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Laura Álvarez-Fraga, Juan C Vázquez-Ucha, Marta Martínez-Guitián, Juan A Vallejo, Germán Bou, Alejandro Beceiro, Margarita Poza
Acinetobacter baumannii has emerged in the last decade as an important nosocomial pathogen. To identify genes involved in the course of a pneumonia infection, gene expression profiles were obtained from A. baumannii ATCC 17978 grown in mouse infected lungs and in culture medium. Gene expression analysis allowed us to determine a gene, the A1S_0242 gene (feoA), over-expressed during the pneumonia infection. In the present work, we evaluate the role of this gene, involved in iron uptake. The inactivation of the A1S_0242 gene resulted in an increase susceptibility to oxidative stress and a decrease in biofilm formation, in adherence to A549 cells and in fitness...
January 15, 2018: Virulence
Miriam Moscoso, Patricia García, Maria P Cabral, Carlos Rumbo, Germán Bou
Staphylococcus aureus infections are becoming a major global health issue due to the rapid emergence of multidrug-resistant strains. Therefore, there is an urgent need to develop an effective vaccine to prevent and control these infections. In order to develop a universal immunization strategy, we constructed a mutant derivative of S. aureus 132 which lacks the genes involved in D-alanine biosynthesis, a structural component of cell wall peptidoglycan. This unmarked deletion mutant requires the exogenous addition of D-alanine for in vitro growth...
January 3, 2018: Virulence
Surbhi Verma, Viplendra P S Shakya, Alexander Idnurm
Mitochondria are best known for their role in the production of ATP; however, recent research implicates other mitochondrial functions in the virulence of human pathogenic fungi. Inhibitors of mitochondrial succinate dehydrogenase or the electron transport chain are successfully used to combat plant pathogenic fungi, but similar inhibition of mitochondrial functions has not been pursued for applications in medical mycology. Advances in understanding mitochondrial function relevant to human pathogenic fungi are in four major directions: 1) the role of mitochondrial morphology in virulence, 2) mitochondrial genetics, with a focus on mitochondrial DNA recombination and mitochondrial inheritance 3) the role of mitochondria in drug resistance, and 4) the interaction of mitochondria with other organelles...
December 20, 2017: Virulence
Zainulabedeen R M H Mirza, Thaer Hasan, Veronique Seidel, Jun Yu
No abstract text is available yet for this article.
December 19, 2017: Virulence
Chi-Jan Lin, Chia-Yen Wu, Shang-Jie Yu, Ying-Lien Chen
Candida tropicalis is one of the most important human fungal pathogens causing superficial infections in locations such as the oral mucosa and genital tract, as well as systemic infections with high mortality. In its sister species Candida albicans, the cyclic AMP/protein kinase A (cAMP/PKA) pathway regulates fungal adhesion and dimorphism, both of which correlate closely with virulence. CaTpk1 and CaTpk2, the catalytic subunits of PKA, not only share redundant functions in hyphal growth, adhesion, and biofilm formation, but also have distinct roles in stress responses and pathogenesis, respectively...
December 19, 2017: Virulence
Zhe Zhao, Jinxin Liu, Yiqin Deng, Wen Huang, Chunhua Ren, Douglas R Call, Chaoqun Hu
Vibrio alginolyticus is a Gram-negative bacterium that is an opportunistic pathogen of both marine animals and people. Its pathogenesis likely involves type III secretion system (T3SS) mediated induction of rapid apoptosis, cell rounding and osmotic lysis of infected eukaryotic cells. Herein, we report that effector proteins, Val1686 and Val1680 from V. alginolyticus, were responsible for T3SS-mediated death of fish cells. Val1686 is a Fic-domain containing protein that not only contributed to cell rounding by inhibiting Rho guanosine triphosphatases (GTPases), but was requisite for the induction of apoptosis because the deletion mutant (Δval1686) was severely weakened in its ability to induce cell rounding and apoptosis in fish cells...
December 18, 2017: Virulence
Monica L Vieira, Aline F Teixeira, Giselle Pidde-Queiroz, Ana T C Ching, Denise V Tambourgi, Ana Lucia T O Nascimento, Heiko Herwald
Leptospirosis is a widespread zoonotic and neglected infectious disease of human and veterinary concern that is caused by pathogenic Leptospira species. After entrance in the host, pathogenic leptospires evade the host natural defense mechanisms in order to propagate and disseminate to multiple organs. Myeloperoxidase is an enzyme stored in neutrophils azurophilic granules, and is released upon neutrophil activation to produce mainly hypochlorous acid, a strong oxidant and potent antimicrobial agent. In the present investigation, we studied the modulation of myeloperoxidase activity by L...
December 13, 2017: Virulence
Andrea N García-Pérez, Anne de Jong, Sabryna Junker, Dörte Becher, Monika A Chlebowicz, José C Duipmans, Marcel F Jonkman, Jan Maarten van Dijl
Wound-colonizing microorganisms can form complex and dynamic polymicrobial communities where pathogens and commensals may co-exist, cooperate or compete with each other. The present study was aimed at identifying possible interactions between different bacteria isolated from the same chronic wound of a patient with the genetic blistering disease epidermolysis bullosa (EB). Specifically, this involved two different isolates of the human pathogen Staphylococcus aureus, and isolates of Bacillus thuringiensis and Klebsiella oxytoca...
December 13, 2017: Virulence
Ronan F O'Toole
In this issue of Virulence, Capel and colleagues describe the use of a unique humanised mouse model to elucidate specific interactions between Neisseria meningitidis and human endothelial cells during blood-borne infection in vivo. Here, a number of the key findings from their study and their implications for our understanding of invasive meningococcal disease are explored.
December 8, 2017: Virulence
Francisco Romero Pastrana, John M Thompson, Marjolein Heuker, Hedzer Hoekstra, Carly A Dillen, Roger V Ortines, Alyssa G Ashbaugh, Julie E Pickett, Matthijs D Linssen, Nicholas M Bernthal, Kevin P Francis, Girbe Buist, Marleen van Oosten, Gooitzen M van Dam, Daniel L J Thorek, Lloyd S Miller, Jan Maarten van Dijl
Staphylococcus aureus infections are a major threat in healthcare, requiring adequate early-stage diagnosis and treatment. This calls for novel diagnostic tools that allow noninvasive in vivo detection of staphylococci. Here we performed a preclinical study to investigate a novel fully-human monoclonal antibody 1D9 that specifically targets the immunodominant staphylococcal antigen A (IsaA). We show that 1D9 binds invariantly to S. aureus cells and may further target other staphylococcal species. Importantly, using a human post-mortem implant model and an in vivo murine skin infection model, preclinical feasibility was demonstrated for 1D9 labeled with the near-infrared fluorophore IRDye800CW to be applied for direct optical imaging of in vivo S...
November 23, 2017: Virulence
Krishnendu Mukherjee, Andreas Vilcinskas
Parasitic fungi are the only pathogens that can infect insect hosts directly through their proteinaceous exoskeleton. Penetration of the cuticle requires the release of fungal enzymes, including proteinases, which act as virulence factors. Insects can sense fungal infections and activate innate immune responses, including the synthesis of antifungal peptides and proteinase inhibitors that neutralize the incoming proteinases. This well-studied host response is epigenetically regulated by histone acetylation/deacetylation...
November 23, 2017: Virulence
Manasi Balachandran, David A Bemis, Stephen A Kania
Staphylococcus pseudintermedius is an opportunistic pathogen in dogs and the most frequent cause of canine pyoderma. Protein A, a potent virulence factor in S. aureus is encoded by the spa gene. S. pseudintermedius possesses genes seemingly analogous to spa, but the expression and the characteristics of their products have not been directly determined. The purpose of this study was to test isolates from major clonal groups for the presence of spa gene orthologs, quantitate their expression levels, and to characterize protein A in S...
November 20, 2017: Virulence
Sophia Johler
No abstract text is available yet for this article.
November 16, 2017: Virulence
Judith A Smith
No abstract text is available yet for this article.
November 16, 2017: Virulence
Nirmal Robinson
No abstract text is available yet for this article.
November 16, 2017: Virulence
Susmita Das, Shilpa Ray, Daniel Ryan, Bikash Sahu, Mrutyunjay Suar
Salmonella enterica subsp. I serovar Enteritidis (S. Enteritidis), one of the causative agents for non-typhoidal gastrointestinal diseases in humans is an intracellular bacterium and mechanism for its invasion into host cells is critical to cause infection. The virulence of the pathogen is explained by the expression of genes located on its pathogenicity islands, mostly encoded under SPI-1 and SPI-2. However, S. Typhimurium SL1344, despite sharing ∼98% of its genome with S. Enteritidis P125109, lacks few regions of differences (ROD) that are hypothesized to impart virulence potential to S...
November 13, 2017: Virulence
Adeline L Jorjão, Luciane D Oliveira, Liliana Scorzoni, Lívia Mara A Figueiredo-Godoi, Marcia Cristina A Prata, Antonio Olavo C Jorge, Juliana C Junqueira
Galleria mellonella is a well-accepted insect model for the study of pathogen-host interactions and antimicrobial compounds. The main advantages of this model include the low cost of maintenance, the fast life cycle, the possibility of using a large number of caterpillars and the innate immune system, which is evolutionarily conserved relative to mammals. Because of these advantages, different research groups have been working to implement the rearing of G. mellonella in laboratory conditions. This protocol describes our experience in the rearing of G...
November 13, 2017: Virulence
Michael J Davis, Michail S Lionakis
No abstract text is available yet for this article.
November 10, 2017: Virulence
Harald Rouha, Susanne Weber, Philipp Janesch, Barbara Maierhofer, Karin Gross, Ivana Dolezilkova, Irina Mirkina, Zehra C Visram, Stefan Malafa, Lukas Stulik, Adriana Badarau, Eszter Nagy
Pathogenesis of Staphylococcus aureus is increasingly recognized to be driven by powerful toxins. Staphylococcus aureus employs up to six pore-forming toxins to subvert the human host defense and to promote bacterial invasion: alpha-hemolysin that disrupts epithelial and endothelial barriers and five leukocidins that lyse phagocytes involved in bacterial clearance. Previously, we described two human monoclonal antibodies (mAbs), ASN-1 that neutralizes alpha-hemolysin and four leukocidins (LukSF-PV, LukED, HlgAB, HlgCB), and ASN-2 that inactivates the 5(th) leukocidin, LukGH...
November 3, 2017: Virulence
Elena Capel, Jean-Philippe Barnier, Aldert L Zomer, Christine Bole-Feysot, Thomas Nussbaumer, Anne Jamet, Hervé Lécuyer, Daniel Euphrasie, Zoé Virion, Eric Frapy, Philippe Pélissier, Olivier Join-Lambert, Thomas Rattei, Sandrine Bourdoulous, Xavier Nassif, Mathieu Coureuil
Neisseria meningitidis is the causative agent of cerebrospinal meningitis and that of a rapidly progressing fatal septic shock known as purpura fulminans. Meningococcemia is characterized by bacterial adhesion to human endothelial cells of the microvessels. Host specificity has hampered studies on the role of blood vessels colonization in N. meningitidis associated pathogenesis. In this work, using a humanized model of SCID mice allowing the study of bacterial adhesion to human cells in an in vivo context we demonstrate that meningococcal colonization of human blood vessels is a prerequisite to the establishment of sepsis and lethality...
November 3, 2017: Virulence
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