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  • 251. Keeney, Jill B
    et al.
    Chapman, Karen B
    Lauermann, Vit
    Voytas, Daniel F
    Åström, Stefan U
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    von Pawel-Rammingen, Ulrich
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Byström, Anders
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Boeke, Jeff D
    Multiple molecular determinants for retrotransposition in a primer tRNA1995In: Molecular and Cellular Biology, ISSN 0270-7306, E-ISSN 1098-5549, Vol. 15, no 1, p. 217-226Article in journal (Refereed)
    Abstract [en]

    Retroviruses and long terminal repeat-containing retroelements use host-encoded tRNAs as primers for the synthesis of minus strong-stop DNA, the first intermediate in reverse transcription of the retroelement RNA. Usually, one or more specific tRNAs, including the primer, are selected and packaged within the virion. The reverse transcriptase (RT) interacts with the primer tRNA and initiates DNA synthesis. The structural and sequence features of primer tRNAs important for these specific interactions are poorly understood. We have developed a genetic assay in which mutants of tRNA(iMet), the primer for the Ty1 retrotransposon of Saccharomyces cerevisiae, can be tested for the ability to serve as primers in the reverse transcription process. This system allows any tRNA mutant to be tested, regardless of its ability to function in the initiation of protein synthesis. We find that mutations in the T psi C loop and the acceptor stem regions of the tRNA(iMet) affect transposition most severely. Conversely, mutations in the anticodon region have only minimal effects on transposition. Further study of the acceptor stem and other mutants demonstrates that complementarity to the element primer binding site is a necessary but not sufficient requirement for effective tRNA priming. Finally, we have used interspecies hybrid initiator tRNA molecules to implicate nucleotides in the D arm as additional recognition determinants. Ty3 and Ty1, two very distantly related retrotransposons, require similar molecular determinants in this primer tRNA for transposition.

  • 252. Kent, Robyn S
    et al.
    Modrzynska, Katarzyna K
    Cameron, Rachael
    Philip, Nisha
    Billker, Oliver
    Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK.
    Waters, Andrew P
    Inducible developmental reprogramming redefines commitment to sexual development in the malaria parasite Plasmodium berghei2018In: Nature Microbiology, E-ISSN 2058-5276, Vol. 3, no 11, p. 1206-1213Article in journal (Refereed)
    Abstract [en]

    During malaria infection, Plasmodium spp. parasites cyclically invade red blood cells and can follow two different developmental pathways. They can either replicate asexually to sustain the infection, or differentiate into gametocytes, the sexual stage that can be taken up by mosquitoes, ultimately leading to disease transmission. Despite its importance for malaria control, the process of gametocytogenesis remains poorly understood, partially due to the difficulty of generating high numbers of sexually committed parasites in laboratory conditions1. Recently, an apicomplexa-specific transcription factor (AP2-G) was identified as necessary for gametocyte production in multiple Plasmodium species2,3, and suggested to be an epigenetically regulated master switch that initiates gametocytogenesis4,5. Here we show that in a rodent malaria parasite, Plasmodium berghei, conditional overexpression of AP2-G can be used to synchronously convert the great majority of the population into fertile gametocytes. This discovery allowed us to redefine the time frame of sexual commitment, identify a number of putative AP2-G targets and chart the sequence of transcriptional changes through gametocyte development, including the observation that gender-specific transcription occurred within 6 h of induction. These data provide entry points for further detailed characterization of the key process required for malaria transmission.

  • 253. Khalil, Hussein
    et al.
    Hörnfeldt, Birger
    Evander, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Magnusson, Magnus
    Olsson, Gert
    Ecke, Frauke
    Dynamics and Drivers of Hantavirus Prevalence in Rodent Populations2014In: Vector Borne and Zoonotic Diseases, ISSN 1530-3667, E-ISSN 1557-7759, Vol. 14, no 8, p. 537-551Article, review/survey (Refereed)
    Abstract [en]

    Human encroachment on wildlife habitats has contributed to the emergence of several zoonoses. Pathogenic hantaviruses are hosted by rodents and cause severe diseases in the Americas and Eurasia. We reviewed several factors that potentially drive prevalence (the proportion of infected rodents) in host populations. These include demography, behavior, host density, small mammal diversity, predation, and habitat and landscape characteristics. This review is the first to include a quantitative summary of the literature investigating hantavirus prevalence in rodents. Demographic structure and density were investigated the most and predation the least. Reported effects of demographic structure and small mammal diversity were consistent, whereby reproductive males were most likely to be infected and prevalence decreased with small mammal diversity. The influences of habitat and landscape properties are often complex and indirect. The relationship between density and prevalence merits more investigation. Most hantavirus hosts are habitat generalists and their control is challenging. Incorporating all potential factors and their interactions is essential to understanding and controlling infection in host populations.

  • 254. Khalil, Hussein
    et al.
    Olsson, Gert
    Ecke, Frauke
    Evander, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Hjertqvist, Marika
    Magnusson, Magnus
    Löfvenius, Mikaell Ottosson
    Hörnfeldt, Birger
    The importance of bank vole density and rainy winters in predicting nephropathia epidemica incidence in Northern Sweden.2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 11, article id e111663Article in journal (Refereed)
    Abstract [en]

    Pathogenic hantaviruses (family Bunyaviridae, genus Hantavirus) are rodent-borne viruses causing hemorrhagic fever with renal syndrome (HFRS) in Eurasia. In Europe, there are more than 10,000 yearly cases of nephropathia epidemica (NE), a mild form of HFRS caused by Puumala virus (PUUV). The common and widely distributed bank vole (Myodes glareolus) is the host of PUUV. In this study, we aim to explain and predict NE incidence in boreal Sweden using bank vole densities. We tested whether the number of rainy days in winter contributed to variation in NE incidence. We forecast NE incidence in July 2013-June 2014 using projected autumn vole density, and then considering two climatic scenarios: 1) rain-free winter and 2) winter with many rainy days. Autumn vole density was a strong explanatory variable of NE incidence in boreal Sweden in 1990-2012 (R2 = 79%, p<0.001). Adding the number of rainy winter days improved the model (R2 = 84%, p<0.05). We report for the first time that risk of NE is higher in winters with many rainy days. Rain on snow and ground icing may block vole access to subnivean space. Seeking refuge from adverse conditions and shelter from predators, voles may infest buildings, increasing infection risk. In a rainy winter scenario, we predicted 812 NE cases in boreal Sweden, triple the number of cases predicted in a rain-free winter in 2013/2014. Our model enables identification of high risk years when preparedness in the public health sector is crucial, as a rainy winter would accentuate risk.

  • 255. Kiflemariam, S
    et al.
    Mignardi, M
    Bergh, Anders
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Nilsson, Maria
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Sjöblom, T
    Direct detection of TMPRSS2-ERG rearrangements in prostate cancer by Padlock Probes2012In: European Journal of Cancer, ISSN 0959-8049, E-ISSN 1879-0852, Vol. 48, no S5, p. S110-S110Article in journal (Other academic)
  • 256. Kirrander, Peter
    et al.
    Kolaric, Aleksandra
    Helenius, Gisela
    Windahl, Torgny
    Andrén, Ove
    Stark, Jennifer Rider
    Lillsunde-Larsson, Gabriella
    Elgh, Fredrik
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Karlsson, Mats
    Human papillomavirus prevalence, distribution and correlation to histopathological parameters in a large Swedish cohort of men with penile carcinoma2011In: BJU International, ISSN 1464-4096, E-ISSN 1464-410X, Vol. 108, no 3, p. 355-359Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: To analyse the overall and type-specific human papillomavirus (HPV) prevalence and distribution in penile carcinoma and determine the correlation to histopathological parameters.

    PATIENTS AND METHODS: In this retrospective study, we analysed HPV status in 241 patients with penile carcinoma, treated at Örebro University Hospital, Örebro, Sweden, between 1984 and 2008. Age and date at diagnosis was recorded. The tumour specimens were categorized according to the UICC 2002 TNM classification. A subset of patients was operatively staged with regard to lymph node status. A commercially available Real Time PCR was used to detect 13 different types of HPV (6,11,16,18,31,33,35,45,51,52,56,58 and 59).

    RESULTS: We excluded 25 patients due to low DNA quality. Of the remaining 216, 179 (82.9%) tumour specimens were HPV infected. The majority of cases positive for HPV (70.4%) were infected by a single-type. The most frequent type was HPV 16 followed by HPV 18. No significant association between HPV status and pathological tumour stage, grade or lymph node status was found.

    CONCLUSION: The HPV prevalence found is higher than in most other studies, further strengthening HPV as an etiological agent in penile carcinoma. Furthermore, the high prevalence of HPV 16 and 18 raises the question of what potential impact current HPV vaccines that target these specific HPV types might have on penile carcinoma. No significant association between HPV status and histopathological parameters was found in the present study. Additional investigations are needed to draw final conclusions on the prognostic value of HPV status in penile carcinoma.

  • 257. Klingspor, Lena
    et al.
    Ullberg, Mans
    Rydberg, Johan
    Kondori, Nahid
    Serrander, Lena
    Swanberg, Jonas
    Nilsson, Kenneth
    Jendle Bengten, Cecilia
    Johansson, Marcus
    Granlund, Margareta
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Tornqvist, Eva
    Nyberg, Anders
    Kindlund, Karin
    Ygge, Minna
    Kartout-Boukdir, Dalila
    Toepfer, Michael
    Halldin, Eva
    Kahlmeter, Gunnar
    Ozenci, Volkan
    Epidemiology of fungaemia in Sweden: a nationwide retrospective observational survey2018In: Mycoses (Berlin), ISSN 0933-7407, E-ISSN 1439-0507, Vol. 61, no 10, p. 777-785Article in journal (Refereed)
    Abstract [en]

    Objectives:

    To identify the epidemiology and antifungal susceptibilities of Candida spp. among blood culture isolates to identify the epidemiology and antifungal susceptibilities of Candida spp. among blood culture isolates in Sweden.

    Methods: The study was a retrospective, observational nationwide laboratory-based surveillance for fungaemia and fungal meningitis and was conducted from September 2015 to August 2016.

    Results: In total, 488 Candida blood culture isolates were obtained from 471 patients (58% males). Compared to our previous study, the incidence of candidaemia has increased from 4.2/100000 (2005-2006) to 4.7/100000 population/year (2015-2016). The three most common Candida spp. isolated from blood cultures were Candida albicans (54.7%), Candida glabrata (19.7%) and species in the Candida parapsilosis complex (9.4%). Candida resistance to fluconazole was 2% in C.albicans and between 0% and 100%, in non-albicans species other than C.glabrata and C.krusei. Resistance to voriconazole was rare, except for C.glabrata, C.krusei and C.tropicalis. Resistance to anidulafungin was 3.8% while no Candida isolate was resistant to amphotericin B.

    Conclusions: We report an overall increase in candidaemia but a minor decrease of C.albicans while C.glabrata and C.parapsilosis remain constant over this 10-year period.

  • 258. Korch, C
    et al.
    Mountain, H A
    Byström, Anders S
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Cloning, nucleotide sequence, and regulation of MET14, the gene encoding the APS kinase of Saccharomyces cerevisiae1991In: Molecular General Genetics, ISSN 0026-8925, E-ISSN 1432-1874, Vol. 229, no 1, p. 96-108Article in journal (Refereed)
    Abstract [en]

    The MET14 gene of Saccharomyces cerevisiae, encoding APS kinase (ATP:adenylylsulfate-3'-phosphotransferase, EC 2.7.1.25), has been cloned. The nucleotide sequence predicts a protein of 202 amino acids with a molecular mass of 23,060 dalton. Translational fusions of MET14 with the beta-galactosidase gene (lacZ) of Escherichia coli confirmed the results of primer extension and Northern blot analyses indicating that the ca. 0.7 kb mRNA is transcriptionally repressed by the presence of methionine in the growth medium. By primer extension the MET14 transcripts were found to start between positions -25 and -45 upstream of the initiator codon. Located upstream of the MET14 gene is a perfect match (positions -222 to -229) with the previously proposed methionine-specific upstream activating sequence (UASMet). This is the same as the consensus sequence of the Centromere DNA Element I (CDEI) that binds the Centromere Promoter Factor I (CPFI) and of two regulatory elements of the PHO5 gene to which the yeast protein PHO4 binds. The human oncogenic protein c-Myc also has the same recognition sequence. Furthermore, in the 270 bp upstream of the MET14 coding region there are several matches with a methionine-specific upstream negative (URSMet) control element. The significance of these sequences was investigated using different upstream deletion mutations of the MET14 gene which were fused to the lacZ gene of E. coli and chromosomally integrated. We find that the methionine-specific UASMet and one of the URSMet lie in regions necessary for strong activation and weak repression of MET14 transcription, respectively. We propose that both types of control are exerted on MET14.

  • 259.
    Kozlenkov, Alexey
    Umeå University, Faculty of Medicine, Medical Biosciences.
    Structural / functional studies on human alkaline phosphatases2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The recent elucidation of the three-dimensional structure of human placental alkaline phosphatase (PLAP) has enabled me to perform structural studies aimed at characterizing the properties of human PLAP and tissue-nonspecific AP (TNAP) as paradigms for mammalian APs in general, using site-directed mutagenesis, protein expression, kinetic analysis and computer modeling.

    In Paper I, we found that a single critical E429G substitution explains the difference in stability and kinetics between the common allelic variants of PLAP and the D allozyme. In Paper II, we demonstrated the role of residue E429 in PLAP in stabilizing the active site metals, elucidated the distinct roles of residues H153 and H317 in catalysis, and the relative importance of five Cys residues in PLAP. We also discovered the significance of Y367, a unique feature of mammalian APs, for enzyme stability and specific inhibition by amino acids. Paper III focused on the identification and mutagenesis analysis of a novel, non-catalytic peripheral binding site of PLAP that appears to mediate a mitogenic effect of PLAP. This site provides indications that PLAP may function as a fetal growth factor.

    The last two papers focus on the TNAP isozyme as paradigm. A deficiency in TNAP activity is the cause of the human disease hypophosphatasia, characterized by rickets, osteomalacia and occasionally epileptic seizures. Paper IV has been able to partially explain the variable expressivity of hypophosphatasia traits by examining site-directed mutants of TNAP and performing kinetic analysis using natural substrates PPi and PLP. Finally, Paper V has clarified the mechanism of inhibition of TNAP by uncompetitive inhibitors L-homoarginine, levamisole and theophylline. We identified residues that confer to TNAP its distinct inhibitory properties. These data have significance for future drug design of specific TNAP inhibitors to therapeutically target TNAP as a way of elevating PPi extracellular level and alleviating pathological bone hypermineralization conditions.

  • 260.
    Krajewski, Stefanie Sandra
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Ignatov, Dmitry
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Johansson, Jörgen
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Two Are Better Than One: Dual Targeting of Riboswitches by Metabolite Analogs2017In: Cell Chemical Biology, ISSN 2451-9456, E-ISSN 2451-9448, Vol. 24, no 5, p. 535-537Article in journal (Refereed)
    Abstract [en]

    In this issue of Cell Chemical Biology, Wang et al. (2017) examine the effect of the novel synthetic molecule ribocil-C and the natural compound roseoflavin in Gram-positive pathogens. In methicillin-resistant Staphylococcus aureus (MRSA), ribocil-C and roseoflavin target two autonomous riboswitches simultaneously, thereby inhibiting de novo synthesis and uptake of riboflavin.

  • 261.
    Krajewski, Stefanie Sandra
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Isoz, Isabelle
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Johansson, Jörgen
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Antibacterial and antivirulence effect of 6-N-hydroxylaminopurine in Listeria monocytogenes2017In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 45, no 4, p. 1914-1924Article in journal (Refereed)
    Abstract [en]

    The emerging development of antibiotic resistant bacteria calls for novel types of antibacterial agents. In this work we examined the putative antibacterial effect of purine analogs in Listeria monocytogenes. We show that, among several tested purine analogs, only 6-N-hydroxylaminopurine (6-N-HAP) reduces the viability of the Gram-positive pathogenListeria monocy-togenes. As in Bacillus subtilis, 6-N-HAP terminates expression at guanine riboswitches in L. monocyto-genes hence preventing expression of their downstream genes. However, we show that the bacteriocidal effect of the compound was unlinked to the terminated expression at the guanine riboswitches. When further examining the antimicrobial effect, we observed that 6-N-HAP acts as a potent mutagen in L. monocytogenes, by increasing the mutation rate and inducing the SOS-response. Also, addition of 6N-HAP decreased virulence gene expression by reducing both the levels and activity of the virulence regulator PrfA.

  • 262.
    Kumar, Keshav
    et al.
    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).
    Integrating network analysis with chromatography: introducing a novel chemometry-chromatography based analytical procedure to classify the bacterial cell wall collection2018In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 10, no 10, p. 1172-1180Article in journal (Refereed)
    Abstract [en]

    The present work integrates network analysis with chromatography and proposes a novel analytical procedure to classify the bacterial cell wall collection. The network analysis model can capture the heterogeneity present in the datasets and hence can provide unsupervised classification. The proposed approach is successfully applied for classifying the peptidoglycan samples of certain bacterial collections belonging to the class of Alphaproteobacteria. The obtained classification results are found to correlate well with their relative similarity in the peptidoglycan compositions. In summary, the proposed network analysis approach can be helpful in automatizing the bacterial cell wall analysis. The proposed approach can be useful to accelerate the research related to understanding the morphology of bacterial cell walls, host-pathogen interaction and development of effective antibiotics.

  • 263.
    Kumar, Keshav
    et al.
    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).
    Principal coordinate analysis assisted chromatographic analysis of bacterial cell wall collection: a robust classification approach2018In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 550, p. 8-14Article in journal (Refereed)
    Abstract [en]

    In the present work, Principal coordinate analysis (PCoA) is introduced to develop a robust model to classify the chromatographic data sets of peptidoglycan sample. PcoA captures the heterogeneity present in the data sets by using the dissimilarity matrix as input. Thus, in principle, it can even capture the subtle differences in the bacterial peptidoglycan composition and can provide a more robust and fast approach for classifying the bacterial collection and identifying the novel cell wall targets for further biological and clinical studies. The utility of the proposed approach is successfully demonstrated by analysing the two different kind of bacterial collections. The first set comprised of peptidoglycan sample belonging to different subclasses of Alphaproteobacteria. Whereas, the second set that is relatively more intricate for the chemometric analysis consist of different wild type Vibrio Cholerae and its mutants having subtle differences in their peptidoglycan composition. The present work clearly proposes a useful approach that can classify the chromatographic data sets of chromatographic peptidoglycan samples having subtle differences. Furthermore, present work clearly suggest that PCoA can be a method of choice in any data analysis workflow.

  • 264.
    Kumar, Keshav
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Espaillat, Akbar
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Cava, Felipe
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Molecular Medicine (UCMM). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    PG-metrics: a chemometric-based approach for classifying bacterial peptidoglycan data sets and uncovering their subjacent chemical variability2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 10, article id e0186197Article in journal (Refereed)
    Abstract [en]

    Bacteria cells are protected from osmotic and environmental stresses by an exoskeleton-like polymeric structure called peptidoglycan ( PG) or murein sacculus. This structure is fundamental for bacteria's viability and thus, the mechanisms underlying cell wall assembly and how it is modulated serve as targets for many of our most successful antibiotics. Therefore, it is now more important than ever to understand the genetics and structural chemistry of the bacterial cell walls in order to find new and effective methods of blocking it for the treatment of disease. In the last decades, liquid chromatography and mass spectrometry have been demonstrated to provide the required resolution and sensitivity to characterize the fine chemical structure of PG. However, the large volume of data sets that can be produced by these instruments today are difficult to handle without a proper data analysis work-flow. Here, we present PG-metrics, a chemometric based pipeline that allows fast and easy classification of bacteria according to their muropeptide chromatographic profiles and identification of the subjacent PG chemical variability between e.g. bacterial species, growth conditions and, mutant libraries. The pipeline is successfully validated here using PG samples from different bacterial species and mutants in cell wall proteins. The obtained results clearly demonstrated that PG-metrics pipeline is a valuable bioanalytical tool that can lead us to cell wall classification and biomarker discovery.

  • 265.
    Kumlin, Urban
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Juto, Kinnunen M. Per
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Serum IgG and IgM responses to rhinoviruses as detected by a HRV virus capsid (VP1)-based indirect ELISA2015In: Journal of Clinical Virology, ISSN 1386-6532, E-ISSN 1873-5967, Vol. 70, p. S70-S70Article in journal (Other academic)
  • 266.
    Kurhade, Chaitanya
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Interplay between tick-borne encephalitis virus and the host innate immunity2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Flaviviruses are important emerging and re-emerging arthropod-borne pathogens that cause significant morbidity and mortality in humans. It consists of globally distributed human pathogens such as tick-borne encephalitis virus (TBEV), West Nile virus (WNV), Japanese encephalitis virus (JEV), yellow fever virus (YFV), dengue virus (DENV), and Zika virus (ZIKV). Depending on type, flaviviruses can cause a variety of symptoms ranging from haemorrhage to neurological disorders.

    Virus infection is detected by host pattern recognition receptors (PRRs), and through downstream signalling it leads to the production of interferons (IFNs). These IFNs then act in an autocrine or paracrine manner on the cells to induce various IFN-stimulated genes (ISGs), which have antiviral roles. However, the amount of IFN produced depends on the nature of the PRRs used by host cells to detect a particular virus. Although there are many PRRs present in the host cells, their relative contribution in different cell types and against a specific virus may vary. In the first study, we determined the importance of IPS-1 signalling in immunity and pathogenicity of tick-borne flaviviruses. This is an adaptor protein for cytoplasmic RIG-I-like receptors. Using IPS-1-deficient mice, we showed its importance against TBEV and Langat virus (LGTV) infection (the LGTV model virus belongs to the TBEV serogroup). Absence of IPS-1 leads to uncontrolled virus replication in the central nervous system (CNS), but it has only a minor role in shaping the humoral immune response at the periphery. LGTV-infected IPS-1-deficient mice showed apoptosis, activation of microglia and astrocytes, an elevated proinflammatory response, and recruitment of immune cells to the CNS. Interestingly, we also found that IFN-b upregulation after viral infection was dependent on IPS-1 in the olfactory bulb of the brain.  Thus, our results suggest that local immune microenvironment of distinct brain regions is critical for determination of virus permissiveness.

    Interferons can upregulate several ISGs. Viperin is one such ISG that has a broad-spectrum antiviral action against many viruses. However, the importance of cell type and the significance of viperin in controlling many flavivirus infections in vivo is not known. Using viperin-deficient mice, we found that viperin was necessary for restriction of LGTV replication in the olfactory bulb and cerebrum, but not in the cerebellum. This finding was also confirmed with primary neurons derived from these brain regions. Furthermore, we could also show the particular importance of viperin in cortical neurons against TBEV, WNV, and ZIKV infection. The results suggested that a single ISG can shape the susceptibility and immune response to a flavivirus in different regions of the brain.

    Although viperin is such an important ISG against flaviviruses, the exact molecular mechanism of action is not known. To understand the mechanism, we performed co-immunoprecipitation screening to identify TBEV proteins that could interact with viperin. While viperin interacted with the prM, E, NS2A, NS2B, and NS3 proteins of TBEV, its interaction with NS3 led to its degradation through the proteosomal pathway. Furthermore, viperin could reduce the stability of other viperin-binding TBEV proteins in an NS3-dependent manner. We screened for viperin activity regarding interaction with NS3 proteins of other flaviviruses. Viperin interacted with NS3 of JEV, ZIKV, and YFV, but selectively degraded NS3 proteins of TBEV and ZIKV, and this activity correlated with its antiviral activity against these viruses.

    The last study was based on in vivo characterization of the newly isolated MucAr HB 171/11 strain of TBEV which caused unusual gastrointestinal and constitutional symptoms. This strain was compared with another strain, Torö-2003, of the same European subtype of TBEV but isolated from the different focus. Here we found unique differences in their neuroinvasiveness and neurovirulence, and in the immune response to these two strains.

    In summary, my work shed some light on the interplay between tick-borne flavivirus and the innate immune system. I have shown two examples of CNS region-specific differences in innate immune response regarding both in IFN induction pathways and antiviral effectors. Furthermore, we have investigated the in vivo pathogenesis of a strain of TBEV that caused unusual gastrointestinal and constitutional symptoms.

  • 267.
    Kurhade, Chaitanya
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Zegenhagen, Loreen
    Weber, Elvira
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Nair, Sharmila
    Michaelsen-Preusse, Kristin
    Spanier, Julia
    Gekara, Nelson O.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Kroeger, Andrea
    Överby, Anna K.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Type I Interferon response in olfactory bulb, the site of tick-borne flavivirus accumulation, is primarily regulated by IPS-12016In: Journal of Neuroinflammation, ISSN 1742-2094, E-ISSN 1742-2094, Vol. 13, article id 22Article in journal (Refereed)
    Abstract [en]

    Background: Although type I interferons (IFNs)—key effectors of antiviral innate immunity are known to be induced via different pattern recognition receptors (PRRs), the cellular source and the relative contribution of different PRRs in host protection against viral infection is often unclear. IPS-1 is a downstream adaptor for retinoid-inducible gene I (RIG-I)-like receptor signaling. In this study, we investigate the relative contribution of IPS-1 in the innate immune response in the different brain regions during infection with tick-borne encephalitis virus (TBEV), a flavivirus that causes a variety of severe symptoms like hemorrhagic fevers, encephalitis, and meningitis in the human host.

    Methods: IPS-1 knockout mice were infected with TBEV/Langat virus (LGTV), and viral burden in the peripheral and the central nervous systems, type I IFN induction, brain infiltrating cells, and inflammatory response was analyzed.

    Results: We show that IPS-1 is indispensable for controlling TBEV and LGTV infections in the peripheral and central nervous system. Our data indicate that IPS-1 regulates neuropathogenicity in mice. IFN response is differentially regulated in distinct regions of the central nervous system (CNS) influencing viral tropism, as LGTV replication was mainly restricted to olfactory bulb in wild-type (WT) mice. In contrast to the other brain regions, IFN upregulation in the olfactory bulb was dependent on IPS-1 signaling. IPS-1 regulates basal levels of antiviral interferon-stimulated genes (ISGs) like viperin and IRF-1 which contributes to the establishment of early viral replication which inhibits STAT1 activation. This diminishes the antiviral response even in the presence of high IFN-β levels. Consequently, the absence of IPS-1 causes uncontrolled virus replication, in turn resulting in apoptosis, activation of microglia and astrocytes, elevated proinflammatory response, and recruitment of inflammatory cells into the CNS.

    Conclusions: We show that LGTV replication is restricted to the olfactory bulb and that IPS-1 is a very important player in the olfactory bulb in shaping the innate immune response by inhibiting early viral replication and viral spread throughout the central nervous system. In the absence of IPS-1, higher viral replication leads to the evasion of antiviral response by inhibiting interferon signaling. Our data suggest that the local microenvironment of distinct brain regions is critical to determine virus permissiveness.

  • 268.
    Kuru, Erkin
    et al.
    Indiana University, Bloomington, USA.
    Hughes, H Velocity
    Indiana University, Bloomington, USA.
    Brown, Pamela J
    Indiana University, Bloomington, USA.
    Hall, Edward
    Indiana University, Bloomington, USA.
    Tekkam, Srinivas
    Indiana University, Bloomington, USA.
    Cava, Felipe
    Universidad Autonoma de Madrid, Campus de Cantoblanco, Madrid, Spain.
    de Pedro, Miguel A
    Universidad Autonoma de Madrid, Campus de Cantoblanco, Madrid, Spain.
    Brun, Yves V
    Indiana University, Bloomington, USA.
    VanNieuwenhze, Michael S
    Indiana University, Bloomington, USA.
    In Situ probing of newly synthesized peptidoglycan in live bacteria with fluorescent D-amino acids2012In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 51, no 50, p. 12519-12523Article in journal (Refereed)
    Abstract [en]

    Tracking a bug's life: Peptidoglycan (PG) of diverse bacteria is labeled by exploiting the tolerance of cells for incorporating different non-natural D-amino acids. These nontoxic D-amino acids preferably label the sites of active PG synthesis, thereby enabling fine spatiotemporal tracking of cell-wall dynamics in phylogenetically and morphologically diverse bacteria. HCC = 7-hydroxycoumarin, NBD = 7-nitrobenzofurazan, TAMRA = carboxytetramethylrhodamine.

  • 269. Kusmierek, Maria
    et al.
    Hossmann, Joern
    Witte, Rebekka
    Opitz, Wiebke
    Vollmer, Ines
    Volk, Marcel
    Heroven, Ann Kathrin
    Wolf-Watz, Hans
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Dersch, Petra
    A bacterial secreted translocator hijacks riboregulators to control type III secretion in response to host cell contact2019In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 15, no 6, article id e1007813Article in journal (Refereed)
    Abstract [en]

    Numerous Gram-negative pathogens use a Type III Secretion System (T3SS) to promote virulence by injecting effector proteins into targeted host cells, which subvert host cell processes. Expression of T3SS and the effectors is triggered upon host cell contact, but the underlying mechanism is poorly understood. Here, we report a novel strategy of Yersinia pseudotuberculosis in which this pathogen uses a secreted T3SS translocator protein (YopD) to control global RNA regulators. Secretion of the YopD translocator upon host cell contact increases the ratio of post-transcriptional regulator CsrA to its antagonistic small RNAs CsrB and CsrC and reduces the degradosome components PNPase and RNase E levels. This substantially elevates the amount of the common transcriptional activator (LcrF) of T3SS/Yop effector genes and triggers the synthesis of associated virulence-relevant traits. The observed hijacking of global riboregulators allows the pathogen to coordinate virulence factor expression and also readjusts its physiological response upon host cell contact. Author summary Many bacterial pathogens sense contact to host cells and respond by inducing expression of crucial virulence factors. This includes the type III secretion systems (T3SSs) and their substrates, which manipulate different host cell functions to promote colonization and survival of the pathogen within its host. In this study, we used enteropathogenic Yersinia pseudotuberculosis to elucidate the molecular mechanism of how cell contact is transmitted and translated to trigger this process. We found that multiple global riboregulators control the decay and/or translation of the major transcriptional activator of the T3SS. In the absence of cell contact, these important RNA regulators are coopted by one of the substrate proteins of the T3SS to repress expression of the secretion machinery. Translocation of the substrate protein upon cell contact relieves riboregulator-mediated repression. This leads to a strong induction of the master regulator of T3SS/effector gene expression promoting an increase of the virulence potential and provokes a fast adaptation of the pathogen's fitness, e.g. to compensate for the imposed energetic burden.

  • 270. Kuzmenko, Anton
    et al.
    Derbikova, Ksenia
    Salvatori, Roger
    Tankov, Stoyan
    Atkinson, Gemma C.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). University of Tartu, Institute of Technology, Tartu, Estonia.
    Tenson, Tanel
    Ott, Martin
    Kamenski, Piotr
    Hauryliuk, Vasili
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). University of Tartu, Institute of Technology, Tartu, Estonia.
    Aim-less translation: loss of Saccharomyces cerevisiae mitochondrial translation initiation factor mIF3/Aim23 leads to unbalanced protein synthesis2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 18749Article in journal (Refereed)
    Abstract [en]

    The mitochondrial genome almost exclusively encodes a handful of transmembrane constituents of the oxidative phosphorylation (OXPHOS) system. Coordinated expression of these genes ensures the correct stoichiometry of the system's components. Translation initiation in mitochondria is assisted by two general initiation factors mIF2 and mIF3, orthologues of which in bacteria are indispensible for protein synthesis and viability. mIF3 was thought to be absent in Saccharomyces cerevisiae until we recently identified mitochondrial protein Aim23 as the missing orthologue. Here we show that, surprisingly, loss of mIF3/Aim23 in S. cerevisiae does not indiscriminately abrogate mitochondrial translation but rather causes an imbalance in protein production: the rate of synthesis of the Atp9 subunit of F1F0 ATP synthase (complex V) is increased, while expression of Cox1, Cox2 and Cox3 subunits of cytochrome c oxidase (complex IV) is repressed. Our results provide one more example of deviation of mitochondrial translation from its bacterial origins.

  • 271. Kwiecinski, Jakub
    et al.
    Jacobsson, Gunnar
    Karlsson, Maria
    Zhu, Xuefeng
    Wang, Wanzhong
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Bremell, Tomas
    Josefsson, Elisabet
    Jin, Tao
    Staphylokinase Promotes the Establishment of Staphylococcus aureus Skin Infections While Decreasing Disease Severity2013In: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 208, no 6, p. 990-999Article in journal (Refereed)
    Abstract [en]

    Skin infections are frequently caused by Staphylococcus aureus and can lead to a fatal sepsis. The microbial mechanisms controlling the initiation and progression from mild skin infection to a severe disseminated infection remain poorly understood. Using a combination of clinical data and in vitro and ex vivo assays, we show that staphylokinase, secreted by S. aureus, promoted the establishment of skin infections in humans and increased bacterial penetration through skin barriers by activating plasminogen. However, when infection was established, the interaction between staphylokinase and plasminogen did not promote systemic dissemination but induced the opening and draining of abscesses and decreased disease severity in neutropenic mice. Also, increased staphylokinase production was associated with noninvasive S. aureus infections in patients. Our results point out the dual roles of staphylokinase in S. aureus skin infections as promoting the establishment of infections while decreasing disease severity.

  • 272.
    Kübler, André
    et al.
    Johns Hopkins Univ, Sch Med, Ctr TB Res, Baltimore, MD USA.
    Luna, Brian
    Johns Hopkins Univ, Sch Med, Ctr TB Res, Baltimore, MD USA.
    Larsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Ammerman, Nicole C
    KwaZulu Natal Res Inst TB & HIV K RITH, Durban, South Africa.
    Andrade, Bruno B
    NIAID, Immunobiol Sect, Parasit Dis Lab, NIH, Bethesda, MD 20892 USA.
    Orandle, Marlene
    NIAID, Infect Dis Pathogenesis Sect, Comparat Med Branch, NIH, Bethesda, MD 20892 USA.
    Bock, Kevin W
    NIAID, Infect Dis Pathogenesis Sect, Comparat Med Branch, NIH, Bethesda, MD 20892 USA.
    Xu, Ziyue
    NIH, Bethesda, MD 20892 USA.
    Bagci, Ulas
    NIH, Bethesda, MD 20892 USA.
    Molura, Daniel J
    Marshall, John
    Burns, Jay
    Winglee, Kathryn
    Ahidjo, Bintou Ahmadou
    Cheung, Laurene S
    Klunk, Mariah
    Jain, Sanjay K
    Kumar, Nathella Pavan
    Babu, Subash
    Sher, Alan
    Friedland, Jon S
    Elkington, Paul T G
    Bishai, William R
    Mycobacterium tuberculosis dysregulates MMP/TIMP balance to drive rapid cavitation and unrestrained bacterial proliferation.2015In: Journal of Pathology, ISSN 0022-3417, E-ISSN 1096-9896, Vol. 235, no 3, p. 431-444Article in journal (Refereed)
    Abstract [en]

    Active tuberculosis (TB) often presents with advanced pulmonary disease, including irreversible lung damage and cavities. Cavitary pathology contributes to antibiotic failure, transmission, morbidity and mortality. Matrix metalloproteinases (MMPs), in particular MMP-1 are implicated in TB pathogenesis. We explored the mechanisms relating MMP/TIMP imbalance to cavity formation in a modified rabbit model of cavitary TB. Our model results in consistent progression of consolidation to human-like cavities (100% by day 28) with resultant bacillary burdens (>10(7) CFU/g) far greater than those found in matched granulomatous tissue (10(5) CFU/g). Using a novel, breath-hold computerized tomography scanning and image analysis protocol. We show that cavities develop rapidly from areas of densely consolidated tissue. Radiological change correlated with a decrease in functional lung tissue as estimated by changes in lung density during controlled pulmonary expansion (R(2) =0.6356, p < 0.0001). We demonstrated that the expression of interstitial collagenase (MMP-1) is specifically greater in cavitary compared to granulomatous lesions (p < 0.01), and that TIMP-3 significantly decreases at the cavity surface. Our findings demonstrate that an MMP-1/TIMP imbalance, is associated with the progression of consolidated regions to cavities containing very high bacterial burdens. Our model provided mechanistic insight, correlating with human disease at the pathological, microbiological and molecular levels,. It also provides a strategy to investigate therapeutics in the context of complex TB pathology. We used these findings to predict a MMP/TIMP balance in active TB; and confirmed this in human plasma, revealing the potential of MMP/TIMP levels as key components of a diagnostic matrix aimed at distinguishing active from latent TB (PPV=92.9%; 95%CI 66.1-99.8%, NPV=85.6%; 95%CI 77.0-91.9%).

  • 273. Lagerqvist, Nina
    et al.
    Hagstrom, Asa
    Lundahl, Malin
    Nilsson, Elin
    Juremalm, Mikael
    Larsson, Inger
    Alm, Erik
    Bucht, Goran
    Ahlm, Clas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Klingstrom, Jonas
    Molecular Diagnosis of Hemorrhagic Fever with Renal Syndrome Caused by Puumala Virus2016In: Journal of Clinical Microbiology, ISSN 0095-1137, E-ISSN 1098-660X, Vol. 54, no 5, p. 1335-1339Article in journal (Refereed)
    Abstract [en]

    Rodent-borne hantaviruses cause two severe acute diseases: hemorrhagic fever with renal syndrome (HFRS) in Eurasia, and hantavirus pulmonary syndrome (HPS; also called hantavirus cardiopulmonary syndrome [HCPS]) in the Americas. Puumala virus (PUUV) is the most common causative agent of HFRS in Europe. Current routine diagnostic methods are based on serological analyses and can yield inconclusive results. Hantavirus-infected patients are viremic during the early phase of disease; therefore, detection of viral RNA genomes can be a valuable complement to existing serological methods. However, the high genomic sequence diversity of PUUV has hampered the development of molecular diagnostics, and currently no real-time reverse transcription- quantitative (RT)-PCR assay is available for routine diagnosis of HFRS. Here, we present a novel PUUV RT-PCR assay. The assay was validated for routine diagnosis of HFRS on samples collected in Sweden during the winter season from 2013 to 2014. The assay allowed detection of PUUV RNA in 98.7% of confirmed clinical HFRS samples collected within 8 days after symptomatic onset. In summary, this study shows that real-time RT-PCR can be a reliable alternative to serological tests during the early phase of HFRS.

  • 274. Lampe, E. O.
    et al.
    Zingmark, Carl
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Hemnann, L.
    Brudal, E.
    Rishovd, A. L.
    Bröms, Jeanette
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Hagedorn, M.
    Griffiths, G. W.
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Winther-Larsen, H. C.
    A study of virulence factors in the fish pathogen F. noatunensis ssp noatunensis2013In: Fish and Shellfish Immunology, ISSN 1050-4648, E-ISSN 1095-9947, Vol. 34, no 6, p. 1716-1716Article in journal (Refereed)
    Abstract [en]

    The bacterium Francisella noatunensis ssp. noatunensis (in text: F. noatunensis) is the ethiological agent of the disease francisellosis in Atlantic cod. Francisellosis has been one of the major limiting factors in the development of Norwegian aquaculture industry based on Atlantic cod. Lacking an effective treatment or vaccine there is urgent need for studies related to the pathogenesis of the disease.

    The closely related human pathogen F. tularensis is more extensively studied and due to relatively high sequence similarity with F. noatunensis, indirect evidence on important virulence factors can be obtained by reverse genetics. The Francisella Pathogenicity Island (FPI) has been identified in all sequenced genomes of Francisella sp. and contains genes associated with the ability of the bacterium to survive and replicate within macrophages.

    To elucidate the pathogenesis of F. noatunensis, infection assays have been performed on primary cells extracted from the head kidney of Atlantic cod. Disruptive mutations of the potential virulence factors IglC, IglD (important for intracellular growth in F. tularensis subsp.) and ClpB (a heat shock protein identified in F. tularensis), have been constructed in F. noatunensis and the infection pattern is in the process of characterization. Model systems that are utilized in the characterization are the amoebae and professional phagocyte Dictyostelium discoideum, zebrafish and macrophages extracted from head kidney of Atlantic cod.

  • 275. Lampe, Elisabeth O.
    et al.
    Brenz, Yannick
    Herrmann, Lydia
    Repnik, Urska
    Griffiths, Gareth
    Zingmark, Carl
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Winther-Larsen, Hanne C.
    Hagedorn, Monica
    Dissection of Francisella-Host Cell Interactions in Dictyostelium discoideum2016In: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 82, no 5, p. 1586-1598Article in journal (Refereed)
    Abstract [en]

    Francisella bacteria cause severe disease in both vertebrates and invertebrates and include one of the most infectious human pathogens. Mammalian cell lines have mainly been used to study the mechanisms by which Francisella manipulates its host to replicate within a large variety of hosts and cell types, including macrophages. Here, we describe the establishment of a genetically and biochemically tractable infection model: the amoeba Dictyostelium discoideum combined with the fish pathogen Francisella noatunensis subsp. noatunensis. Phagocytosed F. noatunensis subsp. noatunensis interacts with the endosomal pathway and escapes further phagosomal maturation by translocating into the host cell cytosol. F. noatunensis subsp. noatunensis lacking IglC, a known virulence determinant required for Francisella intracellular replication, follows the normal phagosomal maturation and does not grow in Dictyostelium. The attenuation of the F. noatunensis subsp. noatunensis Delta iglC mutant was confirmed in a zebrafish embryo model, where growth of F. noatunensis subsp. noatunensis Delta iglC was restricted. In Dictyostelium, F. noatunensis subsp. noatunensis interacts with the autophagic machinery. The intracellular bacteria colocalize with autophagic markers, and when autophagy is impaired (Dictyostelium Delta atg1), F. noatunensis subsp. noatunensis accumulates within Dictyostelium cells. Altogether, the Dictyostelium-F. noatunensis subsp. noatunensis infection model recapitulates the course of infection described in other host systems. The genetic and biochemical tractability of the system allows new approaches to elucidate the dynamic interactions between pathogenic Francisella and its host organism.

  • 276.
    Larsson, Christer
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Pathobiology of African relapsing fever Borrelia2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Relapsing fever (RF) is a disease caused by tick- or louse-transmitted bacteria of the genus Borrelia. It occurs worldwide but is most common in Africa where it is one of the most prevalent bacterial diseases. The main manifestation is a recurring fever which coincides with massive numbers of bacteria in the blood. Severity ranges from asymptomatic to fatal.

    RF is usually considered a transient disease. In contrast, B. duttonii causes a persistent, residual brain infection in C57BL/6 mice which remains long time after the bacteria are cleared from the blood. The host gene expression pattern is indistinguishable from that of uninfected animals, indicating that persistent bacteria are not recognized by the immune system nor do they cause noticeable tissue damage. This is probably due to the quite low number of bacteria residing in the brain. The silent infection can be reactivated by immunosuppression allowing bacteria to re-enter the blood. To investigate if the residual infection is in a quiescent state or if the bacteria are actively dividing, mice with residual brain infection were treated with the cell-wall disrupting antibiotic ceftriaxone, which is only active against dividing bacteria. Since all mice were cured by ceftriaxone we conclude that the bacteria are actively growing in the brain rather than being in a latent, dormant state. The brain is used as an immunoprivileged site to escape host immune defence and probably as a reservoir for bacteria.

    RF is a common cause of pregnancy complications, miscarriage and neonatal death in sub-Saharan Africa. We established a murine model of gestational relapsing fever to study the pathological development of these complications. B. duttonii infection during pregnancy results in intrauterine growth retardation as well as placental damage and inflammation. Spirochetes cross the maternal-foetal barrier, resulting in congenital infection. Further, pregnancy has a protective effect, resulting in milder disease during pregnancy.

    A clinic-based study to investigate the presence of RF in Togo was performed. Blood from patients with fever were examined for RF by microscopy, GlpQ ELISA and PCR. About 10% of the patients were positive by PCR and 13% had antibodies to GlpQ. Many RF patients originally had a misdiagnosis of malaria, which resulted in ineffective treatment. The inability of microscopic analysis to detect spirochetes demonstrates the need for tests with greater sensitivity. To provide simple, fast, cheap and sensitive diagnostics using equipment available in small health centres, a method based on enrichment of bacteria by centrifugation and detection by Giemsa staining was developed which detects <10 spirochetes/ml.

    To study the phylogeny of RF, IGS and glpQ were sequenced and neighbor joining trees were constructed. B. persica and B. hispanica were distant from the other species iswhereas B. crocidurae appeared to be a heterogeneous species. B. duttonii is polyphyletic in relation to B. recurrentis suggesting that the two species may in fact be the same or have a polyphyletic origin.

  • 277.
    Larsson, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Andersson, Marie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Guo, Betty P
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Nordstrand, Annika
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Hägerstrand, Inga
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Carlsson, Sara
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Complications of pregnancy and transplacental transmission of relapsing-fever borreliosis2006In: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 194, no 10, p. 1367-1374Article in journal (Refereed)
    Abstract [en]

    Relapsing-fever borreliosis caused by Borrelia duttonii is a common cause of complications of pregnancy, miscarriage, and neonatal death in sub-Saharan Africa. We established a murine model of gestational relapsing fever infection for the study of the pathological development of these complications. We demonstrate that B. duttonii infection during pregnancy results in intrauterine growth retardation, as well as placental damage and inflammation, impaired fetal circulation, and decreased maternal hemoglobin levels. We show that spirochetes frequently cross the maternal-fetal barrier, resulting in congenital infection. Furthermore, we compared the severity of infection in pregnant and nonpregnant mice and show that pregnancy has a protective effect. This model closely parallels the consequences of human gestational infection, and our results provide insight into the mechanisms behind the complications of pregnancy that have been reported in human relapsing-fever infection.

  • 278.
    Larsson, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Andersson, Marie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Pelkonen, Jenni
    Guo, Betty
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Nordstrand, Annika
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Persistent brain infection and disease reactivation in relapsing fever borreliosis2006In: Microbes and infection, ISSN 1286-4579, E-ISSN 1769-714X, Vol. 8, no 8, p. 2213-2219Article in journal (Refereed)
    Abstract [en]

    Relapsing fever, an infection caused by Borrelia spirochetes, is generally considered a transient, self-limiting disease in humans. The present study reveals that murine infection by Borrelia duttonii can be reactivated after an extended time as a silent infection in the brain, with no bacteria appearing in the blood and spirochete load comparable to the numbers in an infected tick. The host cerebral gene expression pattern is indistinguishable from that of uninfected animals, indicating that persistent bacteria are not recognized by the immune system nor cause noticeable tissue damage. Silent infection can be reactivated by immunosuppression, inducing spirochetemia comparable to that of initial densities. B. duttonii has never been found in any host except man and the tick vector. We therefore propose the brain to be a possible natural reservoir of the spirochete. The view of relapsing fever as an acute disease should be extended to include in some cases prolonged persistence, a feature characteristic of the related spirochetal infections Lyme disease and syphilis.

  • 279.
    Larsson, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    A novel and simple method for laboratory diagnosis of relapsing Fever borreliosis.2008In: Open Microbiology Journal, ISSN 1874-2858, E-ISSN 1874-2858, Vol. 2, p. 10-2Article in journal (Refereed)
    Abstract [en]

    Relapsing fever caused by Borrelia bacteria is often obscured by malaria and incorrectly treated. Here a novel method for diagnosis is presented. The method is cheap, simple and requires minimal laboratory material. Despite its simplicity, the method shows surprisingly high sensitivity, detecting concentrations less than 10 bacteria/ml blood.

  • 280.
    Larsson, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Comstedt, Pär
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Olsen, Björn
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    First record of Lyme disease Borrelia in the Arctic2007In: Vector Borne and Zoonotic Diseases, ISSN 1530-3667, E-ISSN 1557-7759, Vol. 7, no 3, p. 453-456Article in journal (Refereed)
    Abstract [en]

    The epidemiology and ecology of Lyme disease is very complex, and its reported geographical distribution is constantly increasing. Furthermore, the involvement of birds in long distance dispersal and their role as reservoir hosts is now well established. In this study, we have shown that sea birds in the Arctic region of Norway carry Ixodes uriae ticks infected with Lyme disease Borrelia garinii spirochetes. Interestingly, DNA sequencing showed that these isolates are closely related to B. garinii previously isolated from birds, as well as from clinical specimens in northern Europe.

  • 281.
    Larsson, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Lundqvist, Jenny
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Residual brain infection in murine relapsing fever borreliosis can be successfully treated with ceftriaxone2008In: Microbial Pathogenesis, ISSN 0882-4010, E-ISSN 1096-1208, Vol. 44, no 3, p. 262-264Article in journal (Refereed)
    Abstract [en]

    Like several other spirochetes, relapsing fever Borrelia can cause persistent infection of the central nervous system (CNS). By treating mice harboring residual Borrelia duttonii brain infection with the bacteriocidal, cell wall inhibiting antibiotic ceftriaxone, bacteria were cleared from the brain. This shows that the residual infection is not latent but actively growing.

  • 282.
    Larsson, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Lundqvist, Jenny
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    van Rooijen, Nico
    Bergström, Sven
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    A novel animal model of Borrelia recurrentis louse-borne relapsing fever borreliosis using immunodeficient mice2009In: PLoS Neglected Tropical Diseases, ISSN 1935-2727, E-ISSN 1935-2735, Vol. 3, no 9, p. e522-Article in journal (Refereed)
    Abstract [en]

    Louse-borne relapsing fever (LBRF) borreliosis is caused by Borrelia recurrentis, and it is a deadly although treatable disease that is endemic in the Horn of Africa but has epidemic potential. Research on LBRF has been severely hampered because successful infection with B. recurrentis has been achieved only in primates (i.e., not in other laboratory or domestic animals). Here, we present the first non-primate animal model of LBRF, using SCID (-B, -T cells) and SCID BEIGE (-B, -T, -NK cells) immunocompromised mice. These animals were infected with B. recurrentis A11 or A17, or with B. duttonii 1120K3 as controls. B. recurrentis caused a relatively mild but persistent infection in SCID and SCID BEIGE mice, but did not proliferate in NUDE (-T) and BALB/c (wild-type) mice. B. duttonii was infectious but not lethal in all animals. These findings demonstrate that the immune response can limit relapsing fever even in the absence of humoral defense mechanisms. To study the significance of phagocytic cells in this context, we induced systemic depletion of such cells in the experimental mice by injecting them with clodronate liposomes, which resulted in uncontrolled B. duttonii growth and a one-hundred-fold increase in B. recurrentis titers in blood. This observation highlights the role of macrophages and other phagocytes in controlling relapsing fever infection. B. recurrentis evolved from B. duttonii to become a primate-specific pathogen that has lost the ability to infect immunocompetent rodents, probably through genetic degeneration. Here, we describe a novel animal model of B. recurrentis based on B- and T-cell-deficient mice, which we believe will be very valuable in future research on LBRF. Our study also reveals the importance of B-cells and phagocytes in controlling relapsing fever infection.

  • 283.
    Larsson, Pär
    et al.
    Swedish Defense Research Agency, Umeå, Sweden.
    Elfsmark, Daniel
    Swedish Defense Research Agency, Umeå, Sweden.
    Svensson, Kerstin
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Wikström, Per
    Swedish Defense Research Agency, Umeå, Sweden.
    Forsman, Mats
    Swedish Defense Research Agency, Umeå, Sweden.
    Brettin, Thomas
    Keim, Paul
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Molecular evolutionary consequences of niche restriction in Francisella tularensis, a facultative intracellular pathogen2009In: PLoS pathogens, ISSN 1553-7374, Vol. 5, no 6, p. e1000472-Article in journal (Refereed)
    Abstract [en]

    Francisella tularensis is a potent mammalian pathogen well adapted to intracellular habitats, whereas F. novicida and F. philomiragia are less virulent in mammals and appear to have less specialized lifecycles. We explored adaptations within the genus that may be linked to increased host association, as follows. First, we determined the genome sequence of F. tularensis subsp. mediasiatica, the only subspecies that had not been previously sequenced. This genome, and those of 12 other F. tularensis isolates, were then compared to the genomes of F. novicida (three isolates) and F. philomiragia (one isolate). Signs of homologous recombination were found in approximately 19.2% of F. novicida and F. philomiragia genes, but none among F. tularensis genomes. In addition, random insertions of insertion sequence elements appear to have provided raw materials for secondary adaptive mutations in F. tularensis, e.g. for duplication of the Francisella Pathogenicity Island and multiplication of a putative glycosyl transferase gene. Further, the five major genetic branches of F. tularensis seem to have converged along independent routes towards a common gene set via independent losses of gene functions. Our observations suggest that despite an average nucleotide identity of >97%, F. tularensis and F. novicida have evolved as two distinct population lineages, the former characterized by clonal structure with weak purifying selection, the latter by more frequent recombination and strong purifying selection. F. tularensis and F. novicida could be considered the same bacterial species, given their high similarity, but based on the evolutionary analyses described in this work we propose retaining separate species names.

  • 284.
    Larsson, Sofie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Identification of new biomarkers to subgroup prostate cancer patients with high risk of distant metastasis2017Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 285. Lasswitz, Lisa
    et al.
    Chandra, Naresh
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Arnberg, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Gerold, Gisa
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Wallenberg Centre for Molecular Medicine at Umeå University (WCMM). Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany.
    Glycomics and Proteomics Approaches to Investigate Early Adenovirus-Host Cell Interactions2018In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 430, no 13, p. 1863-1882Article in journal (Refereed)
    Abstract [en]

    Adenoviruses as most viruses rely on glycan and protein interactions to attach to and enter susceptible host cells. The Adenoviridae family comprises more than 80 human types and they differ in their attachment factor and receptor usage, which likely contributes to the diverse tropism of the different types. In the past years, methods to systematically identify glycan and protein interactions have advanced. In particular sensitivity, speed and coverage of mass spectrometric analyses allow for high-throughput identification of glycans and peptides separated by liquid chromatography. Also, developments in glycan microarray technologies have led to targeted, high-throughput screening and identification of glycan-based receptors. The mapping of cell surface interactions of the diverse adenovirus types has implications for cell, tissue, and species tropism as well as drug development. Here we review known adenovirus interactions with glycan- and protein-based receptors, as well as glycomics and proteomics strategies to identify yet elusive virus receptors and attachment factors. We finally discuss challenges, bottlenecks, and future research directions in the field of non-enveloped virus entry into host cells.

  • 286.
    Laurie, Andrew D.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Bernardo, Lisandro M D
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Sze, Chun Chau
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Skärfstad, Eleonore
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Szalewska-Palasz, Agnieszka
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Nyström, Thomas
    Shingler, Victoria
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    The role of the alarmone (p)ppGpp in sigma N competition for core RNA polymerase2003In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 278, no 3, p. 1494-1503Article in journal (Refereed)
    Abstract [en]

    Some promoters, including the DmpR-controlled sigma(N)-dependent Po promoter, are effectively rendered silent in cells lacking the nutritional alarmone (p)ppGpp. Here we demonstrate that four mutations within the housekeeping sigma(D)-factor can restore sigma(N)-dependent Po transcription in the absence of (p)ppGpp. Using both in vitro and in vivo transcription competition assays, we show that all the four sigma(D) mutant proteins are defective in their ability to compete with sigma(N) for available core RNA polymerase and that the magnitude of the defect reflects the hierarchy of restoration of transcription from Po in (p)ppGpp-deficient cells. Consistently, underproduction of sigma(D) or overproduction of the anti-sigma(D) protein Rsd were also found to allow (p)ppGpp-independent transcription from the sigma(N)-Po promoter. Together with data from the direct effects of (p)ppGpp on sigma(N)-dependent Po transcription and sigma-factor competition, the results support a model in which (p)ppGpp serves as a master global regulator of transcription by differentially modulating alternative sigma-factor competition to adapt to changing cellular nutritional demands.

  • 287.
    Lavander, Moa
    et al.
    Department of Medical Countermeasures, Division of NBC-Defense, Swedish Defense Research Agency.
    Sundberg, Lena
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Department of Medical Countermeasures, Division of NBC-Defense, Swedish Defense Research Agency.
    Edqvist, Petra
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Lloyd, Scott
    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).
    Wolf-Watz, Hans
    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).
    Forsberg, Åke
    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).
    Proteolytic Cleavage of the FlhB Homologue YscU of Yersinia pseudotuberculosis Is Essential for Bacterial Survival2002In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 184, no 16, p. 4500-4509Article in journal (Refereed)
    Abstract [en]

    Pathogenic Yersinia species employ a type III secretion system (TTSS) to target antihost factors, Yop proteins, into eukaryotic cells. The secretion machinery is constituted of ca. 20 Ysc proteins, nine of which show significant homology to components of the flagellar TTSS. A key event in flagellar assembly is the switch from secreting-assembling hook substrates to filament substrates, a switch regulated by FlhB and FliK. The focus of this study is the FlhB homologue YscU, a bacterial inner membrane protein with a large cytoplasmic C-terminal domain. Our results demonstrate that low levels of YscU were required for functional Yop secretion, whereas higher levels of YscU lowered both Yop secretion and expression. Like FlhB, YscU was cleaved into a 30-kDa N-terminal and a 10-kDa C-terminal part. Expression of the latter in a wild-type strain resulted in elevated Yop secretion. The site of cleavage was at a proline residue, within the strictly conserved amino acid sequence NPTH. A YscU protein with an in-frame deletion of NPTH was cleaved at a different position and was nonfunctional with respect to Yop secretion. Variants of YscU with single substitutions in the conserved NPTH sequence--i.e., N263A, P264A, or T265A--were not cleaved but retained function in Yop secretion. Elevated expression of these YscU variants did, however, result in severe growth inhibition. From this we conclude that YscU cleavage is not a prerequisite for Yop secretion but is rather required to maintain a nontoxic fold.

  • 288.
    Le Rhun, Anaïs
    et al.
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Charpentier, Emmanuelle
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Small RNAs in streptococci2012In: RNA Biology, ISSN 1547-6286, E-ISSN 1555-8584, Vol. 9, no 4, p. 414-426Article in journal (Refereed)
    Abstract [en]

    The group of streptococci includes species responsible for severe diseases in humans. To adapt to their environment and infect their hosts, streptococci depend on precise regulation of gene expression. The last decade has witnessed increasing findings of small RNAs (sRNAs) having regulatory functions in bacteria. More recently, genome-wide screens revealed that streptococcal genomes also encode multiple sRNAs. Some sRNAs including the class of CRISPR RNAs (crRNAs) play critical roles in streptococcal adaptation and virulence. Analysis of sRNA mechanisms uncovered three sRNAs that target in trans mRNA (FasX), sRNA (tracrRNA) and DNA (crRNA). Overall, the current understanding of sRNA-mediated regulation in streptococci remains very limited. Given the complexity of regulatory networks and the number of recently predicted sRNAs, future research should reveal new functions and mechanisms for the streptococcal sRNAs. Here, we provide a comprehensive summary of the information available on the topic.

  • 289. Lekmeechai, Sujinna
    et al.
    Su, Yu-Ching
    Brant, Marta
    Alvarado-Kristensson, Maria
    Vallström, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Obi, Ikenna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Riesbeck, Kristian
    Helicobacter pylori Outer Membrane Vesicles Protect the Pathogen From Reactive Oxygen Species of the Respiratory Burst2018In: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 9, article id 1837Article in journal (Refereed)
    Abstract [en]

    Outer membrane vesicles (OMVs) play an important role in the persistence of Helicobacter pylori infection. Helicobacter OMVs carry a plethora of virulence factors, including catalase (KatA), an antioxidant enzyme that counteracts the host respiratory burst. We found KatA to be enriched and surface-associated in OMVs compared to bacterial cells. This conferred OMV-dependent KatA activity resulting in neutralization of H2O2 and NaClO, and rescue of surrounding bacteria from oxidative damage. The antioxidant activity of OMVs was abolished by deletion of KatA. In conclusion, enrichment of antioxidative KatA in OMVs is highly important for efficient immune evasion.

  • 290.
    Lenman, Annasara
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Adenovirus-host interactions: implications for tropism and therapy2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Human adenoviruses (HAdVs) are common viruses often associated withgastrointestinal, ocular and respiratory infections. They can infect a widevariety of cells, both dividing and non-dividing. HAdVs attach to and infecttarget cells through interactions with cellular receptors. It has also beenshown that HAdVs can use soluble host components in body fluids forindirect binding to target cells, a feature that enables the usage of new typesof receptors resulting in a more efficient HAdV infection. We thereforeevaluated the influence of soluble components from four different bodyfluids on HAdV infection of epithelial cells, representing the respiratory andocular tropism of most HAdVs. We found that plasma, saliva, and tear fluidpromote binding and infection of HAdV-5 (species C) and that plasmapromotes infection of HAdV-31 (species A). Further binding and infectionexperiments identified coagulation factor IX (FIX) and X (FX) as thecomponents of plasma responsible for increase of HAdV-5 infection whileFIX alone mediates increase of HAdV-31 infection. We found that as little as1% of the physiological concentration of these factors is required to facilitatemaximum binding.

    The effect of coagulation factors on HAdV infection was thereafterextended to include all species A HAdVs: HAdV-12, -18 and -31. Species AHAdVs normally cause infections involving the airways and/or the intestine.These infections are often mild but species A HAdVs in general, and HAdV-31 in particular, have been shown to cause severe and life-threateninginfections in immunocompromised patients. We show here that FIXefficiently increase HAdV-18 and -31 (but not HAdV-12) binding andinfection of human epithelial cells, representing the respiratory andgastrointestinal tropism. FIX was shown to interact with the hexon proteinof HAdV-31 and surface plasmon resonance analysis revealed that theHAdV-31:FIX interaction is slightly stronger than that of the HAdV-5:FIX/FX interactions, but more interestingly, the half-lives of theseinteractions are profoundly different. By performing binding and infectionexperiments using cells expressing specific glycosaminoglycans (GAGs) and ivGAG-cleaving enzymes we found that the HAdV-31:FIX and HAdV-5:FIX/FX complexes bind to heparan sulfate-containing GAGs on targetcells, but we could also see a difference in GAG dependence and specificitybetween these complexes.We conclude that the use of coagulation factors might be of moreimportance than previously recognized and that this may affect not only theliver tropism seen when administering adenovirus vectors into thecirculation but also regulate primary infections by wild-type viruses of theirnatural target cells. We also believe that our findings may contribute tobetter design of HAdV-based vectors for gene and cancer therapy and thatthe interaction between the HAdV-31 hexon and FIX may serve as a targetfor antiviral treatment.

    HAdV vectors are mainly based on HAdV-5 and several problems haverecently become evident when using these vectors. Major challenges withHAdV-5 based vectors include pre-existing neutralizing antibodies, pooraccess to the receptor CAR (coxsackie and adenovirus receptor), and offtarget effects to the liver due to interactions with coagulation factors. Theneed for new HAdV vectors devoid of these problems is evident.HAdV-52 is one of only three HAdVs that are equipped with two differentfiber proteins, one long and one short. We show here, by means of bindingand infection experiments, that HAdV-52 can use CAR as a cellular receptor,but that most of the binding is dependent on sialic acid-containingglycoproteins. Flow cytometry, ELISA and surface plasmon resonanceanalyses revealed that the terminal knob domain of the long fiber (52LFK)binds to CAR, and the knob domain of the short fiber (52SFK) binds tosialylated glycoproteins. X-ray crystallographic analysis of 52SFK in complexwith sialic acid revealed a new sialic acid binding site compared to otherknown adenovirus:glycan interactions. Moreover, glycan array analysisidentified α2,8-linked oligosialic acid, mimicking the naturally occurringpolysialic acid (PSia), as a potential sialic acid-containing glycan receptor for52SFK. ELISA and surface plasmon resonance confirmed the ability of52SFK to interact with PSia. Flow cytometry analysis also showed a fivefold vincrease in binding of 52SFK to PSia-expressing cells compared to controlcells. X-ray crystallographic analysis of 52SFK in complex with oligo-PSiarevealed engagement at the non-reducing end of oligo-PSia to the canonicalsialic acid-binding site, but also suggested the presence of a 'steering rim'consisting of positively charged amino acids contributing to the contact bylong-range electrostatic interactions.

    PSia is nearly absent on cells in healthy adults but can be expressed inhigh amounts on several types of cancers including: glioma, neuroblastomaand lung cancer. We show here that the short fiber of HAdV-52 bindsspecifically to PSia. Taking into account that HAdV-52 has a supposedly lowseroprevalence and is incapable of interacting with coagulation factors webelieve that HAdV-52 based vectors can be useful for treatment of cancertypes with elevated PSia expression.

  • 291.
    Lenman, Annasara
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Liaci, A. Manuel
    Liu, Yan
    Frängsmyr, Lars
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Frank, Martin
    Blaum, Bärbel S.
    Chai, Wengang
    Podgorski, Iva I.
    Harrach, Balázs
    Benko, Mária
    Feizi, Ten
    Stehle, Thilo
    Arnberg, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Polysialic acid is a cellular receptor for human adenovirus 522018In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 115, no 18, p. E4264-E4273Article in journal (Refereed)
    Abstract [en]

    Human adenovirus 52 (HAdV-52) is one of only three known HAdVs equipped with both a long and a short fiber protein. While the long fiber binds to the coxsackie and adenovirus receptor, the function of the short fiber in the virus life cycle is poorly understood. Here, we show, by glycan microarray analysis and cellular studies, that the short fiber knob (SFK) of HAdV-52 recognizes long chains of α-2,8-linked polysialic acid (polySia), a large posttranslational modification of selected carrier proteins, and that HAdV-52 can use polySia as a receptor on target cells. X-ray crystallography, NMR, molecular dynamics simulation, and structure-guided mutagenesis of the SFK reveal that the nonreducing, terminal sialic acid of polySia engages the protein with direct contacts, and that specificity for polySia is achieved through subtle, transient electrostatic interactions with additional sialic acid residues. In this study, we present a previously unrecognized role for polySia as a cellular receptor for a human viral pathogen. Our detailed analysis of the determinants of specificity for this interaction has general implications for protein-carbohydrate interactions, particularly concerning highly charged glycan structures, and provides interesting dimensions on the biology and evolution of members of Human mastadenovirus G.

  • 292.
    Lenman, Annasara
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Liaci, A. Manuel
    Liu, Yan
    Årdahl, Carin
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Rajan, Anandi
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Nilsson, Emma
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Bradford, Will
    Kaeshammer, Lisa
    Jones, Morris S.
    Frängsmyr, Lars
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Feizi, Ten
    Stehle, Thilo
    Arnberg, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Human Adenovirus 52 Uses Sialic Acid-containing Glycoproteins and the Coxsackie and Adenovirus Receptor for Binding to Target Cells2015In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 11, no 2, article id e1004657Article in journal (Refereed)
    Abstract [en]

    Most adenoviruses attach to host cells by means of the protruding fiber protein that binds to host cells via the coxsackievirus and adenovirus receptor (CAR) protein. Human adenovirus type 52 (HAdV-52) is one of only three gastroenteritis-causing HAdVs that are equipped with two different fiber proteins, one long and one short. Here we show, by means of virion-cell binding and infection experiments, that HAdV-52 can also attach to host cells via CAR, but most of the binding depends on sialylated glycoproteins. Glycan microarray, flow cytometry, surface plasmon resonance and ELISA analyses reveal that the terminal knob domain of the long fiber (52LFK) binds to CAR, and the knob domain of the short fiber (52SFK) binds to sialylated glycoproteins. X-ray crystallographic analysis of 52SFK in complex with 2-O-methylated sialic acid combined with functional studies of knob mutants revealed a new sialic acid binding site compared to other, known adenovirus: glycan interactions. Our findings shed light on adenovirus biology and may help to improve targeting of adenovirus-based vectors for gene therapy.

  • 293.
    Lenman, Annasara
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Mueller, Steffen
    Nygren, Mari I
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Frängsmyr, Lars
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Stehle, Thilo
    Arnberg, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Coagulation factor IX mediates serotype-specific binding of species A adenoviruses to host cells2011In: Journal of Virology, ISSN 0022-538X, E-ISSN 1098-5514, Vol. 85, no 24, p. 13420-13431Article in journal (Refereed)
    Abstract [en]

    Human species A adenoviruses (HAdVs) comprise three serotypes: HAdV-12, -18, and -31. These viruses are common pathogens and cause systemic infections that usually involve the airways and/or intestine. In immunocompromised individuals, species A adenoviruses in general, and HAdV-31 in particular, cause life-threatening infections. By combining binding and infection experiments, we demonstrate that coagulation factor IX (FIX) efficiently enhances binding and infection by HAdV-18 and HAdV-31, but not by HAdV-12, in epithelial cells originating from the airways or intestine. This is markedly different from the mechanism for HAdV-5 and other human adenoviruses, which utilize coagulation factor X (FX) for infection of host cells. Surface plasmon resonance experiments revealed that the affinity of the HAdV-31 hexon-FIX interaction is higher than that of the HAdV-5 hexon-FX interaction and that the half-lives of these interactions are profoundly different. Moreover, both HAdV-31-FIX and HAdV-5-FX complexes bind to heparan sulfate-containing glycosaminoglycans (GAGs) on target cells, but binding studies utilizing cells expressing specific GAGs and GAG-cleaving enzymes revealed differences in GAG dependence and specificity between these two complexes. These findings add to our understanding of the intricate infection pathways used by human adenoviruses, and they may contribute to better design of HAdV-based vectors for gene and cancer therapy. Furthermore, the interaction between the HAdV-31 hexon and FIX may also serve as a target for antiviral treatment.

  • 294.
    Lerner, Ulf H
    Umeå University, Faculty of Medicine, Department of Odontology, Molecular Periodontology. Centrum för ben- och artritforskning, Institutionen för medicin, Sahlgrenska akademin, Göteborgs universitet, Göteborg.
    Skelettet i käkar och annorstädes: 4. Skelettet som ett hormonproducerande organ med betydelse för energimetabolism och fosfatutsöndring2012In: Tandläkartidningen, ISSN 0039-6982, Vol. 104, no 8, p. 60-68Article in journal (Refereed)
    Abstract [sv]

    Ny forskning visar att skelettet inte bara regleras av hormoner utan också producerar hormoner. Dessa hormoner påverkar fettceller, insulinproducerande celler i bukspottkörteln och njurens fosfatreglering.

  • 295.
    Li, Danyang
    et al.
    College of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, PR China.
    Han, Jing
    College of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, PR China.
    Guo, Xiong
    College of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, PR China.
    Qu, Chengjuan
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Yu, Fangfang
    College of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, PR China.
    Wu, Xiaofang
    College of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, PR China.
    The effects of T-2 toxin on the prevalence and development of Kashin–Beck disease in China: a meta-analysis and systematic review2016In: Toxicology Research, ISSN 2045-4538, Vol. 5, no 3, p. 731-751Article, review/survey (Refereed)
    Abstract [en]

    To reveal the influence of T-2 toxin detection rate and detection amount in food samples on Kashin–Beck disease (KBD), and define a linking mechanism between T-2 toxin induced chondrocytes or cartilage damage and KBD pathological changes, seven electronic databases were searched to obtain epidemiological and experimental studies. For epidemiological studies, subgroup analyses of the positive detection rate (PDR) of the T-2 toxin and PDR of the T-2 toxin with concentrations (PDRC of T-2) >100 ng g−1 were carried out, together with a histogram of the T-2 toxin concentrations in different food types in KBD and non-KBD areas. For experimental studies, a systematic review of a variety of chondrocyte and cartilage changes and damage induced by the T-2 toxin was performed. As a result, in epidemiological studies, meta-analysis demonstrated that the T-2 toxin PDR and the overall PDRC of T-2 toxin >100 ng g−1 showed a slightly significant increase in KBD areas than that in non-KBD areas separately. From the histogram, T-2 toxin accumulation was more serious in endemic areas, especially in wheat flour samples. In experimental studies, the T-2 toxin could induce damage of chondrocytes and cartilage, and inhibit cell proliferation by promoting apoptosis and catabolism as well as intracellular injuries, which is similar to the characteristics of KBD. In conclusion, the amount of T-2 toxin detected has a more significant influence on KBD prevalence and development as compared to the T-2 toxin detection rate. Besides, the T-2 toxin induces chondrocyte and cartilage damage through apoptosis, catabolism promotion and intracellular impairment, which is similar to the KBD change.

  • 296. Li, Yunlong
    et al.
    Hu, Yangbo
    Francis, Matthew S.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Chen, Shiyun
    RcsB positively regulates the Yersinia Ysc-Yop type III secretion system by activating expression of the master transcriptional regulator LcrF2015In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 17, no 4, p. 1219-1233Article in journal (Refereed)
    Abstract [en]

    The Rcs phosphorelay is a complex signaling pathway used by the family Enterobacteriaceae to sense, respond and adapt to environmental changes during free-living or host-associated lifestyles. In this study, we show that the Rcs phosphorelay pathway positively regulates the virulence plasmid encoded Ysc-Yop type III secretion system (T3SS) in the enteropathogen Yesinia pseudotuberculosis. Both the overexpression of the wild-type Rcs regulator RcsB or the constitutive active RscB(D56E) variant triggered more abundant Ysc-Yop synthesis and secretion, whereas the non-phosphorylatable mutant RcsB(D56Q) negated this. Congruently, enhanced Yops expression and secretion occurred in an in cis rscB(D56E) mutant but not in an isogenic rscB(D56Q) mutant. Screening for regulatory targets of RcsB identified the virG-lcrF operon that encodes for LcrF, the Ysc-Yop T3SS master regulator. Protein-DNA binding assays confirmed that RcsB directly bound to this operon promoter, which subsequently caused stimulated lcrF transcription. Moreover, active RcsB enhanced the ability of bacteria to deliver Yop effectors into immune cells during cell contact, and this promoted an increase in bacterial viability. Taken together, our study demonstrates the role of the Rcs system in regulating the Ysc-Yop T3SS in Yersinia and reports on RcsB being the first transcriptional activator known to directly control lcrF transcription.

  • 297.
    Li, Yunlong
    et al.
    Center for Emerging Infectious Diseases, Wuhan Institute of Virology, The Chinese Academy of Sciences, Wuhan, China.
    Li, Lamei
    Center for Emerging Infectious Diseases, Wuhan Institute of Virology, The Chinese Academy of Sciences, Wuhan, China.
    Huang, Li
    Center for Emerging Infectious Diseases, Wuhan Institute of Virology, The Chinese Academy of Sciences, Wuhan, China.
    Francis, Matthew
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Hu, Yangbo
    Center for Emerging Infectious Diseases, Wuhan Institute of Virology, The Chinese Academy of Sciences, Wuhan, China.
    Chen, Shiyun
    Center for Emerging Infectious Diseases, Wuhan Institute of Virology, The Chinese Academy of Sciences, Wuhan, China.
    Yersinia Ysc-Yop type III secretion feedback inhibition is relieved through YscV-dependent recognition and secretion of LcrQ2014In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 91, no 3, p. 494-507Article in journal (Refereed)
    Abstract [en]

    Human pathogenic Yersinia species share a virulence plasmid encoding the Ysc-Yop type III secretion system (T3SS). A plasmid-encoded anti-activator, LcrQ, negatively regulates the expression of this secretion system. Under inducible conditions, LcrQ is secreted outside of bacterial cells and this activates the T3SS, but the mechanism of targeting LcrQ for type III secretion remains largely unknown. In this study, we characterized the regulatory role of the export apparatus component YscV. Depletion or overexpression of YscV compromised Yop synthesis and this primarily prevented secretion of LcrQ. It followed that a lcrQ deletion reversed the repressive effects of excessive YscV. Further characterization demonstrated that the YscV residues 493–511 located within the C-terminal soluble cytoplasmic domain directly bound with LcrQ. Critically, YscV-LcrQ complex formation was a requirement for LcrQ secretion, since YscVΔ493–511 failed to secrete LcrQ. This forced a cytoplasmic accumulation of LcrQ, which predictably caused the feedback inhibition of Yops synthesis. Based on these observations, we proposed a model for the YscV-dependent secretion of LcrQ and its role in regulating Yop synthesis in Yersinia.

  • 298. Liaci, AM
    et al.
    Chandra, Naresh
    Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Section of Virology.
    Munender, S
    Liu, Y
    Pfenning, V
    Bachmann, P
    Caraballo, R
    Chai, W
    Johansson, E
    Cupelli, K
    Hassemer, T
    Blaum, B
    Elofsson, M
    Feizi, T
    Arnberg, N
    Stehle, T
    Primary attachment receptors of human adenovirus type 36Manuscript (preprint) (Other academic)
  • 299.
    Lindberg, Stina
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Molecular analysis of transcription factors in uropathogenic E. coli adhesin operons2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main causative agent of human urinary tract infections is the uropathogenic Escherichia coli (UPEC) pathotype. It may cause disease due to its ability to express a number of bacterial virulence factors. Fimbrial adhesins are particularly important for the initial establishment of infection in the urinary tract. The fimbriae are hair-like structures protruding from the bacterial cell and by attaching to specific receptors in the urinary tract they mediate adherence to different cell types, allowing the bacteria to resist the shear forces from urine flow. The UPEC strains generally carry multiple determinants for fimbrial adhesins. Previous studies have indicated that there is a co-regulation between different fimbrial genes and one factor that has been implicated in this is the PapB protein, acting as a transcriptional regulator of P-fimbrial expression. The PapB protein can be regarded as the prototype of a family of fimbrial regulators that show high homology between different fimbrial operons. One homolog is FocB, regulator of F1C fimbriae. In this study, the role of the FocB protein in the regulation of F1C fimbriae as well as in the co-regulation with other fimbrial genes was investigated. It was observed that FocB binds to DNA, similarly to PapB, in an oligomeric fashion and that PapB and FocB can form hetero-oligomeric complexes, which appear to have a repressive role in the regulation of the F1C fimbriae. In addition, the FocB protein also had a repressive effect on transcription of the fim operon, which encodes theType 1 fimbriae. For further analysis of FocB in vitro, we developed efficient procedures for purification of the protein and established conditions for its crystal formation with the aim to conduct X-ray diffraction studies. By the hanging-drop vapour-diffusion method, we obtained crystals that in the X-ray analysis diffracted sufficiently well to allow modelling of a high resolution structure of FocB. The structural model was considered in relation to the DNA binding properties of the protein. The FocB analysis represents the first structural model of this family of transcriptional factors. This model should aid in further understanding of the roles and functions of these proteins in the regulation of the UPEC fimbrial operons. The complexity of the system, with multiple factors involved in the regulation of fimbrial operons, was revealed in earlier studies of the PapI protein showing that PapI activates transcription of the pap operon as a part of a complex with the global regulator Lrp. However, PapI itself did not appear to bind to DNA and its mode of action has remained unclear. By genetic analyses and in vitro studies we show that PapI may interact also with the α subunit of the RNA polymerase. This finding indicates that PapI might directly interact with the transcriptional apparatus and thus aid in the activation of pap expression. Bacteria are frequently releasing outer membrane vesicles (OMVs) from their surface. We studied the release of the haemolysin toxin from E. coli in connection with formation of OMVs and found that the toxin was tightly associated with the vesicles in an active form. By overproduction of the PapB or PapI regulators in order to maximise the population of bacteria expressing fimbriae, we could detect P fimbriae proteins associated with OMVs that displayed specific adhesion to receptor-coated beads. This suggests a possible scenario in which the vesicles canfunction as directed vehicles of bacterial virulence factors.

  • 300.
    Lindberg, Stina
    et al.
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Nilsson, Ulf J.
    Organic Chemistry, Lund University.
    Nyunt Wai, Sun
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Uhlin, Bernt Eric
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Detection of functional P fimbriae proteins in E. coli outer membrane vesiclesManuscript (preprint) (Other academic)
    Abstract [en]

    Background: Outer membrane vesicles (OMVs) are continuously released from the surface of Gram negative bacteria. The composition of the OMVs is similar to that of the outer membrane and may include periplasmic constituents. Studies have shown that OMVs also may have a role in the delivery of bacterial toxins to the extracellular space. Results: In this study we investigate the association of P fimbriae proteins to OMVs from both genetically manipulated E. coli laboratory strains and a uropathogenic isolate. We found that the OMVs could carry functionally active P fimbriae proteins on their surface and we observed specific attachment of OMVs to beads coated with the P fimbrial galabiose receptor. Conclusions: Our results suggest that OMVs can carry functionally active fimbrial proteins on their surface and that they may have a role in specific delivery of bacterial components to target cells.

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