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  • American Society for Microbiology  (6)
  • 1
    Online Resource
    Online Resource
    Activity of a Holin-Endolysin System in the Insecticidal Pathogenicity Island of Yersinia enterocolitica
    American Society for Microbiology ; 2018
    In:  Journal of Bacteriology Vol. 200, No. 16 ( 2018-08-15)
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 200, No. 16 ( 2018-08-15)
    Abstract: Yersinia enterocolitica is a pathogen that causes gastroenteritis in humans. Because of its low-temperature-dependent insecticidal activity, it can oscillate between invertebrates and mammals as host organisms. The insecticidal activity of strain W22703 is associated with a pathogenicity island of 19 kb (Tc-PAI Ye ), which carries regulators and genes encoding the toxin complex (Tc). The island also harbors four phage-related and highly conserved genes of unknown functions, which are polycistronically transcribed. Two open reading frames showed significant homologies to holins and endolysins and exhibited lytic activity in Escherichia coli cells upon overexpression. When a set of Yersinia strains was tested in an equivalent manner, highly diverse susceptibilities to lysis were observed, and some strains were resistant to lysis. If cell lysis occurred (as demonstrated by membrane staining), it was more pronounced when two accessory elements of the cassette coding for an i-spanin and an o-spanin were included in the overexpression construct. The pore-forming function of the putative holin, HolY, was demonstrated by complementation of the lysis defect of a phage λ S holin mutant. In experiments performed with membrane preparations, ElyY exhibited high specificity for W22703 peptidoglycan, with a cleavage activity resembling that of lysozyme. Although the functionality of the lysis cassette from Tc-PAI Ye was demonstrated in this study, its biological role remains to be elucidated. IMPORTANCE The knowledge of how pathogens survive in the environment is pivotal for our understanding of bacterial virulence. The insecticidal and nematocidal activity of Yersinia spp., by which the bacteria gain access to nutrients and thus improve their environmental fitness, is conferred by the toxin complex (Tc) encoded on a highly conserved pathogenicity island termed Tc-PAI Ye . While the regulators and the toxin subunits of the island had been characterized in some detail, the role of phage-related genes within the island remained to be elucidated. Here, we demonstrate that this cassette encodes a holin, an endolysin, and two spanins that, at least upon overexpression, lyse Yersinia strains.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00180-18
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Concerted Action of the FasL/Fas and Perforin/Granzyme A and B Pathways Is Mandatory for the Development of Early Viral Hepatitis but Not for Recovery from Viral Infection
    American Society for Microbiology ; 2001
    In:  Journal of Virology Vol. 75, No. 18 ( 2001-09-15), p. 8781-8791
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 75, No. 18 ( 2001-09-15), p. 8781-8791
    Abstract: Cytotoxic T lymphocytes (CTL) play a major role in the recovery from primary viral infections and the accompanying tissue injuries. However, it is unclear to what extent the two main cytolytic pathways, perforin-granzyme A and B exocytosis and Fas ligand (FasL)-Fas interaction, contribute to these processes. Here we have employed mouse strains with either spontaneous mutations or targeted gene defects in one or more components of either of the two cytolytic pathways to analyze the molecular basis of viral clearance and induction of hepatitis during lymphocytic choriomeningitis virus infection. Our results reveal that viral clearance is solely dependent on perforin but that virus-induced liver damage only occurs when both the FasL/Fas and the perforin pathways, including granzymes A and B, are simultaneously activated. The finding that development of hepatitis but not viral clearance is dependent on the concomitant activation of FasL-Fas and perforin-granzymes may be helpful in designing novel strategies to prevent hepatic failures during viral infections.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.75.18.8781-8791.2001
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2001
    detail.hit.zdb_id: 1495529-5
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  • 3
    Online Resource
    Online Resource
    Pharmacokinetics and Antifungal Activity of Echinocandins in Ascites Fluid of Critically Ill Patients
    American Society for Microbiology ; 2021
    In:  Antimicrobial Agents and Chemotherapy Vol. 65, No. 7 ( 2021-06-17)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 65, No. 7 ( 2021-06-17)
    Abstract: The pharmacokinetics and antifungal activity of the echinocandins anidulafungin (AFG), micafungin (MFG), and caspofungin (CAS) were assessed in ascites fluid and plasma of critically ill adults treated for suspected or proven invasive candidiasis. Ascites fluid was obtained from ascites drains or during paracentesis. The antifungal activity of the echinocandins in ascites fluid was assessed by incubation of Candida albicans and Candida glabrata at concentrations of 0.03 to 16.00 μg/ml. In addition, ascites fluid samples obtained from our study patients were inoculated with the same isolates and evaluated for fungal growth. These patient samples had to be spiked with echinocandins to restore the original concentrations because echinocandins had been lost during sterile filtration. In ascites fluid specimens of 29 patients, echinocandin concentrations were below the simultaneous plasma levels. Serial sampling in 20 patients revealed a slower rise and decline of echinocandin concentrations in ascites fluid than in plasma. Proliferation of C. albicans in ascites fluid was slower than in culture medium and growth of C. glabrata was lacking, even in the absence of antifungals. In CAS-spiked ascites fluid samples, fungal CFU counts moderately declined, whereas spiking with AFG or MFG had no relevant effect. In ascites fluid of our study patients, echinocandin concentrations achieved by therapeutic doses did not result in a consistent eradication of C. albicans or C. glabrata . Thus, therapeutic doses of AFG, MFG, or CAS may result in ascites fluid concentrations preventing relevant proliferation of C. albicans and C. glabrata , but do not warrant reliable eradication.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.02565-20
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 4
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    Online Resource
    Evaluation of the Qvella FAST System and the FAST-PBC cartridge for rapid species identification and antimicrobial resistance testing directly from positive blood cultures
    American Society for Microbiology ; 2023
    In:  Journal of Clinical Microbiology
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology
    Abstract: Blood culture diagnostics require rapid and accurate identification (ID) of pathogens and antimicrobial susceptibility testing (AST). Standard procedures, involving conventional cultivation on agar plates, may take up to 48 hours or more until AST completion. Recent approaches aim to shorten the processing time of positive blood cultures (PBC). The FAST System is a new technology, capable of purifying and concentrating bacterial/fungal pathogens from positive blood culture media and producing a bacterial suspension called “liquid colony” (LC), which can be further used in downstream analyses (e.g., ID and AST). Here, we evaluated the performance of the FAST System LC generated from PBC in comparison to our routine workflow including ID by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using Sepsityper, AST by automatized MicroScan WalkAway plus and directly inoculated disk diffusion (DD), and MICRONAUT-AM for yeast/fungi. A total of 261 samples were analyzed, of which 86.6% (226/261) were eligible for the comparative ID and AST analyses. In comparison to the reference technique (culture-grown colonies), ID concordance of the FAST System LC and Sepsityper was 150/154 (97.4%) and 123/154 (79.9%), respectively, for Gram positive; 67/70 (95.7%) and 64/70 (91.4%), respectively, for Gram negative. For AST, categorical agreement (CA) of the FAST System LC in comparison to the routine workflow for Gram-positive bacteria was 96.1% and 98.7% for MicroScan and DD, respectively. Similar results were obtained for Gram-negative bacteria with 96.6% and 97.5% of CA for MicroScan and DD, respectively. Taken together, the FAST System LC allowed the laboratory to significantly reduce the time to obtain correct ID and AST (automated MicroScan) results 1 day earlier and represents a promising tool to expedite the processing of PBC.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/jcm.00569-23
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
    detail.hit.zdb_id: 1498353-9
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Role of p38 and Early Growth Response Factor 1 in the Macrophage Response to Group B Streptococcus
    American Society for Microbiology ; 2009
    In:  Infection and Immunity Vol. 77, No. 6 ( 2009-06), p. 2474-2481
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 77, No. 6 ( 2009-06), p. 2474-2481
    Abstract: Group B streptococcus (GBS), the most frequent single isolate in neonatal sepsis and meningitis, potently activates inflammatory macrophage genes via myeloid differentiation antigen 88 (MyD88). However, events parallel to and downstream of MyD88 that instruct the macrophage response are incompletely understood. In this study, we found that only MyD88, not the Toll-like receptor (TLR) adapter proteins MAL/TIRAP, TRIF, and TRAM, essentially mediates the cytokine (tumor necrosis factor [TNF] and interleukin-6) and chemokine (RANTES) responses to whole GBS organisms, although MAL, TRIF, and TRAM have been shown to mediate the responses to substructures in other gram-positive and gram-negative bacteria. GBS-induced, MyD88-dependent phosphorylation of the mitogen-activated protein kinase p38 activated the transcription factor AP-1 and early growth response factor 1 (Egr-1) but not NF-κB. Furthermore, phosphorylation of Ets-like molecule 1 (Elk-1) was mediated by p38. However, in contrast to Egr-1 and AP-1, Elk-1 was dispensable for transcriptional activation of TNF by GBS organisms. Studies of macrophages from Elk-1-deficient mice revealed that Elk-1 was furthermore nonessential for the TNF responses to purified TLR2 and TLR4 agonists, which was in notable contrast to what was revealed in studies employing in vitro expression systems. In conclusion, MyD88, p38, and Egr-1, but not Elk-1, essentially mediate the inflammatory cytokine response to GBS organisms.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.01343-08
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2009
    detail.hit.zdb_id: 1483247-1
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  • 6
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    Online Resource
    Reconstitution of the Ancestral Glycoprotein of Human Endogenous Retrovirus K and Modulation of Its Functional Activity by Truncation of the Cytoplasmic Domain
    American Society for Microbiology ; 2009
    In:  Journal of Virology Vol. 83, No. 24 ( 2009-12-15), p. 12790-12800
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 83, No. 24 ( 2009-12-15), p. 12790-12800
    Abstract: Endogenous retroviruses present in the human genome provide a rich record of ancient infections. All presently recognized elements, including the youngest and most intact proviruses of the human endogenous retrovirus K(HML-2) [HERV-K(HML-2)] family, have suffered postinsertional mutations during their time of chromosomal residence, and genes encoding the envelope glycoprotein (Env) have not been spared these mutations. In this study, we have, for the first time, reconstituted an authentic Env of a HERV-K(HML-2) provirus by back mutation of putative postinsertional amino acid changes of the protein encoded by HERV-K113. Aided by codon-optimized expression, we demonstrate that the reconstituted Env regained its ability to be incorporated into retroviral particles and to mediate entry. The original ancient HERV-K113 Env was synthesized as a moderately glycosylated gp95 precursor protein cleaved into surface and transmembrane (TM) subunits. Of the nine N-linked oligosaccharides, four are part of the TM subunit, contributing 15 kDa to its apparent molecular mass of 41 kDa. The carbohydrates, as well as the cytoplasmic tail, are critical for efficient intracellular trafficking, processing, stability, and particle incorporation. Whereas deletions of the carboxy-terminal 6 residues completely abrogated cleavage and virion association, more extensive truncations slightly enhanced incorporation but dramatically increased the ability to mediate entry of pseudotyped lentiviruses. Although the first HERV-K(HML-2) elements infected human ancestors about 30 million years ago, our findings indicate that their glycoproteins are in most respects remarkably similar to those of classical contemporary retroviruses and can still mediate efficient entry into mammalian cells.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.01368-09
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2009
    detail.hit.zdb_id: 1495529-5
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