• Bacterial interference with canonical NF kappa B signalling 

      Johannessen, Mona; Askarian, Fatemeh; Sangvik, Maria; Sollid, Johanna U. Ericson (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-10)
    • Bacterial membrane-derived vesicles attenuate vancomycin activity against methicillin-resistant staphylococcus aureus 

      Kumaraswamy, Monika; Wiull, Kamilla; Joshi, Bishnu; Sakoulas, George; Kousha, Armin; Vaaje-Kolstad, Gustav; Johannessen, Mona; Hegstad, Kristin; Nizet, Victor; Askarian, Fatemeh (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-29)
      Methicillin-resistant Staphylococcus aureus (MRSA) has evolved numerous antimicrobial resistance mechanisms and is identified as a serious public health threat by the World Health Organization and U.S. Centers for Disease Control and Prevention. The glycopeptide vancomycin (VAN) remains a cornerstone of therapy for severe MRSA infections despite increasing reports of therapeutic failure in hospitalized ...
    • Chitinolytic enzymes contribute to the pathogenicity of Aliivibrio salmonicida LFI1238 in the invasive phase of cold-water vibriosis 

      Skåne, Anna; Edvardsen, Per Kristian Thorén; Cordara, Gabriele; Loose, Jennifer Sarah Maria; Leitl, Kira Daryl; Krengel, Ute; Sørum, Henning; Askarian, Fatemeh; Vaaje-Kolstad, Gustav (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-08-08)
      Background - Aliivibrio salmonicida is the causative agent of cold-water vibriosis in salmonids (Oncorhynchus mykiss and Salmo salar L.) and gadidae (Gadus morhua L.). Virulence-associated factors that are essential for the full spectrum of A. salmonicida pathogenicity are largely unknown. Chitin-active lytic polysaccharide monooxygenases (LPMOs) have been indicated to play roles in both chitin ...
    • Comparative exoproteome profiling of an invasive and a commensal Staphylococcus haemolyticus isolate 

      Cavanagh, Jorunn Pauline; Pain, Maria Charlene Ronessen; Askarian, Fatemeh; Bruun, Jack-Ansgar; Urbarova, Ilona; Wai, Sun Nyunt; Schmidt, Frank; Johannessen, Mona (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-22)
      Staphylococcus haemolyticus is a skin commensal emerging as an opportunistic pathogen. Nosocomial isolates of S. haemolyticus are the most antibiotic resistant members of the coagulase negative staphylococci (CoNS), but information about other S. haemolyticus virulence factors is scarce. Bacterial membrane vesicles (MVs) are one mediator of virulence by enabling secretion and long distance delivery ...
    • Comparative exoproteome profiling of an invasive and a commensal Staphylococcus haemolyticus isolate 

      Cavanagh, Jorunn Pauline; Pain, Maria Charlene Ronessen; Askarian, Fatemeh; Bruun, Jack-Ansgar; Urbarova, Ilona; Wai, Sun Nyunt; Schmidt, Frank; Johannessen, Mona (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-22)
      <p><i>Staphylococcus haemolyticus</i> is a skin commensal emerging as an opportunistic pathogen. Nosocomial isolates of <i>S. haemolyticus</i> are the most antibiotic resistant members of the coagulase negative staphylococci (CoNS), but information about other <i>S. haemolyticus</i> virulence factors is scarce. Bacterial membrane vesicles (MVs) are one mediator of virulence by enabling secretion and ...
    • Culturable autochthonous gut bacteria in Atlantic salmon (Salmo salar L.) fed diets with or without chitin. Characterization by 16S rRNA gene sequencing, ability to produce enzymes and in vitro growth inhibition of four fish pathogens 

      Askarian, Fatemeh; Zhou, Zhigang; Olsen, Rolf Erik; Sperstad, Sigmund; Ringø, Einar (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      The present investigation evaluated the effect of chitin (5% supplementation) on the adherent aerobic intestinal microbiota of Atlantic salmon (Salmo salar L.). One hundred and seventy three isolates were isolated but 34 isolates died prior to positive identification. Sixty four out of 139 autochthonous gut bacteria were further identified by 16S rRNA gene sequencing and further tested for protease, ...
    • The effect of different feeding regimes on enzyme activities of gut microbiota in Atlantic cod (Gadus morhua L.) 

      Askarian, Fatemeh; Sperstad, Sigmund; Merrifield, Daniel L; Arun Kumar, Ray; Ringø, Einar (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      The aims of this study were: (1) evaluate enzyme-producing bacteria isolated from the GI tract of Atlantic cod, (2) identify the most promising enzyme-producing bacteria by 16S rRNA gene sequencing and (3) to assess whether these bacteria have the ability to inhibit in vitro growth of four well known pathogenic bacteria; Aeromonas salmonicida subsp. salmonicida, V. (L.) anguillarum, Moritella viscosa ...
    • Enterococcus faecium produces membrane vesicles containing virulence factors and antimicrobial resistance related proteins 

      Wagner, Theresa; Joshi, Bishnu; James Peter, Jessin Janice; Askarian, Fatemeh; Skalko-Basnet, Natasa; Hagestad, Ole Christian; Mekhlif, Ahmed; Wai, Sun Nyunt; Hegstad, Kristin; Johannessen, Mona (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-30)
      <i>Enterococcus faecium</i> is a commensal but also a bacteremia causing pathogen, which is inherently resistant to several antimicrobials and has a great ability to acquire new traits. Bacterial membrane vesicles (MVs) are increasingly recognized as a mode of cell-free communication and a way to deliver virulence factors and/or antimicrobial resistance determinants. These features make MVs interesting ...
    • Enterococcus faecium TIR-Domain Genes Are Part of a Gene Cluster Which Promotes Bacterial Survival in Blood 

      Wagner, Theresa; James Peter, Jessin Janice; Paganelli, Fernanda; Willems, Rob J.L.; Askarian, Fatemeh; Pedersen, Torunn Annie; Top, Janetta; de Haas, Carla; van strijp, Jos A. G.; Johannessen, Mona; Hegstad, Kristin (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-03)
      <i>Enterococcus faecium</i> has undergone a transition to a multidrug-resistant nosocomial pathogen. The population structure of <i>E. faecium</i> is characterized by a sharp distinction of clades, where the hospital-adapted lineage is primarily responsible for bacteremia. So far, factors that were identified in hospital-adapted strains and that promoted pathogenesis of nosocomial <i>E. faecium</i> ...
    • Flagella-mediated secretion of a novel Vibrio cholerae cytotoxin affecting both vertebrate and invertebrate hosts 

      Dongre, Mitesh; Singh, Bhupender; Aung, Kyaw Min; Larsson, Per; Miftakhova, Regina; Persson, Karina; Askarian, Fatemeh; Johannessen, Mona; Hofsten, Jonas von; Persson, Jenny L.; Erhardt, Marc; Tuck, Simon; Uhlin, Bernt Eric; Wai, Sun Nyunt (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-07)
      Using <i>Caenorhabditis elegans</i> as an infection host model for <i>Vibrio cholerae</i> predator interactions, we discovered a bacterial cytotoxin, MakA, whose function as a virulence factor relies on secretion via the flagellum channel in a proton motive force-dependent manner. The MakA protein is expressed from the polycistronic <i>makDCBA</i> (<i>m</i>otility-<i>a</i>ssociated <i>k</i>illing ...
    • Genetic variability in the sdrD gene in Staphylococcus aureus from healthy nasal carriers 

      Ajayi, Clement; Åberg, Espen; Askarian, Fatemeh; Sollid, Johanna U Ericson; Johannessen, Mona; Hanssen, Anne Merethe (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-16)
      <p><i>Background</i>: <i>Staphylococcus aureus</i> cell wall anchored Serine Aspartate repeat containing protein D (<i>sdrD</i>) is a member of the microbial surface component recognising adhesive matrix molecules (MSCRAMMs). It is involved in the bacterial adhesion and virulence. However the extent of genetic variation in <i>S. aureus sdrD</i> gene within isolates from healthy carriers are not ...
    • Histological and bacteriological changes in intestine of beluga (Huso huso) following ex vivo exposure to bacterial strains 

      Salma, Wahida; Zhou, Zhigang; Wang, Wenwan; Askarian, Fatemeh; Kousha, Armin; Ebrahimi, Maryam Tajabadi; Myklebust, Reidar; Ringø, Einar (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      In the present study the intestinal sac method (ex vivo) was used to evaluate the interactions between lactic acid bacteria and staphylococci in the gastrointestinal (GI) tract of beluga (Huso huso). The distal intestine (DI) of beluga was exposed ex vivo to Staphylococcus aureus, Leuconostoc mesenteroides and Lactobacillus plantarum. Histological changes following bacterial exposure were assessed ...
    • Immunization with lytic polysaccharide monooxygenase CbpD induces protective immunity against Pseudomonas aeruginosa pneumonia 

      Askarian, Fatemeh; Tsai, Chih-Ming; Cordara, Gabriele; Zurich, Raymond H.; Bjånes, Elisabet; Golten, Ole; Sørensen, Henrik Vinther; Kousha, Armin; Meier, Angela; Chikwati, Elvis Mashingaidze; Bruun, Jack-Ansgar; Ludviksen, Judith K; Choudhury, Biswa; Trieu, Desmond; Davis, Stanley; Edvardsen, Per Kristian Thorén; Mollnes, Tom Eirik; Liu, George Y.; Krengel, Ute; Conrad, Douglas J.; Vaaje-Kolstad, Gustav; Nizet, Victor (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-17)
      Pseudomonas aeruginosa (PA) CbpD belongs to the lytic polysaccharide monooxygenases (LPMOs), a family of enzymes that cleave chitin or related polysaccharides. Here, we demonstrate a virulence role of CbpD in PA pneumonia linked to impairment of host complement function and opsonophagocytic clearance. Following intratracheal challenge, a PA ΔCbpD mutant was more easily cleared and produced less ...
    • The interaction between Staphylococcus aureus SdrD and desmoglein 1 is important for adhesion to host cells 

      Askarian, Fatemeh; Ajayi, Clement; Hanssen, Anne-Merethe; Van Sorge, Nina M.; Pettersen, Ingvild; Diep, Dzung Bao; Sollid, Johanna U. Ericson; Johannessen, Mona (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-29)
      <i>Staphylococcus aureus</i> is known as a frequent colonizer of the skin and mucosa. Among bacterial factors involved in colonization are adhesins such as the microbial surface components recognizing adhesive matrix molecules (MSCRAMMs). Serine aspartate repeat containing protein D (SdrD) is involved in adhesion to human squamous cells isolated from the nose. Here, we identify Desmoglein 1 ...
    • The lytic polysaccharide monooxygenase CbpD promotes Pseudomonas aeruginosa virulence in systemic infection 

      Askarian, Fatemeh; Uchiyama, Satoshi; Masson, Helen; Sørensen, Henrik Vinther; Golten, Ole; Bunæs, Anne Cathrine; Mekasha, Sophanit; Røhr, Åsmund Kjendseth; Kommedal, Eirik Garpestad; Ludviksen, Judith Anita; Arntzen, Magnus Øverlie; Schmidt, Benjamin; Zurich, Raymond H.; Van Sorge, Nina M.; Eijsink, Vincent; Krengel, Ute; Mollnes, Tom Eirik; Lewis, Nathan E.; Nizet, Victor; Vaaje-Kolstad, Gustav (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-23)
      The recently discovered lytic polysaccharide monooxygenases (LPMOs), which cleave polysaccharides by oxidation, have been associated with bacterial virulence, but supporting functional data is scarce. Here we show that CbpD, the LPMO of <i>Pseudomonas aeruginosa</i>, is a chitin-oxidizing virulence factor that promotes survival of the bacterium in human blood. The catalytic activity of CbpD was ...
    • Molecular determinants involved during Staphylococcus aureus colonization and/or infection 

      Askarian, Fatemeh (Doctoral thesis; Doktorgradsavhandling, 2014-09-26)
      Given the link between the compelling impact of Staphylococcus aureus colonization on the risk and outcome of infection, strategies to prevent nasal colonization could be an appealing method of fighting infection. The ability of S. aureus to colonize and infect a host is a balance between its multitudes of virulence factors and the host immune defence mechanisms. Despite the multiple bacterial factors ...
    • Serine-aspartate-repeat protein D Increases Staphylococcus aureus Virulence and Survival in Blood 

      Askarian, Fatemeh; Uchiyama, Satoshi; Valderrama, J. Andrés; Ajayi, Clement; Sollid, Johanna U. E.; Van Sorge, Nina M.; Nizet, Victor; van strijp, Jos A. G.; Johannessen, Mona (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-10-17)
      Staphylococcus aureus expresses a panel of cell wall-anchored adhesins, including proteins belonging to the microbial surface components recognizing adhesive matrix molecule (MSCRAMM) family, exemplified by the serine-aspartate repeat protein D (SdrD), which serve key roles in colonization and infection. Deletion of sdrD from S. aureus subsp. aureus strain NCTC8325-4 attenuated bacterial survival ...
    • Staphylococcus aureus Membrane-derived Vesicles Promote Bacterial Virulence and Confer Protective Immunity in Murine Infection Models 

      Askarian, Fatemeh; Lapek Jr., John D.; Dongre, Mitesh; Tsai, Chih-Ming; Kumaraswamy, Monika; Kousha, Armin; Valderrama, J. Andrés; Ludviksen, Judith K; Cavanagh, Jorunn Pauline; Uchiyama, Satoshi; Mollnes, Tom Eirik; Gonzalez, David J.; Wai, Sun Nyunt; Victor, Nizet; Johannessen, Mona (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-20)
      <i>Staphylococcus aureus</i> produces membrane-derived vesicles (MVs), which share functional properties to outer membrane vesicles. Atomic force microscopy revealed that <i>S. aureus</i>-derived MVs are associated with the bacterial surface or released into the surrounding environment depending on bacterial growth conditions. By using a comparative proteomic approach, a total of 131 and 617 proteins ...
    • A staphylococcus aureus TIR domain protein virulence factor blocks TLR2-mediated NF-κB signaling 

      Askarian, Fatemeh; van Sorge, Nina; Sangvik, Maria; Beasley, Federico C; Henriksen, Jørn Remi; Sollid, Johanna U Ericson; van Strijp, Jos A. G.; Nizet, Victor; Johannessen, Mona (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Transcriptome profiling of staphylococcus aureus associated extracellular vesicles reveals presence of small RNA-cargo 

      Joshi, Bishnu; Singh, Bhupender; Nadeem, Aftab; Askarian, Fatemeh; Wai, Sun Nyunt; Johannessen, Mona; Hegstad, Kristin (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-13)
      Bacterial extracellular vesicles (EVs) have a vital role in bacterial pathogenesis. However, to date, the small RNA-cargo of EVs released by the opportunistic pathogen Staphylococcus aureus has not been characterized. Here, we shed light on the association of small RNAs with EVs secreted by S. aureus MSSA476 cultured in iron-depleted bacteriologic media supplemented with a subinhibitory dosage of ...