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  • 551. Wilhelmsson, Peter
    et al.
    Fryland, Linda
    Lindblom, Pontus
    Sjöwall, Johanna
    Ahlm, Clas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Berglund, Johan
    Haglund, Mats
    Henningsson, Anna J
    Nolskog, Peter
    Nordberg, Marika
    Nyberg, Clara
    Ornstein, Katharina
    Nyman, Dag
    Ekerfelt, Christina
    Forsberg, Pia
    Lindgren, Per-Eric
    A prospective study on the incidence of Borrelia burgdorferi sensu lato infection after a tick bite in Sweden and On the Åland Islands, Finland (2008-2009)2016In: Ticks and Tick-borne Diseases, ISSN 1877-959X, E-ISSN 1877-9603, Vol. 7, no 1, p. 71-79Article in journal (Refereed)
    Abstract [en]

    Lyme borreliosis (LB) is a common and increasing tick-borne disease in Europe. The risk of acquiring a Borrelia infection after a tick bite is not fully known. Therefore, we investigated the incidence of Borrelia infection after a bite by a Borrelia-infected tick and if the Borrelia load and/or the duration of tick-feeding influenced the risk of infection. During 2008-2009, ticks and blood samples were collected from 1546 tick-bitten persons from Sweden and the Åland Islands, Finland. Follow-up blood samples were taken 3 months after the tick bite. The duration of tick feeding was microscopically estimated and Borrelia was detected and quantified in ticks by real-time PCR. Anti-Borrelia antibodies were detected in sera using ELISA tests and immunoblot. Five percent (78/1546) of the study participants developed Borrelia infection (LB diagnosis and/or seroconversion) after a tick bite (45% bitten by Borrelia-infected ticks and 55% bitten by uninfected ticks). Of these, 33 developed LB (whereof 9 also seroconverted) while 45 participants seroconverted only. Experience of non-specific symptoms was more frequently reported by Borrelia-infected participants compared to uninfected participants. All who seroconverted removed "their" ticks significantly later than those who did not. The Borrelia load in the ticks did not explain the risk of seroconversion. Regional and sex differences in the Borrelia seroprevalence were found. The risk of developing a Borrelia infection after a bite by a Borrelia-infected tick is small but increases with the duration of tick feeding.

  • 552.
    Wilms, Torben
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Otorhinolaryngology.
    Khan, Gulfaraz
    Coates, Philip J
    Sgaramella, Nicola
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Fåhraeus, Robin
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology. Masaryk Mem Canc Inst, RECAMO, Zluty Kopec 7, Brno, Czech Republic; Univ Paris Diderot, INSERM, UMRS1162, 27 Rue Juliette Dodu, Paris, France .
    Hassani, Asma
    Philip, Pretty S
    Norberg Spaak, Lena
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Otorhinolaryngology.
    Califano, Luigi
    Colella, Giuseppe
    Olofsson, Katarina
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Otorhinolaryngology.
    Loizou, Christos
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Otorhinolaryngology.
    Franco, Renato
    Nylander, Karin
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    No evidence for the presence of Epstein-Barr virus in squamous cell carcinoma of the mobile tongue2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 9, article id e0184201Article in journal (Refereed)
    Abstract [en]

    Squamous cell carcinoma of the head and neck (SCCHN) comprises a large group of cancers in the oral cavity and nasopharyngeal area that typically arise in older males in association with alcohol/tobacco usage. Within the oral cavity, the mobile tongue is the most common site for tumour development. The incidence of tongue squamous cell carcinoma (TSCC) is increasing in younger people, which has been suggested to associate with a viral aetiology. Two common human oncogenic viruses, human papilloma virus (HPV) and Epstein-Barr virus (EBV) are known causes of certain types of SCCHN, namely the oropharynx and nasopharynx, respectively. EBV infects most adults worldwide through oral transmission and establishes a latent infection, with sporadic productive viral replication and release of virus in the oral cavity throughout life. In view of the prevalence of EBV in the oral cavity and recent data indicating that it infects tongue epithelial cells and establishes latency, we examined 98 cases of primary squamous cell carcinoma of the mobile tongue and 15 cases of tonsillar squamous cell carcinoma for the presence of EBV-encoded RNAs (EBERs), EBV DNA and an EBV-encoded protein, EBNA-1. A commercially available in situ hybridisation kit targeting EBER transcripts (EBER-ISH) showed a positive signal in the cytoplasm and/or nuclei of tumour cells in 43% of TSCCs. However, application of control probes and RNase A digestion using in-house developed EBER-ISH showed identical EBER staining patterns, indicating non-specific signals. PCR analysis of the BamH1 W repeat sequences did not identify EBV genomes in tumour samples. Immunohistochemistry for EBNA-1 was also negative. These data exclude EBV as a potential player in TSCC in both old and young patients and highlight the importance of appropriate controls for EBER-ISH in investigating EBV in human diseases.

  • 553. Wolter, Nicole
    et al.
    Cohen, Cheryl
    Tempia, Stefano
    Madhi, Shabir A.
    Venter, Marietjie
    Moyes, Jocelyn
    Walaza, Sibongile
    Kgokong, Babatyi Malope
    Groome, Michelle
    du Plessis, Mignon
    Pretorius, Marthi
    Dawood, Halima
    Kahn, Kathleen
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. Center for Global Health Research.
    Variava, Ebrahim
    Klugman, Keith P.
    von Gottberg, Anne
    HIV and Influenza Virus Infections Are Associated With Increased Blood Pneumococcal Load: A Prospective, Hospital-Based Observational Study in South Africa, 2009-20112014In: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 209, no 1, p. 56-65Article in journal (Refereed)
    Abstract [en]

    Background. Increased pneumococcal loads are associated with severe outcomes. We determined the prevalence of pneumococcal DNA in blood specimens from patients hospitalized with acute lower respiratory tract infection and identified factors associated with invasive pneumococcal pneumonia, bacterial loads, and death. Methods. A total of 8523 patients were enrolled as part of prospective hospital-based surveillance. Blood was collected for quantitative pneumococcal (tytA) detection, and nasopharyngeal specimens were collected for detection of influenza virus and other respiratory viruses by real-time polymerase chain reaction. Results. Of 6396 cases (75%) with /ytA results, 422 (7%) were positive for pneumococcal DNA. The prevalences of human immunodeficiency virus (HIV) and influenza virus were 51% (2965/5855) and 8% (485/6358), respectively. On multivariable analysis, HIV infection (adjusted odds ratio [aOR], 2.4; 95% confidence interval [CI], 1.6-3.6), influenza virus coinfection (aOR, 1.4; 95% CI, 1.2-2.1), oxygen therapy during admission (a0R, 1.6; 95% CI, 1.1-2.3) and in-hospital death (aOR, 2.1; 95% CI, 1.1-4.0) were significantly associated with increased pneumococcal load. Among /ytA-positive patients, after adjustment for length of hospitalization, duration of symptoms, and oxygen therapy during admission, pneumococcal loads >= 10,000 DNA copies/mi. (a0R, 3.6; 95% CI, 1.8-7.2) were associated with increased risk of death. Conclusions. HIV and influenza virus infections were associated with elevated pneumococcal loads, which, in turn, were associated with increased risk of death.

  • 554. Wolter, Nicole
    et al.
    Tempia, Stefano
    Cohen, Cheryl
    Madhi, Shabir A.
    Venter, Marietjie
    Moyes, Jocelyn
    Walaza, Sibongile
    Malope-Kgokong, Babatyi
    Groome, Michelle
    du Plessis, Mignon
    Magomani, Victoria
    Pretorius, Marthi
    Hellferscee, Orienka
    Dawood, Halima
    Kahn, Kathleen
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. MRC/Wits Rural Public Health and Health Transition Research Unit Research Unit (Agincourt), Faculty of Health Sciences, University of the Witwatersrand, Johannesburg ; INDEPTH Network, Accra, Ghana.
    Variava, Ebrahim
    Klugman, Keith P.
    von Gottberg, Anne
    High nasopharyngeal pneumococcal density, increased by viral coinfection, is associated with invasive pneumococcal pneumonia2014In: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 210, no 10, p. 1649-1657Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: We identified factors associated with pneumococcal colonization, high colonization density, and invasive pneumococcal pneumonia among patients hospitalized with acute lower respiratory tract infections (ALRTIs). METHODS: In 2010, 4025 cases were enrolled in surveillance in South Africa. A total of 969 of 4025 systematically selected nasopharyngeal-oropharyngeal specimens (24%) were tested for respiratory viruses and Streptococcus pneumoniae by real-time polymerase chain reaction. Of these, 749 (77%) had blood tested for S. pneumoniae. RESULTS: Pneumococcal colonization was detected in 55% of cases (534 of 969). On multivariable analysis that controlled for age and tuberculosis treatment, infection with influenza virus (adjusted odds ratio [OR], 2.2; 95% confidence interval [CI], 1.1-4.5), adenovirus (adjusted OR, 1.7; 95% CI, 1.1-2.7), rhinovirus (adjusted OR, 1.6; 95% CI, 1.1-2.3), and human immunodeficiency virus (HIV; adjusted OR, 1.6; 95% CI, 1.1-2.4) were associated with pneumococcal colonization. High colonization density was associated with respiratory virus coinfection (adjusted OR, 1.7; 95% CI, 1.1-2.6) and invasive pneumococcal pneumonia (adjusted OR, 2.3; 95% CI, 1.3-4.0), after adjustment for age and sex. Seven percent (52 of 749) had pneumococci detected in blood. On multivariable analysis among colonized cases, invasive pneumococcal pneumonia was associated with HIV (adjusted OR, 3.2; 95% CI, 1.4-7.5), influenza virus (adjusted OR, 8.2; 95% CI, 2.7-25.0), high colonization density (adjusted OR, 18.7; 95% CI, 2.3-155.1), and >= 5 days of hospitalization (adjusted OR, 3.7; 95% CI, 1.7-8.2). CONCLUSIONS: Respiratory virus infection was associated with elevated colonization density and, in turn, invasive pneumococcal pneumonia.

  • 555.
    Yadav, Akhilesh K.
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Espaillat, Akbar
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Cava, Felipe
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Bacterial Strategies to Preserve Cell Wall Integrity Against Environmental Threats2018In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, article id 2064Article, review/survey (Refereed)
    Abstract [en]

    Bacterial cells are surrounded by an exoskeleton-like structure, the cell wall, composed primarily of the peptidoglycan (PG) sacculus. This structure is made up of glycan strands cross-linked by short peptides generating a covalent mesh that shapes bacteria and prevents their lysis due to their high internal osmotic pressure. Even though the PG is virtually universal in bacteria, there is a notable degree of diversity in its chemical structure. Modifications in both the sugars and peptides are known to be instrumental for bacteria to cope with diverse environmental challenges. In this review, we summarize and discuss the cell wall strategies to withstand biotic and abiotic environmental insults such as the effect of antibiotics targeting cell wall enzymes, predatory PG hydrolytic proteins, and PG signaling systems. Finally we will discuss the opportunities that species-specific PG variability might open to develop antimicrobial therapies.

  • 556. Yamamoto, Shouji
    et al.
    Mitobe, Jiro
    Ishikawa, Takahiko
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Ohnishi, Makoto
    Watanabe, Haruo
    Izumiya, Hidemasa
    Regulation of natural competence by the orphan two-component system sensor kinase ChiS involves a non-canonical transmembrane regulator in Vibrio cholerae2014In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 91, no 2, p. 326-347Article in journal (Refereed)
    Abstract [en]

    In Vibrio cholerae, 41 chitin-inducible genes, including the genes involved in natural competence for DNA uptake, are governed by the orphan two-component system (TCS) sensor kinase ChiS. However, the mechanism by which ChiS controls the expression of these genes is currently unknown. Here, we report the involvement of a novel transcription factor termed TfoS' in this process. TfoS is a transmembrane protein that contains a large periplasmic domain and a cytoplasmic AraC-type DNA-binding domain, but lacks TCS signature domains. Inactivation of tfoS abolished natural competence as well as transcription of the tfoR gene encoding a chitin-induced small RNA essential for competence gene expression. A TfoS fragment containing the DNA-binding domain specifically bound to and activated transcription from the tfoR promoter. Intracellular TfoS levels were unaffected by disruption of chiS and coexpression of TfoS and ChiS in Escherichia coli recovered transcription of the chromosomally integrated tfoR::lacZ gene, suggesting that TfoS is post-translationally modulated by ChiS during transcriptional activation; however, this regulation persisted when the canonical phosphorelay residues of ChiS were mutated. The results presented here suggest that ChiS operates a chitin-induced non-canonical signal transduction cascade through TfoS, leading to transcriptional activation of tfoR.

  • 557. Zapatero-Belinchon, Francisco J.
    et al.
    Dietzel, Erik
    Dolnik, Olga
    Doehner, Katinka
    Costa, Rui
    Hertel, Barbara
    Veselkova, Barbora
    Kirui, Jared
    Klintworth, Anneke
    Manns, Michael P.
    Poehlmann, Stefan
    Pietschmann, Thomas
    Krey, Thomas
    Ciesek, Sandra
    Gerold, Gisa
    Umeå University, Faculty of Medicine, Wallenberg Centre for Molecular Medicine at Umeå University (WCMM). Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Section of Virology. TWINCORE, Center for Experimental and Clinical Infection Research, Institute for Experimental Virology, Hannover, Germany.
    Sodeik, Beate
    Becker, Stephan
    von Hahn, Thomas
    Characterization of the Filovirus-Resistant Cell Line SH-SY5Y Reveals Redundant Role of Cell Surface Entry Factors2019In: Viruses, ISSN 1999-4915, E-ISSN 1999-4915, Vol. 11, no 3, article id 275Article in journal (Refereed)
    Abstract [en]

    Filoviruses infect a wide range of cell types with the exception of lymphocytes. The intracellular proteins cathepsin B and L, two-pore channel 1 and 2, and bona fide receptor Niemann-Pick Disease C1 (NPC1) are essential for the endosomal phase of cell entry. However, earlier steps of filoviral infection remain poorly characterized. Numerous plasma membrane proteins have been implicated in attachment but it is still unclear which ones are sufficient for productive entry. To define a minimal set of host factors required for filoviral glycoprotein-driven cell entry, we screened twelve cell lines and identified the nonlymphocytic cell line SH-SY5Y to be specifically resistant to filovirus infection. Heterokaryons of SH-SY5Y cells fused to susceptible cells were susceptible to filoviruses, indicating that SH-SY5Y cells do not express a restriction factor but lack an enabling factor critical for filovirus entry. However, all tested cell lines expressed functional intracellular factors. Global gene expression profiling of known cell surface entry factors and protein expression levels of analyzed attachment factors did not reveal any correlation between susceptibility and expression of a specific host factor. Using binding assays with recombinant filovirus glycoprotein, we identified cell attachment as the step impaired in filovirus entry in SH-SY5Y cells. Individual overexpression of attachment factors T-cell immunoglobulin and mucin domain 1 (TIM-1), Axl, Mer, or dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) rendered SH-SY5Y cells susceptible to filovirus glycoprotein-driven transduction. Our study reveals that a lack of attachment factors limits filovirus entry and provides direct experimental support for a model of filoviral cell attachment where host factor usage at the cell surface is highly promiscuous.

  • 558.
    Zhang, Ce
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Liu, Yonggang
    Gilthorpe, Jonathan
    Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM).
    van der Maarel, Johan RC
    MRP14 (S100A9) protein interacts with alzheimer beta-amyloid peptide and induces its fibrillization2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 3, p. e32953-Article in journal (Refereed)
    Abstract [en]

    Increasing evidence supports the contribution of local inflammation to the development of Alzheimer's disease (AD) pathology, although the precise mechanisms are not clear. In this study, we demonstrate that the pro-inflammatory protein S100A9 interacts with the A beta 1-40 peptide and promotes the formation of fibrillar beta-amyloid structures. This interaction also results in reduced S100A9 cytotoxicity by the binding of S100A9 toxic species to A beta 1-40 amyloid structures. These results suggest that secretion of S100A9 during inflammation promotes the formation of amyloid plaques. By acting as a sink for toxic species, plaque formation may be the result of a protective response within the brain of AD patients, in part mediated by S100A9.

  • 559.
    Zhang, Lei-Qing
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Mei, Ya-Fang
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Wadell, Göran
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Human adenovirus serotypes 4 and 11 show higher binding affinity and infectivity for endothelial and carcinoma cell lines than serotype 52003In: Journal of General Virology, ISSN 0022-1317, E-ISSN 1465-2099, Vol. 84, no 3, p. 687-695Article in journal (Refereed)
    Abstract [en]

    Adenoviruses are promising vectors for human cancer gene therapy. However, the extensively used adenoviruses serotypes 2 and 5 (Ad2 and Ad5) from species C have a major disadvantage in being highly prevalent; thus, most adults have an immunity against the two viruses. Furthermore, the expression of coxsackievirus and adenovirus receptors for Ad2 and Ad5 varies in different cells. This study aims to identify adenovirus serotypes with specific tropism for endothelial cells and epithelial tumour cells. Comparison of the binding affinities of Ad31, Ad11, Ad5, Ad37, Ad4 and Ad41, belonging to species A-F, respectively, to established cell lines of hepatoma (HepG2), breast cancer (CAMA and MG7), prostatic cancer (DU145 and LNCaP) and laryngeal cancer (Hep2), as well as to endothelial cells (HMEC), was carried out by flow cytometric analysis. Ad11 from species B showed markedly higher binding affinity than Ad5 for the endothelial cell line and all carcinoma cell lines studied. Ad4 showed a specific binding affinity for hepatoma cells and laryneal carcinoma cells. The ability of Ad11, Ad4 and Ad5 to be expressed in hepatoma, breast cancer and endothelial cell lines was studied by immunostaining and (35)S-labelling of viral proteins in infected cells. Ad11 and Ad4 manifested a higher proportion of infected cells and a higher degree of hexon expression than Ad5.

  • 560. Zhang, Shu-sheng
    et al.
    Park, Chae Gyu
    Zhang, Pei
    Bartra, Sara Schesser
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Plano, Gregory V
    Klena, John D
    Skurnik, Mikael
    Hinnebusch, B Joseph
    Chen, Tie
    Plasminogen activator Pla of Yersinia pestis utilizes murine DEC-205 (CD205) as a receptor to promote dissemination2008In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 283, no 46, p. 31511-21Article in journal (Refereed)
    Abstract [en]

    Yersinia pestis, a Gram-negative bacterium that causes bubonic and pneumonic plague, is able to rapidly disseminate to other parts of its mammalian hosts. Y. pestis expresses plasminogen activator (PLA) on its surface, which has been suggested to play a role in bacterial dissemination. It has been speculated that Y. pestis hijacks antigen-presenting cells, such as macrophages (MPhis) and dendritic cells, to be delivered to lymph nodes to initiate dissemination and infection. Both alveolar MPhis and pulmonary dendritic cells express a C-type lectin receptor, DEC-205 (CD205), which mediates antigen uptake and presentation. However, no ligand has been identified for DEC-205. In this study, we show that the invasion of alveolar MPhisby Y. pestis depends both in vitro and in vivo on the expression of PLA. DEC-205-expressing MPhis and transfectants, but not their negative counterparts, phagocytosed PLA-expressing Y. pestis and Escherichia coli K12 more efficiently than PLA-negative controls. The interactions between PLA-expressing bacteria and DEC-205-expressing transfectants or alveolar MPhis could be inhibited by an anti-DEC-205 antibody. Importantly, the blockage of the PLA-DEC-205 interaction reduced the dissemination of Y. pestis in mice. In conclusion, murine DEC-205 is a receptor for PLA of Y. pestis, and this host-pathogen interaction appears to play a key role in promoting bacterial dissemination.

  • 561.
    Zhao, Jing
    et al.
    Logistical Engineering University.
    Chen, Jie
    University of Missouri-Kansas City.
    Yang, Ting-Hong
    Logistical Engineering University.
    Holme, Petter
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Insights into the pathogenesis of axial spondyloarthropathy from network and pathway analysis2012In: BMC Systems Biology, ISSN 1752-0509, E-ISSN 1752-0509, Vol. 6, p. S4-Article in journal (Refereed)
    Abstract [en]

    Background

    Complex chronic diseases are usually not caused by changes in a single causal gene but by an unbalanced regulating network resulting from the dysfunctions of multiple genes or their products. Therefore, network based systems approach can be helpful for the identification of candidate genes related to complex diseases and their relationships. Axial spondyloarthropathy (SpA) is a group of chronic inflammatory joint diseases that mainly affect the spine and the sacroiliac joints. The pathogenesis of SpA remains largely unknown.

    Results

    In this paper, we conducted a network study of the pathogenesis of SpA. We integrated data related to SpA, from the OMIM database, proteomics and microarray experiments of SpA, to prioritize SpA candidate disease genes in the context of human protein interactome. Based on the top ranked SpA related genes, we constructed a SpA specific PPI network, identified potential pathways associated with SpA, and finally sketched an overview of biological processes involved in the development of SpA.

    Conclusions

    The protein-protein interaction (PPI) network and pathways reflect the link between the two pathological processes of SpA, i.e., immune mediated inflammation, as well as imbalanced bone modelling caused new boneformation and bone loss. We found that some known disease causative genes, such as TNFand ILs, play pivotal roles in this interaction.

  • 562. Zocher, Georg
    et al.
    Mistry, Nitesh
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Frank, Martin
    Hähnlein-Schick, Irmgard
    Ekström, Jens-Ola
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Arnberg, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Stehle, Thilo
    A sialic acid binding site in a human picornavirus2014In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 10, no 10, p. e1004401-Article in journal (Refereed)
    Abstract [en]

    The picornaviruses coxsackievirus A24 variant (CVA24v) and enterovirus 70 (EV70) cause continued outbreaks and pandemics of acute hemorrhagic conjunctivitis (AHC), a highly contagious eye disease against which neither vaccines nor antiviral drugs are currently available. Moreover, these viruses can cause symptoms in the cornea, upper respiratory tract, and neurological impairments such as acute flaccid paralysis. EV70 and CVA24v are both known to use 5-N-acetylneuraminic acid (Neu5Ac) for cell attachment, thus providing a putative link between the glycan receptor specificity and cell tropism and disease. We report the structures of an intact human picornavirus in complex with a range of glycans terminating in Neu5Ac. We determined the structure of the CVA24v to 1.40 angstrom resolution, screened different glycans bearing Neu5Ac for CVA24v binding, and structurally characterized interactions with candidate glycan receptors. Biochemical studies verified the relevance of the binding site and demonstrated a preference of CVA24v for alpha 2,6-linked glycans. This preference can be rationalized by molecular dynamics simulations that show that alpha 2,6-linked glycans can establish more contacts with the viral capsid. Our results form an excellent platform for the design of antiviral compounds to prevent AHC.

  • 563.
    Åberg, Anna
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    New insights into the role of ppGpp and DksA through their effect on transcriptional regulation of housekeeping and colonization related genes of Escherichia coli2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bacteria have the ability to sense different environmental signals. When an environmental stress is detected, bacteria rapidly adjust their gene expression profile to be able to survive and thrive. The transduction of such environmental signals often requires the coordinated involvement of several factors that constitute complex regulatory networks. Hence, depending on the combination of signals, a unique gene expression profile required to adapt to the specific stress conditions is generated. Proteins are the best-known regulatory factors. However, non-proteinaceous molecules are also important in signal-responsive control of bacterial gene expression. Alarmones are low molecular weight non-proteinaceous regulatory factors which can characteristically be rapidly turned-over to mediate instant changes in gene expression. One such alarmone is the modified nucleotide ppGpp, which directly binds to RNA polymerase to alter its activity. The levels of this alarmone are expected to rapidly increase in response to any environmental stress that result in slow proliferation. DksA, a putative ppGpp co-regulator that likewise directly targets RNA polymerase, has been suggested to be required for both the positive and negative regulation mediated by ppGpp in Escherichia coli.

    This thesis describes dissection of the role of ppGpp and DksA on transcriptional regulation, primarily using the fim genetic determinant that encodes for the type 1 fimbriae. Type 1 fimbriae are involved in adhesion to abiotic surface and initial adhesion/invasion of bladder cells, as well as in biofilm formation. We found that ppGpp regulates phase variation by increasing the sub-population of cells that express the fimbriae. The effect of ppGpp was ultimately traced to its role in transcription of the fimB gene that encodes a recombinase involved in the phase variation process (paper 1). In contrast, we unexpectedly found that lack of DksA causes an increase, rather than a decrease, in transcription from the fimB P2 promoter in vivo. However, in vitro transcription studies demonstrated that ppGpp and DksA, both independently and co-dependently, stimulate transcription from the fimB P2 promoter. These seemingly contradictory results from the in vivo and in vitro transcriptional studies were shown to be, at least in part, a consequence of the increased association of Gre-factors with RNA polymerase that can occur in the absence of DksA in vivo (paper 2).

    The results outlined above have implications for the role of ppGpp and/or DksA in global gene expression. Using gene expression profile (microarray analysis) during the transition from logarithmic to stationary phase of E. coli, we found that while most of the genes regulated by ppGpp and DksA are regulated in the same direction by the two factors, many were not. In addition to the fim genes, genes involved in flagella functioning, taxis responses, and a few genes encoding different transport systems are also differentially regulated in ppGpp- and DksA-deficient strains in vivo. Our results clearly indicate that the effect of deficiencies in ppGpp and DksA is far more complex than phenotypic similarity of the corresponding mutants anticipated by the proposed concerted action of ppGpp and DksA on gene expression (paper 2 & 3).

  • 564.
    Åberg, Anna
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Fernández-Vázquez, Jorge
    Departament de Microbiologia, Universitat de Barcelona, Avgda. Diagonal 645, 08028 Barcelona, Spain.
    Cabrer-Panes, Juan David
    Departament de Microbiologia, Universitat de Barcelona, Avgda. Diagonal 645, 08028 Barcelona, Spain.
    Sánchez, Alex
    Departament d'Estadística, Universitat de Barcelona, Avgda. Diagonal 645, 08028 Barcelona, Spain.
    Balsalobre, Carlos
    Departament de Microbiologia, Universitat de Barcelona, Avgda. Diagonal 645, 08028 Barcelona, Spain.
    Similar and divergent effects of ppGpp and DksA deficiencies on transcription in Escherichia coli2009In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 191, no 10, p. 3226-3236Article in journal (Refereed)
    Abstract [en]

    The concerted action of ppGpp and DksA in transcription has been widely documented. In disparity with this model, phenotypic studies showed that ppGpp and DksA might also have independent and opposing roles in gene expression in Escherichia coli. In this study we used a transcriptomic approach to compare the global transcriptional patterns of gene expression in strains deficient in ppGpp (ppGpp(0)) and/or DksA (DeltadksA). Approximately 6 and 7% of all genes were significantly affected by more than twofold in ppGpp- and DksA-deficient strains, respectively, increasing to 13% of all genes in the ppGpp(0) DeltadksA strain. Although the data indicate that most of the affected genes were copositively or conegatively regulated by ppGpp and DksA, some genes that were independently and/or differentially regulated by the two factors were found. The large functional group of chemotaxis and flagellum synthesis genes were notably differentially affected, with all genes being upregulated in the DksA-deficient strain but 60% of them being downregulated in the ppGpp-deficient strain. Revealingly, mutations in the antipausing Gre factors suppress the upregulation observed in the DksA-deficient strain, emphasizing the importance of the secondary channel of the RNA polymerase for regulation and fine-tuning of gene expression in E. coli.

  • 565.
    Åberg, Anna
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Gideonsson, Pär
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Brännström, Kristoffer
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    The Helicobacter pylori sialic acid binding adhesin SabA is regulated via a network of two-component systemsManuscript (preprint) (Other academic)
    Abstract [en]

    The acid-responsive signaling system ArsRS plays a key role in regulating factors important for survival in acidic conditions during infection of the human stomach by Helicobacter pylori. In addition, ArsRS was suggested to control the disease-associated attachment protein SabA, however, mechanistic data is still lacking. We show that the repressing effect of the ArsRS system on SabA expression occurs both at acidic and neutral conditions and is mediated at the transcriptional level. Purified His6-ArsR binds PsabA DNA at several sites, with varying affinity and independent of phosphorylation status and H. pylori strains showed unique cognate PsabA sequences to tweak the ArsR binding ability, resulting in strain-dependent repression of SabA expression. By site-directed mutagenesis we reveal key amino acids for the binding activity of ArsR. Finally, we show that that ArsR binds to A/T-rich DNA as dimers or larger multimers, suggesting that ArsR has affinity for DNA structures rather than to a specific promoter DNA sequence. SabA expression is further influenced by the FlgRS and CrdRS two-component systems, illustrating a complicated crosstalk among regulatory networks in H. pylori.

  • 566.
    Åhlund, Monika K
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Rydén, Patrik
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Stöven, Svenja
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Directed screen of Francisella novicida virulence determinants using Drosophila melanogaster2010In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 78, no 7, p. 3118-3128Article in journal (Refereed)
    Abstract [en]

    Francisella tularensis is a highly virulent, facultative intracellular human pathogen whose virulence mechanisms are not well understood. Occasional outbreaks of tularemia and the potential use of F. tularensis as a bioterrorist agent warrant better knowledge about the pathogenicity of this bacterium. Thus far, genome-wide in vivo screens for virulence factors have been performed in mice, all however restricted by the necessity to apply competition-based, negative-selection assays. We wanted to individually evaluate putative virulence determinants suggested by such assays and performed directed screening of 249 F. novicida transposon insertion mutants by using survival of infected fruit flies as a measure of bacterial virulence. Some 20% of the genes tested were required for normal virulence in flies; most of these had not previously been investigated in detail in vitro or in vivo. We further characterized their involvement in bacterial proliferation and pathogenicity in flies and in mouse macrophages. Hierarchical cluster analysis of mutant phenotypes indicated a functional linkage between clustered genes. One cluster grouped all but four genes of the Francisella pathogenicity island and other loci required for intracellular survival. We also identified genes involved in adaptation to oxidative stress and genes which might induce host energy wasting. Several genes related to type IV pilus formation demonstrated hypervirulent mutant phenotypes. Collectively, the data demonstrate that the bacteria in part use similar virulence mechanisms in mammals as in Drosophila melanogaster but that a considerable proportion of the virulence factors active in mammals are dispensable for pathogenicity in the insect model.

  • 567.
    Åström, Morgan
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Using 2-pyridones as molecular tools to understand chlamydiae genetics2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 568.
    Åström, Stefan U.
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Byström, Anders S
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    The yeast initiator tRNAMet can act as an elongator tRNA(Met) in vivo1993In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 233, no 1, p. 43-58Article in journal (Refereed)
    Abstract [en]

    Saccharomyces cerevisiae uses two different methionine accepting tRNAs during protein synthesis. One, tRNA(iMet), is used exclusively during the initiation of translation whereas the other, tRNA(mMet), is used during the elongation of translation. To study the unique features of each methionine tRNA species, we constructed yeast strains with null alleles of the five elongator methionine tRNA (EMT) genes and strains with null alleles of the four initiator methionine tRNA (IMT) genes, respectively. Consequently, growth of these strains was dependent either on a tRNA(mMet) or a tRNA(iMet), respectively, encoded from a plasmid-derived gene. For both null mutants, the plasmid carrying the wild-type gene can be selected against and exchanged for another plasmid derived EMT or IMT gene (wild-type or mutant). A high gene dosage of the wild-type IMT gene could restore growth to the elongator-depleted strain. However, wild-type EMT genes in a high gene dosage never restored growth of the initiator depleted strain. Thus, the elongator tRNA(Met) is much more restricted to participate in the initiation of translation than the initiator tRNA(Met) is restricted to participate in the elongation process. Using the two null mutants, we have identified tRNA(mMet) mutants, which show reduced elongator activity, and tRNA(iMet) mutants, with improved elongator activity in the elongator depleted strain. Also, tRNA(mMet) mutants that function as an initiator tRNA in the initiator depleted strain were identified. From this mutant analysis, we showed that the conserved U/rT at position 54 of the elongator tRNA(Met) is an important determinant for an elongator tRNA. The most important determinant for an initiator was shown to be the acceptor stem and especially the conserved A1.U72 base-pair. Mutant tRNAs, with reduced activity in either process, were investigated for enhanced activity during overproduction of the alpha and beta-subunits of the eukaryotic initiation factor 2 (eIF-2) or the eukaryotic elongation factor 1 alpha (eEF-1 alpha). The data suggest that the U/rT of the elongator at position 54 is important for eEF-1 alpha recognition and that the acceptor stem of the initiator is important for eIF-2 recognition.

  • 569. Öhrvik, Helena
    et al.
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Identification of New Potential Interaction Partners for Human Cytoplasmic Copper Chaperone Atox1: Roles in Gene Regulation?2015In: International Journal of Molecular Sciences, ISSN 1422-0067, E-ISSN 1422-0067, Vol. 16, no 8, p. 16728-16739Article in journal (Refereed)
    Abstract [en]

    The human copper (Cu) chaperone Atox1 delivers Cu to P-1B type ATPases in the Golgi network, for incorporation into essential Cu-dependent enzymes. Atox1 homologs are found in most organisms; it is a 68-residue ferredoxin-fold protein that binds Cu in a conserved surface-exposed Cys-X-X-Cys (CXXC) motif. In addition to its well-documented cytoplasmic chaperone function, in 2008 Atox1 was suggested to have functionality in the nucleus. To identify new interactions partners of Atox1, we performed a yeast two-hybrid screen with a large human placenta library of cDNA fragments using Atox1 as bait. Among 98 million fragments investigated, 25 proteins were found to be confident interaction partners. Nine of these were uncharacterized proteins, and the remaining 16 proteins were analyzed by bioinformatics with respect to cell localization, tissue distribution, function, sequence motifs, three-dimensional structures and interaction networks. Several of the hits were eukaryotic-specific proteins interacting with DNA or RNA implying that Atox1 may act as a modulator of gene regulation. Notably, because many of the identified proteins contain CXXC motifs, similarly to the Cu transport reactions, interactions between these and Atox1 may be mediated by Cu.

  • 570.
    Överby Wernstedt, Anna
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Weber, Friedemann
    Hiding from intracellular pattern recognition receptors, a passive strategy of flavivirus immune evasion2011In: Virulence, ISSN 2150-5594, E-ISSN 2150-5608, Vol. 2, no 3, p. 238-240Article in journal (Refereed)
    Abstract [en]

    Tick-borne encephalitis virus (TBEV) is a medically important flavivirus in Europe and Asia, causing meningitis and encephalitis in thousands of people annually. Despite its relevance for public health, the interaction of TBEV with the type I interferon (IFN) system is poorly characterized. Induction of these antiviral cytokines is normally triggered by cytoplasmic recognition of viral signature molecules such as double-stranded (ds) RNA. In a recent paper, we showed that TBEV infection leads to formation of intracellular membrane vesicles which protect the viral dsRNA from cellular recognition. This delays the onset of antiviral IFN production sufficiently enough for an unhindered release of progeny viruses over 24 h. Thus, TBEV has evolved a stealth strategy to outrun the antiviral IFN response.

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