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Cellular Microbiology

Nanna Johnsen, Aimi D M Hamilton, Anne Sofie Greve, Mette G Christensen, Jacob R Therkildsen, Julia Wehmöller, Marianne Skals, Helle A Praetorius
α-haemolysin (HlyA) from uropathogenic Escherichia coli has been demonstrated to be a significant virulence factor for ascending urinary tract infections. Once the E. coli reach the well-vascularised kidneys, there is a high risk of bacteraemia and a subsequent septic host response. Despite this, HlyA has the potential to accelerate the host response both directly and via its ability to facilitate ATP release from cells. It has not been settled whether HlyA aggravates bacteraemia into a septic state. To address this, we used an E...
February 13, 2019: Cellular Microbiology
Johannes Westman, Bernhard Hube, Gregory D Fairn
Membrane bilayers of eukaryotic cells are an amalgam of lipids and proteins that distinguish organelles and compartmentalize cellular functions. The mammalian cell has evolved mechanisms to sense membrane tension or damage and respond as needed. In the case of the plasma membrane and phagosomal membrane these bilayers act as a barrier to microorganisms and are a conduit by which the host interacts with pathogens, including fungi such as Candida, Cryptococcus, Aspergillus or Histoplasma species. Due to their size, morphological flexibility, ability to produce long filaments, secrete pathogenicity factors, and their potential to replicate within the phagosome, fungi can assault host membranes in a variety of physical and biochemical ways...
February 10, 2019: Cellular Microbiology
Lei He, Yun Lin, Zhen-Huang Ge, Shi-Yu He, Bei-Bei Zhao, Dong Shen, Jian-Guo He, Yong-Jun Lu
The major virulence determinant of Legionella pneumophila is the type IVB secretion system (T4BSS), which delivers approximately 330 effector proteins into the host cell to modulate various cellular processes. However, the functions of most effector proteins remain unclear. WipA, an effector, was the first phosphotyrosine phosphatase of Legionella with unknown function. In this study we found that WipA induced relatively strong growth defects in yeast in a phosphatase activity-dependent manner. Phosphoproteomics data showed that WipA was likely involved into endocytosis, FcγR-mediated phagocytosis, tight junction, and regulation of actin cytoskeleton pathways...
January 31, 2019: Cellular Microbiology
Takeshi Yamamoto, Yutaka Kida, Koichi Kuwano
Epithelial cell shedding is a defense mechanism against infectious microbes that use these cells as an infection foothold, and that eliminates microbes from infection foci by removing infected cells. Mycoplasma pneumoniae, a causative agent of respiratory infections, is known to adhere to and colonize the surface of ciliated airway epithelial cells; it produces a large amount of hydrogen peroxide, indicating its capability of regulating hydrogen peroxide-induced infected cell detachment. In this study, we found that M...
January 31, 2019: Cellular Microbiology
Ying Wen, Shouwen Chen, Zhiwei Jiang, Zhuang Wang, Jinchao Tan, Tianjian Hu, Qiyao Wang, Xiangshan Zhou, Yuanxing Zhang, Qin Liu, Dahai Yang
Inflammasomes are important innate immune components in mammals. However, the bacterial factors modulating inflammasome activation in fish, and the mechanisms by which they alter fish immune defenses, remain to be investigated. In this work, a mutant of the fish pathogen Edwardsiella piscicida (E. piscicida), called 0909I, was shown to overexpress hemolysin, which could induce a robust pyroptotic-like cell death dependent on caspase-5-like-activity during infection in fish non-phagocyte cells. E. piscicida hemolysin was found to mainly associate with bacterial outer membrane vesicles (OMVs), which were internalized into the fish cells via a dynamin-dependent endocytosis and induced pyroptotic-like cell death...
January 31, 2019: Cellular Microbiology
Adela Martin-Vicente, Ana Camila Oliveira Souza, Qusai Al Abdallah, Wenbo Ge, Jarrod R Fortwendel
Proper hyphal morphogenesis is essential for the establishment and progression of invasive disease caused by filamentous fungi. In the human pathogen Aspergillus fumigatus, signaling cascades driven by Ras and Ras-like proteins orchestrate a wide variety of cellular processes required for hyphal growth. For activation, these proteins require interactions with Ras-subfamily specific guanine nucleotide exchange factors (RasGEFs). Although Ras-protein networks are essential for virulence in all pathogenic fungi, the importance of RasGEF proteins is largely unexplored...
January 30, 2019: Cellular Microbiology
Samuel J Ellis, Muhammad Yasir, Douglas F Browning, Stephen J W Busby, Stephanie Schuller
Enteroaggregative E. coli (EAEC) are important intestinal pathogens causing acute and persistent diarrhoeal illness worldwide. Although many putative EAEC virulence factors have been identified, their association with pathogenesis remains unclear. As environmental cues can modulate bacterial virulence, we investigated the effect of oxygen and human intestinal epithelium on EAEC virulence gene expression to determine the involvement of respective gene products in intestinal colonisation and pathogenesis. Using in vitro organ culture of human intestinal biopsies, we established the colonic epithelium as the major colonisation site of EAEC strains 042 and 17-2...
January 23, 2019: Cellular Microbiology
Nicholas J Katris, Huiling Ke, Geoffrey I McFadden, Giel G van Dooren, Ross F Waller
Apicomplexan parasites including Toxoplasma gondii and Plasmodium spp. manufacture a complex arsenal of secreted proteins used to interact with and manipulate their host environment. These proteins are organised into three principle exocytotic compartment types according to their functions: micronemes for extracellular attachment and motility, rhoptries for host cell penetration, and dense granules for subsequent manipulation of the host intracellular environment. The order and timing of these events during the parasite's invasion cycle dictates when exocytosis from each compartment occurs...
January 23, 2019: Cellular Microbiology
Hendrik Koliwer-Brandl, Paulina Knobloch, Caroline Barisch, Amanda Welin, Nabil Hanna, Thierry Soldati, Hubert Hilbi
The causative agent of tuberculosis, Mycobacterium tuberculosis, and its close relative Mycobacterium marinum manipulate phagocytic host cells, thereby creating a replication-permissive compartment termed the Mycobacterium-containing vacuole (MCV). The phosphoinositide (PI) lipid pattern is a crucial determinant of MCV formation and is targeted by mycobacterial PI phosphatases. In this study, we establish an efficient phage transduction protocol to construct defined M. marinum deletion mutants lacking one or three phosphatases, PtpA, PtpB and/or SapM...
January 17, 2019: Cellular Microbiology
Kathryn M Matthews, Ethan L Pitman, Tania F de Koning-Ward
Plasmodium parasites that cause the disease malaria have developed an elaborate trafficking pathway to facilitate the export of hundreds of effector proteins into their host cell, the erythrocyte. In this review, we outline how certain effector proteins contribute to parasite survival, virulence and immune evasion. We also highlight how parasite proteins destined for export are recognised at the endoplasmic reticulum to facilitate entry into the export pathway and how the effector proteins are able to transverse the bounding parasitophorous vaculoar membrane (PVM) via the Plasmodium translocon of exported proteins to gain access to the host cell...
January 17, 2019: Cellular Microbiology
Jason King
No abstract text is available yet for this article.
January 16, 2019: Cellular Microbiology
Xiaoyun Yang, Chunling Zhao, Gayan Bamunuarachchi, Yang Wang, Yurong Liang, Chaoqun Huang, Zhengyu Zhu, Dao Xu, Kong Lin, Lakmini Kumari Senavirathna, Lan Xu, Lin Liu
Due to an increasing emergence of new and drug-resistant strains of the influenza A virus (IAV), developing novel measures to combat influenza is necessary. We have previously shown that inhibiting Wnt/β-catenin pathway reduces IAV infection. In this study, we aimed to identify antiviral human microRNAs (miRNAs) that target the Wnt/β-catenin signaling pathway. Using a miRNA expression library, we identified 85 miRNAs that upregulated and 20 miRNAs that downregulated the Wnt/β-catenin signaling pathway. Fifteen miRNAs were validated to upregulate and 5 miRNAs to downregulate the pathway...
January 16, 2019: Cellular Microbiology
Nagaja Capitani, Gaia Codolo, Francesca Vallese, Giovanni Minervini, Alessia Grassi, Fabio Cianchi, Arianna Troilo, Wolfgang Fischer, Giuseppe Zanotti, Cosima T Baldari, Marina de Bernard, Mario M D'Elios
Helicobacter pylori (HP) is a Gram-negative bacterium that chronically infects the stomach of more than 50% of human population and represents a major cause of gastric cancer, gastric lymphoma, gastric autoimmunity and peptic ulcer. It still remains to be elucidated which HP virulence factors are important in the development of gastric disorders. Here we analysed the role of the HP protein HP1454 in the host-pathogen interaction. We found that a significant proportion of T cells isolated from HP patients with chronic gastritis and gastric adenocarcinoma proliferated in response to HP1454...
January 15, 2019: Cellular Microbiology
Alexander Wagner, Christoph Dehio
The α-proteobacterial genus Bartonella comprises a large number of facultative intracellular pathogens that share a common life-style hallmarked by hemotrophic infection and arthropod transmission. Speciation in the four deep-branching lineages (L1-L4) occurred by host adaptation facilitating the establishment of long-lasting bacteremia in specific mammalian reservoir host(s). Two distinct type-IV-secretion systems (T4SSs) acquired horizontally by different Bartonella lineages mediate essential host interactions during infection and represent key innovations for host adaptation...
January 15, 2019: Cellular Microbiology
Boyin Liu, Adam J Blanch, Arman Namvar, Olivia Carmo, Snigdha Tiash, Dean Andrew, Eric Hanssen, Vijay Rajagopal, Matthew W A Dixon, Leann Tilley
The simian parasite Plasmodium knowlesi causes severe and fatal malaria infections in humans, but the process of host cell remodeling that underpins the pathology of this zoonotic parasite is only poorly understood. We have used Serial Block Face-Scanning Electron Microscopy (SBF-SEM) to explore the topography of P. knowlesi-infected red blood cells (RBCs) at different stages of asexual development. The parasite elaborates large flattened cisternae (Sinton Mulligan's clefts) and tubular vesicles, in the host cell cytoplasm, as well as parasitophorous vacuole membrane (PVM) bulges and blebs, and caveolar structures at the RBC membrane...
January 11, 2019: Cellular Microbiology
Melanie Blokesch
No abstract text is available yet for this article.
January 4, 2019: Cellular Microbiology
João Paulo Ferreira Rodrigues, Thiago Souza Onofre, Bruno Couto Barbosa, Éden Ramalho Ferreira, Alexis Bonfim-Melo, Nobuko Yoshida
Host cell invasion by Trypanosoma cruzi metacyclic trypomastigote (MT) is mediated by MT-specific surface molecule gp82, which binds to a still unidentified receptor, inducing lysosome spreading and exocytosis required for the parasitophorous vacuole formation. We examined the involvement of the major lysosome membrane associated LAMP proteins in MT invasion. First, human epithelial HeLa cells were incubated with MT in the presence of antibody to LAMP-1 or LAMP-2. Antibody to LAMP-2, but not to LAMP-1, significantly reduced MT invasion...
January 4, 2019: Cellular Microbiology
Klara Obrova, Marek Cyrklaff, Roland Frank, Gunnar R Mair, Ann-Kristin Mueller
Ferlins mediate calcium-dependent vesicular fusion. Although conserved throughout eukaryotic evolution, their function in unicellular organisms including apicomplexan parasites is largely unknown. Here, we define a crucial role for a ferlin-like protein (FLP) in host-to-vector transmission of the rodent malaria parasite Plasmodium berghei. Infection of the mosquito vectors requires the formation of free gametes and their fertilisation in the mosquito midgut. Mature gametes will only emerge upon secretion of factors that stimulate the disruption of the red blood cell membrane and the parasitophorous vacuole membrane...
December 29, 2018: Cellular Microbiology
Alberto Fernández-Oliva, Paula Ortega-González, Cristina Risco
No abstract text is available yet for this article.
December 26, 2018: Cellular Microbiology
Maurizio Brigotti, Dorothea Orth-Höller, Domenica Carnicelli, Elisa Porcellini, Elisabetta Galassi, Pier Luigi Tazzari, Francesca Ricci, Francesco Manoli, Ilse Manet, Heribert Talasz, Herbert H Lindner, Cornelia Speth, Thomas Erbeznik, Stefan Fuchs, Wilfried Posch, Sneha Chatterjee, Reinhard Würzner
Hemolytic uremic syndrome (eHUS) is a severe complication of human infections with Shiga toxins (Stxs)-producing Escherichia coli. A key step in the pathogenesis of eHUS is the interaction of Stxs with blood components before the targeting of renal endothelial cells. Here we show that a single proteolytic cleavage in the Stx2a A-subunit, resulting into two fragments (A1 and A2) linked by a disulfide bridge (cleaved Stx2a), dictates different binding abilities. Uncleaved Stx2a was confirmed to bind to human neutrophils and to trigger leukocyte/platelet aggregate formation, while cleaved Stx2a was ineffective...
December 22, 2018: Cellular Microbiology
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