References of "Zecchinon, Laurent"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailLes facteurs de virulence d’Actinobacillus pleuropneumoniae, l’agent étiologique de la pleuropneumonuie porcine
Vanden Bergh, Philippe ULg; Fett, Thomas ULg; Zecchinon, Laurent ULg et al

in Annales de Médecine Vétérinaire (2008), 152(2), 74-96

Porcine pleuropneumonia caused by Actinobacillus pleuropneumoniae is a frequent and highly infectious disease generating significant economic losses related to deficiency in zootechnical profits and ... [more ▼]

Porcine pleuropneumonia caused by Actinobacillus pleuropneumoniae is a frequent and highly infectious disease generating significant economic losses related to deficiency in zootechnical profits and intensive use of antibiotics. This synthesis aims to review the bacterium elements necessary to pathogenesis development. At first time, we describe activation, secretion and cytotoxic action of Apx toxins, recognized as A. pleuropneumoniae major virulence factors. Then, we develop the other ones which are the lipopolysaccharides, the polysaccharidic capsule, the fimbriae, iron and other nutrients capture systems, various proteases, installation of certain metabolic ways, flagella and the biofilm. [less ▲]

Detailed reference viewed: 54 (8 ULg)
Full Text
Peer Reviewed
See detailProbing of Actinobacillus pleuropneumoniae ApxIIIA toxin-dependent cytotoxicity towards mammalian peripheral blood mononucleated cells
Vanden Bergh, Philippe ULg; Zecchinon, Laurent ULg; Fett, Thomas ULg et al

in BMC Research Notes (2008)

BACKGROUND: Actinobacillus pleuropneumoniae, the causative bacterial agent of porcine pleuropneumonia, produces Apx toxins which belong to RTX toxin family and are recognized as the major virulence ... [more ▼]

BACKGROUND: Actinobacillus pleuropneumoniae, the causative bacterial agent of porcine pleuropneumonia, produces Apx toxins which belong to RTX toxin family and are recognized as the major virulence factors. So far, their target receptor(s) has not been identified and the disease cytopathogenesis remains poorly understood. Production of an active Apx toxin and characterization of its toxic activity constitute the premises necessary to the description of its interaction with a potential receptor. From this point of view, we produced an active recombinant ApxIIIA toxin in order to characterize its toxicity on peripheral blood mononucleated cells (PBMCs) isolated from several species. FINDINGS: Toxin preparation exercises a strong cytotoxic action on porcine PBMCs which is directly related to recombinant ApxIIIA since preincubation with polymyxin B does not modify the cytotoxicity rate while preincubation with a monospecific polyclonal antiserum directed against ApxIIIA does. The cell death process triggered by ApxIIIA is extremely fast, the maximum rate of toxicity being already reached after 20 minutes of incubation. Moreover, ApxIIIA cytotoxicity is species-specific because llama, human, dog, rat and mouse PBMCs are resistant. Interestingly, bovine and caprine PBMCs are slightly sensitive to ApxIIIA toxin too. Finally, ApxIIIA cytotoxicity is cell type-specific as porcine epithelial cells are resistant. CONCLUSION: We have produced an active recombinant ApxIIIA toxin and characterized its specific cytotoxicity on porcine PBMCs which will allow us to get new insights on porcine pleuropneumonia pathogenesis in the future. [less ▲]

Detailed reference viewed: 48 (3 ULg)
Full Text
Peer Reviewed
See detailMannheimia haemolytica leukotoxin-induced cytolysis of caprine (Capra hircus) leukocytes is mediated by the CD18 subunit of beta2-integrins
Fett, Thomas ULg; Zecchinon, Laurent ULg; Vanden Bergh, Philippe ULg et al

in Microbial Pathogenesis (2008), 45

Mannheimiosis is the major respiratory disease among some ruminants, whereas it is not pathogenic for other mammals, an observation that has been attributed to a specific interaction between Mannheimia ... [more ▼]

Mannheimiosis is the major respiratory disease among some ruminants, whereas it is not pathogenic for other mammals, an observation that has been attributed to a specific interaction between Mannheimia haemolytica leukotoxin (Lkt) and bovine or ovine CD18 subunit of lymphocyte function-associated antigen-1 (LFA-1) and Mac-1. We therefore hypothesized that Lkt utilizes CD18 as its receptor on caprine leukocytes as well. We have transiently transfected the b2-integrins-deficient K-562 cell line with cDNAs encoding caprine CD11a and caprine CD18 to determine the susceptibility of the transfectants to Lktinduced cytolysis. Flow cytometric analysis of the transfectants revealed surface expression of caprine LFA-1 and lysis by Lkt in a concentration-dependent manner whereas the parent cells were not. Moreover, K562 cells expressing caprine CD18 and human or bovine CD11a were also sensitive to Lkt whereas K-562 cells expressing caprine CD11a and human CD18 were not. Taken together, these results indicate that CD18 on caprine leukocytes serves as a receptor for Lkt. [less ▲]

Detailed reference viewed: 20 (8 ULg)
Full Text
Peer Reviewed
See detailThe wild boar (Sus scrofa) Lymphocyte function-associated antigen-1 (CD11a/CD18) receptor : cDNA sequencing, structure analysis and comparison with homologues
Vanden Bergh, Philippe ULg; Zecchinon, Laurent ULg; Fett, Thomas ULg et al

in BMC Veterinary Research (2007), 3

BACKGROUND: The most predominant beta2-integrin lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18, alphaLbeta2), expressed on all leukocytes, is essential for many adhesive functions of the ... [more ▼]

BACKGROUND: The most predominant beta2-integrin lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18, alphaLbeta2), expressed on all leukocytes, is essential for many adhesive functions of the immune system. Interestingly, RTX toxin-producing bacteria specifically target this leukocyte beta2-integrin which exacerbates lesions and disease development. RESULTS: This study reports the sequencing of the wild boar beta2-integrin CD11a and CD18 cDNAs. Predicted CD11a and CD18 subunits share all the main structural characteristics of their mammalian homologues, with a larger interspecies conservation for the CD18 than the CD11a. Besides these strong overall similarities, wild boar and domestic pig LFA-1 differ by 2 (CD18) and 1 or 3 (CD11a) substitutions, of which one is located in the crucial I-domain (CD11a, E168D). CONCLUSION: As most wild boars are seropositive to the RTX toxin-producing bacterium Actinobacillus pleuropneumoniae and because they have sustained continuous natural selection, future studies addressing the functional impact of these polymorphisms could bring interesting new information on the physiopathology of Actinobacillus pleuropneumoniae-associated pneumonia in domestic pigs. [less ▲]

Detailed reference viewed: 23 (3 ULg)
Full Text
Peer Reviewed
See detailKey roles of LFA-1 in leukocyte migration and immune response
Zecchinon, Laurent ULg; Fett, Thomas ULg; Vanden Bergh, Philippe ULg et al

in Clinical & Applied Immunology Reviews (2006), 6

Detailed reference viewed: 17 (1 ULg)
Full Text
Peer Reviewed
See detailAnatomy of the Lymphocyte function-associated antigen-1
Zecchinon, Laurent ULg; Fett, Thomas ULg; Vanden Bergh, Philippe ULg et al

in Clinical & Applied Immunology Reviews (2006), 6

Detailed reference viewed: 20 (2 ULg)
Full Text
Peer Reviewed
See detailLFA-1 and associated diseases: the dark side of a receptor
Zecchinon, Laurent ULg; Fett, Thomas ULg; Vanden Bergh, Philippe ULg et al

in Clinical & Applied Immunology Reviews (2006), 6

Detailed reference viewed: 19 (1 ULg)
Full Text
Peer Reviewed
See detailBind another day: the LFA-1/ICAM-1 interation as therapeutic target
Zecchinon, Laurent ULg; Fett, Thomas ULg; Vanden Bergh, Philippe ULg et al

in Clinical & Applied Immunology Reviews (2006), 6

Detailed reference viewed: 15 (4 ULg)
Full Text
Peer Reviewed
See detailStability domains, substrate-induced conformational changes, and hinge-bending motions in a psychrophilic phosphoglycerate kinase: A microcalorimetric study
Zecchinon, Laurent ULg; Oriol, A.; Netzel, U. et al

in Journal of Biological Chemistry (2005), 280(50), 41307-41314

The cold-active phosphoglycerate kinase from the Antarctic bacterium Pseudomonas sp. TACII18 exhibits two distinct stability domains in the free, open conformation. It is shown that these stability ... [more ▼]

The cold-active phosphoglycerate kinase from the Antarctic bacterium Pseudomonas sp. TACII18 exhibits two distinct stability domains in the free, open conformation. It is shown that these stability domains do not match the structural N- and C-domains as the heat-stable domain corresponds to about 80 residues of the C-domain, including the nucleotide binding site, whereas the remaining of the protein contributes to the main heat-labile domain. This was demonstrated by spectroscopic and microcalorimetric analyses of the native enzyme, of its mutants, and of the isolated recombinant structural domains. It is proposed that the heat-stable domain provides a compact structure improving the binding affinity of the nucleotide, therefore increasing the catalytic efficiency at low temperatures. Upon substrate binding, the enzyme adopts a uniformly more stable closed conformation. Substrate-induced stability changes suggest that the free energy of ligand binding is converted into an increased conformational stability used to drive the hinge-bending motions and domain closure. [less ▲]

Detailed reference viewed: 14 (0 ULg)
Full Text
Peer Reviewed
See detailCloning and characterisation of the primary structure of the sheep lymphocyte function-associated antigen-1 alpha subunit
Fett, Thomas ULg; Zecchinon, Laurent ULg; Baise, Etienne ULg et al

in Molecular Immunology (2005), 42(12), 1503-1508

The leukocyte integrins play a critical role in a number of cellular adhesive interactions during the immune response. The ovine cDNA encoding CD1 1a, the predominant a subunit of the beta(2)-integrin ... [more ▼]

The leukocyte integrins play a critical role in a number of cellular adhesive interactions during the immune response. The ovine cDNA encoding CD1 1a, the predominant a subunit of the beta(2)-integrin family, was sequenced and compared with the human, bovine and murine sequences. Despite some focal differences, it shares all the main characteristics of its known mammalian homologues. Along with the ovine CD18-encoding cDNA, which is available for a few months, the sequence data provided here will allow the Ovis aries beta(2)-integrin CD1 1a/CD18 (LEA-1, alpha(L)beta 2) expression in vitro as a tool to examine the specificities of inflammation in the ovine species. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 14 (1 ULg)
Full Text
Peer Reviewed
See detailHow Mannheimia haemolytica defeats host defence through a kiss of death mechanism
Zecchinon, Laurent ULg; Fett, Thomas ULg; Desmecht, Daniel ULg

in Veterinary Research (2005), 36(Mar-Apr), 133-156

Mannheimia haemolytica induced pneumonias are only observed in goats, sheep and cattle. The bacterium produces several virulence factors,whose principal ones are lipopolysaccharide and leukotoxin. The ... [more ▼]

Mannheimia haemolytica induced pneumonias are only observed in goats, sheep and cattle. The bacterium produces several virulence factors,whose principal ones are lipopolysaccharide and leukotoxin. The latter is cytotoxic only for ruminant leukocytes, a phenomenon that is correlated with its ability to bind and interact with the ruminant beta2-integrin Lymphocyte Function-associated Antigen 1. This paper globally reviews all the information available on host-pathogen interactions underlying respiratory mannheimiosis (formerly pasteurellosis), from the stable and the Petri dish to the biochemical cascade of events triggered by the leukotoxin inside ruminant leukocytes. One conclusion can be made: the most widespread cattle respiratory disease with the most important impact on beef production worldwide, is probably due to a tiny ruminant-specific focal variation in the CD18- and/or CD11a-expressing genes. [less ▲]

Detailed reference viewed: 22 (1 ULg)
Full Text
Peer Reviewed
See detailMolecular characterization of the caprine (Capra hircus) lymphocyte function-associated antigen-1 alpha subunit
Fett, Thomas ULg; Zecchinon, Laurent ULg; Baise, Etienne ULg et al

in BMC Veterinary Research (2005)

Background: Lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18, alpha L beta 2) is required for many cellular adhesive interactions during the immune response. Results: The Capra hircus CD11a ... [more ▼]

Background: Lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18, alpha L beta 2) is required for many cellular adhesive interactions during the immune response. Results: The Capra hircus CD11a-encoding cDNA was sequenced and compared with its human, murine, rat, bovine and ovine counterparts. Despite some focal differences, it shares all the main characteristics of its known mammalian homologues. Conclusion: Therefore, along with the caprine CD18-encoding cDNA, which has been available for a few months, the sequence data revealed here will allow the Capra hircus LFA-1 expression in vitro as a tool to explore the specificities of inflammation in the caprine species. [less ▲]

Detailed reference viewed: 19 (1 ULg)
Full Text
Peer Reviewed
See detailMolecular cloning and characterisation of the CD18 partner in ovine (Ovis aries) beta(2)-integrins
Zecchinon, Laurent ULg; Fett, Thomas ULg; Baise, Etienne ULg et al

in Gene (2004), 334

The leukocyte integrins play a critical role in a number of cellular adhesive interactions during the immune response. We describe here the isolation and characterization of the ovine beta(2) (CD18 ... [more ▼]

The leukocyte integrins play a critical role in a number of cellular adhesive interactions during the immune response. We describe here the isolation and characterization of the ovine beta(2) (CD18) subunit, common to the leukocyte beta(2)-integrin family. The deduced 770-amino-acid sequence reveals a transmembrane protein with 81%, 83% and 95% identity with its murine, human and bovine homologues, respectively. Comparisons of CD18 sequences emphasize the functional importance of the beta(2) subunit I-like domain and included metal ion-dependent adhesion site (MIDAS)-like motif and confirm that of the cytoplasmic tail. The data provided here will offer the possibility to explore new avenues in studies based on the ovine model. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 8 (1 ULg)
Full Text
Peer Reviewed
See detailThe bovine (Bos taurus) CD11a-encoding cDNA: molecular cloning, characterisation and comparison with the human and murine glycoproteins
Fett, Thomas ULg; Zecchinon, Laurent ULg; Baise, Etienne ULg et al

in Gene (2004), 325

The bovine cDNA encoding CD11 a cell-surface glycoprotein involved in multiple leukocyte functions, was sequenced and compared with the human and murine sequences. Despite some focal differences, it ... [more ▼]

The bovine cDNA encoding CD11 a cell-surface glycoprotein involved in multiple leukocyte functions, was sequenced and compared with the human and murine sequences. Despite some focal differences, it shares all the main characteristics of its known mammalian homologs. Along with the bovine CD18-encoding cDNA, which is available for a long time, the sequence data provided here will allow the successful expression of bovine CD11a, thus giving the first opportunity to express the Bos taurus beta(2)-integrin CD11a/CD18 (LFA-1, alpha(L)beta(2)) in vitro as a tool to examine the specificities of inflammation in the bovine species. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 22 (3 ULg)
Full Text
Peer Reviewed
See detailCharacterization of the caprine (Capra hircus) beta-2 integrin CD18-encoding cDNA and identification of mutations potentially responsible for the ruminant-specific virulence of Mannheimia haemolytica
Zecchinon, Laurent ULg; Fett, Thomas ULg; Baise, Etienne ULg et al

in Molecular Membrane Biology (2004), 21(5, Sep-Oct), 289-295

The leukocyte integrins play a critical role in a great number of cellular adhesive interactions during the immune response. We describe here the isolation and characterization of the caprine beta(2 ... [more ▼]

The leukocyte integrins play a critical role in a great number of cellular adhesive interactions during the immune response. We describe here the isolation and characterization of the caprine beta(2) (CD18) sub-unit, common to the leukocyte beta(2)-integrin family. The deduced 770-amino-acid sequence reveals a transmembrane protein with 80, 81, 83, 96 and 99% identity with its canine, murine, human, bovine and ovine homologues respectively. Analysis of CD18 sequences emphasizes the functional importance of the beta(2) sub-unit I-like domain, and included metal ion-dependent adhesion site-like motif and confirms that of the cytoplasmic tail. Moreover, comparisons of ruminant versus non-ruminant CD18 sequences allowed the identification of 16 potential mutation sites that could be held responsible for the unique virulence of Mannheimia haemolytica for ruminants. Mannheimiosis is known to be the major respiratory disease among ruminants, whereas it is not pathogenic for other mammals, an observation that has been attributed to a specific interaction between M. haemolytica leukotoxin and ruminants' CD18. Therefore, the data provided here offer the possibility to explore new avenues in studies based on the caprine model and provide key information for future studies aimed at elucidating the molecular mechanisms underlying the ruminant-specific virulence of M. haemolytica. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
Peer Reviewed
See detailDid Psychrophilic Enzymes Really Win the Challenge?
Zecchinon, Laurent ULg; Claverie, P.; Collins, T. et al

in Extremophiles : Life Under Extreme Conditions (2001), 5(5), 313-21

Organisms living in permanently cold environments, which actually represent the greatest proportion of our planet, display at low temperatures metabolic fluxes comparable to those exhibited by mesophilic ... [more ▼]

Organisms living in permanently cold environments, which actually represent the greatest proportion of our planet, display at low temperatures metabolic fluxes comparable to those exhibited by mesophilic organisms at moderate temperatures. They produce cold-evolved enzymes partially able to cope with the reduction in chemical reaction rates and the increased viscosity of the medium induced by low temperatures. In most cases, the adaptation is achieved through a reduction in the activation energy, leading to a high catalytic efficiency, which possibly originates from an increased flexibility of either a selected area of or the overall protein structure. This enhanced plasticity seems in return to be responsible for the weak thermal stability of cold enzymes. These particular properties render cold enzymes particularly useful in investigating the possible relationships existing between stability, flexibility, and specific activity and make them potentially unrivaled for numerous biotechnological tasks. In most cases, however, the adaptation appears to be far from being fully achieved. [less ▲]

Detailed reference viewed: 22 (0 ULg)
See detailCold-adapted enzymes: an unachieved symphony
D'Amico, Salvino ULg; Claverie, P.; Collins, T. et al

in Storey, K. B.; Storey, J. M. (Eds.) Cell and Molecular Responses to Stress vol.2. Protein adaptations and signal transduction, (2001)

Detailed reference viewed: 36 (3 ULg)