Project description:Polyphasic identification and taxonomy of species within the dermatophyte genus Arthroderma including A. fimbriatum sp. nov and A. cellariae sp. nov
Project description:Although dermatophytes are the most common agents of superficial mycoses in humans and animals, the molecular basis of the pathogenicity of these fungi is largely unknown. In vitro digestion of keratin by dermatophytes is associated with the secretion of multiple proteases, which are assumed to be responsible for their particular specialization to colonize and degrade keratinized host structures during infection. To address this hypothesis a guinea pig infection model was established for the zoophilic dermatophyte Arthroderma benhamiae which causes highly inflammatory cutaneous infections in humans and rodents. Microarray analysis revealed a distinct in vivo protease gene expression profile in the fungal cells, which is surprisingly different from the pattern elicited during in vitro growth on keratin. Instead of the major in vitro expressed proteases others were activated specifically during infection. These enzymes are therefore suggested to fulfill important functions that are not exclusively associated with the degradation of keratin. As the most upregulated in vivo specific A. benhamiae sequence we discovered the gene encoding the serine protease subtilisin 6, which is a known major allergen in the related dermatophyte Trichophyton rubrum and putatively linked to host inflammation. In addition, our approach identified other candidate pathogenicity related factors in A. benhamiae, such as genes encoding key enzymes of the glyoxylate cycle and an opsin-related protein. This first broad transcriptional profiling approach during dermatophyte infection gives new molecular insights into pathogenicity associated mechanisms that make these microorganisms the most successful etiologic agents of superficial mycoses. Keywords: Two-condition experiment, strong proteolytic activity in the supernatant versus no proteolytic activity or infected tissue versus no proteolytic activity
Project description:Although dermatophytes are the most common agents of superficial mycoses in humans and animals, the molecular basis of the pathogenicity of these fungi is largely unknown. In vitro digestion of keratin by dermatophytes is associated with the secretion of multiple proteases, which are assumed to be responsible for their particular specialization to colonize and degrade keratinized host structures during infection. To address this hypothesis a guinea pig infection model was established for the zoophilic dermatophyte Arthroderma benhamiae which causes highly inflammatory cutaneous infections in humans and rodents. Microarray analysis revealed a distinct in vivo protease gene expression profile in the fungal cells, which is surprisingly different from the pattern elicited during in vitro growth on keratin. Instead of the major in vitro expressed proteases others were activated specifically during infection. These enzymes are therefore suggested to fulfill important functions that are not exclusively associated with the degradation of keratin. As the most upregulated in vivo specific A. benhamiae sequence we discovered the gene encoding the serine protease subtilisin 6, which is a known major allergen in the related dermatophyte Trichophyton rubrum and putatively linked to host inflammation. In addition, our approach identified other candidate pathogenicity related factors in A. benhamiae, such as genes encoding key enzymes of the glyoxylate cycle and an opsin-related protein. This first broad transcriptional profiling approach during dermatophyte infection gives new molecular insights into pathogenicity associated mechanisms that make these microorganisms the most successful etiologic agents of superficial mycoses. Keywords: Two-condition experiment, strong proteolytic activity in the supernatant versus no proteolytic activity or infected tissue versus no proteolytic activity Three independently prepared A. benhamiae replicates grown in each of the three media, Sabouraud, soy and keratin-soy medium (designated SabA/B/C, soyA/B/C and keratin-soyA/B/C) were used. ARN from skin samples and fungus together of Guinea Pig infected with A. benhamieae were prepared. Pairwise transcriptional comparisons, i.e. soy versus Sabouraud, keratin-soy versus Sabouraud and Guinea Pig infected versus Sabouraud were done. The total number of slides in this study was 18.
Project description:Next-generation technologies have prompted efforts towards generating a large repertoire of whole-genome sequences. The dermatophyte Arthroderma vanbreuseghemii has been considered as a good model in which to conduct molecular biological studies on this fungal group. Despite the considerable repertoire of molecular tools developed for this fungus, the lack of genomic data has represented a major limitation, preventing effective implementation of those tools. Herein, the authors report the first draft whole-genome sequence of this dermatophytic species. The size of the draft genome was 23 Mb, exhibiting a GC content of 48.1%. Given the significance of secreted proteases in tissue invasion, a comparative analysis of genes encoding extracellular proteases was performed between A. vanbreuseghemii and other dermatophytes. Furthermore, genes that might be involved in DNA repair also were compared among dermatophytes. Moreover, the complete mitochondrial genome of A. vanbreuseghemii was obtained and shown to consist of 24,287 bp with a GC content of 24%. In conclusion, the availability of genomic data for A. vanbreuseghemii is expected to facilitate the implementation of the molecular tools established for this fungus, enhancing our understanding of the biology of dermatophytes.
Project description:For many pathogenic fungi, siderophore-mediated iron acquisition is essential for virulence. The process of siderophore production and further mechanisms to adapt to iron limitation are strictly controlled in fungi to maintain iron homeostasis. Here we demonstrate that the human pathogenic dermatophyte Arthroderma benhamiae produces the hydroxamate siderophores ferricrocin and ferrichrome C. Additionally, we show that the iron regulator HapX is crucial for the adaptation to iron starvation and iron excess, but is dispensable for virulence of A. benhamiae. Deletion of hapX caused downregulation of siderophore biosynthesis genes leading to a decreased production of siderophores during iron starvation. Furthermore, HapX was required for transcriptional repression of genes involved in iron-dependent pathways during iron-depleted conditions. Additionally, the ΔhapX mutant of A. benhamiae was sensitive to high-iron concentrations indicating that HapX also contributes to iron detoxification. In contrast to other pathogenic fungi, HapX of A. benhamiae was redundant for virulence and a ΔhapX mutant was still able to infect keratinized host tissues in vitro. Our findings underline the highly conserved role of the transcription factor HapX for maintaining iron homeostasis in ascomycetous fungi but, unlike in many other human and plant pathogenic fungi, HapX of A. benhamiae is not a virulence determinant.
Project description:Pestiviruses are plus-stranded RNA viruses belonging to the family Flaviviridae. They comprise several important pathogens like classical swine fever virus and bovine viral diarrhea virus that induce economically important animal diseases. In 2017, the last update of pestivirus taxonomy resulted in demarcation of 11 species designated Pestivirus A through Pestivirus K. Since then, multiple new pestiviruses have been reported including pathogens associated with disease in pigs or small ruminants. In addition, pestivirus sequences have been found during metagenomics analysis of different non-ungulate hosts (bats, rodents, whale, and pangolin), but the consequences of this pestivirus diversity for animal health still need to be established. To provide a systematic classification of the newly discovered viruses, we analyzed the genetic relationship based on complete coding sequences (cds) and deduced polyprotein sequences and calculated pairwise distances that allow species demarcation. In addition, phylogenetic analysis was performed based on a highly conserved region within the non-structural protein NS5B. Taking into account the genetic relationships observed together with available information about antigenic properties, host origin, and characteristics of disease, we propose to expand the number of pestivirus species to 19 by adding eight additional species designated Pestivirus L through Pestivirus S.