P27-PPE36 (Rv2108) Mycobacterium tuberculosis Antigen – Member of PPE Protein Family with Surface Localization and Immunological Activities

International audienc

Dire l’entreprise, c’est la modéliser dans sa complexité

L’entreprise ne peut se dire et être dite que par les modèles que l’on en construit : si elle a un projet, elle n’est pas un objet passif et sans nécessité. L’enjeu central est lié aux représentations que l’on se fait de l’entreprise. Les théories de l’organisation ont fourni quelques modèles de références dans la logique desquels se sont développées de nombreuses actlvités qui dominent encore intensément nos cultures entrepreneuriales et donc aussi la communication de l’entreprise, l’article propose de substituer un autre mode de pensée permettant de passer du modèle à la modéllsation. Quelques propriétés fondamentales des systèmes organisés et organisants sont pointées pour déboucher sur la bouclé conceptuelle organisation-information, articulée autour du processus de mémorisation.À firm can only express itself and be expressed through the models that are made of it. If it has a project then it is not a passive, unnecessary object. The central concern is linked to the representations which are made of a flrm. Organization theories have supplled a few reference models from which have developed numerous activities which still intensely dominate our business culture and also business communication strategies. The article proposes to substitute another way of thinking which would pass from the model to modelllng. À few fundamental characteristics of organised and organising systems are identified in order to arrivé at the organisation-information conceptual loop which turns on the process of mémorisation

Lsr2 is an important determinant of intracellular growth and virulence in Mycobacterium abscessus

Mycobacterium abscessus, a pathogen responsible for severe lung infections in cystic fibrosis patients, exhibits either smooth (S) or rough (R) morphotypes. The S-to-R transition correlates with inhibition of the synthesis and/or transport of glycopeptidolipids (GPLs) and is associated with an increase of pathogenicity in animal and human hosts. Lsr2 is a small nucleoid-associated protein highly conserved in mycobacteria, including M. abscessus, and is a functional homologue of the heat-stable nucleoid-structuring protein (H-NS). It is essential in Mycobacterium tuberculosis but not in the non-pathogenic model organism Mycobacterium smegmatis. It acts as a master transcriptional regulator of multiple genes involved in virulence and immunogenicity through binding to AT-rich genomic regions. Previous transcriptomic studies, confirmed here by quantitative PCR, showed increased expression of lsr2 (MAB_0545) in R morphotypes when compared to their S counterparts, suggesting a possible role of this protein in the virulence of the R form. This was addressed by generating lsr2 knock-out mutants in both S (Δlsr2-S) and R (Δlsr2-R) variants, demonstrating that this gene is dispensable for M. abscessus growth. We show that the wild-type S variant, Δlsr2-S and Δlsr2-R strains were more sensitive to H2O2 as compared to the wild-type R variant of M. abscessus. Importantly, virulence of the Lsr2 mutants was considerably diminished in cellular models (macrophage and amoeba) as well as in infected animals (mouse and zebrafish). Collectively, these results emphasize the importance of Lsr2 in M. abscessus virulence

Inhibition of the β-lactamase BlaMab by avibactam improves the in vitro and in vivo efficacy of imipenem against mycobacterium abscessus

Mycobacterium abscessus pulmonary infections are treated with a macrolide (clarithromycin or azithromycin), an aminoglycoside (amikacin), and a β-lactam (cefoxitin or imipenem). The triple combination is used without any β-lactamase inhibitor, even though M. abscessus produces the broad-spectrum β-lactamase BlaMab. We determine whether inhibition of BlaMab by avibactam improves the activity of imipenem against M. abscessus. The bactericidal activity of drug combinations was assayed in broth and in human macrophages. The in vivo efficacy of the drugs was tested by monitoring the survival of infected zebrafish embryos. The level of BlaMab production in broth and in macrophages was compared by quantitative reverse transcription-PCR and Western blotting. The triple combination of imipenem (8 or 32 μg/ml), amikacin (32 μg/ml), and avibactam (4 μg/ml) was bactericidal in broth (<0.1% survival), with 3.2- and 4.3-log10 reductions in the number of CFU being achieved at 72 h when imipenem was used at 8 and 32 μg/ml, respectively. The triple combination achieved significant intracellular killing, with the bacterial survival rates being 54% and 7% with the low (8 μg/ml) and high (32 μg/ml) dosages of imipenem, respectively. In vivo inhibition of BlaMab by avibactam improved the survival of zebrafish embryos treated with imipenem. Expression of the gene encoding BlaMab was induced (20-fold) in the infected macrophages. Inhibition of BlaMab by avibactam improved the efficacy of imipenem against M. abscessus in vitro, in macrophages, and in zebrafish embryos, indicating that this β-lactamase inhibitor should be clinically evaluated. The in vitro evaluation of imipenem may underestimate the impact of BlaMab, since the production of the β-lactamase is inducible in macrophages

Absence of amplification role of the protein KLH on antibody response generated by a MAP Staphyloccocus aureus enterotoxin A (SEA) peptide comparing with the corresponding monomeric peptide

International audienceStaphuloccocus aureus enterotoxin A (SEA) is a toxin involved in numerous food poisoning cases. To develop a detection test specific for, different approaches have been envisaged to obtain highest antibody titer sera against a peptide sequence from this protein. The present work compares the properties of antibodies raised against the peptide epitope by classical and multiple antigen peptide (MAP) system approaches. Different immunization protocols were used: BALB/c mice were immunized either with the peptide or the MAP alone in Freund's adjuvant, co-immunized with the keyhole limpet hemocyanin (KLH) protein or, with the peptide, conjugated to this carrier KLH protein. The extent of reaction of the antibodies to the MAP construct with the parent protein was found to be significantly less than the antibodies raised against the monomeric peptide coimmunized with or conjugated to a carrier protein but more that the antibodies raised against the peptide alone. Inversely, co-immunization of the MAP with the KLH was not able to raise the immune response as it was observed with the monomeric peptide. The results suggest that, for the epitope chosen here, MAP constructs were not the most effective option to induce sera with high levels of antibodies that react with the native protein

Antibody response to Mycobacterium tuberculosis p27-PPE36 antigen in sera of pulmonary tuberculosis patients

International audienc

Étude de la réponse immunitaire anti-peptidique en fonction du contexte du peptide et du vecteur d'immunisation

Différents PAMPs (adjuvant complet de Freund, ADN bactérien et flagelline), des motifs microbiens activant les récepteurs de la réponse immunitaire innée, sont utilisés à la fois comme vecteur et comme adjuvant pour trois antigènes (un peptide de la flagelline de Clostridium tyrobutyricum, protéines P27 de Mycobacterium tuberculoses et POMP91 B de Chlamydophyla abortus). Les réponses immunitaires cellulaires et humorales sont étudiées chez des souris immunisées par les différentes formulations. Les réponses observées sont spécifiques des antigènes utilisés et des modes d'immunisation pratiqués. En général, les réponses montrent un effet adjuvant de la flagelline recombinante à laquelle est couplé l'antigène sur la réponse cellulaire de type Thl. Les réponses cellulaires induites par cette formulation sont meilleures que celles issues de l'immunisation génique. Par ailleurs, les anticorps anti-P27 ont permis d'attribuer une localisation pariétale à cette protéine PPE de M. tuberculosis.Varions PAMPs (complete Freund's adjuvant, bacterial DNA and flagel in), bacterial patterns inducing innate immune response receptors, are used as vectors and as adjuvants for three antigens (a peptid from Clostridium tyrobutyricum flagellin, the P27 Mycobacterium tuberculosis and POMP91B Chlamydophyla abortus proteins). Cellular and humoral immune responses are analyzed in mice immunized with the différent formulations. Observed responses are specific of antigens used and of immunization modes practiced. Generally, responses present an adjuvant effect of recombinant flagellin fused with antigen on Thl cellular response. Cellular responses induced with this formulation are better than those obtained from genetic immunization. Otherwise, anti-P27 antibodies allowed to allocate a peripheral localization for this PPE M. tuberculoses protein.BREST-BU Droit-Sciences-Sports (290192103) / SudocSudocFranceF

Immune Response to Chlamydophila abortus POMP91B Protein in the Context of Different Pathogen Associated Molecular Patterns (PAMP); Role of Antigen in the Orientation of Immune Response

International audienceIn a previous study, we used bacterial flagellin to deliver antigens such as p27 of Mycobacterium tuberculosis to a host immune system and obtained a potent Th1 response compared to those obtained with Freund's adjuvant and DNA immunization. In the current study, using a POMP91B antigen of Chlamydophila abortus, a human and animal pathogen, as a model, we found that this antigen is unable to promote Th1 response. However, this antigen, unlike others, was able to induce a good Th2 response and IL-4 production after immunization by recombinant protein in Freund's adjuvant or in phosphate buffered saline. Our results suggest that immune response is not only dependent on the immunization adjuvant, but also dependent on the nature of antigen used