Spring Conference 2011 - Society for General Microbiology

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Please note: Abstracts are published as received from the authors and are not subject to editing. 43 Spring Meeting 11–14 April 2011 Harrogate – www.sgmharrogate2011.org.uk SESSION AbSTrACTS ↑Contents HA08 Cont. pathway. in addition, we studied the iFN stimulatory ability of viral rNA (vrNA), which carries a viral protein (VPg) covalently linked to its 5’ end, versus VPg-lacking rNA transcribed in vitro (ivt rNA). interestingly, while vrNA could induce MDA5-mediated iFN-α/β response, ivt rNA failed to do so. This indicates an additional role of VPg in activating MDA5, possibly as a signal for ‘non-self’ rNA. TLr structural biology and the discrimination of Gram+ and Gram– bacteria Nick Gay Dept of Biochemistry, University of Cambridge Elucidation of the component parts and mechanism whereby Toll-like receptors (Tlrs) signal has involved over 10 years of research by many investigators. This has led to a reasonably detailed description of the main signaling pathways activated by Tlrs. Studying this system continues to provide insight into the initiation and control of the innate immune response, and the role dysregulation of these proteins and processes plays in infectious and inflammatory diseases. An important theme to emerge from molecular studies in the last two years is that Toll pathways are dependent on initial stimulus induced dimerization of the receptors by microbial pathogen associated molecules such as lipids and non-self nucleic acids. in particular the mechanisms by which Gram –ve lPS and Gram +ve di- and tri-acylated lipoproteins activate the the Tlr4 and Tlr2/(1,6) pathway have been elucidated. initial activation leads to the formation of a highly oligomeric, membrane associated complexes in the cytosol that act as a scaffold for numerous signaling and regulatory molecules that act in these pathways. Most remarkable has been analysis of the Myddosome, a complex formed by the death domains of the MyD88 and irAK signaling adaptors. C-type lectin signaling in infection and immunity Teunis B.H. Geijtenbeek Host Defense group, Center for Experimental & Molecular Medicine, Academic Medical Center, Amsterdam, The Netherlands (Email: T.B.Geijtenbeek@amc.uva.nl) Adaptive immune responses by dendritic cells (DCs) are controlled by pathogen recognition and. C-type lectins are crucial in tailoring immune responses to pathogens. upon pathogen binding, C-type lectins trigger distinct innate signaling pathways that induce specific cytokines to dictate T cell polarization. recent data demonstrate that C-type lectin signaling seems to control NF-κB activation, either by enhancing or inactivating transcriptional activity of specific NF-κB subunits. Dissecting the signaling pathways induced by C-type lectins and their effects on host immunity is essential to understand the molecular mechanisms leading to adaptive immune responses. Here i will discuss the molecular signaling pathways induced by the C-type lectin dectin-1 that control T cell polarization and il-1β processing to induce pathogen-tailored immunity. T helper type 17 (Th-17) responses are required to combat fungal infections and the cytokines il-1β, il-6 and il-23 secreted by human DCs induce Th-17 polarization. Fungi binding to Dectin-1 induce raf-1 that integrates with the Syk signaling at the level of NF-κB activation, which leads to specific cytokine responses. i will discuss the consequences of the Syk/ raf-1 signaling pathways and demonstrate that both are essential to induce T 1- and T -17-polarizing cytokines. Furthermore, i will discuss H H the importance of dectin-1 signaling in the processing of il-1β, which is crucial to Th-17 responses as well as innate immune responses. Induction and inhibition of type I IFN responses by rNA viruses Adolfo García-Sastre1,2,3 1 2 3 Dept of Microbiology, Dept of Medicine, Division of Infectious Diseases, Global Health & Emerging Pathogens Institute, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, New York 10029, USA The cytoplasmic antiviral sensor riG-i plays a key role in rNA virus recognition and initiation of the innate immune response. Activation of riG-i by immunostimulatory rNA leads to its association with mitochondrially localized adaptor MAVS and downstream signaling resulting in production of type i iFN and other proinflamatory cytokines. immunoprecipitation of riG-i/rNA complexes from virus infected cells allowed us to analyze rNA molecules which specifically interact with riG-i during the course of viral infection. unbiased deep sequencing analysis along with biochemical characterization of isolated rNA revealed specific viral sequences associated with riG-i in Sendai and influenza virus infected cells. However, in influenza virus infected cells, induction of iFN is prevented due to expression of the viral NS1 protein. This multi-functional protein interacts with and inhibits different components of the cell machinery, including TriM25 and CPSF30, preventing an optimal expression of iFN in virus-infected cells. Other rNA viruses, like flaviviruses, are potent inhibitors of iFN signaling. in the case of dengue virus, this is in part mediated by the viral protein NS5, that binds to STAT2 and targets it to degradation. The interplay between induction and evasion of iFN by rNA viruses plays a major role in viral pathogenesis. s o c i e t y f o r g e n e r a l Microbiology
Please note: Abstracts are published as received from the authors and are not subject to editing. 44 Spring Meeting 11–14 April 2011 Harrogate – www.sgmharrogate2011.org.uk SESSION AbSTrACTS ↑Contents HA08 Cont. & HA09 recognition of paramyxoviruses by pattern recognition receptors Steve Goodbourn Biomedical Sciences Research Centre, St George’s, University of London, London SW17 0RE Paramyxoviruses are conventionally considered good inducers of type i interferons (iFN-α/β). recent studies have focused on the importance of the cytoplasmic pattern recognition receptor riG-i as a sensor of infection, apparently by recognition of uncapped 5´-triphosphorylated virus-specific rNA molecules. Whilst riG-i is undoubtedly important in inducing iFN production, mda-5 also senses paramyxovirus infection and is correspondingly activated. The nature of the virus PAMPs that activate riG-i and mda-5 remain unclear, but our data demonstrate that virus molecules generated by aberrant transcription and/or replication events leading to the production of defective interfering viruses are the most effective inducers. Viruses in general mount a major challenge to the iFN system, and paramyxoviruses are no exception. indeed, most paramyxoviruses encode mechanisms to inhibit both the production of, and response to, type i iFN. The V proteins of many paramyxoviruses limit the production of iFN-β by direct interaction with mda-5, and the mechanism of this inhibition will be discussed. Since paramyxoviruses also activate riG-i it is probably necessary for these viruses to inhibit riG-i or the downstream consequences of riG-i activation. Our studies indicate that paramyxoviruses utilise a diverse range of strategies to limit the extent of riG-i activation. HA09 Food biosecurity ↑Contents british meat teetering on a knife edge – what’s the value of traditional meat inspection? ANNETTE NiGSCH1 , Bojan Blagojevic1,2 , Nikolaos Dadios1 , Silvia Alonso1 1 2 Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield Hertfordshire AL9 7TA; Dept of Veterinary Medicine, Faculty of Agriculture, University of Novi Sad, Serbia background: Meat inspection (Mi), comprising ante- and post-mortem inspection, represents a fundamental control point for the various hazards associated with the meat production chain. Whereas at the time when Mi was established (19th c.) animal diseases presented with macroscopic lesions in specific organs of the animal and were easily identifiable during carcase inspection, today new threats have become more prevalent. While some of these hazards may cause clinical disease on the animal host, many exist sub-clinically. A debate has started at Eu level: policy makers and stakeholders suggest the traditional Mi system at the slaughterhouse is not fit anymore to protect the public against these diseases and a radical overhaul and a new way of thinking is necessary. Project description: To evaluate the risk of missing hazards for public health, animal health and animal welfare associated with current Mi practices a qualitative risk assessment was undertaken. in a second step changes in risk resulting from variation in post-mortem activities were assessed driven by following questions: a.) how does the risk change if specific carcase parts / organs are no longer inspected; b.) which alternative steps are suitable to achieve equal levels of protection if the traditional Mi is altered. Epidemiology of CTX-M ESbL Escherichia coli on cattle farms N.G. COlDHAM1 , M. Stokes1 , H. Wearing1 , l.C. Snow1 , M. Wootton2 , r.A. Howe2 , C.J. Teale1 1 2 Veterinary Laboratories Agency (Weybridge), New Haw, Addlestone, Surrey KT15 3NB; Specialist Antimicrobial Chemotherapy Unit, Public Health Wales, Microbiology Cardiff, University Hospital Wales, Health Park, Cardiff CF14 4XW Extended spectrum beta lactamase (ESBl) enzymes are capable of inactivating 3rd and 4th generation cephalosporin antibiotics which are commonly used in hospitals as front line treatments. A year long passive surveillance study of CTx-M E. coli in a particular study area of Wales detected CTx-M sequence types 14 (group 9, n=3) and 15 (group 1, n=7) in faeces from cattle and sheep. Geographical analysis revealed that the CTx-M gene from veterinary sources was widespread. Next, network analysis was used to investigate the dissemination of CTx-M-14 E. coli from a study farm from which the dairy animals had been sold. The prevalence of CTx-M E. coli in the population of farms linked by animal movements to this farm was 59% (not significant) compared with 37% in the controls. However, farms which had used 3rd /4th generation cephalosporin antibiotics were 4 times more likely to have CTx-M E. coli. The veterinary isolates from these studies were compared to human CTx-M-14 ESBl isolates (n=19) from Wales using a multiplex PCr. This revealed that some CTx-M-14 isolates from human (n=3 of 19) and veterinary (n=6 of 14) sources shared a plasmid with similar backbone genes. s o c i e t y f o r g e n e r a l Microbiology
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