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See detailSecreted subtilisins of Microsporum canis are involved in adherence of arthroconidia to feline corneocytes.
Baldo, Aline ULg; Tabart, Jeremy; Vermout, Sandy et al

in Journal of Medical Microbiology (2008), 57(Pt 9), 1152-1156

Microsporum canis is a pathogenic fungus that causes a superficial cutaneous infection called dermatophytosis, mainly in cats and humans. The mechanisms involved in adherence of M. canis to epidermis have ... [more ▼]

Microsporum canis is a pathogenic fungus that causes a superficial cutaneous infection called dermatophytosis, mainly in cats and humans. The mechanisms involved in adherence of M. canis to epidermis have never been investigated. Here, a model was developed to study the adherence of M. canis to feline corneocytes through the use of a reconstructed interfollicular feline epidermis (RFE). In this model, adherence of arthroconidia to RFE was found to be time-dependent, starting at 2 h post-inoculation and still increasing at 6 h. Chymostatin, a serine protease inhibitor, inhibited M. canis adherence to RFE by 53%. Moreover, two mAbs against the keratinolytic protease subtilisin 3 (Sub3) inhibited M. canis adherence to RFE by 23%, suggesting that subtilisins, and Sub3 in particular, are involved in the adherence process. [less ▲]

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See detailSecreted dipeptidyl peptidases as potential virulence factors for Microsporum canis.
Vermout, Sandy; Baldo, Aline ULg; Tabart, Jeremy et al

in FEMS Immunology & Medical Microbiology (2008), 54(3), 299-308

Dermatophytoses caused by Microsporum canis are frequently encountered in cats and dogs; they are highly contagious and readily transmissible to humans. In this study, two single genes, respectively ... [more ▼]

Dermatophytoses caused by Microsporum canis are frequently encountered in cats and dogs; they are highly contagious and readily transmissible to humans. In this study, two single genes, respectively coding for dipeptidyl peptidases IV and V (DppIV and DppV), were isolated and characterized. Both proteins share homology with serine proteases of the S9 family, some of which display properties compatible with implication in pathogenic processes. Both genes are expressed in vivo in experimentally infected guinea-pigs and in naturally infected cats, and when the fungus is grown on extracellular matrix proteins as the sole nitrogen and carbon source. DppIV and V were produced as active recombinant proteases in the yeast Pichia pastoris; the apparent molecular weight of rDppV is 83 kDa, whereas rDppIV appears as a doublet of 95 and 98 kDa. Like other members of its enzymatic subfamily, rDppIV has an unusual ability to cleave Pro-X bonds. This activity does not enhance the solubilization of keratin by fungal secreted endoproteases, and the protease probably acts solely on small soluble peptides. RDppV showed no ability to induce delayed-type hypersensitivity (DTH) skin reactions in guinea-pigs, despite the known immunogenic properties of homologous proteins. [less ▲]

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See detailDermatophytes and Dermatophytoses
Chaturvedi, Vishnu; Bouchara, Jean-Philippe; Mignon, Bernard ULg

in Mycopathologia (2008), 166(5-6), 235-424

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See detailNouvelles données sur la teigne chez le chien et le chat
Mignon, Bernard ULg

in Le Nouveau Praticien Vétérinaire (2008)

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See detailEditorial: dermatophytes and dermatophytoses: a reappraisal for the twenty-first century
Bouchara, J. P.; Mignon, Bernard ULg; Chaturvedi, V.

in Mycopathologia (2008), 166(5-6), 235-237

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See detailRNA silencing in the dermatophyte Microsporum canis
Vermout, S.; Tabart, J.; Baldo, Aline ULg et al

in FEMS Microbiology Letters (2007), 275(1), 38-45

Dermatomycoses caused by Microsporum canis are frequent in domestic animals and easily transmissible to humans. Several proteases secreted by this fungus were identified as potential virulence factors ... [more ▼]

Dermatomycoses caused by Microsporum canis are frequent in domestic animals and easily transmissible to humans. Several proteases secreted by this fungus were identified as potential virulence factors, but the construction of deficient strains is required to investigate their role in the pathogenesis of the disease. Using target genes encoding two of these proteases, a first evaluation of the utility of RNA-mediated silencing as a reverse genetic tool in dermatophytes was carried out. SUB3 and DPPIV, respectively coding for a subtilisin and a dipeptidyl peptidase, were both down-regulated, by means of two plasmid constructs designed to express an RNA hairpin that corresponds to part of their respective sequence. The degree of attenuation was evaluated by enzymatic assay of the transformants culture supernatants, and by real-time reverse transcriptase-polymerase chain reaction. Enzymatic activities and expression levels varied from less than 5% to 100% of that of control transformants obtained with plasmid without hairpin inserts. Inhibition was globally more efficient for SUB3 than for DPPIV. These results show that RNA silencing can be used for functional genomics in M. canis, and particularly to circumvent the limits and technical difficulties of conventional disruption methods. [less ▲]

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See detailReconstructed interfollicular feline epidermis as a model for Microsporum canis dermatophytosis
Tabart, Jérémy; Baldo, Aline ULg; Vermout, Sandy et al

in Journal of Medical Microbiology (2007), 56(7), 971-975

Microsporum canis is a pathogenic fungus that causes a superficial cutaneous infection called dermatophytosis. The complexity of mechanisms involved in dermatophytic infections makes relevant in vivo ... [more ▼]

Microsporum canis is a pathogenic fungus that causes a superficial cutaneous infection called dermatophytosis. The complexity of mechanisms involved in dermatophytic infections makes relevant in vivo studies particularly difficult to perform. The aim of this study was to develop a new in vitro model of M. canis dermatophytosis using feline fetal keratinocytes in reconstructed interfollicular epidermis, and to investigate its relevance in studying the host-pathogen relationship. Histological analysis of reconstructed interfollicular feline epidermis (RFE) revealed a fully differentiated epidermis. A proliferation assay showed replicating cells only in the basal layer, indicating that RFE is a well-stratified living tissue, leading to the formation of a horny layer. Histopathological analysis of RFE infected by M. canis arthroconidia revealed that the fungus invades the stratum corneum and produces SUB3, a keratinase implicated in the infectious process. In view of these results, an M. canis dermatophytosis model on RFE seems to be a useful tool to investigate mechanisms involved in natural M. canis feline infections. [less ▲]

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See detailLes mécanismes d'adhérence des champignons responsables de mycoses superficielles
Baldo, Aline ULg; Mathy, Anne ULg; Vermout, S. et al

in Annales de Médecine Vétérinaire (2007), 151

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See detailBiting Midges Overwintering In Belgium
Losson, Bertrand ULg; Mignon, Bernard ULg; Paternostre, Julien ULg et al

in Veterinary Record : Journal of the British Veterinary Association (2007), 160(13), 451-452

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See detailReconstructed interfollicular feline epidermis as a model for the screening of drugs against Microsporum canis
Mignon, Bernard ULg; Tabart, J.; Baldo, Aline ULg et al

in Veterinary Dermatology (2007), 18

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See detailAttitude pratique à tenir face à une dermatose prurigineuse chez le chat
Mignon, Bernard ULg

Conference given outside the academic context (2006)

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See detailIn vitro entomopathogenic activity of Beauveria bassiana against Psoroptes spp. (Acari : Psoroptidae)
Lekimme, Mireille ULg; Mignon, Bernard ULg; Tombeux, S. et al

in Veterinary Parasitology (2006), 139(1-3), 196-202

An indigenous strain (IHEM 18747) of Beauveria bassiana (Balsamo) Vuillemin (Deuteromycetes) was evaluated for its in vitro entomopathogenic activity against the parasitic mite Psoroptes ovis Hering ... [more ▼]

An indigenous strain (IHEM 18747) of Beauveria bassiana (Balsamo) Vuillemin (Deuteromycetes) was evaluated for its in vitro entomopathogenic activity against the parasitic mite Psoroptes ovis Hering (Acari: Psoroptidae) from rabbits. The following aspects were evaluated: (1) effects of conidial concentration on the viability of adult females; (2) influence of the infection on the fertility, and on the hatchability of eggs; (3) and transmission of infection between mites, and from contaminated surface. Adult females immersed into increasing concentrations of conidia (10(4)-10(9) conidia ml(-1)) showed a dose-related susceptibility. At the highest concentration of conidia, LT50 was 1.6 days while LT50 of the controls reached 5.8 days. The fungus was able to sporulate on the body surface and 100% of the mites were covered with mycelium after immersion in solutions containing 10(7)-10(9) conidia ml(-1). One hundred percent of healthy mites exposed to infected cadavers or surfaces acquired the infection (LT50 reached 1.9 and 1.73 days, respectively, versus 6.1 and 5.1 days in controls, respectively). Egg laying was not reduced by the fungal infection but both the hatchability of the eggs and the life span of the emerging larvae were significantly reduced. Eggs directly infected with the fungus did not show reduced hatchability but the life span of the larvae was shortened. It is concluded that B. bassiana has a high entomopathogenic activity against Psoroptes spp. The in vivo use of this biocontrol agent against Psoroptes spp. in rabbit, sheep and cattle deserves further attention. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailIn vitro tests for evaluation of the hatchability of the eggs of Psoroptes mites following exposure to acaricidal compounds.
Lekimme, Mireille ULg; Mignon, Bernard ULg; Leclipteux, Thierry ULg et al

in Medical and Veterinary Entomology (2006), 20(1), 102-105

Three in vitro assays for the evaluation of the hatchability of the eggs of the mite Psoroptes ovis (Hering) (Acari: Psoroptidae) are described. Preliminary trials showed that hatching occurs at very high ... [more ▼]

Three in vitro assays for the evaluation of the hatchability of the eggs of the mite Psoroptes ovis (Hering) (Acari: Psoroptidae) are described. Preliminary trials showed that hatching occurs at very high rates when eggs are incubated under conditions of high humidity, on a liquid medium and in agarose dishes. These three protocols were compared, taking into account the ease of preparation, follow-up and accuracy of counting. The best protocol was found to be the use of agarose dishes. It was accurate, easy to carry out and reproducible for further evaluation of existing or potentially new compounds against both adults and eggs of Psoroptes spp. The acaricidal properties of phoxim and amitraz were then evaluated against eggs and adults using the three protocols. Results showed that for both drugs, in vitro adulticidal activity was complete, whereas the in vitro ovicidal activity was only partial. Nevertheless, efficacy of amitraz against both adults and eggs was shown to be higher than that of phoxim. [less ▲]

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See detailEffect of sampling method and culture conditions on the result of fungal culture in the diagnosis of canine sino-nasal aspergillosis.
Legarrérès, A.; Clercx, Cécile ULg; Mignon, Bernard ULg et al

in Proceedings of the 24th VCRS meeting (2006)

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See detailKinetics of Microsporum canis adherence using an in vitro model of reconstituted feline epidermis
Baldo, Aline ULg; Tabart, J.; Vermout, S. et al

Conference (2006)

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See detailDermatophyties
Mignon, Bernard ULg

in Guaguère E., Prélaud P. (Ed.) Guide pratique de dermatologie canine (2006)

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