Thesis (Ph. D.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 187-199).

<b>Introduction:</b> Respiratory Syncytial Virus is the major viral cause of lower respiratory tract disease in young children worldwide, with the greatest burden of disease in infants aged 1-3 months. Consequently, vaccine development has centered on a vaccine to directly protect the infants in this age group. The fundamental problem is that these young infants are poor responders to candidate RSV vaccines. This thesis focuses on the use of mathematical models to explore the merits of vaccination. <b>Methods:</b> Following development and analysis of a simple non-age-structured ODE model, we elaborate this to a Realistic Age Structured model (RAS) capturing the key epidemiological characteristics of RSV and incorporating age-specific vaccination options. The compartmental ODE model was calibrated using agespecific and time series hospitalization data from a rural coastal Kenyan population. The determination of Who Acquires Infection From Whom (WAIFW) matrix was done using social contact data from 1) a synthetic mixing matrix generated from primarily household occupancy data and 2) a diary study that we conducted in the Kilifi Health and Demographic Surveillance System (KHDSS). The vaccine was assumed to elicit partial immunity equivalent to wild type infection and its impact was measured by the ratio of hospitalized RSV cases after to before introduction. of vaccination. Uncertainty and sensitivity analysis were undertaken using Latin Hypercube Sampling (LHS) and partial rank correlation respectively. Given the importance of households in the transmission of respiratory infections, an exploratory household model was developed to capture the transmission dynamics of RSV A and B in a population of households. <b>Results:</b> From the analytical work of the simple ODE model, we have demonstrated that the model has the potential to exhibit a backward bifurcation curve within realistic parameter ranges. Both the diary and the synthetic mixing matrices had similar characteristics i.e. strong assortative mixing in individuals less than 30 years old and strong mixing between children less than 5 years and adults between 20 and 50 years old. When the two matrices were jointly linearly regressed, their elements were well correlated with an R2 ~ 0.6. The RAS model was capable of capturing the age-specific disease and the temporal epidemic nature of RSV in the specified location. Introduction of routine universal vaccination at ages varying from the first month of life to the 10th year of life resulted in optimal long-term benefit at 7 months (for the diary contact model) and 5 months (for the synthetic contact model). The greatest benefit arose under the assumption of age-related mixing with the contact diary data with no great deal of effectiveness lost when the vaccine is delayed between 5 and 12 months of age from birth. Vaccination was also shown to change the temporal dynamics of RSV hospitalizations and also to increase the average age at primary infection. From the sensitivity analysis, we identified the duration of RSV specific maternal antibodies, duration of primary and tertiary infections as the most important parameters in explaining the imprecision observed in predicting both the age specific hospitalizations and the optimal month at vaccination. Results from the household model have demonstrated that the household epidemic profile may be different from the general population with strong interaction of the viruses in the household that do not necessarily reflect at the population level. <b>Conclusion:</b> The synthetic matrix method would be a preferable alternative route in estimating mixing patterns in populations with the required socio-demographic data. Retrospectively, the synthetic mixing data can be used to reconstruct contact patterns in the past and therefore beneficial in assessing the effect of demographic transition in disease transmission. Universal infant vaccination has the potential to significantly reduce the burden of RSV associated disease, even with delayed vaccination between 5 and 12 months. This age class represents the group that is being targeted by vaccines that are currently under development. More accurate data measuring the duration of RSV specific maternal antibodies and the duration of infections are required to reduce the uncertainty in the model predictions.

In nature, proteins with weak binding affinity often use a multivalency approach to enhance protein affinity via an avidity effect. Interested in this multivalency approach, we have isolated a carbohydrate binding module (CBM) that recognises sialic acid (known as a CBM40 domain) from both Vibrio cholerae (Vc) and Streptococcus pneumoniae (Sp) NanA sialidases, and generated multivalent polypeptides from them using molecular biology. Multivalent CBM40 constructs were designed either using a tandem repeat approach to produce trimeric or tetrameric forms that we call Vc3CBM and Vc4CBM, respectively, or through the addition of a trimerization domain derived from Pseudomonas aeruginosa pseudaminidase to produce three trimeric forms of proteins known as Vc-CBMTD (WT), Vc-CBMTD (Mutant) and Sp-CBMTD). Due to the position and flexibility of the linker between the trimerization domain and the CBM40 domain, site directed mutagenesis was employed to introduce a disulphide bond between the monomers at positions S164C and T83C of the CBM40 domain in order to promote a stable orientation of the binding site for easier access of sialic acids. Data from isothermal titration calorimetry (ITC) reveals that interaction of multivalent CBM40 proteins with α(2,3)-sialyllactose was mainly enthalpy driven with entropy contributing unfavorably to the interaction suggesting that these proteins establish a strong binding affinity to their ligand minimizing dissociation to produce stable multivalent molecules. However, using surface plasmon resonance (SPR), a mixed balance of entropy and enthalpy contributions was found with all constructs as determined by Van't Hoff plots. This proved that binding does not occur through a simple protein-ligand interaction but through disruption of hydrophobic and/or ionic hydration that provide the driving force to the process. Interestingly, the valency of multiple-linked polypeptides also plays an important part in the protein stabilization. However, little is known about their detailed structure when in multivalent form, as attempts to crystallize the whole protein molecule of Vc-CBMTD (WT) failed due to linker and domain flexibility. Only the trimerization domain (TD) part from Pseudomonas aeruginosa pseudaminidase was successfully crystallized and structure was determined to 3.0 Å without its CBM40 domain attached. In this thesis, we have also reported on the potential anti-influenza and anti- parainfluenza properties of these proteins, which were found to block attachment and inhibit infection of several influenza A and parainfluenza virus strains in vitro. As widely mentioned in literature, terminal sialic acids on the cell surface of mammalian host tissue provide a target for various pathogenic organisms to bind. Levels of viral inhibition were greatest against A/Udorn/72 H3N2 virus for Vc4CBM and Vc3CBM constructs with the lowest EC50 of 0.59 µM and 0.94 µM respectively, however most of the multivalent proteins tested were also effective against A/WSN/33 H1N1 and A/PR8/34 H1N1 subtypes. For parainfluenza virus, all constructs containing V. cholerae sialidase CBM40 domain showed great effect in inhibiting virus infection during cell protection assay. The best EC50 values were 0.2 µM from Vc-CBMTD (WT) followed by 1.17 µM from Vc4CBM and 1.78 µM from Vc-CBMTD (Mutant) which was against hPIV2, hPIV3 and hPIV5 infections respectively. Only a construct from S. pneumoniae sialidase known as Sp-CBMTD showed negligible effect on cell protection. All constructs were further tested for cytotoxicity in mammalian cell culture as well as undergoing an inhibition study on viral replication proteins. For the in vivo study, we also demonstrated the effectiveness of Vc4CBM to protect cotton rats and mice from hPIV3 and Streptococcus pneumoniae infections, when given intranasally in advance or on the day of infection. Therefore, these novel multivalent proteins could be promising candidates as broad-spectrum inhibitors or as a prophylactic treatment for both influenza and parainfluenza associated diseases.

published_or_final_version / abstract / Microbiology / Master / Master of Philosophy

jdelvall@upc.edu.pe / Acute respiratory infections are responsible for high morbi–mortality in Peruvian children. However, the etiological agents are poorly identified. This study, conducted during the pandemic outbreak of H1N1 influenza in 2009, aims to determine the main etiological agents responsible for acute respiratory infections in children from Lima, Peru. Nasopharyngeal swabs collected from 717 children with acute respiratory infections between January 2009 and December 2010 were analyzed by multiplex RT-PCR for 13 respiratory viruses: influenza A, B, and C virus; parainfluenza virus (PIV) 1, 2, 3, and 4; and human respiratory syncytial virus (RSV) A and B, among others. Samples were also tested with direct fluorescent-antibodies (DFA) for six respiratory viruses. RT-PCR and DFA detected respiratory viruses in 240 (33.5%) and 85 (11.9%) cases, respectively. The most common etiological agents were RSV-A (15.3%), followed by influenza A (4.6%), PIV-1 (3.6%), and PIV-2 (1.8%). The viruses identified by DFA corresponded to RSV (5.9%) and influenza A (1.8%). Therefore, respiratory syncytial viruses (RSV) were found to be the most common etiology of acute respiratory infections. The authors suggest that active surveillance be conducted to identify the causative agents and improve clinical management, especially in the context of possible circulation of pandemic viruses

Sia Sin Fun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 105-121). / Abstracts in English and Chinese. / STATEMENT --- p.i / ACKNOWLEDGEMENTS --- p.ii / ABSTRACT --- p.iii / ABSTRACT (CHINESE VERSION) --- p.v / TABLE OF CONTENTS --- p.vi / ABBREVIATIONS --- p.xi / LIST OF FIGURES --- p.xv / LIST OF TABLES --- p.xvi / Chapter CHAPTER ONE: --- INTRODUCTION / Chapter 1.1 --- The interferon / Chapter 1.1.1 --- Classification of interferons --- p.1 / Chapter 1.1.1.1 --- Type IIFN --- p.2 / Chapter 1.1.1.2 --- Type II IFN --- p.3 / Chapter 1.1.2 --- Biosynthesis of IFN --- p.3 / Chapter 1.1.3 --- IFN-α/β receptor and signal transduction --- p.8 / Chapter 1.1.4 --- Functions induced by IFN / Chapter 1.1.4.1 --- Antiviral activity of IFN-α/β --- p.11 / Chapter 1.1.4.1.1 --- PKR (double-stranded RNA-dependent protein kinase) --- p.11 / Chapter 1.1.4.1.2 --- The 2-5A synthetase/RNase L system (The 2-5A system) --- p.16 / Chapter 1.1.4.1.3 --- Mx proteins --- p.17 / Chapter 1.1.4.2 --- Immunomodulatory function of IFN-α/β --- p.18 / Chapter 1.1.4.3 --- Inhibition of cell growth --- p.18 / Chapter 1.1.4.4 --- Control of apoptosis --- p.19 / Chapter 1.1.5 --- The significance of IFN system --- p.20 / Chapter 1.1.6 --- Subtype of murine IFN-α --- p.21 / Chapter 1.1.7 --- Production of IFN in response to infection --- p.23 / Chapter 1.1.8 --- Existing methods to determine the IFN-α subtypes productionin response to stimulus --- p.24 / Chapter 1.2 --- Influenza virus --- p.27 / Chapter 1.2.1 --- Classification --- p.27 / Chapter 1.2.2 --- The structure of influenza virus --- p.29 / Chapter 1.2.3 --- The viral genome and proteins --- p.29 / Chapter 1.2.4 --- Replicative cycle of influenza virus / Chapter 1.2.4.1 --- "Virus adsorption, entry and uncoating" --- p.31 / Chapter 1.2.4.2 --- Transcription and replication of vRNA --- p.31 / Chapter 1.2.4.3 --- Synthesis of viral proteins --- p.32 / Chapter 1.2.4.4 --- Packaging and budding of progeny virus --- p.33 / Chapter 1.2.5 --- Viral inhibition of the IFN response --- p.33 / Chapter 1.3 --- Aim of study --- p.35 / Chapter CHAPTER TWO: --- MATERIALS AND METHODS / Chapter 2.1 --- Overall procedures --- p.37 / Chapter 2.2 --- Materials / Chapter 2.2.1 --- "Cell line, bacterial strain and vector" --- p.40 / Chapter 2.2.2 --- Chemicals --- p.40 / Chapter 2.2.3 --- "Culture media, buffer and other solutions" --- p.41 / Chapter 2.2.4 --- Reagents and nucleic acids --- p.41 / Chapter 2.2.5 --- Reaction kits --- p.42 / Chapter 2.2.6 --- Solutions --- p.42 / Chapter 2.2.7 --- Solutions of reaction kits --- p.43 / Chapter 2.2.8 --- Major equipments --- p.44 / Chapter 2.2.9 --- Primers --- p.44 / Chapter 2.2.10 --- Cell lysate --- p.45 / Chapter 2.3 --- Methods / Chapter 2.3.1 --- Design of IFN-α whole coding region and subtype specific primers using OLIGO´ёØ ver 50 --- p.46 / Chapter 2.3.2 --- Construction of plasmid DNA with the whole coding region of IFN-α gene / Chapter 2.3.2.1 --- Isolation of genomic DNA from L929 cells --- p.46 / Chapter 2.3.2.2 --- Amplification of whole coding region of IFN-α subtypes --- p.47 / Chapter 2.3.2.3 --- Preparation of plasmid DNA --- p.48 / Chapter 2.3.2.4 --- Restriction digestion of the vector pBluescript SKII (-) with SmaI --- p.48 / Chapter 2.3.2.5 --- Purification of DNA fragments from agarose gel --- p.49 / Chapter 2.3.2.6 --- Blunt end ligation --- p.49 / Chapter 2.3.2.7 --- Transformation --- p.49 / Chapter 2.3.2.8 --- Screening by polymerase chain reaction --- p.50 / Chapter 2.3.2.9 --- DNA sequencing --- p.50 / Chapter 2.3.3 --- Test on IFN-α subtype specific primers / Chapter 2.3.3.1 --- Determination of the specificity of IFN-α subtype specific primers by PCR --- p.51 / Chapter 2.3.3.2 --- Determination of the amplification of a particular subtype in the presence of excess of other templates --- p.51 / Chapter 2.3.4 --- Induction of expression of IFN in fibroblast L929 cells / Chapter 2.3.4.1 --- By chemical agents Poly(I) Poly(C) and DEAE --- p.52 / Chapter 2.3.4.2 --- By infection with influenza virus (A/NWS/33 and B/Lee/40) --- p.52 / Chapter 2.3.5 --- Detection of IFN-α subtypes expression / Chapter 2.3.5.1 --- Isolation of total RNA by guandidium thiocyanate - cesium chloride ultracentrifugation --- p.53 / Chapter 2.3.5.2 --- Synthesis of first strand cDNA --- p.54 / Chapter 2.3.5.3 --- Normalization of RNA samples --- p.54 / Chapter 2.3.5.4 --- RT-PCR amplification of the IFN-α subtypes --- p.54 / Chapter 2.3.5.5 --- "RT-PCR amplification of IFN-γ, IFN-α receptor 1，IFN-α receptor 2 (transmembrane and soluble form) and IFN-(3" --- p.55 / Chapter CHAPTER THREE: --- RESULTS / Chapter 3.1 --- Designing of primers for IFN-α genes --- p.56 / Chapter 3.1.1 --- Design of IFN-α primers for amplification of whole coding region --- p.56 / Chapter 3.1.2 --- Design of IFN-α subtype specific primers --- p.58 / Chapter 3.2 --- Cloning of the IFN-α subtype genes / Chapter 3.2.1 --- Purification of genomic DNA --- p.59 / Chapter 3.2.2 --- PCR conditions used for amplification of whole coding region of mIFN-α subtypes --- p.61 / Chapter 3.2.3 --- Subcloning the whole coding region of IFN-α genes from amplified fragments --- p.63 / Chapter 3.3 --- Optimization of specific amplification condition for subtype specific primers by cross-PCR --- p.64 / Chapter 3.4 --- Determination of the amplification of a particular subtype in the excess of other templates --- p.67 / Chapter 3.5 --- Determination of the gene expression in poly (I) poly (C) treated L929 cells / Chapter 3.5.1 --- Spectrophotometric analysis of total RNA --- p.70 / Chapter 3.5.2 --- Agarose gel electrophoresis of RNA --- p.72 / Chapter 3.5.3 --- Normalization of RNA sample --- p.73 / Chapter 3.5.4 --- Detection of IFN-α subtypes mRNA in L929 cell induced with poly(I) poly(C)-DEAE dextran --- p.74 / Chapter 3.5.5 --- "Detection of IFN-γ, IFN-α/β receptor and IFN-β expressionin Poly(I) Poly(C)-DEAE dextran or DEAE dextran treated L929 cells" --- p.70 / Chapter 3.6 --- Measurement of gene expression in L929 cells infected with influenza virus / Chapter 3.6.1 --- Spectrophotometric analysis of total RNA --- p.83 / Chapter 3.6.2 --- Agarose gel electrophoresis of RNA samples --- p.84 / Chapter 3.6.3 --- Normalization of RNA samples --- p.86 / Chapter 3.6.4 --- Detection of IFN-α subtypes mRNA in L929 cell infected with influenza A/NWS/33 virus --- p.87 / Chapter 3.6.5 --- Detection of IFN-α subtypes mRNA in L929 cells infected with influenza B/Lee/40 virus --- p.90 / Chapter 3.6.6 --- "Detection of IFN-γ, IFN-α/β receptor and IFN-β expression in L929 cells infected with A/NWS/33 and B/Lee/40" --- p.93 / Chapter CHAPTER FOUR: --- DISCUSSION --- p.97 / REFERENCES --- p.105 / APPENDIX --- p.122

Lam, Ka Han. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 77-82). / Abstracts in English and Chinese. / Acknowledgement --- p.ii / Abstract --- p.iii / 摘要 --- p.v / Content --- p.vii / List of Abbreviations and Symbols --- p.xi / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Severity of influenza --- p.1 / Chapter 1.2 --- Introduction of influenza viruses --- p.3 / Chapter 1.2.1 --- Virion and genome structure --- p.4 / Chapter 1.2.2 --- The replication cycle of influenza viruses --- p.5 / Chapter 1.3 --- Influenza virus NP --- p.8 / Chapter 1.3.1 --- The importance of NP in RNP structure maintenance --- p.9 / Chapter 1.3.2 --- NP self oligomerization --- p.10 / Chapter 1.3.3 --- NP-RNA interaction --- p.12 / Chapter 1.3.4 --- NP and other interacting partners --- p.13 / Chapter 1.4 --- Aim of the project --- p.16 / Chapter Chapter 2 --- Materials and Methods / Chapter 2.1 --- Biological materials --- p.18 / Chapter 2.2 --- Construction of NP mutants --- p.19 / Chapter 2.3 --- Luciferase assay --- p.22 / Chapter 2.4 --- Western blot --- p.23 / Chapter 2.5 --- Protein expression and purification --- p.23 / Chapter 2.6 --- Circular dichroism spectroscopy --- p.24 / Chapter 2.7 --- Static Light scattering --- p.24 / Chapter 2.8 --- Surface plasmon resonance --- p.25 / Chapter 2.9 --- Co-immunoprecipitation (co-IP) --- p.26 / Chapter Chapter 3 --- Identification of residues crucial for NPB oligomerization and ribonucleoprotein activity / Chapter 3.1 --- Introduction --- p.27 / Chapter 3.2 --- Result --- p.31 / Chapter 3.2.1 --- NPB mutants showed deficiency in overall transcription and replication activity --- p.31 / Chapter 3.2.2 --- Expression and purification of NP mutants with low RNP activity --- p.37 / Chapter 3.2.2.1 --- Expression of MBP-tagged NP variants --- p.37 / Chapter 3.2.2.2 --- Purification of MBP-tagged NP variants --- p.38 / Chapter 3.2.3 --- Secondary structures of NP variants were comparable t o wild type NP --- p.41 / Chapter 3.2.4 --- NP variants with low RNP activity were abnormal in oligomerization in vitro --- p.42 / Chapter 3.2.5 --- NP variants with low RNP activity were impaired in homo-oligomer formation in vivo --- p.45 / Chapter 3.2.6 --- Discussion --- p.47 / Chapter Chapter 4 --- Identification of residues crucial for NP 一 RNA interaction and ribonucleoprotein activity / Chapter 4.1 --- Introduction --- p.56 / Chapter 4.2 --- Result --- p.58 / Chapter 4.2.1 --- NPB mutants showed deficiency in overall transcription and replication activity --- p.58 / Chapter 4.2.2 --- Expression and purification of NP variants with low RNP activity --- p.62 / Chapter 4.2.3 --- Secondary structures of NP variants were comparable t o wild type NP --- p.63 / Chapter 4.2.4 --- NP variants with low RNP activity were abnormal in RNA binding --- p.64 / Chapter 4.3 --- Discussion --- p.68 / Chapter Chapter 5 --- Conclusion and future prospect --- p.73 / Copyright --- p.76 / References --- p.77

Chan, Wing Tung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 129-152). / Abstracts in English and Chinese. / Acknowledgements --- p.2 / Abstract --- p.3 / 摘要 --- p.5 / Table of Contents --- p.7 / List of Abbreviations and symbols --- p.13 / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Epidemics and pandemics of influenza virus --- p.17 / Chapter 1.2 --- Biology of influenza virus --- p.19 / Chapter 1.2.1 --- Types of influenza virus --- p.19 / Chapter 1.2.2 --- Viral structure and viral proteins --- p.20 / Chapter 1.2.3 --- Life cycle of influenza virus --- p.21 / Chapter 1.2.4 --- An ever-changing virus --- p.22 / Chapter 1.3 --- Pathogenesis and immunology of influenza virus --- p.24 / Chapter 1.3.1 --- Diseases and symptoms caused by influenza virus infection --- p.24 / Chapter 1.3.2 --- Production of cytokines during influenza virus infection --- p.25 / Chapter 1.3.3 --- Immune responses in the hosts --- p.27 / Chapter 1.4 --- Non-structural protein 1 (NS1) --- p.28 / Chapter 1.4.1 --- Overview of NS1 --- p.28 / Chapter 1.4.2 --- Roles of NS1 in influenza virus infection --- p.29 / Chapter 1.5 --- Aims of study --- p.33 / Chapter Chapter 2 --- Materials and Methods / Chapter 2.1 --- Materials --- p.34 / Chapter 2.1.1 --- Chemical reagents --- p.34 / Chapter 2.1.2 --- Buffers --- p.37 / Chapter 2.1.2.1 --- Preparation of buffers --- p.37 / Chapter 2.1.2.2 --- Commonly used buffers --- p.37 / Chapter 2.1.3 --- Strains and plasmids --- p.40 / Chapter 2.1.4 --- Primer list --- p.40 / Chapter 2.2 --- Methods --- p.42 / Chapter 2.2.1 --- Preparation of competent cells --- p.42 / Chapter 2.2.2 --- Molecular cloning --- p.43 / Chapter 2.2.2.1 --- Amplification of the target genes by PCR --- p.43 / Chapter 2.2.2.2 --- Agarose gel electrophoresis --- p.43 / Chapter 2.2.2.3 --- Extraction and purification of DNA from agarose gels --- p.44 / Chapter 2.2.2.4 --- Restriction digestion of DNA --- p.45 / Chapter 2.2.2.5 --- Ligation of digested insert and expression vector --- p.45 / Chapter 2.2.2.6 --- Transformation and plating out transformants --- p.46 / Chapter 2.2.2.7 --- Verification of insert by PCR --- p.46 / Chapter 2.2.2.8 --- Mini-preparation of plasmid DNA --- p.47 / Chapter 2.2.2.9 --- Confirmation of insertion in the miniprep DNA by restriction digestion --- p.48 / Chapter 2.2.2.10 --- Sequencing of the plasmid DNA --- p.48 / Chapter 2.2.3 --- Cell culture --- p.53 / Chapter 2.2.3.1 --- Cultivation of human lung epithelial NCI-H292 cells --- p.53 / Chapter 2.2.3.2 --- Transfection of cell culture --- p.53 / Chapter 2.2.4 --- Western blot analysis --- p.54 / Chapter 2.2.4.1 --- Protein extraction --- p.54 / Chapter 2.2.4.2 --- Determination of protein concentration --- p.54 / Chapter 2.2.4.3 --- Protein Blotting --- p.55 / Chapter 2.2.4.4 --- Membrane blocking and antibody incubations --- p.56 / Chapter 2.2.4.5 --- Detection of proteins --- p.57 / Chapter 2.2.5 --- Total RNA extraction --- p.58 / Chapter 2.2.5.1 --- Preparation of cell culture for total RNA extraction --- p.58 / Chapter 2.2.5.2 --- Spectrophotometric analysis of total RNA --- p.58 / Chapter 2.2.5.3 --- Agarose gel electrophoresis of total RNA --- p.59 / Chapter 2.2.6 --- DNA Microarray --- p.60 / Chapter 2.2.6.1 --- Preparation of biotin-labeled antisense cRNA --- p.60 / Chapter 2.2.6.2 --- "Hybridization, washing and scanning of DNA microarray chips" --- p.60 / Chapter 2.2.6.3 --- Data processing and analysis --- p.61 / Chapter 2.2.7 --- Quantitative real-time PCR (QRT-PCR) --- p.62 / Chapter 2.2.7.1 --- Preparation of cDNA --- p.62 / Chapter 2.2.7.2 --- Analysis of mRNA gene expression by QRT-PCR --- p.62 / Chapter Chapter 3 --- Roles of NS1A and NS1B on cellular gene expression / Chapter 3.1 --- Introduction --- p.63 / Chapter 3.2 --- Results --- p.67 / Chapter 3.2.1 --- NS1 protein expression in transfected NCI-H292 cells --- p.67 / Chapter 3.2.2 --- Purity and integrity of total RNA extracted --- p.67 / Chapter 3.2.3 --- Microarray data processing and analysis --- p.70 / Chapter 3.2.3.1 --- Genes perturbed by NS1A --- p.88 / Chapter 3.2.3.1.1 --- Effect of NS1A on antiviral gene expression --- p.91 / Chapter 3.2.3.1.2 --- Regulation of JAK-STAT pathway by NS1A --- p.92 / Chapter 3.2.3.2 --- Genes perturbed by NS1B --- p.93 / Chapter 3.2.3.2.1 --- Effects of NS1B on IFN-stimulated gene expression --- p.96 / Chapter 3.2.3.3 --- Genes perturbed by both NS1A and NS1B --- p.96 / Chapter 3.2.4 --- Verification of differentially expressed genes --- p.98 / Chapter 3.3 --- Discussion --- p.100 / Chapter 3.3.1 --- Human lung epithelial cell line as a model --- p.100 / Chapter 3.3.2 --- DNA microarray technology --- p.101 / Chapter 3.3.3 --- Different actions of NS1A and NS1B on host cell gene expression --- p.102 / Chapter 3.3.4 --- Novel roles of NSIA --- p.103 / Chapter 3.3.5 --- Novel role of NSIB --- p.107 / Chapter 3.3.6 --- Implications --- p.108 / Chapter Chapter 4 --- "Roles of NSIA, NS1B and NS1C on cytokine expression" / Chapter 4.1 --- Introduction --- p.109 / Chapter 4.2 --- Results --- p.113 / Chapter 4.2.1 --- NS1 protein expression in transfected NCI-H292 cells --- p.113 / Chapter 4.2.2 --- Purity and integrity of total RNA extracted --- p.113 / Chapter 4.2.3 --- QRT-PCR --- p.116 / Chapter 4.3 --- Discussion --- p.119 / Chapter 4.3.1 --- Human lung epithelial cell line as a model for cytokine study --- p.119 / Chapter 4.3.2 --- Implications of different cytokine patterns induced by different NS1 proteins --- p.120 / Chapter Chapter 5 --- General Discussion and Future Perspectives --- p.125 / References --- p.129

Abstract not available

Los virus de influenza aviar de alta patogenicidad (IAAP) causan una enfermedad muy severa en pollos, los cuales frecuentemente inducen lesiones en el sistema nervioso central (SNC). Esta tesis recoge los resultados de tres estudios que se llevaron a cabo para determinar el mecanismo de patogénesis y neurotropismo, así como establecer la ruta de entrada al SNC para un virus H7N1 IAAP. En el primer estudio se estableció un modelo animal de infección en pollos libres de patógenos específicos, que consistía en la inoculación intranasal con el virus H7N1 IAAP. Para establecer este modelo, se utilizaron tres diferentes dosis del virus, obteniendo que las dosis más altas producen una enfermedad similar a la reportada para otros virus de IAAP. Además, se observó que las dosis más bajas causan infección demostrada porque con las dosis más bajas, el virus es hallado en muestras de tejido, muestras de heces y secreciones respiratorias. Adicionalmente, se pudo comprobar el alto neurotropismo del virus, ya que aún en pollos inoculados con bajas dosis el RNA viral es hallado en el CNS. La viremia fue detectada a un día post infección (dpi), sugiriendo que está podría ser la vía de diseminación al SNC. En el segundo estudio, se determinó la distribución topográfica del antígeno viral en el SNC durante las primeras horas post infección, lo cual permitió determinar que el virus se disemina de forma simétrica y bilateral en núcleos neurales del diencéfalo, mesencéfalo y rombencéfalo. La distribución del antígeno viral indica que el bulbo olfatorio y los nervios periféricos están involucrados en el proceso de invasión del SNC. El hallazgo de receptores aviares y humanos en las células endoteliales explica porque estas células son tan sensibles a la infección. El RNA viral fue hallado en el líquido cerebro espinal el primer dpi, lo que indica que el virus atraviesa la barrera hemato-encefálica (BHE). En el tercer estudio, la alteración de la BHE inducido por el virus H7N1 IAAP fue demostrado usando tres diferentes métodos que incluye la perfusión intracardial de Azul de Evans, la detección de la extravasación de la proteína del suero IgY, y evaluación del patrón de tinción con el marcador de las uniones fuertes de la BHE, ZO-1 y claudin-1. El antígeno viral fue observado a las 24 hpi en las células endoteliales, mientras que el daño de la BHE fue observado a las 36 hpi y 48 hpi. En resumen, se puede afirmar que el virus H7N1 IAAP se disemina por la vía hematógena durante las primeras horas pi, posiblemente favorecido por la presencia de receptores en las células endoteliales del sistema nervioso central, y poco después daña la BHE durante las primeras horas de infección como se demuestra por la presencia de extravasación del azul de Evans and IgY del suero. / Highly pathogenic avian influenza viruses (HPAIV) cause a very severe systemic disease in chickens, in which is also frequent to find central nervous system (CNS) lesions. In this thesis, three studies were undertaken in order to determine the mechanism of pathogenesis, the neurotropism and establish the route of entry into the CNS use for a H7N1 HPAI virus. In the first study, an animal model was set up that consisted of SPF chickens inoculated intranasally with the H7N1 HPAI virus. To do that, three different doses were used, obtaining that the highest dose induced a disease similar to the produce by other HPAI viruses, moreover, it was also observed that very low doses also cause infection demonstrated because viral RNA was found in tissues samples, faeces and respiratory secretions. Besides, the high neurotropism of this virus was demonstrated because still in chickens inoculated with low doses, viral RNA is found in the brain. Viremia was detected at one dpi, which indicated that the bloodstream is the pathway of viral spreading to the brain. In the second study, the topographical distribution study of the viral antigen during the first dpi was determined, which allow to determine that the virus disseminates showing a symmetrical and bilateral pattern in the diencephalon, mesencephalon and rhombencephalon, whereas in the telencephalon and cerebellum it was multifocal and random. Viral antigen distribution indicates that the olfactory bulb (OB) and peripheral nerves are not involved in the process of virus invasion into the brain. Avian and human influenza receptors were found in endothelial cells which explain why these cells are so sensitive to the infection. Viral RNA was found in cerebrospinal fluid (CSF) at one dpi, indicating that the virus was able to cross blood brain barrier (BBB). In the third study, the disruption of the BBB induce by the H7N1 HPAI was demonstrated using three different methods that include the intracardial perfusion of the tracer Evans blue (EB), detection of the extravasation serum IgY, and evaluation of the pattern of staining of the tight junction proteins ZO-1 and claudin-1. Viral antigen can be observed as early as 24 hpi in the endothelial cells, whereas disruption was detected at 36 and 48 hpi. In summary, it can be asserted that this H7N1 HPAIV disseminates via the haematogenous route early during the infection, favored by the presence of abundant receptors on the CNS endothelial cells, and soon after it disrupts the BBB during the first hours of infection as demonstrated by the presence of EB and serum IgY extravasation.