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Pathogens, Volume 7, Issue 4 (December 2018)

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Open AccessArticle Epigallocatechin Gallate Remodelling of Hfq Amyloid-Like Region Affects Escherichia coli Survival
Received: 11 November 2018 / Revised: 22 November 2018 / Accepted: 26 November 2018 / Published: 1 December 2018
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Abstract
Hfq is a pleiotropic regulator that has key roles in the control of genetic expression. The protein noticeably regulates translation efficiency and RNA decay in Gram-negative bacteria, due to the Hfq-mediated interaction between small regulatory noncoding RNA and mRNA. This property is of
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Hfq is a pleiotropic regulator that has key roles in the control of genetic expression. The protein noticeably regulates translation efficiency and RNA decay in Gram-negative bacteria, due to the Hfq-mediated interaction between small regulatory noncoding RNA and mRNA. This property is of primary importance for bacterial adaptation and virulence. We have previously shown that the Hfq E. coli protein, and more precisely its C-terminal region (CTR), self-assembles into an amyloid-like structure. In the present work, we demonstrate that epigallocatechin gallate (EGCG), a major green tea polyphenol compound, targets the Hfq amyloid region and can be used as a potential antibacterial agent. We analysed the effect of this compound on Hfq amyloid fibril stability and show that EGCG both disrupts Hfq-CTR fibrils and inhibits their formation. We show that, even if EGCG affects other bacterial amyloids, it also specifically targets Hfq-CTR in vivo. Our results provide an alternative approach for the utilisation of EGCG that may be used synergistically with conventional antibiotics to block bacterial adaptation and treat infections. Full article
(This article belongs to the Special Issue Inactivate Bacterial Resistance Mechanisms)
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Open AccessArticle Morphological and Molecular Variation Between Fusarium avenaceum, Fusarium arthrosporioides and Fusarium anguioides Strains
Received: 8 October 2018 / Accepted: 26 October 2018 / Published: 29 November 2018
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Abstract
Fusarium avenaceum and closely related species are common fungi on various plants, cultivated in different climatic regions. The aim of this study was to determine the taxonomic affiliations of the F. avenaceum, Fusarium arthrosporioides, and Fusarium anguioides strains by using morphological, physiological
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Fusarium avenaceum and closely related species are common fungi on various plants, cultivated in different climatic regions. The aim of this study was to determine the taxonomic affiliations of the F. avenaceum, Fusarium arthrosporioides, and Fusarium anguioides strains by using morphological, physiological and molecular-genetic approaches. Twenty-six single-spored morphologically identified strains, which were mainly from cereals, were investigated in order to find out, if they belong to a separate species. Pathogenicity of strains to wheat seedlings and ISSR (Inter Simple Sequence Repeats) fingerprint and beta-tubulin DNA sequence patterns were analyzed. According to phylogenetic analyses, the strains could be divided into two big groups consisting of mostly F. avenaceum or F. anguioides strains. F. arthrosporioides was not detected as a separate species by the sum of the characters. F. anguioides was characterized as a separate species, which could be identified by morphological and molecular data. High genetic diversity of the F. avenaceum and related species was revealed. One F. anguioides strain (rudbeckia, Vladivostok, Russia), had an identical beta-tubulin sequence with two previously sequenced strains of Fusarium tricinctum species complex, which were isolated from dicotyledonous plants in Asia. Full article
(This article belongs to the Special Issue Fusarium)
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Open AccessReview Fusarium, an Entomopathogen—A Myth or Reality?
Received: 8 October 2018 / Revised: 24 November 2018 / Accepted: 26 November 2018 / Published: 28 November 2018
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Abstract
The Fusarium species has diverse ecological functions ranging from saprophytes, endophytes, and animal and plant pathogens. Occasionally, they are isolated from dead and alive insects. However, research on fusaria-insect associations is very limited as fusaria are generalized as opportunistic insect-pathogens. Additionally, their phytopathogenicity
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The Fusarium species has diverse ecological functions ranging from saprophytes, endophytes, and animal and plant pathogens. Occasionally, they are isolated from dead and alive insects. However, research on fusaria-insect associations is very limited as fusaria are generalized as opportunistic insect-pathogens. Additionally, their phytopathogenicity raises concerns in their use as commercial biopesticides. Insect biocontrol potential of Fusarium is favored by their excellent soil survivability as saprophytes, and sometimes, insect-pathogenic strains do not exhibit phytopathogenicity. In addition, a small group of fusaria, those belonging to the Fusarium solani species complex, act as insect mutualists assisting in host growth and fecundity. In this review, we summarize mutualism and pathogenicity among fusaria and insects. Furthermore, we assert on Fusarium entomopathogenicity by analyzing previous studies clearly demonstrating their natural insect-pathogenicity in fields, and their presence in soils. We also review the presence and/or production of a well-known insecticidal metabolite beauvericin by different Fusarium species. Lastly, some proof-of-concept studies are also summarized, which demonstrate the histological as well as immunological changes that a larva undergoes during Fusarium oxysporum pathogenesis. These reports highlight the insecticidal properties of some Fusarium spp., and emphasize the need of robust techniques, which can distinguish phytopathogenic, mutualistic and entomopathogenic fusaria. Full article
(This article belongs to the Special Issue Fusarium)
Open AccessArticle Relation between Biofilm and Virulence in Vibrio tapetis: A Transcriptomic Study
Received: 28 September 2018 / Revised: 20 November 2018 / Accepted: 23 November 2018 / Published: 26 November 2018
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Abstract
Marine pathogenic bacteria are able to form biofilms on many surfaces, such as mollusc shells, and they can wait for the appropriate opportunity to induce their virulence. Vibrio tapetis can develop such biofilms on the inner surface of shells of the Ruditapes philippinarum
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Marine pathogenic bacteria are able to form biofilms on many surfaces, such as mollusc shells, and they can wait for the appropriate opportunity to induce their virulence. Vibrio tapetis can develop such biofilms on the inner surface of shells of the Ruditapes philippinarum clam, leading to the formation of a brown conchiolin deposit in the form of a ring, hence the name of the disease: Brown Ring Disease. The virulence of V. tapetis is presumed to be related to its capacity to form biofilms, but the link has never been clearly established at the physiological or genetic level. In the present study, we used RNA-seq analysis to identify biofilm- and virulence-related genes displaying altered expression in biofilms compared to the planktonic condition. A flow cell system was employed to grow biofilms to obtain both structural and transcriptomic views of the biofilms. We found that 3615 genes were differentially expressed, confirming that biofilm and planktonic lifestyles are very different. As expected, the differentially expressed genes included those involved in biofilm formation, such as motility- and polysaccharide synthesis-related genes. The data show that quorum sensing is probably mediated by the AI-2/LuxO system in V. tapetis biofilms. The expression of genes encoding the Type VI Secretion System and associated exported proteins are strongly induced, suggesting that V. tapetis activates this virulence factor when living in biofilm. Full article
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Open AccessArticle Kupffer Cells Survive Plasmodium berghei Sporozoite Exposure and Respond with a Rapid Cytokine Release
Received: 24 October 2018 / Revised: 20 November 2018 / Accepted: 21 November 2018 / Published: 24 November 2018
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Abstract
The liver stage of the Plasmodium life cycle features sporozoite traversal of the liver sinusoidal barrier through Kupffer cells (KCs) followed by invasion of hepatocytes. Little is known about the interaction of Plasmodium sporozoites with KCs, the liver-resident macrophages. Previous reports suggest KCs
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The liver stage of the Plasmodium life cycle features sporozoite traversal of the liver sinusoidal barrier through Kupffer cells (KCs) followed by invasion of hepatocytes. Little is known about the interaction of Plasmodium sporozoites with KCs, the liver-resident macrophages. Previous reports suggest KCs do not mount a pro-inflammatory response and undergo cell death following this interaction. Our work explores this interaction using primary rat KCs (PRKCs) and Plasmodium berghei sporozoites. We analyzed PRKC culture supernatants for markers of an immunological response through cytokine arrays. Additionally, cell wounding and death were assessed by monitoring lactate dehydrogenase (LDH) levels in these supernatants and by live/dead cell imaging. We found that PRKCs mount an immunological response to P. berghei sporozoites by releasing a diverse set of both pro- and anti-inflammatory cytokines, including IFNγ, IL-12p70, Mip-3α, IL-2, RANTES, IL-1α, IL-4, IL-5, IL-13, EPO, VEGF, IL-7, and IL-17α. We also observed no difference in LDH level or live/dead staining upon sporozoite exposure, suggesting that the KCs are not deeply wounded or dying. Overall, our data suggest that sporozoites may be actively modulating the KC’s reaction to their presence and altering the way the innate immune system is triggered by KCs. Full article
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Open AccessArticle Investigation of Camphor Effects on Fusarium graminearum and F. culmorum at Different Molecular Levels
Received: 16 October 2018 / Revised: 9 November 2018 / Accepted: 19 November 2018 / Published: 22 November 2018
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Abstract
Fusarium graminearum and F. culmorum are phytopathogens, which cause destructive diseases in cereals. Epidemics of these phytopathogens are caused by mycotoxin contamination and the reduction of crop quality. In this study, the alteration due to in vitro camphor treatment on F. culmorum 9F
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Fusarium graminearum and F. culmorum are phytopathogens, which cause destructive diseases in cereals. Epidemics of these phytopathogens are caused by mycotoxin contamination and the reduction of crop quality. In this study, the alteration due to in vitro camphor treatment on F. culmorum 9F and F. graminearum H11 isolates was investigated in terms of epigenetic, cellular, and transcription levels. Camphor with different concentrations (0.2, 0.4, 0.8, 1, 2, and 4 µg/µL) was applied to potato dextrose agar (PDA) growth media. The minimum inhibitory concentration (MIC) and the half maximal inhibitory concentration (IC50) were calculated as 2 and 1 µg/µL, respectively. hog1, mst20, CAT, POD, mgv1, stuA, and tri5 genes, which are related to various cellular processes and pathogenesis, were examined by qPCR assay. qPCR analysis showed that camphor treatment leads to the downregulation of tri5 expression but the upregulation of the remaining genes. Apoptosis and oxidative stress were confirmed via acridine orange/ethidium bromide (AO/EB) and dichlorofluorescin diacetate (DCF-DA) staining, respectively. Moreover, coupled restriction enzyme digestion-random amplification (CRED-RA) assay, used for DNA methylation analysis, was carried out to evaluate epigenetic alterations. The decrease in genomic template stability (GTS) values, which resulted due to the alterations in random amplified polymorphic DNA (RAPD) profiles caused by camphor treatment, were detected as 97.60% in F. culmorum 9F and 66.27% in F. graminearum H-11. The outer and inner methylated cytosine profiles are determined by CRED-RA assay as type I–IV epigenetic alterations. The outcomes indicated that camphor could lead to alterations at several molecular levels of F. graminearum and F. culmorum. Full article
(This article belongs to the Special Issue Fusarium)
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Open AccessCommunication Soil Chemical Properties Barely Perturb the Abundance of Entomopathogenic Fusarium oxysporum: A Case Study Using a Generalized Linear Mixed Model for Microbial Pathogen Occurrence Count Data
Received: 30 September 2018 / Revised: 20 October 2018 / Accepted: 31 October 2018 / Published: 16 November 2018
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Abstract
Fusarium oxysporum exhibits insect pathogenicity—however, generalized concerns of releasing phytopathogens within agroecosystems marred its entomopathogenicity-related investigations. In a previous study, soils were sampled from Douro vineyards and adjacent hedgerows. In this study, 80 of those soils were analyzed for their chemical properties and
[...] Read more.
Fusarium oxysporum exhibits insect pathogenicity—however, generalized concerns of releasing phytopathogens within agroecosystems marred its entomopathogenicity-related investigations. In a previous study, soils were sampled from Douro vineyards and adjacent hedgerows. In this study, 80 of those soils were analyzed for their chemical properties and were subsequently co-related with the abundance of entomopathogenic F. oxysporum, after insect baiting of soils with Galleria mellonella and Tenebrio molitor larvae. The soil chemical properties studied were organic matter content; total organic carbon; total nitrogen; available potassium; available phosphorus; exchangeable cations, such as K+, Na+, Ca2+, and Mg2+; pH; total acidity; degree of base saturation; and effective cation exchange capacity. Entomopathogenic F. oxysporum was found in 48 soils, i.e., 60% ± 5.47%, of the total soil samples. Out of the 1280 insect larvae used, 93, i.e., 7.26% ± 0.72%, were found dead by entomopathogenic F. oxysporum. Stepwise deletion of non-significant variables using a generalized linear model was followed by a generalized linear mixed model (GLMM). A higher C:N (logarithmized) (p < 0.001) and lower exchangeable K+ (logarithmized) (p = 0.008) were found significant for higher fungal abundance. Overall, this study suggests that entomopathogenic F. oxysporum is robust with regard to agricultural changes, and GLMM is a useful statistical tool for count data in ecology. Full article
(This article belongs to the Special Issue Fusarium)
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Open AccessReview Modelling a Silent Epidemic: A Review of the In Vitro Models of Latent Tuberculosis
Received: 29 October 2018 / Revised: 5 November 2018 / Accepted: 13 November 2018 / Published: 15 November 2018
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Abstract
Tuberculosis (TB) is the primary cause of death by a single infectious agent; responsible for around two million deaths in 2016. A major virulence factor of TB is the ability to enter a latent or Non-Replicating Persistent (NRP) state which is presumed untreatable.
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Tuberculosis (TB) is the primary cause of death by a single infectious agent; responsible for around two million deaths in 2016. A major virulence factor of TB is the ability to enter a latent or Non-Replicating Persistent (NRP) state which is presumed untreatable. Approximately 1.7 billion people are latently infected with TB and on reactivation many of these infections are drug resistant. As the current treatment is ineffective and diagnosis remains poor, millions of people have the potential to reactivate into active TB disease. The immune system seeks to control the TB infection by containing the bacteria in a granuloma, where it is exposed to stressful anaerobic and nutrient deprived conditions. It is thought to be these environmental conditions that trigger the NRP state. A number of in vitro models have been developed that mimic conditions within the granuloma to a lesser or greater extent. These different models have all been utilised for the research of different characteristics of NRP Mycobacterium tuberculosis, however their disparity in approach and physiological relevance often results in inconsistencies and a lack of consensus between studies. This review provides a summation of the different NRP models and a critical analysis of their respective advantages and disadvantages relating to their physiological relevance. Full article
(This article belongs to the Section Human Pathogens)
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Open AccessArticle Hsp90 Interacts with the Bacterial Effector NleH1
Received: 26 September 2018 / Revised: 31 October 2018 / Accepted: 11 November 2018 / Published: 13 November 2018
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Abstract
Enterohemorrhagic Escherichia coli (EHEC) utilizes a type III secretion system (T3SS) to inject effector proteins into host cells. The EHEC NleH1 effector inhibits the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway by reducing the nuclear translocation of the ribosomal protein S3
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Enterohemorrhagic Escherichia coli (EHEC) utilizes a type III secretion system (T3SS) to inject effector proteins into host cells. The EHEC NleH1 effector inhibits the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway by reducing the nuclear translocation of the ribosomal protein S3 (RPS3). NleH1 prevents RPS3 phosphorylation by the IκB kinase-β (IKKβ). IKKβ is a central kinase in the NF-κB pathway, yet NleH1 only restricts the phosphorylation of a subset of the IKKβ substrates. We hypothesized that a protein cofactor might dictate this inhibitory specificity. We determined that heat shock protein 90 (Hsp90) interacts with both IKKβ and NleH1 and that inhibiting Hsp90 activity reduces RPS3 nuclear translocation. Full article
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Open AccessArticle SseL Deubiquitinates RPS3 to Inhibit Its Nuclear Translocation
Received: 23 September 2018 / Revised: 2 November 2018 / Accepted: 5 November 2018 / Published: 7 November 2018
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Abstract
Many Gram-negative bacterial pathogens use type III secretion systems to deliver virulence proteins (effectors) into host cells to counteract innate immunity. The ribosomal protein S3 (RPS3) guides NF-κB subunits to specific κB sites and plays an important role in the innate response to
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Many Gram-negative bacterial pathogens use type III secretion systems to deliver virulence proteins (effectors) into host cells to counteract innate immunity. The ribosomal protein S3 (RPS3) guides NF-κB subunits to specific κB sites and plays an important role in the innate response to bacterial infection. Two E. coli effectors inhibit RPS3 nuclear translocation. NleH1 inhibits RPS3 phosphorylation by IKK-β, an essential aspect of the RPS3 nuclear translocation process. NleC proteolysis of p65 generates an N-terminal p65 fragment that competes for full-length p65 binding to RPS3, thus also inhibiting RPS3 nuclear translocation. Thus, E. coli has multiple mechanisms by which to block RPS3-mediated transcriptional activation. With this in mind, we considered whether other enteric pathogens also encode T3SS effectors that impact this important host regulatory pathway. Here we report that the Salmonella Secreted Effector L (SseL), which was previously shown to function as a deubiquitinase and inhibit NF-κB signaling, also inhibits RPS3 nuclear translocation by deubiquitinating this important host transcriptional co-factor. RPS3 deubiquitination by SseL was restricted to K63-linkages and mutating the active-site cysteine of SseL abolished its ability to deubiquitinate and subsequently inhibit RPS3 nuclear translocation. Thus, Salmonella also encodes at least one T3SS effector that alters RPS3 activities in the host nucleus. Full article
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Open AccessArticle Pathotypes of Xanthomonas axonopodis pv. dieffenbachiae Isolated from Anthurium andraeanum in China
Received: 9 September 2018 / Revised: 21 October 2018 / Accepted: 29 October 2018 / Published: 6 November 2018
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Abstract
Anthurium blight, caused by Xanthomonas axonopodis pv. dieffenbachiae (Xad), is one of the most serious diseases of Anthurium andraeanum. However, little is known about variations in virulence between Xad pathotypes. Here, we examined the virulence of 68 Xad strains isolated from
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Anthurium blight, caused by Xanthomonas axonopodis pv. dieffenbachiae (Xad), is one of the most serious diseases of Anthurium andraeanum. However, little is known about variations in virulence between Xad pathotypes. Here, we examined the virulence of 68 Xad strains isolated from 30 anthurium plants from five regions of China against five different anthurium cultivars. Seven bacterial pathotypes were identified based on disease index and incidence analyses following foliar spray or leaf-clip inoculation. The resulting disease susceptibility patterns for pathotypes I–VII were RRRSS, RRSRS, RSRSR, RRSSS, RSSRS, RSSSS, and SSSSS, respectively. Overall, 72% of tested strains belonged to pathotypes VI or VII and were highly virulent. A further 22.1% of strains showed medium-level virulence and were classed as pathotype III, IV, or V, while the remaining 5.9% of strains were pathotype I or II, showing low virulence. Further analysis revealed differences in the virulence of Xad strains from the same anthurium cultivar, with variation also observed in pathovars associated with the same cultivar from different areas. Our results reveal the diversity and complexity of the Xad population structure in China and suggest that investigation of Xad pathotypes provides useful information to guide the identification and use of resistant varieties of A. andraeanum. Full article
(This article belongs to the Section Plant Pathogens)
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Open AccessReview Improving the Breadth of the Host’s Immune Response to Lassa Virus
Received: 21 September 2018 / Revised: 20 October 2018 / Accepted: 24 October 2018 / Published: 28 October 2018
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Abstract
In 2017, the global Coalition for Epidemic Preparedness (CEPI) declared Lassa virus disease to be one of the world’s foremost biothreats. In January 2018, World Health Organization experts met to address the Lassa biothreat. It was commonly recognized that the diversity of Lassa
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In 2017, the global Coalition for Epidemic Preparedness (CEPI) declared Lassa virus disease to be one of the world’s foremost biothreats. In January 2018, World Health Organization experts met to address the Lassa biothreat. It was commonly recognized that the diversity of Lassa virus (LASV) isolated from West African patient samples was far greater than that of the Ebola isolates from the West African epidemic of 2013–2016. Thus, vaccines produced against Lassa virus disease face the added challenge that they must be broadly-protective against a wide variety of LASV. In this review, we discuss what is known about the immune response to Lassa infection. We also discuss the approaches used to make broadly-protective influenza vaccines and how they could be applied to developing broad vaccine coverage against LASV disease. Recent advances in AIDS research are also potentially applicable to the design of broadly-protective medical countermeasures against LASV disease. Full article
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Open AccessReview Armillaria Root-Rot Pathogens: Species Boundaries and Global Distribution
Received: 21 September 2018 / Revised: 21 October 2018 / Accepted: 21 October 2018 / Published: 24 October 2018
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Abstract
This review considers current knowledge surrounding species boundaries of the Armillaria root-rot pathogens and their distribution. In addition, a phylogenetic tree using translation elongation factor subunit 1-alpha (tef-1α) from isolates across the globe are used to present a global phylogenetic framework
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This review considers current knowledge surrounding species boundaries of the Armillaria root-rot pathogens and their distribution. In addition, a phylogenetic tree using translation elongation factor subunit 1-alpha (tef-1α) from isolates across the globe are used to present a global phylogenetic framework for the genus. Defining species boundaries based on DNA sequence-inferred phylogenies has been a central focus of contemporary mycology. The results of such studies have in many cases resolved the biogeographic history of species, mechanisms involved in dispersal, the taxonomy of species and how certain phenotypic characteristics have evolved throughout lineage diversification. Such advances have also occurred in the case of Armillaria spp. that include important causal agents of tree root rots. This commenced with the first phylogeny for Armillaria that was based on IGS-1 (intergenic spacer region one) DNA sequence data, published in 1992. Since then phylogenies were produced using alternative loci, either as single gene phylogenies or based on concatenated data. Collectively these phylogenies revealed species clusters in Armillaria linked to their geographic distributions and importantly species complexes that warrant further research. Full article
(This article belongs to the Special Issue Fungal Pathogens of Forest Trees)
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Open AccessArticle Biochemical Characterization of Clinical Strains of Staphylococcus spp. and Their Sensitivity to Polyphenols-Rich Extracts from Pistachio (Pistacia vera L.)
Received: 14 September 2018 / Revised: 11 October 2018 / Accepted: 19 October 2018 / Published: 22 October 2018
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Abstract
We characterized a number of clinical strains of Staphylococcus spp. and investigated their sensitivity against polyphenols-rich extracts from natural raw and roasted pistachios (NPRE and RPRE, respectively). Out of 31 clinical isolates of Staphylococcus spp., 23 were coagulase-positive and identified as S. aureus
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We characterized a number of clinical strains of Staphylococcus spp. and investigated their sensitivity against polyphenols-rich extracts from natural raw and roasted pistachios (NPRE and RPRE, respectively). Out of 31 clinical isolates of Staphylococcus spp., 23 were coagulase-positive and identified as S. aureus, of which 21 were MRSA. Polyphenols-rich extracts from natural pistachios and roasted pistachios were prepared: the total phenols content, expressed as gallic acid equivalent (GAE)/100 g fresh weight (FW), was higher in natural pistachios (359.04 ± 8.124 mg) than roasted pistachios (225.18 ± 5.055 mg). The higher total phenols content in natural pistachios also correlated to the higher free-radical scavenging activity found by DPPH assay: NPRE and RPRE showed IC50 values of 0.85 (C.L. 0.725–0.976 mg mL−1) and 1.15 (C.L. 0.920–1.275 mg mL−1), respectively. Both NPRE and RPRE were active against S. aureus 6538P and Staph. spp. clinical isolates, with RPRE being the most active (MIC values ranging between 31.25 and 2000 μg mL−1). The antimicrobial potential of pistachios could be used to identify novel treatments for S. aureus skin infections. Full article
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Open AccessReview Fungal Pathogens of Maize Gaining Free Passage Along the Silk Road
Received: 19 August 2018 / Revised: 3 October 2018 / Accepted: 6 October 2018 / Published: 11 October 2018
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Abstract
Silks are the long threads at the tips of maize ears onto which pollen land and sperm nuclei travel long distances to fertilize egg cells, giving rise to embryos and seeds; however fungal pathogens also use this route to invade developing grain, causing
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Silks are the long threads at the tips of maize ears onto which pollen land and sperm nuclei travel long distances to fertilize egg cells, giving rise to embryos and seeds; however fungal pathogens also use this route to invade developing grain, causing damaging ear rots with dangerous mycotoxins. This review highlights the importance of silks as the direct highways by which globally important fungal pathogens enter maize kernels. First, the most important silk-entering fungal pathogens in maize are reviewed, including Fusarium graminearum, Fusarium verticillioides, and Aspergillus flavus, and their mycotoxins. Next, we compare the different modes used by each fungal pathogen to invade the silks, including susceptible time intervals and the effects of pollination. Innate silk defences and current strategies to protect silks from ear rot pathogens are reviewed, and future protective strategies and silk-based research are proposed. There is a particular gap in knowledge of how to improve silk health and defences around the time of pollination, and a need for protective silk sprays or other technologies. It is hoped that this review will stimulate innovations in breeding, inputs, and techniques to help growers protect silks, which are expected to become more vulnerable to pathogens due to climate change. Full article
(This article belongs to the Special Issue Fusarium)
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Open AccessArticle Challenge Studies to Determine the Ability of Foods to Support the Growth of Listeria monocytogenes
Received: 27 July 2018 / Revised: 1 October 2018 / Accepted: 2 October 2018 / Published: 5 October 2018
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Abstract
Listeria monocytogenes is a foodborne pathogen that causes listeriosis, a relatively rare, but potentially fatal, disease, with a mortality rate of 20–30%. In general, European Regulations require the absence of L. monocytogenes in five samples of 25 g before the food has left
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Listeria monocytogenes is a foodborne pathogen that causes listeriosis, a relatively rare, but potentially fatal, disease, with a mortality rate of 20–30%. In general, European Regulations require the absence of L. monocytogenes in five samples of 25 g before the food has left the producer, but if the food has been demonstrated not to support the growth of L. monocytogenes, up to 100 cfu g−1 are allowed in the food (except for foods for infants or medical purposes) during its shelf-life under reasonably foreseeable storage conditions. It is important for food producers to determine if their food supports the growth of L. monocytogenes. The European Union Reference Laboratory for L. monocytogenes published a Technical Guidance document for conducting shelf-life studies on L. monocytogenes in ready-to-eat foods in June 2014. Primarily based on the EURL guidance document for conducting challenge studies, the ability of cheese (feta and soft goat’s milk cheese), cold-smoked salmon, coleslaw, and pork pate to support the growth of L. monocytogenes was determined using a starting inoculum of approximately 100 cfu g−1. The cheese and pork pate were incubated at 8 °C for 14 days; the smoked salmon was incubated at 6 °C for 5 days and 8 °C for 9 days; and the coleslaw was incubated at 8 °C for 7 days and 12 °C for 14 days. The results showed that the smoked salmon and pork pate supported growth, while coleslaw and cheese did not. From this study, it is evident that there are factors in food other than pH, water activity, and total bacterial count (TBC) that can inhibit the ability of L. monocytogenes to grow in food. Full article
Open AccessArticle Effect of Cetylpyridinium Chloride (CPC) on Colony Formation of Common Nontuberculous Mycobacteria
Received: 18 September 2018 / Revised: 25 September 2018 / Accepted: 30 September 2018 / Published: 5 October 2018
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Abstract
Cetylpyridinium chloride (CPC) is widely used to decontaminate water samples for the cultivation of nontuberculous mycobacteria (NTM). The rationale for using CPC is that it kills more non mycobacteria than NTM and thereby prevents the outgrowth and detection of mycobacterial colonies on solid
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Cetylpyridinium chloride (CPC) is widely used to decontaminate water samples for the cultivation of nontuberculous mycobacteria (NTM). The rationale for using CPC is that it kills more non mycobacteria than NTM and thereby prevents the outgrowth and detection of mycobacterial colonies on solid media. The few CPC-susceptibility measurements that have been published, suggest that CPC-decontamination does kill significant numbers of NTM. We confirm that observation here and further demonstrate that CPC-susceptibility varied significantly by one log between representative NTM species and between strains of the same species. CPC-susceptibility was the same for cells collected from cultures or water-acclimated (P = 0.6485, T-test) and CPC-susceptibility was relatively similar over the range of commonly employed CPC dosages. We conclude that use of CPC as decontaminating agent may lead to failure to recover an NTM isolate and considerable underestimates of NTM numbers. Full article
Open AccessBrief Report Identification of Differentially Expressed Genes in BALB/c Mouse Liver upon Primary Infection with DENV1 and Sequential Heterologous Infection with DENV2
Received: 6 September 2018 / Revised: 28 September 2018 / Accepted: 28 September 2018 / Published: 2 October 2018
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Abstract
Dengue virus (DENV) results in 100 million cases of infections and 22,000 deaths per year. Liver involvement, thrombocytopenia, haemorrhage and plasma leakage are characteristic manifestations of severe forms of DENV infection. However, the molecular pathways of DENV infection have not been comprehensively studied
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Dengue virus (DENV) results in 100 million cases of infections and 22,000 deaths per year. Liver involvement, thrombocytopenia, haemorrhage and plasma leakage are characteristic manifestations of severe forms of DENV infection. However, the molecular pathways of DENV infection have not been comprehensively studied compared to the host immunological responses. We performed an in vivo study using the BALB/c mouse model with a modified mRNA differential display methodology (GeneFishingTM) using the annealing control primer (ACP) system to capture differentially expressed genes (DEGs) in mice liver upon primary infection with DENV1 and sequential heterologous infection with DENV2. Secondary heterologous infection with DENV2 was carried out at Immunoglobulin IgM and IgG peaks following the primary DENV1 infection with the hope of determining any potential effect antibodies IgM and IgG may have on sequential heterologous infection. 30 DEGs were identified and sequenced across all three treatment groups and they belong to a variety of important pathways such as apoptosis, innate immune response, inflammatory response, metabolic processes and oxidative stress. Analysis of differentially expressed genes in response to viral infection offers valuable knowledge about the dynamic and complex association between host cell and the virus. Furthermore, some DEGs identified support DENV induced liver damage. Full article
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Open AccessArticle Effects of Specific Electric Field Stimulation on the Release and Activity of Secreted Acid Phosphatases from Leishmania tarentolae and Implications for Therapy
Received: 31 July 2018 / Revised: 31 August 2018 / Accepted: 21 September 2018 / Published: 27 September 2018
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Abstract
Leishmaniasis is a neglected tropical disease with 1.6 million new cases reported each year. However, there are few safe, effective, and affordable treatments provided to those affected by this disease. Still under-appreciated as potential pharmaceutical targets, especially for cutaneous leishmaniasis infections, are the
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Leishmaniasis is a neglected tropical disease with 1.6 million new cases reported each year. However, there are few safe, effective, and affordable treatments provided to those affected by this disease. Still under-appreciated as potential pharmaceutical targets, especially for cutaneous leishmaniasis infections, are the two isozymes of secreted acid phosphatase (SAP). These enzymes are involved in the survival of the parasite in the sand fly vector, and in infecting host macrophages. While the application of electric or electromagnetic fields as a medicinal therapeutic is not new, the utility of electric field application for the treatment of leishmaniasis is under studied. Studies involving the effects of electric fields on the cell secretion of SAP or the activity of SAP that has been secreted prior to electrical stimulation have not yet been reported. This work is the first report on the effect of specific electric fields on the activity of Leishmania tarentolae secreted acid phosphatases and the modulation of this secretion from the cells. In addition, the kinetic constants for the enzyme isoforms were determined as a function of days in culture and removal of carbohydrate from the glycosylated enzymes, while using a glycosidase, was shown to affect these kinetic constants. Full article
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Open AccessArticle Effect of Arbuscular Mycorrhizal Fungi on Pratylenchus penetrans Infestation in Apple Seedlings under Greenhouse Conditions
Received: 31 July 2018 / Revised: 18 September 2018 / Accepted: 19 September 2018 / Published: 21 September 2018
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Abstract
A major problem in fruit cultivation in Flanders is replant disease due to a lack of uncultivated soils available for new plantings. Replant disease can cause poor growth and affect time to full production, however Arbuscular Mycorrhizal Fungi (AMF) can prove their usefulness
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A major problem in fruit cultivation in Flanders is replant disease due to a lack of uncultivated soils available for new plantings. Replant disease can cause poor growth and affect time to full production, however Arbuscular Mycorrhizal Fungi (AMF) can prove their usefulness with regard to these problems. To further investigate the effect of AMF on nematodes, different AMF species were amended to potted apple seedlings in the presence of the nematode Pratylenchus penetrans. Generally, apple seedlings grew better in the presence of nematodes when mycorrhiza were inoculated into the soil. Moreover, a positive correlation (R2 ≥ 0.88) was found between the percentage root length colonization of the roots of apple seedlings, by AMF species, and nematode reduction in the soil of the seedlings. Indigenous AMF could colonize the roots of apple seedlings the most efficiently, resulting in a higher biocontrol effect. Besides, a synergistic effect was observed when two AMF strains were applied together leading to a significant growth response of the seedlings. Full article
(This article belongs to the Special Issue Soilborne Plant Pathogens)
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