Subtilisin Sub3 is involved in adherence of Microsporum canis to human and animal epidermis

Remarkable Phenotypic Virulence Factors of Microsporum canis and Their Associated Genes: A Systematic Review

Microsporum canis is a widely distributed dermatophyte, which is among the main etiological agents of dermatophytosis in humans and domestic animals. This fungus invades, colonizes and nourishes itself on the keratinized tissues of the host through various virulence factors. This review will bring together the known information about the mechanisms, enzymes and their associated genes relevant to the pathogenesis processes of the fungus and will provide an overview of those virulence factors that should be better studied to establish effective methods of prevention and control of the disease. Public databases using the MeSH terms "Microsporum canis", "virulence factors" and each individual virulence factor were reviewed to enlist a series of articles, from where only original works in English and Spanish that included relevant information on the subject were selected. Out of the 147 articles obtained in the review, 46 were selected that reported virulence factors for M. canis in a period between 1988 and 2023. The rest of the articles were discarded because they did not contain information on the topic (67), some were written in different languages (3), and others were repeated in two or more databases (24) or were not original articles (7). The main virulence factors in M. canis are keratinases, fungilisins and subtilisins. However, less commonly reported are biofilms or dipeptidylpeptidases, among others, which have been little researched because they vary in expression or activity between strains and are not considered essential for the infection and survival of the fungus. Although it is known that they are truly involved in resistance, infection and metabolism, we recognize that their study could strengthen the knowledge of the pathogenesis of M. canis with the aim of achieving effective treatments, as well as the prevention and control of infection.

Subtilisin 3 production from Microsporum canis is independent of keratin substrate availability

Dermatophytes are highly infectious fungi that cause superficial infections in keratinized tissues in humans and animals. This group of fungi is defined by their ability to digest keratin and encompasses a wide range of species. We investigated a critical adhesion protein, subtilisin 3, utilized by Microsporum canis during initial stages of infection, analyzing its production and expression under varying growth conditions. Additionally, as this protein must be expressed and produced for dermatophyte infections to occur, we developed and optimized a diagnostic antibody assay targeting this protein. Subtilisin 3 levels were increased in culture when grown in baffled flasks and supplemented with either l-cysteine or cat hair. As subtilisin 3 was also produced in cultures not supplemented with keratin or cysteine, this study demonstrated that subtilisin 3 production is not reliant on the presence of keratin or its derivatives. These findings could help direct future metabolic studies of dermatophytes, particularly during the adherence phase of infections.

The inhibitory effects of zinc oxide nanoparticles on clinical isolates of Microsporum canis in dogs and cats

INTRODUCTION

Microsporum canis is the most common dermatophyte infecting pets and their owners, and its long duration of treatment and increasing rate of drug resistance have caused the attention of researchers to be directed towards the use of nanoparticles and new alternatives for treatment. This study investigated the antifungal effects of zinc oxide (ZnO) nanoparticles on clinical isolates of M. canis in dogs and cats and subtilisin 1 (SUB1) gene expression.

MATERIALS AND METHODS

Zinc oxide nanoparticles were prepared using the wet chemical method at a concentration of 4000 ppm. Its antifungal potential was evaluated at concentrations of 62.5-4000 ppm by disk diffusion and microdilution methods against 10 isolates of M. canis. The effect of this product on SUB1 gene expression was investigated by quantitative real-time PCR method.

RESULTS

The results of the disk diffusion test showed that the highest inhibitory diameter was at the highest concentration of ZnO nanoparticles (34 mm), and the inhibitory zone was observed in dilutions up to 250 ppm. The minimum inhibitory concentration (MIC) of ZnO nanoparticles was between 250 and 500 ppm, and the minimum fungicidal concentration was between 500 and 1000 ppm. There was a significant reduction in SUB1 gene expression in sub-MIC concentration (125-250 ppm) (p < 0.05).

CONCLUSION

This study showed that ZnO nanoparticles have a concentration-dependent inhibitory effect on M. canis. Moreover, ZnO nanoparticles could decrease the expression of SUB1, an enzyme involved in fungi adhesion to the epidermis. Nevertheless, more studies must be done in the future to determine the possible side effects and safety of ZnO nanoparticles along with their efficacy in vivo.

Dermatophyte infection: from fungal pathogenicity to host immune responses

Dermatophytosis is a common superficial infection caused by dermatophytes, a group of pathogenic keratinophilic fungi. Apart from invasion against skin barrier, host immune responses to dermatophytes could also lead to pathologic inflammation and tissue damage to some extent. Therefore, it is of great help to understand the pathogenesis of dermatophytes, including fungal virulence factors and anti-pathogen immune responses. This review aims to summarize the recent advances in host-fungal interactions, focusing on the mechanisms of anti-fungal immunity and the relationship between immune deficiency and chronic dermatophytosis, in order to facilitate novel diagnostic and therapeutic approaches to improve the outcomes of these patients.

Characterization of Pseudogymnoascus destructans conidial adherence to extracellular matrix: Association with fungal secreted proteases and identification of candidate extracellular matrix binding proteins

Pseudogymnoascus destructans is the etiological agent of white-nose syndrome (WNS), a fungal skin infection of hibernating bats. Pathophysiology of the disease involves disruption of bat metabolism and hibernation patterns, which subsequently causes premature emergence and mortality. However, information on the mechanism(s) and virulence factors of P. destructans infection is minimally known. Typically, fungal adherence to host cells and extracellular matrix (ECM) is the critical first step of the infection. It allows pathogenic fungi to establish colonization and provides an entry for invasion in host tissues. In this study, we characterized P. destructans conidial adherence to laminin and fibronectin. We found that P. destructans conidia adhered to laminin and fibronectin in a dose-dependent, time-dependent and saturable manner. We also observed changes in the gene expression of secreted proteases, in response to ECM exposure. However, the interaction between fungal conidia and ECM was not specific, nor was it facilitated by enzymatic activity of secreted proteases. We therefore further investigated other P. destructans proteins that recognized ECM and found glyceraldehyde-3-phosphate dehydrogenase and elongation factor 1-alpha among the candidate proteins. Our results demonstrate that P. destructans may use conidial surface proteins to recognize laminin and fibronectin and facilitate conidial adhesion to ECM. In addition, other non-specific interactions may contribute to the conidial adherence to ECM. However, the ECM binding protein candidates identified in this study highlight additional potential fungal virulence factors worth investigating in the P. destructans mechanism of infection in future studies.

Current Topics in Dermatophyte Classification and Clinical Diagnosis

Dermatophytes are highly infectious fungi that cause superficial infections in keratinized tissues in humans and animals. This group of fungi is defined by their ability to digest keratin and encompasses a wide range of species. Classification of many of these species has recently changed due to genetic analysis, potentially affecting clinical diagnosis and disease management. In this review, we discuss dermatophyte classification including name changes for medically important species, current and potential diagnostic techniques for detecting dermatophytes, and an in-depth review of Microsporum canis, a prevalent zoonotic dermatophyte. Fungal culture is still considered the “gold standard” for diagnosing dermatophytosis; however, modern molecular assays have overcome the main disadvantages of culture, allowing for tandem use with cultures. Further investigation into novel molecular assays for dermatophytosis is critical, especially for high-density populations where rapid diagnosis is essential for outbreak prevention. A frequently encountered dermatophyte in clinical settings is M. canis, which causes dermatophytosis in humans and cats. M. canis is adapting to its primary host (cats) as one of its mating types (MAT1-2) appears to be going extinct, leading to a loss of sexual reproduction. Investigating M. canis strains around the world can help elucidate the evolutionary trajectory of this fungi.

A Comparative Study on the Phenotypic Versus Molecular Identification of Clinical Dermatophytes

Dermatophytosis is the superficial infection of keratinized tissue like skin, hair, and nails, in humans and animals, by a group of closely related fungi known as dermatophytes. Phenotypic identification of dermatophytes, especially through classical methods can be difficult and uncertain at times, especially when differentiating species with overlapping characteristics. Alternative identification methods based on amplification and sequence analysis of the highly polymorphic internal transcribed spacer (ITS) sequences flanking the 5.8S ribosomal RNA gene has proven to be quite sensitive and reliable. The objective of our study was to compare the phenotypic and the ITS sequencing-based methods for the identification of clinically isolated dermatophyte specimens from Puducherry, India. A total of 13 clinical samples from 39 suspected cases were found positive for dermatophytes using KOH/DMSO preparations. Specimens were subsequently cultured in Sabouraud dextrose agar (SDA) supplemented with chloramphenicol, gentamicin, and cycloheximide. Dermatophytes were identified based on culture characteristics and microscopic examination in lactophenol cotton blue preparations. ITS sequencing was additionally performed after PCR amplification for species identification. Identification based on phenotype through microscopy and culture methods confirmed infections with Trichophyton mentagrophytes (n = 11), T. rubrum (n = 1), and Microsporum gypseum (n = 1). The strains were confirmed by ITS sequencing without any discrepancy with phenotypic identification. Identification of common dermatophytes based on phenotypic characteristics may be used as a reliable method of diagnosis where sophisticated methods like ITS sequencing and PCR are unavailable.

Comprehensive Assessment of the Virulence Factors sub 3, sub 6 and mcpA in the Zoonotic Dermatophyte Trichophyton benhamiae Using FISH and qPCR

Skin infections by keratinophilic fungi are commonly referred to as dermatophytosis and represent a major health burden worldwide. Although patient numbers are on the rise, data on virulence factors, their function and kinetics are scarce. We employed an ex vivo infection model based on guinea pig skin explants (GPSE) for the zoonotic dermatophyte Trichophyton (T.) benhamiae to investigate kinetics of the virulence factors subtilisin (sub) 3, sub 6, metallocarboxypeptidase A (mcpA) and isocitrate lyase (isol) at gene level for ten days. Fluorescence in situ hybridization (FISH) and quantitative polymerase chain reaction (qPCR) were used to detect and quantify the transcripts, respectively. Kingdom-spanning, species-specific and virulence factor-specific probes were successfully applied to isolated fungal elements showing inhomogeneous fluorescence signals along hyphae. Staining results for inoculated GPSE remained inconsistent despite thorough optimization. qPCR revealed a significant increase of sub 3- and mcpA-transcripts toward the end of culture, sub 6 and isol remained at a low level throughout the entire culture period. Sub 3 is tightly connected to the de novo formation of conidia during culture. Since sub 6 is considered an in vivo disease marker. However, the presented findings urgently call for further research on the role of certain virulence factors during infection and disease.

Assessment of the subtilisin gene profile in Trichophyton verrucosum isolated from human and animal dermatophytoses in two-stage multiplex PCR

AIMS

Keratin is a fibrous and recalcitrant structural protein and the third most abundant polymer in nature after cellulose and chitin. Subtilisin-like proteases (SUB) are a group of serine endoproteases, coded by seven genes (SUB1-7), which decompose keratin structures and have been isolated from dermatophytes. Herein, we identified the SUB genes in 30 clinical isolates of Trichophyton verrucosum obtained from human and animal dermatophytosis as well as asymptomatic animal carriers.

METHODS AND RESULTS

We designed and proposed a two-stage multiplex PCR technique to detect all seven genes encoding serine proteases in dermatophytes. The analysis revealed the presence SUB1 and SUB2 amplicons in all strains regardless of the host. In the group of isolates obtained from humans, all seven subtilisin genes were shown in 40% of the strains. In T. verrucosum from asymptomatic animals, none of the isolates showed the presence of all seven subtilisin genes, and only 30% had six genes. In turn, 10% of the isolates from symptomatic animals demonstrated all seven subtilisins amplicons.

CONCLUSIONS

In conclusion, the severity of infection and ability of T. verrucosum to cause dermatophytosis in humans may not be related to specific genes but their accumulation and synergistic effects of their products.

SIGNIFICANCE AND IMPACT OF THE STUDY

Dermatophytes are pathogenic filamentous fungi with capacity to attack keratinized structures such as skin, hair and nails, causing cutaneous superficial infections. Indeed, a biological characteristic of dermatophytes is their ability to invade keratin-rich tissues by producing enzymes. Various degrees of inflammatory responses can be induced exactly by the enzymes. Subtilisin-like proteases are endoproteases, which decompose keratin structures. Our study identifies SUB genes in clinical isolates of T. verrucosum obtained from human and animal dermatophytosis as well as asymptomatic animal carriers.

Comparative Analysis of Putative Virulence-Associated Factors of Microsporum canis Isolates from Human and Animal Patients

Microsporum canis is a zoophilic dermatophyte and the most common fungus isolated from dogs and cats worldwide. To invade skin, this pathogen uses different enzymes, which may be associated with virulence, that contribute to the fungal pathogenicity. The aim of this study is to compare the expression of enzymes that may be associated with virulence, and thermotolerance of M. canis strains isolated from dogs, cats, and humans. The in vitro expression of the enzymes keratinase, catalase, urease, hemolysin, and aspartic protease was evaluated in 52 M. canis strains recently isolated from 14 human patients, 12 dogs, 15 symptomatic, and 11 asymptomatic cats. In addition, thermotolerance was assessed by comparative analysis of fungal growth at 25 °C and 35 °C. Keratinase activity was low in 34 and moderate in 18 strains. Aspartic-protease activity was low in 7, moderate in 33, and high in 12 strains. Hemolysin activity was low in 44 and moderate in 8 strains. All strains were classified as low producers of catalase. All but three strains produced urease in vitro, with a broad range of activity. The strains presented in vitro growth at the two studied temperatures were classified as presenting low (36.5%), medium (44.3%), or high (19.2%) thermotolerance. There was no statistically significant difference in the new putative virulence-associated factors studied among the different hosts, which suggests that they may have a similar role on human, cat, and dog infection. Also, no difference was observed between strains isolated from symptomatic and asymptomatic cats. This suggests that these factors have a limited impact on the fate of feline dermatophytosis caused by M. canis.

Evaluation of an Explanted Porcine Skin Model to Investigate Infection with the Dermatophyte Trichophyton rubrum

Dermatophytosis is a fungal infection of skin, hair and nails, and the most frequently found causative agent is Trichophyton rubrum. The disease is very common and often recurring, and it is therefore difficult to eradicate. To develop and test novel treatments, infection models that are representative of the infection process are desirable. Several infection models have been developed, including the use of cultured cells, isolated corneocytes, explanted human skin or reconstituted human epidermis. However, these have various disadvantages, ranging from not being an accurate reflection of the site of infection, as is the case with, for example, cultured cells, to being difficult to scale up or having ethical issues (e.g., explanted human skin). We therefore sought to develop an infection model using explanted porcine skin, which is low cost and ethically neutral. We show that in our model, fungal growth is dependent on the presence of skin, and adherence of conidia is time-dependent with maximum adherence observed after ~ 2 h. Scanning electron microscopy suggested the production of fibril-like material that links conidia to each other and to skin. Prolonged incubation of infected skin leads to luxurious growth and invasion of the dermis, which is not surprising as the skin is not maintained in conditions to keep the tissue alive, and therefore is likely to lack an active immune system that would limit fungal growth. Therefore, the model developed seems useful to study the early stages of infection. Furthermore, we demonstrate that the model can be used to test novel treatment regimens for tinea infections.

FSH1 regulates the phenotype and pathogenicity of the pathogenic dermatophyte Microsporum canis

Microsporum canis (M. canis) is a common pathogen that causes tinea capitis and is present worldwide. The incidence of M. canis infection, particularly tinea capitis, has been increasing in China. In our previous studies, family of serine hydrolases 1 (FSH1) was identified as a potential virulence factor in tinea capitis infection caused by M. canis. To determine the function of this gene in M. canis, FSH1 was knocked down using double-stranded RNA interference mediated by Agrobacterium tumefaciens. Reverse transcription-quantitative PCR analysis was used to confirm gene knockdown. Loss of FSH1 expression by RNAi resulted in a minor phenotype alteration, but M. canis pathogenicity in guinea pig cutaneous infection was decreased compared with the wild-type strain. To the best of our knowledge, the present study is the first to demonstrate that FSH1 is associated with macroconidia septa formation and is an important contributor to M. canis virulence. These findings may advance the understanding of the function of the FSH1 gene and provide a foundation for future studies on macroconidia septa formation and pathogenicity of M. canis.

Keratin hydrolysis by dermatophytes

Dermatophytes are the most common cause of superficial fungal infections (tinea infections) and are a specialized group of filamentous fungi capable of infecting and degrading keratinised tissues, including skin, hair, and nail. Essential to their pathogenicity and virulence is the production of a broad spectrum of proteolytic enzymes and other key proteins involved in keratin biodegradation and utilization of its breakdown products. The initial stage of biodegradation of native keratin is considered to be sulfitolysis, in which the extensive disulfide bridges present in keratin are hydrolyzed, although some secreted subtilisins can degrade dye-impregnated keratin azure without prior reduction (Sub3 and Sub4). Sulfitolysis facilitates the extracellular biodegradation of keratin by the dermatophytes' extensive array of endo- and exoproteases. The importance of dermatophyte proteases in infection is widely recognized, and these enzymes have also been identified as important virulence determinants and allergens. Finally, the short peptide and amino acid breakdown products are taken up by the dermatophytes, using as yet poorly characterised transporters, and utilized for metabolism. In this review, we describe the process of keratin biodegradation by dermatophytes, with an especial focus on recent developments in cutting edge molecular biology and '-omic' studies that are helping to dissect the complex process of keratin breakdown and utilization.

In vitro models of dermatophyte infection to investigate epidermal barrier alterations

Fungal infections of the skin, known as dermatophytoses, are initiated at the epidermal barrier and lead to dysfunctions of the stratum corneum and cornified skin appendages. Dermatophytosis affects a significant part of the human population and, despite the availability of effective treatments, its prevalence is still increasing. Numerous dermatophyte species are able to induce lesions in both animals and humans, with different clinical pictures and host inflammatory responses. The understanding of the infectious process and of tissue responses has been impeded by discrepancies between observations in vivo or in research models. Indeed, cells cultured as monolayers do not undergo the keratinization process required to study the adherence and invasion of dermatophytes. Animal models lack relevance to study human dermatophytosis because of species-specific differences in the development of lesions and inflammatory responses. This review focuses on the recent development of cultured human skin equivalents, which partly overcomes those limitations and allows improved understanding of the pathogenesis of dermatophytosis in human being, especially the impacts of infection on epidermal barrier integrity.

Modeling dermatophytosis in reconstructed human epidermis: A new tool to study infection mechanisms and to test antifungal agents

Dermatophytosis is a superficial fungal infection of keratinized structures that exhibits an increasing prevalence in humans and is thus requesting novel prophylactic strategies and therapies. However, precise mechanisms used by dermatophytes to adhere at the surface of the human epidermis and invade its stratum corneum are still incompletely identified, as well as the responses provided by the underlying living keratinocytes during the infection. We hereby report development of an in vitro model of human dermatophytosis through infection of reconstructed human epidermis (RHE) by arthroconidia of the anthropophilic Trichophyton rubrum species or of the zoophilic Microsporum canis and Arthroderma benhamiae species. By modulating density of arthroconidia in the inoculum and duration of exposure to such pathogens, fungal infection limited to the stratum corneum was obtained, mimicking severe but typical in vivo situation. Fungal elements in infected RHE were monitored over time by histochemical analysis using periodic-acid Schiff-staining or quantified by qPCR-detection of fungal genes inside RHE lysates. This model brings improvements to available ones, dedicated to better understand how dermatophytes and epidermis interact, as well as to evaluate preventive and therapeutic agents. Indeed, miconazole topically added to RHE was demonstrated to inhibit fungal infection in this model.

Genomic insight into pathogenicity of dematiaceous fungus Corynespora cassiicola

Corynespora cassiicola is a common plant pathogen that causes leaf spot disease in a broad range of crop, and it heavily affect rubber trees in Malaysia (Hsueh, 2011; Nghia et al., 2008). The isolation of UM 591 from a patient's contact lens indicates the pathogenic potential of this dematiaceous fungus in human. However, the underlying factors that contribute to the opportunistic cross-infection have not been fully studied. We employed genome sequencing and gene homology annotations in attempt to identify these factors in UM 591 using data obtained from publicly available bioinformatics databases. The assembly size of UM 591 genome is 41.8 Mbp, and a total of 13,531 (≥99 bp) genes have been predicted. UM 591 is enriched with genes that encode for glycoside hydrolases, carbohydrate esterases, auxiliary activity enzymes and cell wall degrading enzymes. Virulent genes comprising of CAZymes, peptidases, and hypervirulence-associated cutinases were found to be present in the fungal genome. Comparative analysis result shows that UM 591 possesses higher number of carbohydrate esterases family 10 (CE10) CAZymes compared to other species of fungi in this study, and these enzymes hydrolyses wide range of carbohydrate and non-carbohydrate substrates. Putative melanin, siderophore, ent-kaurene, and lycopene biosynthesis gene clusters are predicted, and these gene clusters denote that UM 591 are capable of protecting itself from the UV and chemical stresses, allowing it to adapt to different environment. Putative sterigmatocystin, HC-toxin, cercosporin, and gliotoxin biosynthesis gene cluster are predicted. This finding have highlighted the necrotrophic and invasive nature of UM 591.

Genome Anatomy of Pyrenochaeta unguis-hominis UM 256, a Multidrug Resistant Strain Isolated from Skin Scraping

Pyrenochaeta unguis-hominis is a rare human pathogen that causes infection in human skin and nail. P. unguis-hominis has received little attention, and thus, the basic biology and pathogenicity of this fungus is not fully understood. In this study, we performed in-depth analysis of the P. unguis-hominis UM 256 genome that was isolated from the skin scraping of a dermatitis patient. The isolate was identified to species level using a comprehensive multilocus phylogenetic analysis of the genus Pyrenochaeta. The assembled UM 256 genome has a size of 35.5 Mb and encodes 12,545 putative genes, and 0.34% of the assembled genome is predicted transposable elements. Its genomic features propose that the fungus is a heterothallic fungus that encodes a wide array of plant cell wall degrading enzymes, peptidases, and secondary metabolite biosynthetic enzymes. Antifungal drug resistance genes including MDR, CDR, and ERG11/CYP51 were identified in P. unguis-hominis UM 256, which may confer resistance to this fungus. The genome analysis of P. unguis-hominis provides an insight into molecular and genetic basis of the fungal lifestyles, understanding the unrevealed biology of antifungal resistance in this fungus.

Antifungal activity of berberine hydrochloride and palmatine hydrochloride against Microsporum canis -induced dermatitis in rabbits and underlying mechanism

Background

Phellodendron amurense, exhibits antifungal activity mainly by bioactive components including berberine hydrochloride and palmatine hydrochloride. This study was conducted to evaluate the antifungal effects of berberine hydrochloride, palmatine hydrochloride, and a mixture of both substances against Microsporum canis in vivo and in vitro.

Methods

The minimal inhibitory concentrations (MICs) of monomers and clotrimazole were determined using 1.5 % tryptic soy agar. The effects of these drugs on Microsporum canis growth was detected by determining dry weight. Transmission electron microscopy (TEM) was performed to observe the effect of chemicals on cell ultrastructure. Differential mRNA expressions of eight genes of M. canis treated with berberine or palmatine or their combination at different time points were determined by real-time PCR. NADH enzyme concentration was also detected. Clinical evaluation via in-vivo antifungal assay was also performed. Skin histology PAS staining was also carried out.

Results

Results showed that MICs of berberine, palmatine and clotrimazole were 1, 1, and 0.015 mg/mL, respectively. No significant difference was observed among the growth curves of the three groups before 18 h was reached. TEM showed that these drugs could destroy the cell membrane and organelles of M. canis at different time points. After 30 h of incubation, relative mRNA expressions of the genes in the combined group were significantly higher than those in the other groups including the clotrimazole group (P < 0.05); Palmatine initially induced the mRNA up-regulation of PGAL4, FSH1, PQ-LRP, NADH1 and NDR in M. canis; by contrast, berberine maintained a high expression level of these genes to shorten fungal life cycle and eradicate M. canis. Clinical results showed that combined treatment was more effective than single administration of each monomer or clotrimazole. Hence, berberine mixed with palmatine significantly elicited antifungal activities and could be used to treat M. canis in rabbits.

Conclusion

These results provide a comprehensive view of the mechanism of berberine and palmatine in anti-M. canis activity.

Assessment of immunogenicity and protective efficacy of Microsporum canis secreted components coupled to monophosphoryl lipid-A adjuvant in a vaccine study using guinea pigs

Microsporum canis is the most common dermatophyte in pets and is of zoonotic importance but currently there is no effective vaccine available to prevent dermatophytosis. The aim of this work was to assess the immunogenicity and protective efficacy of secreted components (SC) from M. canis adjuvanted with the monophosphoryl lipid-A (MPLA), in a vaccine study using the guinea pig as an experimental model. Animals were vaccinated with either the SC adjuvanted with the MPLA, the MPLA adjuvant alone or PBS three times at two-week intervals, until 42 days prior to M. canis infection. A blind evaluation of dermatophytosis symptoms development and fungal persistence in skin was monitored weekly. The antibody response towards the SC and the levels of Interferon (IFN)γ and Interleukin-4 expressed in peripheral blood mononuclear cells were assessed along or at the end of the study period respectively. The animals that received MPLA had a significantly lower clinical score than those inoculated with PBS. However, no significant difference was observed between the guinea pigs vaccinated with the SC adjuvanted with the MPLA and those having received MPLA alone. The results also showed that vaccination induced a strong antibody response towards the SC and an increase in IFNγ mRNA level. Our results show that the MPLA adjuvant used in this vaccine study can induce per se a partial protection against a M. canis infection. Although they induce a delayed-type hypersensitivity reaction in guinea pigs, the SC do not confer a protection under the present experimental conditions.