References of "Desmecht, Daniel"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailInterferon-induced Sus scrofa Mx1 blocks endocytic traffic of incoming influenza A virus particles
Palm, Mélanie; Garigliany, Mutien-Marie ULg; Cornet, François ULg et al

in Veterinary Research (2010), 41(3), 29

The interferon-induced Mx proteins of vertebrates are dynamin-like GTPases, some isoforms of which can additionally inhibit the life cycle of certain RNA viruses. Here we show that the porcine Mx1 protein ... [more ▼]

The interferon-induced Mx proteins of vertebrates are dynamin-like GTPases, some isoforms of which can additionally inhibit the life cycle of certain RNA viruses. Here we show that the porcine Mx1 protein (poMx1) inhibits replication of influenza A virus and we attempt to identify the step at which the viral life cycle is blocked. In infected cells expressing poMx1, the level of transcripts encoding the viral nucleoprotein is significantly lower than normal, even when secondary transcription is prevented by exposure to cycloheximide. This reveals that a pretranscriptional block participates to the anti-influenza activity. Binding and internalization of incoming virus particles are normal in the presence of poMx1 but centripetal traffic to the late endosomes is interrupted. Surprisingly but decisively, poMx1 significantly alters binding of early endosome autoantigen 1 to early endosomes and/or early endosome size and spatial distribution. This is compatible with impairment of traffic of the endocytic vesicles to the late endosomes. [less ▲]

Detailed reference viewed: 62 (27 ULg)
Full Text
Peer Reviewed
See detailViral induction of Zac1b through TLR3- and IRF3-dependent pathways
Warzée, Barbara ULg; Mesnil, Claire ULg; Hober, D. et al

in Molecular Immunology (2010), 48(1-3), 119-127

Zinc finger protein regulator of apoptosis and cell cycle arrest (Zac1) is a transcription factor able to induce apoptosis or cell cycle arrest through independent pathways. In spite of the important ... [more ▼]

Zinc finger protein regulator of apoptosis and cell cycle arrest (Zac1) is a transcription factor able to induce apoptosis or cell cycle arrest through independent pathways. In spite of the important potential functions attributed to Zac1, little is known of its physiological regulation and biological function. We discovered that variant Zac1b was expressed in murine embryonic fibroblasts (MEFs) treated with polyriboinosinic polyribocytidylic acid [poly(I:C)], a synthetic double-stranded RNA. This regulation occurred mainly through Toll-Like Receptor 3 (TLR3)- and Interferon Regulatory Factor 3 (IRF3)-dependent pathways. As TLR3 and IRF3 are central activators of antiviral immunity, we hypothesized that Zac1 may be implicated in antiviral responses. In line with this notion, we observed that Zac1b was expressed in MEFs infected with Encephalomyocarditis virus (EMCV). We also observed that Zac1-deficient MEFs were less sensitive to EMCV-induced cell death than wild-type MEFs. However, Zac1 gene inactivation had no effect on the survival of mice infected with EMCV. In conclusion, this study describes for the first time a transcriptional regulation of Zac1b, induced by synthetic dsRNA and RNA viruses, the functional significance of which remains to be further investigated. [less ▲]

Detailed reference viewed: 68 (20 ULg)
Full Text
Peer Reviewed
See detailRisque zoonotique, impact vétérinaire et surveillance des virus influenza A porcins dans le cadre de l'émergence du virus pandémique influenza A/H1N1 (2009)
Cardoen, S.; Thiry, Etienne ULg; Caij, A. B. et al

in Annales de Médecine Vétérinaire (2010), 154(1), 30-47

Detailed reference viewed: 20 (0 ULg)
Full Text
Peer Reviewed
See detailComparative study of Murid gamma-herpesvirus 4 infection in mice and in a natural host, the bank voles.
François, Sylvie ULg; Vidick, Sarah ULg; Sarlet, Michaël ULg et al

in Journal of General Virology (The) (2010)

Gamma-herpesviruses are archetypal pathogenic persistent viruses. The known human gamma-herpesviruses (Epstein-Barr virus and Kaposi's Sarcoma-associated Herpesvirus) are host-specific and therefore lack ... [more ▼]

Gamma-herpesviruses are archetypal pathogenic persistent viruses. The known human gamma-herpesviruses (Epstein-Barr virus and Kaposi's Sarcoma-associated Herpesvirus) are host-specific and therefore lack a convenient in vivo infection model. This makes related animal gamma-herpesviruses an important source of information. We are studying Murid herpesvirus 4 (MuHV-4), a virus originally isolated from bank voles (Myodes glareolus). MuHV-4 infection of inbred laboratory mouse strains (Mus musculus) is commonly used as a general model of gamma-herpesvirus pathogenesis. However, MuHV-4 has not been isolated from house mice, and no systematic comparison has been made between experimental MuHV-4 infections of mice and bank voles. We have therefore characterized MuHV-4 (strain MHV-68) infection of bank voles, both through global luciferase imaging and through classical virological methods. As in mice, intranasal virus inoculation led to productive replication in bank vole lungs, accompanied by massive cellular infiltrates. However, the extent of lytic virus replication was ~1000 fold lower in bank voles than in mice. Peak latency titers in lymphoid tissue were also lower, although latency was still established. Finally, we tested viral transmission between animals maintained in captivity. However, as observed in mice, MuHV-4 did not transmit between voles in these conditions. In conclusion, this study revealed that despite quantitative differences, replication and latency sites of MuHV-4 are comparable in bank voles and in mice. It appears therefore so far that Mus musculus represents a suitable host for studying gamma-herpesvirus pathogenesis with MuHV-4. Establishing transmission conditions in captivity will be a vital step for further research in that field. [less ▲]

Detailed reference viewed: 110 (38 ULg)
Full Text
Peer Reviewed
See detailDescriptive study of 32 cases of doxycycline-overdosed calves.
Brihoum, Mounir ULg; Amory, Hélène ULg; Desmecht, Daniel ULg et al

in Journal of Veterinary Internal Medicine (2010), 24(5), 1203-10

BACKGROUND: Reports of doxycycline-induced toxicity are limited despite common use of this antibiotic to treat infectious respiratory disorders in calves. OBJECTIVE: To describe previously unreported ... [more ▼]

BACKGROUND: Reports of doxycycline-induced toxicity are limited despite common use of this antibiotic to treat infectious respiratory disorders in calves. OBJECTIVE: To describe previously unreported kidney lesions and diagnostic test results in doxycycline-overdosed calves and to compare these results with other findings reported previously. ANIMALS: Thirty-two calves that presented with adverse effects after receiving high doses of doxycycline as a treatment for mild respiratory disorders. METHOD: Retrospective review of medical records. RESULTS: Clinical examination identified mainly lethargy, dyspnea, cough, tongue paresia or paralysis associated with dysphagia and sialorrhea, tachycardia, tachypnea, and signs of myopathy. Blood analysis indicated increases in creatine kinase, lactate dehydrogenase, aspartate aminotransferase, and sorbitol dehydrogenase activities and increased serum creatinine and urea concentrations. ECG recordings and Doppler echocardiography examination identified ventricular premature beats and a decrease in left ventricular global and systolic function, respectively. Necropsy and histopathology disclosed necrosis of the myocardium, tongue, and some striated muscles, acute renal tubular necrosis, and fatty degeneration or congestion of the liver. CONCLUSIONS: Most of these findings corroborate previous observations made in doxycycline-overdosed calves, and further suggest myocardial and striated muscular toxicity as well as renal toxicity in doxycycline-overdosed calves. [less ▲]

Detailed reference viewed: 73 (16 ULg)
Peer Reviewed
See detailComparative study of Murid gammaherpesvirus 4 infection in mice and in its natural host, the bank voles.
François, Sylvie ULg; Vidick, Sarah ULg; Koteja, Pawel et al

Poster (2009, December 11)

Gammaherpesviruses are the archetypes of persistent viruses that have been identified in a range of animals from mice to man. They are host-range specific and establish persistent, productive infections ... [more ▼]

Gammaherpesviruses are the archetypes of persistent viruses that have been identified in a range of animals from mice to man. They are host-range specific and establish persistent, productive infections of immunocompetent hosts. Thus, infected individuals simultaneously both elicit antiviral protective immune response and secrete infectious virions. The best studied gammaherpesviruses are Human herpesvirus 4 and Human herpesvirus 8. As these viruses have no well-established in vivo infection model, related animal gammaherpesviruses are an important source of information. We are studying Murid herpesvirus 4 (MuHV-4), a virus that has originally been isolated from bank voles (Myodes glareolus). Although MuHV-4 has not been isolated from house mice (Mus musculus), infection of inbred laboratory mouse strains is commonly accepted as a good model for studying gammaherpesviruses in vivo. It has however never been possible to monitor viral reexcretion and virus transmission in this species suggesting that this model could be imperfect. In this study, we therefore characterized MuHV-4 infection in its natural host, the bank voles, through classical virological methods but also through global luciferase imaging for an anatomical complete view of the infection. Results obtained show that, after intra-nasal infection, the natural route of infection is similar in mice and voles. Following nasal productive infection, the virus spreads to the lung where the infection is accompanied by massive cellular infiltrates. By opposition to extensive viral replication observed in mice, the different analyses indicated that the viral replication was ~1000 fold lower in bank voles. This lower replication did however not affect colonization of latency sites in superficial cervical lymph nodes and spleen as measured by real-time PCR quantification of viral genomes in these organs. In conclusion, this study revealed that MuHV-4 can experimentally infect bank voles, the supposed natural host, but with a lower replicative power. As, gammaherpesvirus epidemiology indicates that transmission correlates with the latent load, our results suggest that gammaherpesviruses may have evolved to infect their hosts without extensive lytic spread. In the future, establishment of experimental transmission in a population of Myodes glareolus should help us to better understand mechanisms used by gammaherpesviruses to evade immune response. [less ▲]

Detailed reference viewed: 16 (6 ULg)
Full Text
Peer Reviewed
See detailPorcine CD18 mediates Actinobacillus pleuropneumoniae ApxIII species-specific toxicity
Vanden bergh, Philippe; Zecchinon, Laurent; Fett, Thomas ULg et al

in Veterinary Research (2009), 40(4), 33

Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, produces Apx toxins that are recognized as major virulence factors. Recently, we showed that ApxIIIA-cytotoxic activity ... [more ▼]

Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, produces Apx toxins that are recognized as major virulence factors. Recently, we showed that ApxIIIA-cytotoxic activity specifically targets Sus scrofa leukocytes. Since both LtxA from Aggregatibacter actinomycetem comitans (aggressive periodontitis in humans) and LktA from Mannheimia haemolytica (pneumonia in ruminants) share this characteristic, respectively towards human and ruminant leukocytes, and because both use the CD18 subunit to interact with their respective LFA-1, we hypothesized that ApxIIIA was likely to bind porcine CD18 to exercise its deleterious effects on pig leukocytes. A beta(2)-integrin-deficient ApxIIIA-resistant human erythroleukemic cell line was transfected either with homologous or heterologous CD11a/ CD18 heterodimers using a set of plasmids coding for human (ApxIIIA-resistant), bovine (-resistant) and porcine (-susceptible) CD11a and CD18 subunits. Cell preparations that switched from ApxIIIA-resistance to -susceptibility were then sought to identify the LFA-1 subunit involved. The results showed that the ApxIIIA-resistant recipient cell line was rendered susceptible only if the CD18 partner within the LFA-1 heterodimer was that of the pig. It is concluded that porcine CD18 is necessary to mediate A. pleuropneumoniae ApxIIIA toxin-induced leukolysis. [less ▲]

Detailed reference viewed: 270 (2 ULg)
See detailSurra-induced lymphopenia is directly triggered by a membrane-associated parasite protein
Antoine-Moussiaux, Nicolas ULg; Cornet, Anne ULg; Cornet, François et al

Conference (2009, May 24)

Detailed reference viewed: 18 (7 ULg)
Full Text
Peer Reviewed
See detailA non-cytosolic protein of Trypanosoma evansi induces CD45-dependent lymphocyte death.
Antoine-Moussiaux, Nicolas ULg; Cornet, Anne ULg; Cornet, François ULg et al

in PLoS ONE (2009), 4(5), 5728

In a recent study dealing with a mouse model of Trypanosoma evansi-associated disease, a remarkable synchrony between the parasitaemia peak and the white-blood-cell count nadir was noticed. The present ... [more ▼]

In a recent study dealing with a mouse model of Trypanosoma evansi-associated disease, a remarkable synchrony between the parasitaemia peak and the white-blood-cell count nadir was noticed. The present study was designed to establish whether there is a direct causal link between the parasite load during its exponential phase of growth and the disappearance of peripheral blood leukocytes. In vitro experiments performed with trypanosomes and purified peripheral blood mononucleated cells revealed the existence of a lymphotoxin embedded in the T. evansi membrane: a protein sensitive to serine proteases, with a molecular mass of less than 30 kDa. Lymphocytes death induced by this protein was found to depend on the intervention of a lymphocytic protein tyrosine phosphatase. When lymphocytes were exposed to increasing quantities of a monoclonal antibody raised against the extracellular portion of CD45, a transmembrane protein tyrosine phosphatase covering over 10% of the lymphocyte surface, T. evansi membrane extracts showed a dose-dependent decrease in cytotoxicity. As the regulatory functions of CD45 concern not only the fate of lymphocytes but also the activation threshold of the TCR-dependent signal and the amplitude and nature of cytokinic effects, this demonstration of its involvement in T. evansi-dependent lymphotoxicity suggests that T. evansi might manipulate, via CD45, the host's cytokinic and adaptive responses. [less ▲]

Detailed reference viewed: 86 (32 ULg)
Full Text
Peer Reviewed
See detailHost-parasite interactions in trypanosomiasis: On the way to an anti-disease strategy.
Antoine-Moussiaux, Nicolas ULg; Buscher, Philippe; Desmecht, Daniel ULg

in Infection and Immunity (2009), 77(4), 1276-1284

African trypanosomiasis (AT) is a family of parasitic conditions affecting both man and livestock, impairing development in sub-Saharan Africa, throughout the 10 million km(2) habitat zone of the common ... [more ▼]

African trypanosomiasis (AT) is a family of parasitic conditions affecting both man and livestock, impairing development in sub-Saharan Africa, throughout the 10 million km(2) habitat zone of the common vector, Glossina spp. ... [less ▲]

Detailed reference viewed: 34 (5 ULg)
Peer Reviewed
See detailInvestigations on Surra-induced lymphopoenia in a murine model
Antoine-Moussiaux, Nicolas ULg; Cornet, Anne ULg; Cornet, et al

Conference (2009, March)

Detailed reference viewed: 14 (3 ULg)
Full Text
Peer Reviewed
See detailLa mannheimiose : d’une liaison (moléculaire) fatale à une des principales maladies d’élevage des ruminants
Fett, Thomas ULg; Zecchinon, Laurent; Vanden Bergh, Philippe et al

in Annales de Médecine Vétérinaire (2009), 153(1), 31-53

Les pneumonies bactériennes constituent un problème majeur dans l'élevage et l'engraissement des bovins, avec des répercussions très élevées en termes de morbidité et de mortalité. Parmi les différentes ... [more ▼]

Les pneumonies bactériennes constituent un problème majeur dans l'élevage et l'engraissement des bovins, avec des répercussions très élevées en termes de morbidité et de mortalité. Parmi les différentes causes biologiques recensées, Mannheimia haemolytica tient le haut de l’affiche puisqu’elle est connue comme agent pathogène compliquant principal, voire systématique. Une de ses particularités est qu’elle ne déclenche de pneumonie broncho-alvéolaire fibrino-hémorragique que chez les ruminants. Les lésions observées résultent d’une nécrose en masse des neutrophiles et macrophages et du relarguage de leurs différents constituants. Au niveau moléculaire, cette spécificité trouve son origine dans l’intimité de la liaison entre la leucotoxine, le facteur de virulence majeur de la bactérie, et la sous-unité CD18 des récepteurs de surface leucocytaires bêta2-intégrines. La revue décrit cette liaison et ses conséquences aux niveaux macroscopique et microscopique, avant de faire le point sur les dernières avancées de la recherche et d’ébaucher quelques perspectives thérapeutiques. [less ▲]

Detailed reference viewed: 35 (5 ULg)
Full Text
Peer Reviewed
See detailA Critical Appraisal of Carbon Monoxide Uptake Measurements for the Follow-up of Experimental Respiratory Diseases in the Laboratory Mouse
Habyarimana, Jean Adélite; Flandre, Thierry; Faisca, Pedro et al

in Scandinavian Journal of Laboratory Animal Science (2009), 36(3), 229-240

Adaptation of double-chamber plethysmography to the laboratory mouse was recently proven to yield stable and reliable pulmonary function values. This approach to investigation of the respiratory function ... [more ▼]

Adaptation of double-chamber plethysmography to the laboratory mouse was recently proven to yield stable and reliable pulmonary function values. This approach to investigation of the respiratory function in mice owes its success to its decisive advantages in terms of non-invasiveness, practical implementation and generation of quantitative flow/volume measurements and nondisputed airway resistance calculation. When implemented to screen the resistance/susceptibility patterns to pathogens displayed by a panel of mouse inbred strains, the resistance value obtained was indeed able to detect tracheobronchic inflammation and to scale its severity. However, extension of the pathological process to most distal parts of the respiratory system did not translate in further alteration of resistance, suggesting that its value rather reflects constraints acting on airflow in the airways than pathologic processes located in the more distal parts of the lungs. In this context, we hypothesized that a more exhaustive functional picture could be obtained, still noninvasively, by combining double-chamber plethysmography with carbon monoxide (CO) uptake measurements. The feasibility of CO-uptake measurements in mice was demonstrated and the conditions under which reproducibility can be maximized were defined. Differences linked to strain, somatic growth, and sex were examined and discussed, and reference values in growing male and female conscious and healthy BALB/cBy, SJL/J, C57BL/6, C3H/HeN, DBA/2 and 129/Sv mice were given. Finally, double-chamber plethysmography and CO-uptake values were proven to be exquisitely complementary in assessing and dissecting the functional impact of Sendai virus pneumonia in the laboratory mouse. [less ▲]

Detailed reference viewed: 54 (10 ULg)
Full Text
Peer Reviewed
See detailModulating mouse innate immunity to RNA viruses by expressing the Bos taurus Mx system.
Garigliany, Mutien-Marie ULg; Cloquette, Karine ULg; Leroy, Michael et al

in Transgenic Research (2009), 18(5), 719-32

Mx proteins are interferon-induced members of the dynamin superfamily of large guanosine triphosphatases. These proteins have attracted much attention because some display antiviral activity against ... [more ▼]

Mx proteins are interferon-induced members of the dynamin superfamily of large guanosine triphosphatases. These proteins have attracted much attention because some display antiviral activity against pathogenic RNA viruses, such as members of the orthomyxoviridae, bunyaviridae, and rhabdoviridae families. Among the diverse mammalian Mx proteins examined so far, we have recently demonstrated in vitro that the Bos taurus isoform 1 (boMx1) is endowed with exceptional anti-rabies-virus activity. This finding has prompted us to seek an appropriate in vivo model for confirming and evaluating gene therapy strategies. Using a BAC transgene, we have generated transgenic mouse lines expressing the antiviral boMx1 protein and boMx2 proteins under the control of their natural promoter and short- and long-range regulatory elements. Expressed boMx1 and boMx2 are correctly assembled, as deduced from mRNA sequencing and western blotting. Poly-I/C-subordinated expression of boMx1 was detected in various organs by immunohistochemistry, and transgenic lines were readily classified as high- or low-expression lines on the basis of tissue boMx1 concentrations measured by ELISA. Poly-I/C-induced Madin-Darby bovine kidney cells, bovine turbinate cells, and cultured cells from high-expression line of transgenic mice were found to contain about the same concentration of boMx1, suggesting that this protein is produced at near-physiological levels. Furthermore, insertion of the bovine Mx system rendered transgenic mice resistant to vesicular-stomatitis-virus-associated morbidity and mortality, and embryonic fibroblasts derived from high-expression transgenic mice were far less permissive to the virus. These results demonstrate that the Bos taurus Mx system is a powerful anti-VSV agent in vivo and suggest that the transgenic mouse lines generated here constitute a good model for studying in vivo the various antiviral functions-known and yet to be discovered-exerted by bovine Mx proteins, with priority emphasis on the antirabic function of boMx1. [less ▲]

Detailed reference viewed: 62 (13 ULg)
See detailLa cytolyse des leucocytes caprins induite par la leucotoxine de Mannheimia haemolytica est mediée par la sous-unité CD18 des bêta2-intégrines
Fett, Thomas ULg; Zecchinon, Laurent; Vanden bergh, Philippe et al

Conference (2008, September 23)

La mannheimiose est la maladie respiratoire prédominante parmi les ruminants alors qu’elle n’affecte pas les autres mammifères. Cette spécificité d’espèces trouve son origine dans l’interaction tout aussi ... [more ▼]

La mannheimiose est la maladie respiratoire prédominante parmi les ruminants alors qu’elle n’affecte pas les autres mammifères. Cette spécificité d’espèces trouve son origine dans l’interaction tout aussi spécifique entre la leucotoxine (LktA) de Mannheimia haemolytica et la sous-unité CD18 du récepteur LFA-1 des bêtes bovine et ovine. Nous avons ainsi postulé que la LktA utilisait également le CD18 comme récepteur sur les leucocytes caprins. Pour démontrer cette hypothèse, nous avons transfecté la lignée lymphoblastique K-562, naturellement déficiente en bêta2-intégrines, avec les ADNcs encodant les CD11a et CD18 caprins afin de déterminer la susceptibilité des transfectants à la cytolyse induite par la LktA. Une analyse par cytométrie en flux a révélé l’expression en surface du LFA-1 caprin et la lyse par la LktA de manière dose-dépendante alors que la lignée parentale restait insensible. Par ailleurs, les cellules K-562 exprimant le CD18 caprin et le CD11a humain ou bovin sont également sensibles à la LktA alors que les K-562 exprimant le CD11a caprin et le CD18 humain ne le sont pas. Pris dans leur ensemble, ces résultats indiquent que le CD18 des leucocytes caprins sert de récepteur à la LktA de Mannheimia haemolytica. [less ▲]

Detailed reference viewed: 32 (0 ULg)
See detailÉvaluation de 16 mutants du CD18 bovin en vue d’identifier le motif moléculaire responsable de la spécificité d’espèces de Mannheimia haemolytica envers les ruminants
Zecchinon, Laurent; Fett, Thomas ULg; Vanden bergh, Philippe et al

Conference (2008, September 23)

La mannheimiose est la maladie respiratoire prédominante parmi les ruminants alors qu’elle n’affecte pas les autres mammifères. Elle trouve son origine dans l’interaction spécifique entre la leucotoxine ... [more ▼]

La mannheimiose est la maladie respiratoire prédominante parmi les ruminants alors qu’elle n’affecte pas les autres mammifères. Elle trouve son origine dans l’interaction spécifique entre la leucotoxine (LktA) de Mannheimia hæmolytica et la sous-unité CD18 des récepteurs LFA-1 (CD11a/CD18) et Mac-1 (CD11b/CD18) des ruminants. La comparaison des séquences des CD18 de ces derniers et des non-ruminants nous a préalablement permis de mettre en évidence 16 sites qui pouvaient être tenus pour responsables de la spécificité d’espèces de M. haemolytica. Nous avons ainsi utilisé la lignée lymphoblastique humaine K-562, naturellement déficientes en bêta2-intégrines et donc insensibles à la LktA, pour la transfecter de manière transitoire avec les ADNcs codant pour le CD11a bovin et soit le CD18 bovin original, soit une version de celui-ci muté à une des positions d’intérêt, pour obtenir 17 lignées cellulaires différentes. Une analyse par cytométrie en flux a révélé l’expression en surface du LFA-1 bovin natif et de 15 des 16 mutants. Toutes les lignées (sauf celle n’exprimant pas son LFA-1 muté) ont présenté une sensibilité à la cytolyse induite par la LktA et ce, de manière dose-dépendante. Pris dans leur ensemble, ces résultats suggèrent que si certains des sites relevés précédemment jouent un rôle-clé dans la susceptibilité à la LktA de Mannheimia haemolytica, ils ne le font pas à titre individuel. [less ▲]

Detailed reference viewed: 17 (2 ULg)
See detailLa bêta2-intégrine LFA-1 est le récepteur de la toxine ApxIIIA d’Actinobacillus pleuropneumoniae sur les leucocytes porcins
Vanden bergh, Philippe; Zecchinon, Laurent; Fett, Thomas ULg et al

Conference (2008, September 22)

Actinobacillus pleuropneumoniae, l’agent étiologique de la pleuropneumonie porcine, produit des toxines dites « RTX » (ApxIA, -IIA, -IIIA et -IVA) reconnues comme facteurs de virulence majeurs. Les cibles ... [more ▼]

Actinobacillus pleuropneumoniae, l’agent étiologique de la pleuropneumonie porcine, produit des toxines dites « RTX » (ApxIA, -IIA, -IIIA et -IVA) reconnues comme facteurs de virulence majeurs. Les cibles moléculaires de la liaison de ces toxines sur les cellules porcines n’ont pas été identifiées. Toutefois, il a été démontré que la virulence d’Aggregatibacter actinomycetemcomitans, de Mannheimia haemolytica et de souches pathogènes d’Escherichia coli est associée à l’interaction de leur toxine RTX respective (LtxA, LktA et HlyA) avec le récepteur β2-intégrine CD11a(αL)/CD18(β2) (LFA-1) des leucocytes. Le résultat de cette liaison est une nécrose cellulaire libérant des cytokines et des agents chimiotactiques qui exacerbent l’inflammation et créent un afflux supplémentaire de leucocytes, ce qui génère un cercle vicieux dont on pense qu’il constitue le processus central de la pathogenèse. Comme les toxines Apx sont, moléculairement parlant, très similaires aux toxines précitées, et en raison du fait que les lésions tissulaires qu’elles induisent ressemblent aux lésions causées par les bactéries précitées, nous avons émis l’hypothèse que la pathogenèse de la pleuropneumonie à A. pleuropneumoniae pourrait également dépendre de l’interaction des toxines Apx avec le récepteur LFA-1 porcin (PoLFA-1). Dans ce contexte, nous avons transfecté la lignée lymphoïde humaine K562, réputée ne pas exprimer de β2-intégrines et totalement insensible à la toxine ApxIIIA, avec des plasmides codant les sous-unités PoCD11a et PoCD18. En procédant de la sorte, nous sommes parvenus à rendre cette lignée dûment sensible à la toxine ApxIIIA et en avons conclu que le PoLFA-1 est bien le récepteur enrôlé dans l’interaction cytopathogène. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Full Text
Peer Reviewed
See detailContributions of experimental mouse models to the understanding of African trypanosomiasis.
Antoine-Moussiaux, Nicolas ULg; Magez, Stefan; Desmecht, Daniel ULg

in Trends in Parasitology (2008), 24(9), 411-8

African trypanosomiasis is the collective name for a wide variety of trypanosome infections that affect humans and livestock. In recent years, experimental mice infection models have provided new insights ... [more ▼]

African trypanosomiasis is the collective name for a wide variety of trypanosome infections that affect humans and livestock. In recent years, experimental mice infection models have provided new insights into both human and animal trypanosomiasis. Mouse models seem to be a valuable and versatile tool in trypanosomiasis-associated pathology and immunology research and highlight the variety shown by African trypanosomiases. Indeed, inbred mouse strains have enabled the study of genetic determinants of susceptibility and of the roles of anti-parasite antibodies, inflammatory mediators and anti-inflammatory mediators for each trypanosome species. Remarkable advances relating to the encephalitic stage of sleeping sickness have also been achieved thanks to murine models. The different contributions of murine models to the African trypanosomiases knowledge are presented here. Future search directions are finally proposed, with respect to mouse model opportunities and limitations. [less ▲]

Detailed reference viewed: 34 (8 ULg)
Full Text
Peer Reviewed
See detailFlow cytometric enumeration of parasitaemia and haematologic changes in trypanosoma-infected mice.
Antoine-Moussiaux, Nicolas ULg; Saerens, Dirk; Desmecht, Daniel ULg

in Acta Tropica (2008), 107(2), 139-44

African trypanosomiasis is a severe parasitic disease affecting both man and livestock. It is crucial to expand our fundamental knowledge of the intimate interactions between trypanosomes and their ... [more ▼]

African trypanosomiasis is a severe parasitic disease affecting both man and livestock. It is crucial to expand our fundamental knowledge of the intimate interactions between trypanosomes and their vertebrate hosts in order to develop new and efficient control strategies. The mouse model of trypanosomiasis is the most popular for research purposes because of all the logistic advantages of using this species. Studies of any aspect of trypanosomiases in the mouse systematically require the quantification of some phenotypic traits which translate its degree of resistance/susceptibility to the disease, as blood cell counts. The present study presents a methodological approach combining everyday microsampling of tail blood and its analysis by flow cytometry. The technical options and conditions permitting a fast, reliable and reproducible daily quantification of erythrocyte, reticulocyte, leucocyte and trypanosome counts in the inoculated mouse were established. The protocol proposed allows the multiplication of blood samplings without being exposed to the time-consuming constraint of visual countings, without causing iatrogenic blood cell alterations in the mouse and without requiring specific anti-trypanosome antibodies. [less ▲]

Detailed reference viewed: 23 (5 ULg)