Publications (59) View all
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Article: Identification of epitopes recognized by monoclonal antibodies directed against HTLV-I envelope surface glycoprotein using peptide phage display
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ABSTRACT: Phage peptide libraries constitute powerful tools for the mapping of epitopes recognized by monoclonal antibodies (mAbs). Using screening of phage displayed random peptide libraries we have characterized the binding epitopes of three mAbs directed against the surface envelope glycoprotein (gp46) of the human T-cell leukemia virus type I (HTLV-I). Two phage libraries, displaying random heptapeptides with or without flanking cysteine residues, were screened for binding to mAbs 7G5D8, DB4 and 4F5F6. The SSSSTPL consensus sequence isolated from constrained heptapeptide library defines the epitope recognized by DB4 mAb and corresponds to the exact region 249–252 of the virus sequence. The APPMLPH consensus sequence isolated from non constrained heptapeptide library defines the epitope recognized by 7G5D8 mAb and corresponds to the region 187–193 with a single amino acid substitution, methionine to leucine at position 190. The third consensus sequence LYWPHD isolated from constrained heptapeptide library defines the epitope recognized by 4F5F6 mAb. It corresponds to an epitope without direct equivalence with the virus sequence. The data presented here showed that 7G5D8 and DB4 mAbs are raised against linear epitopes while 4F5F6 mAb recognized a continoous topographic epitope.Letters in Peptide Science 04/2012; 8(2):95-106. -
Article: Love-wave bacteria-based sensor for the detection of heavy metal toxicity in liquid medium.
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ABSTRACT: The present work deals with the development of a Love-wave bacteria-based sensor platform for the detection of heavy metals in liquid medium. The acoustic delay-line is inserted in an oscillation loop in order to record the resonance frequency in real-time. A Polydimethylsiloxane (PDMS) chip with a liquid chamber is maintained by pressure above the acoustic wave propagation path. Bacteria (Escherichia coli) were fixed as bioreceptors onto the sensitive surface of the sensor coated with a polyelectrolyte (PE) multilayer using a simple and efficient layer-by-layer (LbL) electrostatic self-assembly procedure. Poly(allylamine hydrochloride) (PAH cation) and poly(styrene sulfonate) (PSS anion) were alternatively deposited so that the strong attraction between oppositely charged polyelectrolytes resulted in the formation of a (PAH-PSS)(n)-PAH molecular multilayer. The real-time characterization of PE multilayer and bacteria deposition is based on the measurement of the resonance frequency perturbation due to mass loading during material deposition. Real-time response to various concentrations of cadmium (Cd(2+)) and mercury (Hg(2+)) has been investigated. A detection limit as low as 10(-12) mol/l has been achieved, above which the frequency increases gradually up to 10(-3) mol/l, after a delay of 60 s subsequent to their introduction onto bacterial cell-based biosensors. Beyond a 10(-3) mol/l a steep drop in frequency was observed. This response has been attributed to changes in viscoelastic properties, related to modifications in bacteria metabolism.Biosensors & bioelectronics 12/2010; 26(4):1723-6. · 5.43 Impact Factor -
Article: Screening of phage-displayed antibody libraries.
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ABSTRACT: The problem of amplifying a specific antibody in a population of millions of other antibodies has been solved by the immune system using the process of clonal selection Binding of an antigen to an IgM receptor on the surface of B-lymphocytes stimulates the proliferation and differentiation of the lymphocyte until it matures to an IgG-producing plasma cell. To mimic the first step of this process in bacteria, vectors have been constructed for the expression of antibodies on the surface of bacteria and phages (for review see Chapter 32 ).Methods in molecular medicine 01/1998; 13:605-14. -
Article: IgE mediates killing of intracellular Toxoplasma gondii by human macrophages through CD23-dependent, interleukin-10 sensitive pathway.
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ABSTRACT: In addition to helminthic infections, elevated serum IgE levels were observed in many protozoal infections, while their contribution during immune response to these pathogens remained unclear. As IgE/antigen immune complexes (IgE-IC) bind to human cells through FcεRI or FcεRII/CD23 surface molecules, the present study aimed to identify which functional receptor may be involved in IgE-IC interaction with human macrophages, the major effector cell during parasite infection. Human monocyte-derived macrophages were infected with Toxoplasma gondii before being incubated with IgE-IC. IgE receptors were then identified using appropriate blocking antibodies. The activation of cells and parasiticidal activity were evaluated by mediator quantification and direct counting of infected macrophages. RNAs were extracted and cell supernatants were also collected for their content in tumor necrosis factor (TNF)-α, interleukin-10 (IL-10) and nitrites. Sera from symptomatic infected patients were also tested for their content of IgE, IL-10 and nitrites, and compared to values found in healthy donors. Results showed that IgE-IC induced intracellular elimination of parasites by human macrophages. IgE-mediated effect was FcεRI-independent, but required cross-linking of surface FcεRII/CD23, cell activation and the generation of nitric oxide (NO). Although TNF-α was shown to be produced during cell activation, this cytokine had minor contribution in this phenomenon while endogenous and exogenous IL-10 down-regulated parasite killing. Inverse relationship was found between IL-10 and NO expression by infected human macrophages at both mRNA and mediator levels. The relationship between these in vitro data and in vivo levels of various factors in T. gondii infected patients supports the involvement of CD23 antigen and IL-10 expression in disease control. Thus, IgE may be considered as immune mediator during antiprotozoal activity of human macrophages through its ability to trigger CD23 signaling. Increased cell activation by IgE-IC may also account for chronic inflammatory diseases observed in some patients.PLoS ONE 01/2011; 6(4):e18289. · 4.09 Impact Factor -
Article: Corynebacterium mucifaciens in an immunocompetent patient with cavitary pneumonia.
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ABSTRACT: Corynebacterium mucifaciens has been mainly isolated from skin, blood and from other normally-sterile body fluids. It has rarely been described as a human pathogen since its description. We herein report the first case of cavitary pneumonia due to C. mucifaciens in an immunocompetent man returning from Maghreb. C. mucifaciens should be considered as important human pathogen in patients with severe illness and compatible history of exposure even in individuals with no clearly identified immunosuppression.BMC Infectious Diseases 01/2010; 10:355. · 3.12 Impact Factor
