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Viruses, Volume 10, Issue 10 (October 2018)

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Cover Story (view full-size image) Photodynamic inactivation (PDI) employs a photosensitizer, light, and oxygen to create a local [...] Read more.
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Open AccessArticle Biodiversity of Streptococcus thermophilus Phages in Global Dairy Fermentations
Viruses 2018, 10(10), 577; https://doi.org/10.3390/v10100577
Received: 28 September 2018 / Revised: 18 October 2018 / Accepted: 19 October 2018 / Published: 22 October 2018
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Abstract
Streptococcus thermophilus strains are among the most widely employed starter cultures in dairy fermentations, second only to those of Lactococcus lactis. The extensive application of this species provides considerable opportunity for the proliferation of its infecting (bacterio)phages. Until recently, dairy streptococcal phages
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Streptococcus thermophilus strains are among the most widely employed starter cultures in dairy fermentations, second only to those of Lactococcus lactis. The extensive application of this species provides considerable opportunity for the proliferation of its infecting (bacterio)phages. Until recently, dairy streptococcal phages were classified into two groups (cos and pac groups), while more recently, two additional groups have been identified (5093 and 987 groups). This highlights the requirement for consistent monitoring of phage populations in the industry. Here, we report a survey of 35 samples of whey derived from 27 dairy fermentation facilities in ten countries against a panel of S. thermophilus strains. This culminated in the identification of 172 plaque isolates, which were characterized by multiplex PCR, restriction fragment length polymorphism analysis, and host range profiling. Based on this characterisation, 39 distinct isolates representing all four phage groups were selected for genome sequencing. Genetic diversity was observed among the cos isolates and correlations between receptor binding protein phylogeny and host range were also clear within this phage group. The 987 phages isolated within this study shared high levels of sequence similarity, yet displayed reduced levels of similarity to those identified in previous studies, indicating that they are subject to ongoing genetic diversification. Full article
(This article belongs to the Special Issue Viruses of Microbes V: Biodiversity and Future Applications)
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Open AccessArticle Gene Gangs of the Chloroviruses: Conserved Clusters of Collinear Monocistronic Genes
Viruses 2018, 10(10), 576; https://doi.org/10.3390/v10100576
Received: 12 September 2018 / Revised: 12 October 2018 / Accepted: 17 October 2018 / Published: 20 October 2018
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Abstract
Chloroviruses (family Phycodnaviridae) are dsDNA viruses found throughout the world’s inland waters. The open reading frames in the genomes of 41 sequenced chloroviruses (330 ± 40 kbp each) representing three virus types were analyzed for evidence of evolutionarily conserved local genomic “contexts”,
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Chloroviruses (family Phycodnaviridae) are dsDNA viruses found throughout the world’s inland waters. The open reading frames in the genomes of 41 sequenced chloroviruses (330 ± 40 kbp each) representing three virus types were analyzed for evidence of evolutionarily conserved local genomic “contexts”, the organization of biological information into units of a scale larger than a gene. Despite a general loss of synteny between virus types, we informatically detected a highly conserved genomic context defined by groups of three or more genes that we have termed “gene gangs”. Unlike previously described local genomic contexts, the definition of gene gangs requires only that member genes be consistently co-localized and are not constrained by strand, regulatory sites, or intervening sequences (and therefore represent a new type of conserved structural genomic element). An analysis of functional annotations and transcriptomic data suggests that some of the gene gangs may organize genes involved in specific biochemical processes, but that this organization does not involve their coordinated expression. Full article
(This article belongs to the Special Issue Algae Virus)
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Open AccessArticle Mason-Pfizer Monkey Virus Envelope Glycoprotein Cycling and Its Vesicular Co-Transport with Immature Particles
Viruses 2018, 10(10), 575; https://doi.org/10.3390/v10100575
Received: 1 July 2018 / Revised: 10 October 2018 / Accepted: 18 October 2018 / Published: 20 October 2018
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Abstract
The envelope glycoprotein (Env) plays a crucial role in the retroviral life cycle by mediating primary interactions with the host cell. As described previously and expanded on in this paper, Env mediates the trafficking of immature Mason-Pfizer monkey virus (M-PMV) particles to the
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The envelope glycoprotein (Env) plays a crucial role in the retroviral life cycle by mediating primary interactions with the host cell. As described previously and expanded on in this paper, Env mediates the trafficking of immature Mason-Pfizer monkey virus (M-PMV) particles to the plasma membrane (PM). Using a panel of labeled RabGTPases as endosomal markers, we identified Env mostly in Rab7a- and Rab9a-positive endosomes. Based on an analysis of the transport of recombinant fluorescently labeled M-PMV Gag and Env proteins, we propose a putative mechanism of the intracellular trafficking of M-PMV Env and immature particles. According to this model, a portion of Env is targeted from the trans-Golgi network (TGN) to Rab7a-positive endosomes. It is then transported to Rab9a-positive endosomes and back to the TGN. It is at the Rab9a vesicles where the immature particles may anchor to the membranes of the Env-containing vesicles, preventing Env recycling to the TGN. These Gag-associated vesicles are then transported to the plasma membrane. Full article
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Open AccessArticle Improved Baculovirus Vectors for Transduction and Gene Expression in Human Pancreatic Islet Cells
Viruses 2018, 10(10), 574; https://doi.org/10.3390/v10100574
Received: 5 October 2018 / Accepted: 18 October 2018 / Published: 20 October 2018
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Abstract
Pancreatic islet transplantation is a promising treatment for type 1 diabetes mellitus offering improved glycaemic control by restoring insulin production. Improved human pancreatic islet isolation has led to higher islet transplantation success. However, as many as 50% of islets are lost after transplantation
[...] Read more.
Pancreatic islet transplantation is a promising treatment for type 1 diabetes mellitus offering improved glycaemic control by restoring insulin production. Improved human pancreatic islet isolation has led to higher islet transplantation success. However, as many as 50% of islets are lost after transplantation due to immune responses and cellular injury, gene therapy presents a novel strategy to protect pancreatic islets for improved survival post-transplantation. To date, most of the vectors used in clinical trials and gene therapy studies have been derived from mammalian viruses such as adeno-associated or retrovirus. However, baculovirus BacMam vectors provide an attractive and safe alternative. Here, a novel BacMam was constructed containing a frameshift mutation within fp25, which results in virus stocks with higher infectious titres. This improved in vitro transduction when compared to control BacMams. Additionally, incorporating a truncated vesicular stomatitis virus G protein increased transduction efficacy and production of EGFP and BCL2 in human kidney (HK-2) and pancreatic islet β cells (EndoC βH3). Lastly, we have shown that our optimized BacMam vector can deliver and express egfp in intact pancreatic islet cells from human cadaveric donors. These results confirm that BacMam vectors are a viable choice for providing delivery of transgenes to pancreatic islet cells. Full article
(This article belongs to the Special Issue Baculovirus Advances and Applications)
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Open AccessArticle βTrCP is Required for HIV-1 Vpu Modulation of CD4, GaLV Env, and BST-2/Tetherin
Viruses 2018, 10(10), 573; https://doi.org/10.3390/v10100573
Received: 27 September 2018 / Revised: 10 October 2018 / Accepted: 16 October 2018 / Published: 19 October 2018
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Abstract
The Human immunodeficiency virus-1 (HIV-1) accessory protein Vpu modulates numerous proteins, including the host proteins CD4 and BST-2/tetherin. Vpu interacts with the Skp, Cullin, F-Box (SCF) ubiquitin ligase through interactions with the F-Box protein βTrCP (1 and/or 2). This interaction is dependent on
[...] Read more.
The Human immunodeficiency virus-1 (HIV-1) accessory protein Vpu modulates numerous proteins, including the host proteins CD4 and BST-2/tetherin. Vpu interacts with the Skp, Cullin, F-Box (SCF) ubiquitin ligase through interactions with the F-Box protein βTrCP (1 and/or 2). This interaction is dependent on phosphorylation of S52,56 in Vpu. Mutation of S52,56, or inhibition of the SCF, abolishes most Vpu activity against CD4 and partly reduces activity against BST-2/tetherin. Recently, Vpu has also been reported to interact with the clathrin adapter proteins AP-1 and AP-2, and these interactions were also found to be required for BST-2/tetherin antagonism in an S52,56 -dependent manner. In assays where HIV-1 is pseudotyped with gibbon ape leukemia virus (GaLV Env), Vpu has also been found to prevent GaLV Env from being incorporated into viral particles, but the mechanism for this antagonism is not fully understood. To clarify the role of the βTrCPs in Vpu function we used CRISPR/Cas9 to generate a clonal cell line lacking both βTrCP-1 and -2. Vpu activity against CD4 and GaLV Env was abolished in this cell line, and activity against BST-2/tetherin reduced significantly. Mutation of the S52,56 residues no longer affected Vpu activity against BST-2/tetherin in this cell line. These data suggest that the primary role of the S52,56 residues in antagonism of CD4, GaLV Env, and BST-2/tetherin is to recruit the SCF/βTrCP ubiquitin ligase. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessReview The Main Risk Factors of Nipah Disease and Its Risk Analysis in China
Viruses 2018, 10(10), 572; https://doi.org/10.3390/v10100572
Received: 31 August 2018 / Revised: 5 October 2018 / Accepted: 12 October 2018 / Published: 19 October 2018
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Abstract
Nipah disease is a highly fatal zoonosis which is caused by the Nipah virus. The Nipah virus is a BSL-4 virus with fruit bats being its natural host. It is mainly prevalent in Southeast Asia. The virus was first discovered in 1997 in
[...] Read more.
Nipah disease is a highly fatal zoonosis which is caused by the Nipah virus. The Nipah virus is a BSL-4 virus with fruit bats being its natural host. It is mainly prevalent in Southeast Asia. The virus was first discovered in 1997 in Negeri Sembilan, Malaysia. Currently, it is mainly harmful to pigs and humans with a high mortality rate. This study describes the route of transmission of the Nipah virus in different countries and analyzes the possibility of the primary disease being in China and the method of its transmission to China. The risk factors are analyzed for different susceptible populations to Nipah disease. The aim is to improve people’s risk awareness and prevention and control of the disease and reduce its risk of occurring and spreading in China. Full article
(This article belongs to the Special Issue Emerging Viruses)
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Open AccessArticle Ultrastructural Analysis of Chikungunya Virus Dissemination from the Midgut of the Yellow Fever Mosquito, Aedes aegypti
Viruses 2018, 10(10), 571; https://doi.org/10.3390/v10100571
Received: 21 September 2018 / Revised: 15 October 2018 / Accepted: 16 October 2018 / Published: 18 October 2018
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Abstract
The transmission cycle of chikungunya virus (CHIKV) requires that mosquito vectors get persistently infected with the virus, following its oral acqsuisition from a vertebrate host. The mosquito midgut is the initial organ that gets infected with orally acquired CHIKV. Following its replication in
[...] Read more.
The transmission cycle of chikungunya virus (CHIKV) requires that mosquito vectors get persistently infected with the virus, following its oral acqsuisition from a vertebrate host. The mosquito midgut is the initial organ that gets infected with orally acquired CHIKV. Following its replication in the midgut epithelium, the virus exits the midgut and infects secondary tissues including the salivary glands before being transmitted to another host. Here, we investigate the pattern of CHIKV dissemination from the midgut of Aedes aegypti at the ultrastructural level. Bloodmeal ingestion caused overstretching of the midgut basal lamina (BL), which was disrupted in areas adjacent to muscles surrounding the midgut as shown by scanning electron microscopy (SEM). Using both transmission electron microscopy (TEM) and focused ion beam scanning electron microscopy (FIB-SEM) to analyze midgut preparations, mature chikungunya (CHIK) virions were found accumulating at the BL and within strands of the BL at 24–32 h post-infectious bloodmeal (pibm). From 48 h pibm onwards, virions no longer congregated at the BL and became dispersed throughout the basal labyrinth of the epithelial cells. Ingestion of a subsequent, non-infectious bloodmeal caused mature virions to congregate again at the midgut BL. Our study suggests that CHIKV needs a single replication cycle in the midgut epithelium before mature virions directly traverse the midgut BL during a relatively narrow time window, within 48 h pibm. Full article
(This article belongs to the Special Issue Chikungunya Virus and (Re-) Emerging Alphaviruses)
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Open AccessArticle Genome-Wide Transcriptomic Analysis Reveals Insights into the Response to Citrus bark cracking viroid (CBCVd) in Hop (Humulus lupulus L.)
Viruses 2018, 10(10), 570; https://doi.org/10.3390/v10100570
Received: 27 September 2018 / Revised: 12 October 2018 / Accepted: 16 October 2018 / Published: 18 October 2018
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Abstract
Viroids are smallest known pathogen that consist of non-capsidated, single-stranded non-coding RNA replicons and they exploits host factors for their replication and propagation. The severe stunting disease caused by Citrus bark cracking viroid (CBCVd) is a serious threat, which spreads rapidly within hop
[...] Read more.
Viroids are smallest known pathogen that consist of non-capsidated, single-stranded non-coding RNA replicons and they exploits host factors for their replication and propagation. The severe stunting disease caused by Citrus bark cracking viroid (CBCVd) is a serious threat, which spreads rapidly within hop gardens. In this study, we employed comprehensive transcriptome analyses to dissect host-viroid interactions and identify gene expression changes that are associated with disease development in hop. Our analysis revealed that CBCVd-infection resulted in the massive modulation of activity of over 2000 genes. Expression of genes associated with plant immune responses (protein kinase and mitogen-activated protein kinase), hypersensitive responses, phytohormone signaling pathways, photosynthesis, pigment metabolism, protein metabolism, sugar metabolism, and modification, and others were altered, which could be attributed to systemic symptom development upon CBCVd-infection in hop. In addition, genes encoding RNA-dependent RNA polymerase, pathogenesis-related protein, chitinase, as well as those related to basal defense responses were up-regulated. The expression levels of several genes identified from RNA sequencing analysis were confirmed by qRT-PCR. Our systematic comprehensive CBCVd-responsive transcriptome analysis provides a better understanding and insights into complex viroid-hop plant interaction. This information will assist further in the development of future measures for the prevention of CBCVd spread in hop fields. Full article
(This article belongs to the Special Issue Viroid-2018: International Conference on Viroids and Viroid-Like RNAs)
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Open AccessCommunication Time to Harmonize Dengue Nomenclature and Classification
Viruses 2018, 10(10), 569; https://doi.org/10.3390/v10100569
Received: 14 September 2018 / Revised: 5 October 2018 / Accepted: 15 October 2018 / Published: 18 October 2018
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Abstract
Dengue virus (DENV) is estimated to cause 390 million infections per year worldwide. A quarter of these infections manifest clinically and are associated with a morbidity and mortality that put a significant burden on the affected regions. Reports of increased frequency, intensity, and
[...] Read more.
Dengue virus (DENV) is estimated to cause 390 million infections per year worldwide. A quarter of these infections manifest clinically and are associated with a morbidity and mortality that put a significant burden on the affected regions. Reports of increased frequency, intensity, and extended geographical range of outbreaks highlight the virus’s ongoing global spread. Persistent transmission in endemic areas and the emergence in territories formerly devoid of transmission have shaped DENV’s current genetic diversity and divergence. This genetic layout is hierarchically organized in serotypes, genotypes, and sub-genotypic clades. While serotypes are well defined, the genotype nomenclature and classification system lack consistency, which complicates a broader analysis of their clinical and epidemiological characteristics. We identify five key challenges: (1) Currently, there is no formal definition of a DENV genotype; (2) Two different nomenclature systems are used in parallel, which causes significant confusion; (3) A standardized classification procedure is lacking so far; (4) No formal definition of sub-genotypic clades is in place; (5) There is no consensus on how to report antigenic diversity. Therefore, we believe that the time is right to re-evaluate DENV genetic diversity in an essential effort to provide harmonization across DENV studies. Full article
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Open AccessArticle Rapid Construction of a Replication-Competent Infectious Clone of Human Adenovirus Type 14 by Gibson Assembly
Viruses 2018, 10(10), 568; https://doi.org/10.3390/v10100568
Received: 5 September 2018 / Revised: 13 October 2018 / Accepted: 16 October 2018 / Published: 18 October 2018
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Abstract
In 1955, Human adenovirus type 14 (HAdV-B14p) was firstly identified in a military trainee diagnosed as acute respiratory disease (ARD) in the Netherlands. Fifty years later, a genomic variant, HAdV-B14p1, re-emerged in the U.S. and caused large and fatal ARD outbreaks. Subsequently, more
[...] Read more.
In 1955, Human adenovirus type 14 (HAdV-B14p) was firstly identified in a military trainee diagnosed as acute respiratory disease (ARD) in the Netherlands. Fifty years later, a genomic variant, HAdV-B14p1, re-emerged in the U.S. and caused large and fatal ARD outbreaks. Subsequently, more and more ARD outbreaks occurred in Canada, the UK, Ireland, and China, in both military and civil settings. To generate a tool for the efficient characterization of this new genomic variant, a full-length infectious genomic clone of HAdV-B14 was successfully constructed using one-step Gibson Assembly method in this study. Firstly, the full genome of HAdV-B14p1 strain GZ01, the first HAdV-B14 isolate in China, was assembled into pBR322 plasmid by Gibson Assembly. The pBRAdV14 plasmid, generated by Gibson Assembly, was analyzed and verified by PCR, restriction enzymes digestion and the sequencing. Secondly, viruses were rescued from pBRAdV14-transfected A549 cells. The integrity of the rescued viruses was identified by restriction enzyme analysis. The complete sequence of the infectious clone was further sequenced. No mutation was found in the infectious clone during the construction when compared with the parental virus and pBR322 sequences. The direct immunofluorescence assay indicated the expression of the hexon protein. Finally, typical virions were observed; the one-step growth curves further showed that the DNA replication and viral reproduction efficiency of pBRAd14 derived viruses was similar with that of wild-type HAdV-B14 strain. The successful construction of the replication-competent infectious clone of pBRAdV14 facilitates the development of vaccine and antiviral drugs against HAdV-B14, as well as provides a novel strategy for rapid construction of infectious viral clones for other large-genome DNA viruses. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessCommunication The Viral Tegument Protein pp65 Impairs Transcriptional Upregulation of IL-1β by Human Cytomegalovirus through Inhibition of NF-kB Activity
Viruses 2018, 10(10), 567; https://doi.org/10.3390/v10100567
Received: 31 July 2018 / Revised: 11 October 2018 / Accepted: 15 October 2018 / Published: 16 October 2018
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Abstract
Interleukin-1β (IL-1β) is a key effector of the inflammasome complex in response to pathogens and danger signals. Although it is well known that assembly of the inflammasome triggers proteolytic cleavage of the biologically inactive precursor pro-IL-1β into its mature secreted form, the mechanism
[...] Read more.
Interleukin-1β (IL-1β) is a key effector of the inflammasome complex in response to pathogens and danger signals. Although it is well known that assembly of the inflammasome triggers proteolytic cleavage of the biologically inactive precursor pro-IL-1β into its mature secreted form, the mechanism by which human cytomegalovirus (HCMV) regulates IL-1β production via the inflammasome is still poorly understood. Here, we show that the infection of human foreskin fibroblasts (HFFs) with a mutant HCMV lacking the tegument protein pp65 (v65Stop) results in higher expression levels of mature IL-1β compared to its wild-type counterpart, suggesting that pp65 mediates HCMV immune evasion through downmodulation of IL-1β. Furthermore, we show that enhanced IL-1β production by the v65Stop mutant is due in part to induction of DNA binding and the transcriptional activity of NF-κB. Lastly, we demonstrate that HCMV infection of HFFs triggers a non-canonical IL-1β activation pathway where caspase-8 promotes IL-1β maturation independently of caspase-1. Altogether, our findings provide novel mechanistic insights into the interplay between HCMV and the inflammasome system and raise the possibility of targeting pp65 to treat HCMV infection. Full article
(This article belongs to the Special Issue Cytokine Responses in Viral Infections)
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Open AccessPerspective Current Perspectives on High-Throughput Sequencing (HTS) for Adventitious Virus Detection: Upstream Sample Processing and Library Preparation
Viruses 2018, 10(10), 566; https://doi.org/10.3390/v10100566
Received: 11 August 2018 / Revised: 27 September 2018 / Accepted: 11 October 2018 / Published: 16 October 2018
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Abstract
A key step for broad viral detection using high-throughput sequencing (HTS) is optimizing the sample preparation strategy for extracting viral-specific nucleic acids since viral genomes are diverse: They can be single-stranded or double-stranded RNA or DNA, and can vary from a few thousand
[...] Read more.
A key step for broad viral detection using high-throughput sequencing (HTS) is optimizing the sample preparation strategy for extracting viral-specific nucleic acids since viral genomes are diverse: They can be single-stranded or double-stranded RNA or DNA, and can vary from a few thousand bases to over millions of bases, which might introduce biases during nucleic acid extraction. In addition, viral particles can be enveloped or non-enveloped with variable resistance to pre-treatment, which may influence their susceptibility to extraction procedures. Since the identity of the potential adventitious agents is unknown prior to their detection, efficient sample preparation should be unbiased toward all different viral types in order to maximize the probability of detecting any potential adventitious viruses using HTS. Furthermore, the quality assessment of each step for sample processing is also a critical but challenging aspect. This paper presents our current perspectives for optimizing upstream sample processing and library preparation as part of the discussion in the Advanced Virus Detection Technologies Interest group (AVDTIG). The topics include: Use of nuclease treatment to enrich for encapsidated nucleic acids, techniques for amplifying low amounts of virus nucleic acids, selection of different extraction methods, relevant controls, the use of spike recovery experiments, and quality control measures during library preparation. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle Canine Influenza Virus is Mildly Restricted by Canine Tetherin Protein
Viruses 2018, 10(10), 565; https://doi.org/10.3390/v10100565
Received: 10 July 2018 / Revised: 18 September 2018 / Accepted: 10 October 2018 / Published: 16 October 2018
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Abstract
Tetherin (BST2/CD317/HM1.24) has emerged as a key host-cell ·defence molecule that acts by inhibiting the release and spread of diverse enveloped virions from infected cells. We analysed the biological features of canine tetherin and found it to be an unstable hydrophilic type I
[...] Read more.
Tetherin (BST2/CD317/HM1.24) has emerged as a key host-cell ·defence molecule that acts by inhibiting the release and spread of diverse enveloped virions from infected cells. We analysed the biological features of canine tetherin and found it to be an unstable hydrophilic type I transmembrane protein with one transmembrane domain, no signal peptide, and multiple glycosylation and phosphorylation sites. Furthermore, the tissue expression profile of canine tetherin revealed that it was particularly abundant in immune organs. The canine tetherin gene contains an interferon response element sequence that can be regulated and expressed by canine IFN-α. A CCK-8 assay showed that canine tetherin was effective in helping mitigate cellular damage caused by canine influenza virus (CIV) infection. Additionally, we found that the overexpression of canine tetherin inhibited replication of the CIV and that interference with the canine tetherin gene enhanced CIV replication in cells. The impact of canine tetherin on CIV replication was mild. However, these results elucidate the role of the innate immune factor, canine tetherin, during CIV infection for the first time. Full article
(This article belongs to the Special Issue Animal Models for Viral Diseases)
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Open AccessArticle Saccharomyces paradoxus K66 Killer System Evidences Expanded Assortment of Helper and Satellite Viruses
Viruses 2018, 10(10), 564; https://doi.org/10.3390/v10100564
Received: 28 August 2018 / Revised: 5 October 2018 / Accepted: 15 October 2018 / Published: 16 October 2018
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Abstract
The Saccharomycetaceae yeast family recently became recognized for expanding of the repertoire of different dsRNA-based viruses, highlighting the need for understanding of their cross-dependence. We isolated the Saccharomyces paradoxus AML-15-66 killer strain from spontaneous fermentation of serviceberries and identified helper and satellite viruses
[...] Read more.
The Saccharomycetaceae yeast family recently became recognized for expanding of the repertoire of different dsRNA-based viruses, highlighting the need for understanding of their cross-dependence. We isolated the Saccharomyces paradoxus AML-15-66 killer strain from spontaneous fermentation of serviceberries and identified helper and satellite viruses of the family Totiviridae, which are responsible for the killing phenotype. The corresponding full dsRNA genomes of viruses have been cloned and sequenced. Sequence analysis of SpV-LA-66 identified it to be most similar to S. paradoxus LA-28 type viruses, while SpV-M66 was mostly similar to the SpV-M21 virus. Sequence and functional analysis revealed significant differences between the K66 and the K28 toxins. The structural organization of the K66 protein resembled those of the K1/K2 type toxins. The AML-15-66 strain possesses the most expressed killing property towards the K28 toxin-producing strain. A genetic screen performed on S. cerevisiae YKO library strains revealed 125 gene products important for the functioning of the S. paradoxus K66 toxin, with 85% of the discovered modulators shared with S. cerevisiae K2 or K1 toxins. Investigation of the K66 protein binding to cells and different polysaccharides implies the β-1,6 glucans to be the primary receptors of S. paradoxus K66 toxin. For the first time, we demonstrated the coherent habitation of different types of helper and satellite viruses in a wild-type S. paradoxus strain. Full article
(This article belongs to the Special Issue Mycoviruses)
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Open AccessArticle Exchange Protein Directly Activated by cAMP Modulates Ebola Virus Uptake into Vascular Endothelial Cells
Viruses 2018, 10(10), 563; https://doi.org/10.3390/v10100563
Received: 26 July 2018 / Revised: 13 October 2018 / Accepted: 13 October 2018 / Published: 16 October 2018
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Abstract
Members of the family Filoviridae, including Ebola virus (EBOV) and Marburg virus (MARV), cause severe hemorrhagic fever in humans and nonhuman primates. Given their high lethality, a comprehensive understanding of filoviral pathogenesis is urgently needed. In the present studies, we revealed that the
[...] Read more.
Members of the family Filoviridae, including Ebola virus (EBOV) and Marburg virus (MARV), cause severe hemorrhagic fever in humans and nonhuman primates. Given their high lethality, a comprehensive understanding of filoviral pathogenesis is urgently needed. In the present studies, we revealed that the exchange protein directly activated by cAMP 1 (EPAC1) gene deletion protects vasculature in ex vivo explants from EBOV infection. Importantly, pharmacological inhibition of EPAC1 using EPAC-specific inhibitors (ESIs) mimicked the EPAC1 knockout phenotype in the ex vivo model. ESI treatment dramatically decreased EBOV infectivity in both ex vivo vasculature and in vitro vascular endothelial cells (ECs). Furthermore, postexposure protection of ECs against EBOV infection was conferred using ESIs. Protective efficacy of ESIs in ECs was observed also in MARV infection. Additional studies using a vesicular stomatitis virus pseudotype that expresses EBOV glycoprotein (EGP-VSV) confirmed that ESIs reduced infection in ECs. Ultrastructural studies suggested that ESIs blocked EGP-VSV internalization via inhibition of macropinocytosis. The inactivation of EPAC1 affects the early stage of viral entry after viral binding to the cell surface, but before early endosome formation, in a phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)-dependent manner. Our study delineated a new critical role of EPAC1 during EBOV uptake into ECs. Full article
(This article belongs to the Special Issue Emerging Viruses)
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Open AccessArticle Breed Differences in PCV2 Uptake and Disintegration in Porcine Monocytes
Viruses 2018, 10(10), 562; https://doi.org/10.3390/v10100562
Received: 21 September 2018 / Revised: 11 October 2018 / Accepted: 13 October 2018 / Published: 15 October 2018
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Abstract
Porcine circovirus type 2 (PCV2) is associated with various diseases which are designated as PCV2-associated diseases (PCVADs). Their severity varies among breeds. In the diseased pigs, virus is present in monocytes, without replication or full degradation. PCV2 entry and viral outcome in primary
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Porcine circovirus type 2 (PCV2) is associated with various diseases which are designated as PCV2-associated diseases (PCVADs). Their severity varies among breeds. In the diseased pigs, virus is present in monocytes, without replication or full degradation. PCV2 entry and viral outcome in primary porcine monocytes and the role of monocytes in PCV2 genetic susceptibility have not been studied. Here, virus uptake and trafficking were analyzed and compared among purebreds Piétrain, Landrace and Large White and hybrid Piétrain × Topigs20. Viral capsids were rapidly internalized into monocytes, followed by a slow disintegration to a residual level. PCV2 uptake was decreased by chlorpromazine, cytochalasin D and dynasore. The internalized capsids followed the endosomal trafficking pathway, ending up in lysosomes. PCV2 genome was nicked by lysosomal DNase II in vitro, but persisted in monocytes in vivo. Monocytes from purebred Piétrain and the hybrid showed a higher level of PCV2 uptake and disintegration, compared to those from Landrace and Large White. In conclusion, PCV2 entry occurs via clathrin-mediated endocytosis. After entry, viral capsids are partially disintegrated, while viral genomes largely escape from the pathway to avoid degradation. The degree of PCV2 uptake and disintegration differ among pig breeds. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessReview Creating Disease Resistant Chickens: A Viable Solution to Avian Influenza?
Viruses 2018, 10(10), 561; https://doi.org/10.3390/v10100561
Received: 27 September 2018 / Revised: 11 October 2018 / Accepted: 12 October 2018 / Published: 15 October 2018
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Abstract
Influenza A virus (IAV) represents an ongoing threat to human and animal health worldwide. The generation of IAV-resistant chickens through genetic modification and/or selective breeding may help prevent viral spread. The feasibility of creating genetically modified birds has already been demonstrated with the
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Influenza A virus (IAV) represents an ongoing threat to human and animal health worldwide. The generation of IAV-resistant chickens through genetic modification and/or selective breeding may help prevent viral spread. The feasibility of creating genetically modified birds has already been demonstrated with the insertion of transgenes that target IAV into the genomes of chickens. This approach has been met with some success in minimising the spread of IAV but has limitations in terms of its ability to prevent the emergence of disease. An alternate approach is the use of genetic engineering to improve host resistance by targeting the antiviral immune responses of poultry to IAV. Harnessing such resistance mechanisms in a “genetic restoration” approach may hold the greatest promise yet for generating disease resistant chickens. Continuing to identify genes associated with natural resistance in poultry provides the opportunity to identify new targets for genetic modification and/or selective breeding. However, as with any new technology, economic, societal, and legislative barriers will need to be overcome before we are likely to see commercialisation of genetically modified birds. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessReview Temperature Sensitive Mutations in Influenza A Viral Ribonucleoprotein Complex Responsible for the Attenuation of the Live Attenuated Influenza Vaccine
Viruses 2018, 10(10), 560; https://doi.org/10.3390/v10100560
Received: 25 August 2018 / Revised: 3 October 2018 / Accepted: 12 October 2018 / Published: 15 October 2018
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Abstract
Live attenuated influenza vaccines (LAIV) have prevented morbidity and mortality associated with influenza viral infections for many years and represent the best therapeutic option to protect against influenza viral infections in humans. However, the development of LAIV has traditionally relied on empirical methods,
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Live attenuated influenza vaccines (LAIV) have prevented morbidity and mortality associated with influenza viral infections for many years and represent the best therapeutic option to protect against influenza viral infections in humans. However, the development of LAIV has traditionally relied on empirical methods, such as the adaptation of viruses to replicate at low temperatures. These approaches require an extensive investment of time and resources before identifying potential vaccine candidates that can be safely implemented as LAIV to protect humans. In addition, the mechanism of attenuation of these vaccines is poorly understood in some cases. Importantly, LAIV are more efficacious than inactivated vaccines because their ability to mount efficient innate and adaptive humoral and cellular immune responses. Therefore, the design of potential LAIV based on known properties of viral proteins appears to be a highly appropriate option for the treatment of influenza viral infections. For that, the viral RNA synthesis machinery has been a research focus to identify key amino acid substitutions that can lead to viral attenuation and their use in safe, immunogenic, and protective LAIV. In this review, we discuss the potential to manipulate the influenza viral RNA-dependent RNA polymerase (RdRp) complex to generate attenuated forms of the virus that can be used as LAIV for the treatment of influenza viral infections, one of the current and most effective prophylactic options for the control of influenza in humans. Full article
(This article belongs to the Special Issue Structure-Function Relationships in Viral Polymerases)
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Open AccessReview Role of Host Cell Secretory Machinery in Zika Virus Life Cycle
Viruses 2018, 10(10), 559; https://doi.org/10.3390/v10100559
Received: 26 September 2018 / Revised: 11 October 2018 / Accepted: 12 October 2018 / Published: 15 October 2018
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Abstract
The high human cost of Zika virus infections and the rapid establishment of virus circulation in novel areas, including the United States, present an urgent need for countermeasures against this emerging threat. The development of an effective vaccine against Zika virus may be
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The high human cost of Zika virus infections and the rapid establishment of virus circulation in novel areas, including the United States, present an urgent need for countermeasures against this emerging threat. The development of an effective vaccine against Zika virus may be problematic because of the cross reactivity of the antibodies with other flaviviruses leading to antibody-dependent enhancement of infection. Moreover, rapidly replicating positive strand RNA viruses, including Zika virus, generate large spectrum of mutant genomes (quasi species) every replication round, allowing rapid selection of variants resistant to drugs targeting virus-specific proteins. On the other hand, viruses are ultimate cellular parasites and rely on the host metabolism for every step of their life cycle, thus presenting an opportunity to manipulate host processes as an alternative approach to suppress virus replication and spread. Zika and other flaviviruses critically depend on the cellular secretory pathway, which transfers proteins and membranes from the ER through the Golgi to the plasma membrane, for virion assembly, maturation and release. In this review, we summarize the current knowledge of interactions of Zika and similar arthropod-borne flaviviruses with the cellular secretory machinery with a special emphasis on virus-specific changes of the secretory pathway. Identification of the regulatory networks and effector proteins required to accommodate the trafficking of virions, which represent a highly unusual cargo for the secretory pathway, may open an attractive and virtually untapped reservoir of alternative targets for the development of superior anti-viral drugs. Full article
(This article belongs to the Special Issue Viruses and Cellular Metabolism)
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Open AccessBrief Report Systemic Administration and Targeted Delivery of Immunogenic Oncolytic Adenovirus Encapsulated in Extracellular Vesicles for Cancer Therapies
Viruses 2018, 10(10), 558; https://doi.org/10.3390/v10100558
Received: 2 October 2018 / Accepted: 11 October 2018 / Published: 13 October 2018
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Abstract
Oncolytic viruses (OV) are engineered to infect, replicate in and kill cancer cells. Currently, the OV therapeutic approach is mainly restricted to neoplasia amenable to direct local administration of viral particles, while the possibility of a systemic delivery of cancer-tropic viruses would extend
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Oncolytic viruses (OV) are engineered to infect, replicate in and kill cancer cells. Currently, the OV therapeutic approach is mainly restricted to neoplasia amenable to direct local administration of viral particles, while the possibility of a systemic delivery of cancer-tropic viruses would extend the OV application to the treatment of metastatic neoplasia. Herein, we applied in vivo/ex vivo imaging to demonstrate that cancer tropism is achieved when OV are encapsulated inside extracellular vesicles (EV) administered intravenously (i.v.), but not when injected intraperitoneally (i.p.). Moreover, we show that the therapeutic procedure adopted does not alter the immunomodulatory properties of the viruses. Full article
(This article belongs to the Section Antivirals & Vaccines)
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Open AccessArticle Bowman‒Birk Inhibitor Suppresses Herpes Simplex Virus Type 2 Infection of Human Cervical Epithelial Cells
Viruses 2018, 10(10), 557; https://doi.org/10.3390/v10100557
Received: 29 August 2018 / Revised: 9 October 2018 / Accepted: 10 October 2018 / Published: 12 October 2018
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Abstract
The Bowman‒Birk inhibitor (BBI), a protease inhibitor derived from soybeans, has been extensively studied in anti-tumor and anti-inflammation research. We recently reported that BBI has an anti-HIV-1 property in primary human macrophages. Because HSV-2 infection plays a role in facilitating HIV-1 sexual transmission,
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The Bowman‒Birk inhibitor (BBI), a protease inhibitor derived from soybeans, has been extensively studied in anti-tumor and anti-inflammation research. We recently reported that BBI has an anti-HIV-1 property in primary human macrophages. Because HSV-2 infection plays a role in facilitating HIV-1 sexual transmission, we thus examined whether BBI has the ability to inhibit HSV-2 infection. We demonstrated that BBI could potently inhibit HSV-2 replication in human cervical epithelial cells (End1/E6E7). This BBI-mediated HSV-2 inhibition was partially through blocking HSV-2-mediated activation of NF-κB and p38 MAPK pathways. In addition, BBI could activate the JAK/STAT pathway and enhance the expression of several antiviral interferon-stimulated genes (ISGs). Furthermore, BBI treatment of End1/E6E7 cells upregulated the expression of tight junction proteins and reduced HSV-2-mediated cellular ubiquitinated proteins’ degradation through suppressing the ubiquitin‒proteasome system. These observations indicate that BBI may have therapeutic potential for the prevention and treatment of HSV-2 infections. Full article
(This article belongs to the Special Issue Recent Advances of Natural Products in HSV Research)
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Open AccessArticle Characterization of Critical Functions of Long Non-Coding RNAs and mRNAs in Rhabdomyosarcoma Cells and Mouse Skeletal Muscle Infected by Enterovirus 71 Using RNA-Seq
Viruses 2018, 10(10), 556; https://doi.org/10.3390/v10100556
Received: 15 August 2018 / Revised: 7 October 2018 / Accepted: 9 October 2018 / Published: 11 October 2018
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Abstract
Enterovirus 71 (EV71) is the main pathogen of severe hand-foot-mouth disease (HFMD). Long non-coding RNAs (lncRNAs) are recognized as pivotal factors during the pathogenesis of viral infection. However, the critical functions of lncRNAs in EV71–host interactions have not been characterized. Here, for the
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Enterovirus 71 (EV71) is the main pathogen of severe hand-foot-mouth disease (HFMD). Long non-coding RNAs (lncRNAs) are recognized as pivotal factors during the pathogenesis of viral infection. However, the critical functions of lncRNAs in EV71–host interactions have not been characterized. Here, for the first time, we performed global transcriptome analysis of lncRNA and mRNA expression profiles in EV71-infected human rhabdomyosarcoma (RD) cells and skeletal muscle of mice using second-generation sequencing. In our study, a total of 3801 novel lncRNAs were identified. In addition, 23 lncRNAs and 372 mRNAs exhibited remarkable differences in expression levels between infected and uninfected RD cells, while 104 lncRNAs and 2647 mRNAs were differentially expressed in infected skeletal muscle from neonatal mice. Comprehensive bioinformatics analysis included target gene prediction, lncRNA‑mRNA co-expression network construction, as well as gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis mainly focused on differentially-expressed genes (DEGs). Our results suggest that lncRNAs may participate in EV71 infection-induced pathogenesis through regulating immune responses, protein binding, cellular component biogenesis and metabolism. The present study provides novel insights into the functions of lncRNAs and the possible pathogenic mechanism following EV71 infection. Full article
(This article belongs to the Section Animal Viruses)
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Open AccessArticle First Isolation and Characterization of a Group C Banna Virus (BAV) from Anopheles sinensis Mosquitoes in Hubei, China
Viruses 2018, 10(10), 555; https://doi.org/10.3390/v10100555
Received: 18 July 2018 / Revised: 30 September 2018 / Accepted: 9 October 2018 / Published: 11 October 2018
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Abstract
Banna virus (BAV) is considered to be an emerging human pathogen that is transmitted by blood-sucking insects. BAV was isolated from various species of mosquitoes, midges, and livestock. It is widely distributed geographically, since it was identified in China, Vietnam, and Indonesia. Previously
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Banna virus (BAV) is considered to be an emerging human pathogen that is transmitted by blood-sucking insects. BAV was isolated from various species of mosquitoes, midges, and livestock. It is widely distributed geographically, since it was identified in China, Vietnam, and Indonesia. Previously reported evolution studies of BAV indicated that BAV can be divided into two groups, including isolates from China and Vietnam clustered in group A, and Indonesian isolates in group B. In this study, we report the isolation of a new strain of BAV named HB14-71-01 from Anopheles sinensis mosquitoes from Hubei, China. An in vitro comparison study of the HB14-71-01 isolate and the group A BAV revealed differences based on observed cytopathic effect, plaque size, and viral growth rates. Additionally, the phylogenetic analysis indicated that the Hubei isolate belongs to a novel genotype of BAV and emerged nearly 105 years ago (95% highest posterior density (HPD): 35–434), unlike the two previously reported genotypes A and B. Our findings extend the knowledge about the genomic diversity and potential vectors/hosts of BAVs and will improve understanding of the relationships between genetic variation and pathogenicity. Full article
(This article belongs to the Special Issue Emerging Viruses)
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Open AccessCommunication Visualization of a Dinoflagellate-Infecting Virus HcDNAV and Its Infection Process
Viruses 2018, 10(10), 554; https://doi.org/10.3390/v10100554
Received: 7 August 2018 / Revised: 5 October 2018 / Accepted: 7 October 2018 / Published: 11 October 2018
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Abstract
HcDNAV (a type species of Genus Dinodnavirus) is a large double-stranded DNA virus, which lytically infects the bloom-forming marine microalga Heterocapsa circularisquama Horiguchi (Dinophyceae). In the present study, detailed observation of the HcDNAV particle and its infection process was conducted via field
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HcDNAV (a type species of Genus Dinodnavirus) is a large double-stranded DNA virus, which lytically infects the bloom-forming marine microalga Heterocapsa circularisquama Horiguchi (Dinophyceae). In the present study, detailed observation of the HcDNAV particle and its infection process was conducted via field emission scanning electron microscopy (FE-SEM) and epifluorescence microscopy (EFM). Each five-fold vertex of the icosahedral virion was decorated with a protrusion, which may be related to the entry process of HcDNAV into the host. The transverse groove of host cells is proposed to be the main virus entry site. A visible DAPI-stained region, which is considered to be the viroplasm (virus factory), appeared in close proximity to the host nucleus at 11 h post infection (hpi); the putative viral DAPI signal was remarkably enlarged at 11–30 hpi. It was kidney-shaped at 13–15 hpi, horseshoe-shaped at 20 hpi, doughnut-shaped at 30 hpi, and changed into a three-dimensionally complicated shape at 51–53 hpi, by which time most parts of the host cell were occupied by the putative viral DAPI signal. While the virions were within the viroplasm, they were easily distinguishable by their vertex protrusions by FE-SEM. Full article
(This article belongs to the Special Issue Algae Virus)
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Open AccessArticle Roles of orf60a and orf61 in Development of Bacteriophages λ and Φ24B
Viruses 2018, 10(10), 553; https://doi.org/10.3390/v10100553
Received: 22 August 2018 / Revised: 6 October 2018 / Accepted: 9 October 2018 / Published: 11 October 2018
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The exo-xis region of lambdoid bacteriophage genomes contains several established and potential genes that are evolutionarily conserved, but not essential for phage propagation under laboratory conditions. Nevertheless, deletion or overexpression of either the whole exo-xis region and important regulatory elements can significantly influence
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The exo-xis region of lambdoid bacteriophage genomes contains several established and potential genes that are evolutionarily conserved, but not essential for phage propagation under laboratory conditions. Nevertheless, deletion or overexpression of either the whole exo-xis region and important regulatory elements can significantly influence the regulation of phage development. This report defines specific roles for orf60a and orf61 in bacteriophage λ and Φ24B, a specific Shiga toxin-converting phage with clinical relevance. We observed that mutant phages bearing deletions of orf60a and orf61 impaired two central aspects of phage development: the lysis-versus-lysogenization decision and prophage induction. These effects were more pronounced for phage Φ24B than for λ. Surprisingly, adsorption of phage Φ24B on Escherichia coli host cells was less efficient in the absence of either orf60a or orf61. We conclude that these open reading frames (ORFs) play important, but not essential, roles in the regulation of lambdoid phage development. Although phages can propagate without these ORFs in nutrient media, we suggest that they may be involved in the regulatory network, ensuring optimization of phage development under various environmental conditions. Full article
(This article belongs to the Special Issue Viruses of Microbes V: Biodiversity and Future Applications)
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Open AccessShort Note Potential Application of Bacteriophages in Enrichment Culture for Improved Prenatal Streptococcus agalactiae Screening
Viruses 2018, 10(10), 552; https://doi.org/10.3390/v10100552
Received: 9 August 2018 / Revised: 24 September 2018 / Accepted: 9 October 2018 / Published: 10 October 2018
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Abstract
Vertical transmission of Streptococcus agalactiae can cause neonatal infections. A culture test in the late stage of pregnancy is used to screen for the presence of maternal S. agalactiae for intrapartum antibiotic prophylaxis. For the test, a vaginal–rectal sample is recommended to be
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Vertical transmission of Streptococcus agalactiae can cause neonatal infections. A culture test in the late stage of pregnancy is used to screen for the presence of maternal S. agalactiae for intrapartum antibiotic prophylaxis. For the test, a vaginal–rectal sample is recommended to be enriched, followed by bacterial identification. In some cases, Enterococcus faecalis overgrows in the enrichment culture. Consequently, the identification test yields false-negative results. Bacteriophages (phages) can be used as antimicrobial materials. Here, we explored the feasibility of using phages to minimize false-negative results in an experimental setting. Phage mixture was prepared using three phages that specifically infect E. faecalis: phiEF24C, phiEF17H, and phiM1EF22. The mixture inhibited the growth of 86.7% (26/30) of vaginal E. faecalis strains. The simple coculture of E. faecalis and S. agalactiae was used as an experimental enrichment model. Phage mixture treatment led to suppression of E. faecalis growth and facilitation of S. agalactiae growth. In addition, testing several sets of S. agalactiae and E. faecalis strains, the treatment with phage mixture in the enrichment improved S. agalactiae detection on chromogenic agar. Our results suggest that the phage mixture can be usefully employed in the S. agalactiae culture test to increase test accuracy. Full article
(This article belongs to the Special Issue Biotechnological Applications of Phage and Phage-Derived Proteins)
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Open AccessArticle Genetic Characterization and Pathogenicity of a Novel Recombined Porcine Reproductive and Respiratory Syndrome Virus 2 among Nadc30-Like, Jxa1-Like, and Mlv-Like Strains
Viruses 2018, 10(10), 551; https://doi.org/10.3390/v10100551
Received: 6 August 2018 / Revised: 28 September 2018 / Accepted: 28 September 2018 / Published: 9 October 2018
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Recombination among porcine reproductive and respiratory syndrome viruses (PRRSVs), coupled with point mutations, insertions, and deletions occurring in the genome, is considered to contribute to the emergence of new variants. Here, we report the complete genome sequences of a PRRSV field strain, designated
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Recombination among porcine reproductive and respiratory syndrome viruses (PRRSVs), coupled with point mutations, insertions, and deletions occurring in the genome, is considered to contribute to the emergence of new variants. Here, we report the complete genome sequences of a PRRSV field strain, designated SCN17, isolated from a RespPRRS MLV-vaccinated piglet in China in 2017. Sequence alignment revealed that SCN17 had discontinuous 131-amino acid (111 + 1 + 19-aa) deletion in the NSP2-coding region identical to that of NADC30 when compared to VR-2332. Notably, the strain, SCN17, contained an additional 1-aa deletion in NSP2, a 1-aa deletion in ORF5, and a unique 3-nt deletion in the 3′-UTR. Phylogenetic analysis showed that SCN17 clustered into NADC30-like lineage based on ORF5 genotyping, whereas it belonged to an inter-lineage between the NADC30-like and VR-2332-like lineages as established based on the full-length genome. Importantly, the SCN17 was identified as a novel virus recombined between a NADC30-like (moderately pathogenic), a JXA1-like (highly pathogenic), and an attenuated vaccine strain, RespPRRS MLV (parental strain VR-2332). Furthermore, we tested its pathogenicity in piglets. SCN17 infection caused a persistent fever, moderate interstitial pneumonia, and increased the viremia and antibody levels in the inoculated piglets. Of note, all SCN17-infected piglets survived throughout the study. The new virus was showed to be a moderately virulent isolate and have lower pathogenicity than HP-PRRSV strain, SCwhn09CD. Our results provide evidence for the continuing evolution of PRRSV field strain by genetic recombination and mutation leading to outbreaks in the vaccinated pig populations in China. Full article
(This article belongs to the Special Issue Emerging Viruses)
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Open AccessArticle Strain-Dependent Consequences of Zika Virus Infection and Differential Impact on Neural Development
Viruses 2018, 10(10), 550; https://doi.org/10.3390/v10100550
Received: 22 August 2018 / Revised: 2 October 2018 / Accepted: 4 October 2018 / Published: 9 October 2018
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Maternal infection with Zika virus (ZIKV) during pregnancy can result in neonatal abnormalities, including neurological dysfunction and microcephaly. Experimental models of congenital Zika syndrome identified neural progenitor cells as a target of viral infection. Neural progenitor cells are responsible for populating the developing
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Maternal infection with Zika virus (ZIKV) during pregnancy can result in neonatal abnormalities, including neurological dysfunction and microcephaly. Experimental models of congenital Zika syndrome identified neural progenitor cells as a target of viral infection. Neural progenitor cells are responsible for populating the developing central nervous system with neurons and glia. Neural progenitor dysfunction can lead to severe birth defects, namely, lissencephaly, microcephaly, and cognitive deficits. For this study, the consequences of ZIKV infection in human pluripotent stem cell-derived neural progenitor (hNP) cells and neurons were evaluated. ZIKV isolates from Asian and African lineages displayed lineage-specific replication kinetics, cytopathic effects, and impacts on hNP function and neuronal differentiation. The currently circulating ZIKV isolates exhibit a unique profile of virulence, cytopathic effect, and impaired cellular functions that likely contribute to the pathological mechanism of congenital Zika syndrome. The authors found that infection with Asian-lineage ZIKV isolates impaired the proliferation and migration of hNP cells, and neuron maturation. In contrast, the African-lineage infections resulted in abrupt and extensive cell death. This work furthers the understanding of ZIKV-induced brain pathology. Full article
(This article belongs to the Special Issue New Advances on Zika Virus Research)
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Open AccessPerspective Ebola Virus Maintenance: If Not (Only) Bats, What Else?
Viruses 2018, 10(10), 549; https://doi.org/10.3390/v10100549
Received: 1 September 2018 / Revised: 26 September 2018 / Accepted: 3 October 2018 / Published: 9 October 2018
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The maintenance mechanisms of ebolaviruses in African forest ecosystems are still unknown, but indirect evidences point at the involvement of some bat species. Despite intense research, the main bat-maintenance hypothesis has not been confirmed yet. The alternative hypotheses of a non-bat maintenance host
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The maintenance mechanisms of ebolaviruses in African forest ecosystems are still unknown, but indirect evidences point at the involvement of some bat species. Despite intense research, the main bat-maintenance hypothesis has not been confirmed yet. The alternative hypotheses of a non-bat maintenance host or a maintenance community including, or not, several bat and other species, deserves more investigation. However, African forest ecosystems host a large biodiversity and abound in potential maintenance hosts. How does one puzzle out? Since recent studies have revealed that several bat species have been exposed to ebolaviruses, the common denominator to these hypotheses is that within the epidemiological cycle, some bats species must be exposed to the viruses and infected by these potential alternative hosts. Under this constraint, and given the peculiar ecology of bats (roosting behaviour, habitat utilisation, and flight mode), we review the hosts and transmission pathways that can lead to bat exposure and infection to ebolaviruses. In contrast to the capacity of bats to transmit ebolaviruses and other pathogens to many hosts, our results indicate that only a limited number of hosts and pathways can lead to the transmission of ebolaviruses to bats, and that the alternative maintenance host, if it exists, must be amongst them. A list of these pathways is provided, along with protocols to prioritise and investigate these alternative hypotheses. In conclusion, taking into account the ecology of bats and their known involvement in ebolaviruses ecology drastically reduces the list of potential alternative maintenance hosts for ebolaviruses. Understanding the natural history of ebolaviruses is a health priority, and investigating these alternative hypotheses could complete the current effort focused on the role of bats. Full article
(This article belongs to the collection Advances in Ebolavirus, Marburgvirus, and Cuevavirus Research)
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Open AccessArticle Recombinant GII.P16/GII.4 Sydney 2012 Was the Dominant Norovirus Identified in Australia and New Zealand in 2017
Viruses 2018, 10(10), 548; https://doi.org/10.3390/v10100548
Received: 14 September 2018 / Revised: 5 October 2018 / Accepted: 6 October 2018 / Published: 9 October 2018
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For the past two decades, norovirus pandemic variants have emerged every 3–5 years, and dominate until they are replaced by alternate strains. However, this scenario changed in 2016 with the co-circulation of six prevalent viruses, three of which possessed the pandemic GII.4 Sydney
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For the past two decades, norovirus pandemic variants have emerged every 3–5 years, and dominate until they are replaced by alternate strains. However, this scenario changed in 2016 with the co-circulation of six prevalent viruses, three of which possessed the pandemic GII.4 Sydney 2012 capsid. An increased number of institutional gastroenteritis outbreaks were reported within the Oceania region in mid-2017. This study identified emerging noroviruses circulating in Australia and New Zealand in 2017 to assess the changing dynamics of the virus infection. RT-PCR-based methods, next generation sequencing, and phylogenetic analyses were used to genotype noroviruses from both clinical and wastewater samples. Antigenic changes were observed between the capsid of pandemic Sydney 2012 variant and the two new Sydney recombinant viruses. The combination of these antigenic changes and the acquisition of a new ORF1 through recombination could both facilitate their ongoing persistence in the population. Overall, an increased prevalence of GII.P16/GII.4 Sydney 2012 viruses was observed in 2017, replacing the GII.P16/GII.2 recombinant that dominated in the region at the end of 2016. This shift in strain dominance was also observed in wastewater samples, demonstrating the reliability of wastewater as a molecular surveillance tool. Full article
(This article belongs to the Special Issue Emerging Viruses)
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