, for their capacity to enhance DC-mediated anti-tumor effects. Herein, we describe the general characteristics of DCs, focusing on their role in innate and adaptive immunity in the context of the TME. We also examine how DC-OV interaction affects DC recruitment, OV delivery, and anti-tumor immunity activation. Understanding these roles of DCs in the TME and OV infection is critical in devising strategies to further harness the anti-tumor effects of both DCs and OVs, ultimately enhancing the efficacy of OV-based oncotherapy. Full article
(This article belongs to the Special Issue Oncolytic Viruses)
Open AccessReview CDC42 Use in Viral Cell Entry Processes by RNA Viruses
Viruses 2015, 7(12), 6526-6536; doi:10.3390/v7122955
Received: 24 June 2015 / Revised: 3 November 2015 / Accepted: 30 November 2015 / Published: 10 December 2015
PDF Full-text (825 KB) | HTML Full-text | XML Full-text
Abstract
The cellular actin cytoskeleton presents a barrier that must be overcome by many viruses, and it has become increasingly apparent many viral species have developed a diverse repertoire of mechanisms to hijack cellular actin-regulating signalling pathways as part of their cell entry processes.
[...] Read more.
The cellular actin cytoskeleton presents a barrier that must be overcome by many viruses, and it has become increasingly apparent many viral species have developed a diverse repertoire of mechanisms to hijack cellular actin-regulating signalling pathways as part of their cell entry processes. The Rho family GTPase Cdc42 is appreciated as a key moderator of cellular actin dynamics, and the development of specific Cdc42-inhibiting agents has given us an unprecedented ability to investigate its individual role in signalling pathways. However, investigative use of said agents, and the subsequent characterisation of the role Cdc42 plays in viral entry processes has been lacking. Here, we describe the current literature on the role of Cdc42 in human immunodeficiency virus (HIV)-1 cell entry, which represents the most investigated instance of Cdc42 function in viral cell entry processes, and also review evidence of Cdc42 use in other RNA virus cell entries, demonstrating prime areas for more extensive research using similar techniques. Full article
(This article belongs to the Section Antivirals & Vaccines)
Open AccessReview Herpesvirus gB: A Finely Tuned Fusion Machine
Viruses 2015, 7(12), 6552-6569; doi:10.3390/v7122957
Received: 16 October 2015 / Revised: 15 November 2015 / Accepted: 27 November 2015 / Published: 11 December 2015
Cited by 7 | PDF Full-text (2249 KB) | HTML Full-text | XML Full-text
Abstract
Enveloped viruses employ a class of proteins known as fusogens to orchestrate the merger of their surrounding envelope and a target cell membrane. Most fusogens accomplish this task alone, by binding cellular receptors and subsequently catalyzing the membrane fusion process. Surprisingly, in herpesviruses,
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Enveloped viruses employ a class of proteins known as fusogens to orchestrate the merger of their surrounding envelope and a target cell membrane. Most fusogens accomplish this task alone, by binding cellular receptors and subsequently catalyzing the membrane fusion process. Surprisingly, in herpesviruses, these functions are distributed among multiple proteins: the conserved fusogen gB, the conserved gH/gL heterodimer of poorly defined function, and various non-conserved receptor-binding proteins. We summarize what is currently known about gB from two closely related herpesviruses, HSV-1 and HSV-2, with emphasis on the structure of the largely uncharted membrane interacting regions of this fusogen. We propose that the unusual mechanism of herpesvirus fusion could be linked to the unique architecture of gB. Full article
(This article belongs to the Special Issue Viral Glycoprotein Structure)
Open AccessReview Recent Advances in Therapeutic Approaches for Adult T-cell Leukemia/Lymphoma
Viruses 2015, 7(12), 6604-6612; doi:10.3390/v7122960
Received: 30 September 2015 / Revised: 29 November 2015 / Accepted: 3 December 2015 / Published: 14 December 2015
Cited by 6 | PDF Full-text (187 KB) | HTML Full-text | XML Full-text
Abstract
Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell lymphoma caused by human T-cell leukemia/lymphoma virus type 1 (HTLV-1). ATLL occurs in approximately 3%–5% of HTLV-1 carriers during their lifetime and follows a heterogeneous clinical course. The Shimoyama classification has been frequently used for
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Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell lymphoma caused by human T-cell leukemia/lymphoma virus type 1 (HTLV-1). ATLL occurs in approximately 3%–5% of HTLV-1 carriers during their lifetime and follows a heterogeneous clinical course. The Shimoyama classification has been frequently used for treatment decisions in ATLL patients, and antiviral therapy has been reportedly promising, particularly in patients with indolent type ATLL; however, the prognosis continues to be dismal for patients with aggressive-type ATLL. Recent efforts to improve treatment outcomes have been focused on the development of prognostic stratification and improved dosage, timing, and combination of therapeutic modalities, such as antiviral therapy, chemotherapy, allogeneic hematopoietic stem cell transplantation, and molecular targeted therapy. Full article
(This article belongs to the Special Issue Recent Advances in HTLV Research 2015) Printed Edition available
Open AccessReview Innate Immunity and Immune Evasion by Enterovirus 71
Viruses 2015, 7(12), 6613-6630; doi:10.3390/v7122961
Received: 28 September 2015 / Revised: 16 November 2015 / Accepted: 9 December 2015 / Published: 14 December 2015
Cited by 5 | PDF Full-text (1310 KB) | HTML Full-text | XML Full-text
Abstract
Enterovirus 71 (EV71) is a major infectious disease affecting millions of people worldwide and it is the main etiological agent for outbreaks of hand foot and mouth disease (HFMD). Infection is often associated with severe gastroenterological, pulmonary, and neurological diseases that are most
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Enterovirus 71 (EV71) is a major infectious disease affecting millions of people worldwide and it is the main etiological agent for outbreaks of hand foot and mouth disease (HFMD). Infection is often associated with severe gastroenterological, pulmonary, and neurological diseases that are most prevalent in children. Currently, no effective vaccine or antiviral drugs exist against EV71 infection. A lack of knowledge on the molecular mechanisms of EV71 infection in the host and the virus-host interactions is a major constraint to developing specific antiviral strategies against this infection. Previous studies have identified and characterized the function of several viral proteins produced by EV71 that interact with the host innate immune proteins, including type I interferon signaling and microRNAs. These interactions eventually promote efficient viral replication and increased susceptibility to the disease. In this review we discuss the functions of EV71 viral proteins in the modulation of host innate immune responses to facilitate viral replication. Full article
(This article belongs to the Special Issue Recent Progress in Enterovirus Research)
Open AccessReview The Dual Role of Exosomes in Hepatitis A and C Virus Transmission and Viral Immune Activation
Viruses 2015, 7(12), 6707-6715; doi:10.3390/v7122967
Received: 19 August 2015 / Revised: 30 November 2015 / Accepted: 10 December 2015 / Published: 17 December 2015
Cited by 5 | PDF Full-text (534 KB) | HTML Full-text | XML Full-text
Abstract
Exosomes are small nanovesicles of about 100 nm in diameter that act as intercellular messengers because they can shuttle RNA, proteins and lipids between different cells. Many studies have found that exosomes also play various roles in viral pathogenesis. Hepatitis A virus (HAV;
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Exosomes are small nanovesicles of about 100 nm in diameter that act as intercellular messengers because they can shuttle RNA, proteins and lipids between different cells. Many studies have found that exosomes also play various roles in viral pathogenesis. Hepatitis A virus (HAV; a picornavirus) and Hepatitis C virus (HCV; a flavivirus) two single strand plus-sense RNA viruses, in particular, have been found to use exosomes for viral transmission thus evading antibody-mediated immune responses. Paradoxically, both viral exosomes can also be detected by plasmacytoid dendritic cells (pDCs) leading to innate immune activation and type I interferon production. This article will review recent findings regarding these two viruses and outline how exosomes are involved in their transmission and immune sensing. Full article
(This article belongs to the Special Issue Viruses and Exosomes)
Open AccessReview Mechanisms of Hepatitis C Viral Resistance to Direct Acting Antivirals
Viruses 2015, 7(12), 6716-6729; doi:10.3390/v7122968
Received: 6 October 2015 / Revised: 24 November 2015 / Accepted: 8 December 2015 / Published: 18 December 2015
Cited by 15 | PDF Full-text (671 KB) | HTML Full-text | XML Full-text
Abstract
There has been a remarkable transformation in the treatment of chronic hepatitis C in recent years with the development of direct acting antiviral agents targeting virus encoded proteins important for viral replication including NS3/4A, NS5A and NS5B. These agents have shown high sustained
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There has been a remarkable transformation in the treatment of chronic hepatitis C in recent years with the development of direct acting antiviral agents targeting virus encoded proteins important for viral replication including NS3/4A, NS5A and NS5B. These agents have shown high sustained viral response (SVR) rates of more than 90% in phase 2 and phase 3 clinical trials; however, this is slightly lower in real-life cohorts. Hepatitis C virus resistant variants are seen in most patients who do not achieve SVR due to selection and outgrowth of resistant hepatitis C virus variants within a given host. These resistance associated mutations depend on the class of direct-acting antiviral drugs used and also vary between hepatitis C virus genotypes and subtypes. The understanding of these mutations has a clear clinical implication in terms of choice and combination of drugs used. In this review, we describe mechanism of action of currently available drugs and summarize clinically relevant resistance data. Full article
(This article belongs to the Special Issue HCV Drug Resistance)

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Open AccessBrief Report Identification of a New Ribonucleoside Inhibitor of Ebola Virus Replication
Viruses 2015, 7(12), 6233-6240; doi:10.3390/v7122934
Received: 9 July 2015 / Revised: 16 November 2015 / Accepted: 18 November 2015 / Published: 1 December 2015
Cited by 3 | PDF Full-text (917 KB) | HTML Full-text | XML Full-text | Correction
Abstract
The current outbreak of Ebola virus (EBOV) in West Africa has claimed the lives of more than 15,000 people and highlights an urgent need for therapeutics capable of preventing virus replication. In this study we screened known nucleoside analogues for their ability to
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The current outbreak of Ebola virus (EBOV) in West Africa has claimed the lives of more than 15,000 people and highlights an urgent need for therapeutics capable of preventing virus replication. In this study we screened known nucleoside analogues for their ability to interfere with EBOV replication. Among them, the cytidine analogue β-d-N4-hydroxycytidine (NHC) demonstrated potent inhibitory activities against EBOV replication and spread at non-cytotoxic concentrations. Thus, NHC constitutes an interesting candidate for the development of a suitable drug treatment against EBOV. Full article
(This article belongs to the collection Advances in Ebolavirus, Marburgvirus, and Cuevavirus Research)
Open AccessCorrection Correction: Graillot, B.; et al. Progressive Adaptation of a CpGV Isolate to Codling Moth Populations Resistant to CpGV-M. Viruses 2014, 6, 5135–5144
Viruses 2015, 7(12), 6313-6315; doi:10.3390/v7122939
Received: 16 November 2015 / Accepted: 26 November 2015 / Published: 3 December 2015
Cited by 2 | PDF Full-text (302 KB) | HTML Full-text | XML Full-text
Abstract
In our article “Progressive Adaptation of a CpGV Isolate to Codling Moth Populations Resistant to CpGV-M.” (Viruses 2014, 6, 5135–5144; doi:10.3390/v6125135) [1] we obtained resistance values of the codling moth, Cydia pomonella, RGV laboratory colony [2], when challenged with Cydia pomonella
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In our article “Progressive Adaptation of a CpGV Isolate to Codling Moth Populations Resistant to CpGV-M.” (Viruses 2014, 6, 5135–5144; doi:10.3390/v6125135) [1] we obtained resistance values of the codling moth, Cydia pomonella, RGV laboratory colony [2], when challenged with Cydia pomonella Granulovirus, Mexican Isolate (CpGV-M), that were lower than those previously published [2]. Careful analysis of both the RGV colony and the CpGV-M virus stock used led to the realization that a low level contamination of this virus stock with CpGV-R5 occurred. We have made new tests with a verified stock, and the results are now in agreement with those previously published. Full article
(This article belongs to the Section Insect Viruses)
Open AccessCorrection Correction: Moustafa, I.M.; et al. Conformational Ensemble of the Poliovirus 3CD Precursor Observed by MD Simulations and Confirmed by SAXS: A Strategy to Expand the Viral Proteome? Viruses 2015, 7, 5962–5986
Viruses 2015, 7(12), 6537; doi:10.3390/v7122954
Received: 30 November 2015 / Accepted: 30 November 2015 / Published: 11 December 2015
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Abstract The Viruses Editorial Office wishes to add the section “Supplementary Materials” to [? ]. [...] Full article
Open AccessCommentary Spotlight on HIV-1 Nef: SERINC3 and SERINC5 Identified as Restriction Factors Antagonized by the Pathogenesis Factor
Viruses 2015, 7(12), 6730-6738; doi:10.3390/v7122970
Received: 27 October 2015 / Revised: 15 December 2015 / Accepted: 16 December 2015 / Published: 19 December 2015
PDF Full-text (492 KB) | HTML Full-text | XML Full-text
Abstract
The Nef protein is an accessory gene product encoded by human immunodeficiency virus types 1 and 2 (HIV-1/-2) and simian immunodeficiency virus (SIV) that boosts virus replication in the infected host and accelerates disease progression. Unlike the HIV-1 accessory proteins Vif, Vpr and
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The Nef protein is an accessory gene product encoded by human immunodeficiency virus types 1 and 2 (HIV-1/-2) and simian immunodeficiency virus (SIV) that boosts virus replication in the infected host and accelerates disease progression. Unlike the HIV-1 accessory proteins Vif, Vpr and Vpu, Nef was, until recently, not known to antagonize the antiviral activity of a host cell restriction factor. Two recent reports now describe the host cell proteins serine incorporator 3 and 5 (SERINC3 and SERINC5) as potent inhibitors of HIV-1 particle infectivity and demonstrate that Nef counteracts these effects. These findings establish SERINC3/5 as restrictions to HIV replication in human cells and define a novel activity for the HIV pathogenesis factor Nef. Full article
(This article belongs to the Section Editorial)

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