No description available.

A HEp-2 cell culture model was used to investigate the invasive properties of Campylobacter species. Two of twenty-five Campylobacter isolates did not invade HEp-2 cells, and one of these isolates did not adhere to the epithelial cells. Penetration of HEp-2 epithelial cells by C. jejuni was significantly (P < 0.05) inhibited with C. jejuni lysates and a MAb (1B4) in competitive inhibition studies. Immunogold electron microscopic studies revealed that the 1B4 MAb bound to the flagella and cell surface of low passage (invasive) C. jejuni M 96, whereas only the flagella of high passage (non-invasive) C. jejuni were labelled. Western blot analysis revealed that the 1B4 MAb identified an epitope on antigens ranging in size from 66 to 44 kDa in invasive and non-invasive organisms. Antigens were also recognized in lysates prepared only from invasive strains from 42 to 38 kDa. Sodium meta-periodate chemical treatment of C. jejuni lysates significantly (P < 0.05) affected its inhibitory capacity. Additionally, proteinase K and sodium meta-periodate treatment of lysates changed the mobility of antigens recognized by the 1B4 MAb. This suggests that the antigens required for epithelial cell penetration by C. jejuni may be glycoprotein in nature and that the functional binding site is dependent upon an intact carbohydrate moiety. Co-infection of HEp-2 epithelial cells with coxsackievirus B3, echovirus 7, polio virus (LSc type 1), porcine enterovirus and Campylobacter isolates was performed to determine if a synergistic effect could be obtained. The invasiveness of C. jejuni was significantly increased for HEp-2 cells pre-infected with echovirus 7, coxsackievirus B3, and UV-inactivated (non-infectious) coxsackievirus B3 particles. Polio and porcine enterovirus had no effect on C. jejuni adherence and invasiveness. C. hyointestinalis and C. mucosalis, two non-invasive isolates, did not invade virus-infected HEp-2 cells. The increase of invasiveness of C. jejuni appears to be the result of specific interactions between the virus and the HEp-2 cell membrane. The data suggest that the invasiveness of Campylobacter is dependent upon the inherent properties of the organism. Virus-induced cell alterations can potentiate the invasiveness of virulent Campylobacter but are not sufficient to allow internalization by non-invasive bacteria.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.

Gene therapy has shown potential in alleviating a wide range of diseases, ranging from viral infections to autosomal diseases. One of the obstacles to gene therapy reaching its full potential is the inadequacy of methods to deliver therapeutic nucleic sequences. Current delivery of gene therapy entails use of viral and non-viral vectors. Viral vectors are however associated with drawbacks such as potential toxicity, high cost and labour-intensive production. Thus non-viral delivery alternatives are being developed in an attempt to overcome difficulties associated with nucleic acid delivery for gene therapy. Virus-like particles are potentially very useful delivery vehicles as their production is simple and cost effective, the particle surface is amenable to modification and the capsid interior can be altered to accommodate a variety of cargoes. One such particle is the recombinant HBV capsid, which comprises a single species of protein and is tolerant of amino acid substitutions on the surface exposed immunodominant loops. This study aimed to enhance the vector-like properties of the HBV virus-like particle by including amino acid substitutions on the particle surface. These substituted residues in turn provided a conjugation site for tropic and immuno evasive moieties. It was found that lysine substitutions resulted in poor conjugation to the capsid surface, whereas substituted cysteine residues resulted in almost all protein-moiety conjugates forming. In order to introduce lysine and cysteine substitutions, a novel method of cloning into the HBV was generated. In doing so, complicated procedures associated with cloning into the immunodominant loop of the HBV capsid have been alleviated. Ligands containing galactose were utilised on the surface of both the HBV capsid and liposomes to confer hepatotropism. The presence of the galactose moieties on the surface of the HBV capsid prevented indiscriminate cellular uptake in cultured cells, however did not improve hepatotropism. Galactose ligands on the surface of liposomes did improve transfection efficiency, however they required a short linker distance between liposome surface and galactose group. The inclusion of galactose in liposome formulations also provided a means to deliver siRNA to the liver of transgenic HBV mice. It is believed that with alterations to the ligand structure, it is possible to provide HBV capsids with hepatotropism in future experimentation. This study demonstrated that the exposed external surface of the HBV capsid is amenable to convenient conjugation, which potentially facilitates immune evasion and conferring of defined tropism.

Chan Wan Lui Wendy. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 158-162). / Abstracts in English and Chinese. / Acknowledgements --- p.iii / Abstract --- p.v / List of Abbreviations --- p.ix / List of Figures --- p.xii / List of Tables --- p.xvi / Table of Contents --- p.xvii / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter Chapter 2 --- Literature review --- p.3 / Chapter 2.1 --- Malaria --- p.3 / Chapter 2.2 --- History of malaria --- p.4 / Chapter 2.3 --- Malaria parasites --- p.4 / Chapter 2.4 --- Life cycle --- p.5 / Chapter 2.5 --- Potential use of malaria vaccine --- p.6 / Chapter 2.6 --- Merozoite surface protein 1 (MSP1) --- p.7 / Chapter 2.7 --- Potential use of MSPl --- p.8 / Chapter 2.8 --- Significance of MSPl C-terminal fragments --- p.9 / Chapter 2.8.1 --- Significance of MSP142 --- p.9 / Chapter 2.8.2 --- Significance of MSP119 --- p.11 / Chapter 2.9 --- Production of MSPl C-terminal fragments --- p.12 / Chapter 2.10 --- Plants as bioreactors --- p.12 / Chapter 2.11 --- Expression of MSPl C-terminal fragments in transgenic plants --- p.14 / Chapter 2.12 --- Phaseolin and its sorting signal --- p.19 / Chapter 2.13 --- Protein targeting signals --- p.20 / Chapter Chapter 3 --- Material and methods --- p.23 / Chapter 3.1 --- Introduction --- p.23 / Chapter 3.2 --- Chemical and enzymes --- p.23 / Chapter 3.3 --- Cloning --- p.24 / Chapter 3.3.1 --- MSP142 and MSP119 constructs --- p.24 / Chapter 3.3.2 --- Protein targeting fusion constructs --- p.24 / Chapter 3.3.3 --- GUS fusion Constructs --- p.30 / Chapter (a) --- Particle bombardment --- p.30 / Chapter (b) --- GUS fusion constructs for plant transformation --- p.32 / Chapter (c) --- Modified GUS fusion constructs --- p.38 / Chapter 3.4 --- Cloning of chimeric gene into Agrobacterium binary vector --- p.39 / Chapter 3.4.1 --- Cloning of pSUNl --- p.40 / Chapter 3.4.2 --- Primer sequence --- p.45 / Chapter 3.5 --- Bacterial strains --- p.46 / Chapter 3.6 --- Particle bombardment --- p.46 / Chapter 3.6.1 --- Plant materials --- p.46 / Chapter 3.6.2 --- Microcarrier preparation and coating DNA onto microcarrier --- p.46 / Chapter 3.6.3 --- GUS assay --- p.48 / Chapter 3.7 --- Transgenic expression in Arabidopsis thaliana --- p.49 / Chapter 3.7.1 --- Plant materials --- p.49 / Chapter 3.7.2 --- Agrobacterium transformation --- p.49 / Chapter 3.7.3 --- Vacuum infiltration Arabidopsis transformation --- p.49 / Chapter 3.7.4 --- Selection of successful transformants --- p.50 / Chapter 3.7.5 --- Selection for homozygous plants --- p.51 / Chapter 3.8 --- Transgenic expression in tobacco --- p.51 / Chapter 3.8.1 --- Plant materials --- p.51 / Chapter 3.8.2 --- Agrobacterium transformation --- p.52 / Chapter 3.8.2.1 --- Preparation of Agrobacterium tumefaciens LBA4401 competent cells --- p.52 / Chapter 3.8.3 --- Leaf discs method for tobacco transformation --- p.53 / Chapter 3.8.4 --- GUS staining --- p.54 / Chapter 3.9 --- DNA analysis --- p.55 / Chapter 3.9.1 --- Genomic DNA extraction --- p.55 / Chapter 3.9.2 --- Genomic PCR --- p.55 / Chapter 3.9.3 --- Southern blot --- p.55 / Chapter 3.10 --- RNA analysis --- p.56 / Chapter 3.10.1 --- RNA extraction --- p.56 / Chapter 3.10.2 --- Northern blot --- p.56 / Chapter 3.11 --- Protein analysis --- p.57 / Chapter 3.11.1 --- Protein extraction --- p.57 / Chapter 3.11.2 --- Western blot --- p.58 / Chapter 3.11.3 --- Western blot analysis --- p.58 / Chapter Chapter 4 --- Results --- p.60 / Chapter 4.1 --- Transient assay of gene expression of MSP142 and MSPl19 --- p.60 / Chapter 4.1.1 --- Construction of the GUS fusion constructs --- p.60 / Chapter 4.1.2 --- Particle Bombardment --- p.63 / Chapter 4.2 --- Transgenic analysis of MSP142 and MSPl19 expression --- p.70 / Chapter 4.2.1 --- MSPl42 and MSPl19 constructs and transformation --- p.70 / Chapter 4.2.2 --- Selection of transgenic plants --- p.71 / Chapter 4.2.3 --- Southern analysis --- p.75 / Chapter 4.2.4 --- Northern analysis --- p.77 / Chapter 4.2.5 --- Western analysis --- p.79 / Chapter 4.3 --- Expression of the protein-targeting and GUS fused modified MSP1 constructs --- p.81 / Chapter 4.3.1 --- Construction of the fusion constructs --- p.81 / Chapter (A) --- Protein-targeting constructs --- p.81 / Chapter (B) --- GUS fusion constructs --- p.90 / Chapter B1. --- Constructs for transient assay --- p.90 / Chapter B2. --- Modification of GUS sequence --- p.96 / Chapter B3. --- Constructs for tobacco transformation --- p.100 / Chapter 4.4 --- Transient assay of GUS fused MP42 and MP19 constructs by particle Bombardment --- p.107 / Chapter 4.4.1 --- The GUS fusion constructs --- p.107 / Chapter 4.4.2 --- Modification of GUS --- p.112 / Chapter 4.5 --- Generation of transgenic tobacco --- p.116 / Chapter 4.6 --- Southern analysis --- p.120 / Chapter 4.7 --- Northern analysis --- p.126 / Chapter (A) --- Protein-targeting constructs --- p.126 / Chapter (B) --- GUS fusion constructs --- p.130 / Chapter 4.8 --- Western analysis --- p.133 / Chapter (A) --- Protein-targeting constructs --- p.133 / Chapter (B) --- GUS fusion constructs --- p.139 / Chapter Chapter 5 --- Discussion --- p.146 / Chapter Chapter 6 --- Conclusion --- p.157 / References --- p.158

by Lau On Sun. / Thesis submitted in: November 2003. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 117-127). / Abstracts in English and Chinese. / Acknowledgements --- p.iii / Abstract --- p.v / List of Abbreviations --- p.viii / Table of Contents --- p.x / List of Figures --- p.xiii / List of Tables --- p.xv / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter Chapter 2 --- Literature Review --- p.3 / Chapter 2.1 --- Malaria --- p.3 / Chapter 2.1.1 --- Global situation --- p.3 / Chapter 2.1.2 --- Malaria parasite and its life cycle --- p.4 / Chapter 2.1.3 --- Need for a malarial vaccine --- p.5 / Chapter 2.2 --- Merozoite surface protein 1 and its fragments - the advanced malaria vaccine candidate --- p.7 / Chapter 2.2.1 --- Basic research on MSP1 --- p.7 / Chapter 2.2.2 --- Vaccine research on MSP1 --- p.8 / Chapter 2.3 --- Transgenic plants as recombinant protein production systems --- p.11 / Chapter 2.3.1 --- Characteristics --- p.11 / Chapter 2.3.2 --- Plant-based vaccine --- p.13 / Chapter 2.4 --- Expression of MSP 1 C-terminal fragments in transgenic plants --- p.15 / Chapter 2.4.1 --- Previous studies --- p.15 / Chapter 2.4.2 --- Plant-optimized MSP142 cDNA --- p.18 / Chapter 2.5 --- Phaseolin: its promoter and vacuolar-sorting signal --- p.20 / Chapter 2.6 --- Sorting of soluble protein to vacuoles in plants --- p.22 / Chapter 2.7 --- Winged bean lysine-rich protein and translational fusion strategy --- p.24 / Chapter 2.8 --- Hypotheses and aims of study --- p.26 / Chapter Chapter 3: --- Materials and Methods --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Chemicals --- p.28 / Chapter 3.3 --- Bacterial strains --- p.28 / Chapter 3.4 --- Chimeric gene construction --- p.29 / Chapter 3.4.1 --- Construction of the lysine-rich protein fusion constructs --- p.33 / Chapter 3.4.2 --- Construction of the phaseolin-targeting constructs --- p.37 / Chapter 3.4.3 --- Confirmation of sequence fidelity of chimeric genes --- p.42 / Chapter 3.4.4 --- Cloning of chimeric genes into Agrobacterium binary vector --- p.42 / Chapter 3.5 --- Transgenic expression in Arabidopsis and tobacco --- p.44 / Chapter 3.5.1 --- Plant materials --- p.44 / Chapter 3.5.2 --- Agrobacterium transformation --- p.44 / Chapter 3.5.3 --- Arabidopsis transformation and selection --- p.45 / Chapter 3.5.4 --- Tobacco Transformation and Selection --- p.47 / Chapter 3.5.5 --- Genomic DNA isolation --- p.49 / Chapter 3.5.6 --- Southern blot analysis --- p.49 / Chapter 3.5.7 --- Total silique RNA isolation --- p.50 / Chapter 3.5.8 --- Northern blot analysis --- p.50 / Chapter 3.5.9 --- Protein extraction and SDS-PAGE --- p.51 / Chapter 3.5.10 --- Western blot analysis --- p.52 / Chapter 3.5.11 --- Enterokinase digestion of recombinant LRP fusion protein --- p.53 / Chapter 3.5.12 --- Deglycosylation studies of recombinant MSP142-AFVY --- p.54 / Chapter 3.6 --- Confocal immunoflorescence studies of MSPl42-AFVY in tobacco --- p.55 / Chapter 3.6.1 --- Preparation of sections --- p.55 / Chapter 3.6.2 --- Labeling of fluorescence probes --- p.55 / Chapter 3.6.3 --- Image collection --- p.56 / Chapter 3.7 --- Bacterial expression of MSP 142 and anti-serum production --- p.57 / Chapter 3.7.1 --- pET expression in E. coli --- p.57 / Chapter 3.7.2 --- Purification of recombinant His-MSPl42 --- p.58 / Chapter 3.7.3 --- Immunization of rabbits --- p.59 / Chapter Chapter 4: --- Results --- p.60 / Chapter 4.1 --- Transgenic analysis of lysine-rich protein fusion constructs --- p.60 / Chapter 4.1.1 --- Construction of the lysine-rich protein fusion constructs --- p.60 / Chapter 4.1.2 --- Selection of transgenic plants --- p.62 / Chapter 4.1.3 --- Southern analysis --- p.65 / Chapter 4.1.4 --- Northern analysis --- p.69 / Chapter 4.1.5 --- Western analysis --- p.71 / Chapter 4.1.6 --- Western analysis with anti-LRP --- p.75 / Chapter 4.1.7 --- Enterokinase digestion of recombinant LRP fusion protein --- p.76 / Chapter 4.2 --- Transgenic analysis of phaseolin vacuolar-sorting signal constructs --- p.80 / Chapter 4.2.1 --- Construction of the phaseolin vacuolar-sorting signal constructs --- p.80 / Chapter 4.2.2 --- Selection of transgenic plants --- p.82 / Chapter 4.2.3 --- Southern analysis --- p.85 / Chapter 4.2.4 --- Northern analysis --- p.89 / Chapter 4.2.5 --- Western analysis --- p.91 / Chapter 4.2.6 --- Deglycosylation studies of recombinant MSPl42-AFVY --- p.96 / Chapter 4.2.7 --- Human serum detection of MSP142-AFVY --- p.100 / Chapter 4.3 --- Confocal immunofluorescence studies of MSP142-AFVY in tobacco --- p.102 / Chapter 4.4 --- Bacterial expression of MSPl42 and anti-serum production --- p.105 / Chapter 4.4.1 --- Expression and purification of recombinant His-MSPl42 in E. coli --- p.105 / Chapter 4.4.2 --- Titer and specificity of the anti-serum --- p.107 / Chapter Chapter 5 --- Discussion --- p.109 / Chapter Chapter 6 --- Conclusion --- p.116 / References --- p.117

Abstract not available

T cell surface antigens are thought to play significant roles in immunological functions. They are involved in cellular interactions and T cell activation and proliferation. Characterization of T cell antigens is important in understanding the molecular machanisms underlying immune responses. The subject of this thesis is to characterize a novel murine T cell surface antigen called YE1/48. YE1/48, defined by two rat monoclonal antibodies YE1/48.10.6 and YE1/32.8.5, is a dimeric glycoprotein with molecular size and charge resembling the murine T cell antigen receptor α/β. It was initially detected at high levels on two T cell lymphomas, EL-4 and MBL-2. In my thesis studies, the YE1/48 antigen was characterized biochemically, a cDNA clone was isolated, and its expression in lymphoid cell populations was determined. The YE1/48 antigen was found to be distinct from the T cell receptor based on direct comparisons of their primary sequences as well as immunological analyses. It is likely a homodimer with similar or identical subunits. No homology with any known proteins could be detected, including the human T cell activation antigen CD28 (T44) which also has a similar dimeric structure as YE1/48. No function of the YE1/48 antigen could be derived from its primary sequence or with the use of the two monoclonal antibodies because the antibodies do not appear to bind to the surface of intact normal T lymphocytes. Some intriguing characteristics of the YE1/48 antigen were observed in the current studies. The YE1/48 antigen belongs to a rare group of type II membrane proteins with orientation of the amino-terminus inside the cell and the carboxy-terminus outside. The YE1/48 gene may have two alleles among different mouse strains and may belong to a multigene family. YE1/48 is expressed at low levels on a wide range of T cells with no restriction to their differentiation stages, and on spleen B cells as well as bone marrow cells. Its expression on lymphocytes is not related to activation or proliferation. However, YE1/48 expression appears to be induced at high levels by Abelson Murine Leukemia Virus-transformation of pre-B cells. Moreover, the epitopes defined by the YE1/48.10.6 and YE1.32.8.5 antibodies seem to be exposed only on three T lymphomas but not on normal T cells. It is thus tantalizing to speculate a correlation of the high level expression of YE1/48 antigen and its epitope exposure on transformed lymphocytes with cellular transformation. In summary, YE1/48 was found to be a novel T cell surface antigen which has similar dimeric structure as the murine T cell receptor α/β and human CD28 (T44). It has now been characterized biochemically, molecularly cloned, and its expression on lymphoid cells has been determined. Although the function of YE1/48 antigen remains unknown, a number of intriguing characteristics observed in the current studies have certainly called for further studies on the antigen and the determination of its function. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

Clostridium difficile est une bactérie anaérobie stricte responsable de diarrhées consécutives à une antibiothérapie et de colites pseudomembraneuses. La destruction du microbiote intestinal de barrière favorise l’implantation de C. difficile, qui se multiplie, adhère aux cellules épithéliales et produit les toxines TcdA et TcdB. Les infections à C. difficile sont devenues un problème majeur de santé publique. En particulier les nombreuses rechutes posent un problème thérapeutique. L’immunisation active est une des approches permettant de prévenir les rechutes et réduire l’incidence des infections. Plusieurs essais de vaccination ciblant les toxines sont en cours de développement mais sont sans action sur la première étape de l'infection à C. difficile, la colonisation intestinale. Notre objectif a été de développer une stratégie vaccinale par voie muqueuse pour lutter contre la colonisation intestinale. Des protéines de surface de C. difficile ainsi que la toxine TcdB ayant un rôle dans la pathogénicité ont été sélectionnées et utilisées comme cibles vaccinales. Certains candidats vaccinaux ont été encapsulés afin de pouvoir délivrer les antigènes au niveau de la muqueuse intestinale par voie orale. De plus, pour induire une réponse immunitaire localisée au niveau de la muqueuse intestinale, différents adjuvants ont été testés. Nous avons analysé après vaccination la réponse immunitaire induite au niveau local et systémique. Pour identifier de nouveaux candidats vaccin, le rôle de différentes protéines de surface dans la colonisation intestinale de C. difficile a été caractérisé. L'ensemble des essais in vivo a été mené dans deux modèles animaux de référence pour les infections à C. difficile : la souris et le hamster, pour suivre respectivement la colonisation intestinale par C. difficile et le taux de survie après infection. / Clostridium difficile is an anaerobic bacterium that is responsible for post-antibiotic diarrhea and pseudomembranous colitis. The disruption of the intestinal microbiota barrier effect promotes the establishment of C. difficile, which multiplies, adheres to epithelial cells, and produces the toxins TcdA and TcdB. C. difficile infections are considered as a major public threat. In particular, the multiple recurrences are difficult to treat. Active immunization is one of the new approaches to reduce recurrences and the incidence of these infections. Several vaccine targeting toxins are in development. However, these vaccines have no effect on the first step of C. difficile infection, the host colonization. The objective was to develop a mucosal vaccine strategy to act on intestinal colonization. Surface proteins of C. difficile and TcdB involved in the pathogenicity process were selected and used as vaccine targets. These antigens were produced and encapsulated to deliver them to the intestinal mucosa. Furthermore, to induce a gut mucosal immunity, different adjuvants were tested. After vaccination, we analyzed the local and systemic immune response by immunoassays. Finally, in order to characterize new vaccine candidates, the role of different surface proteins in C. difficile colonization was evaluated. These vaccine trials were conducted in two animal models of reference for C. difficile infections: the mouse and the hamster models, which permit to follow the colonization and the survival rate after infection, respectively.