Phylogeny of dermatophytes with genomic character evaluation of clinically distinct Trichophyton rubrum and T. violaceum

Abstract

Trichophyton rubrum and T. violaceum are prevalent agents of human dermatophyte infections, the former being found on glabrous skin and nail, while the latter is confined to the scalp. The two species are phenotypically different but are highly similar phylogenetically. The taxonomy of dermatophytes is currently being reconsidered on the basis of molecular phylogeny. Molecular species definitions do not always coincide with existing concepts which are guided by ecological and clinical principles. In this article, we aim to bring phylogenetic and ecological data together in an attempt to develop new species concepts for anthropophilic dermatophytes. Focus is on the T. rubrum complex with analysis of rDNA ITS supplemented with LSU, TUB2, TEF3 and ribosomal protein L10 gene sequences. In order to explore genomic differences between T. rubrum and T. violaceum, one representative for both species was whole genome sequenced. Draft sequences were compared with currently available dermatophyte genomes. Potential virulence factors of adhesins and secreted proteases were predicted and compared phylogenetically. General phylogeny showed clear gaps between geophilic species of Arthroderma, but multilocus distances between species were often very small in the derived anthropophilic and zoophilic genus Trichophyton. Significant genome conservation between T. rubrum and T. violaceum was observed, with a high similarity at the nucleic acid level of 99.38 % identity. Trichophyton violaceum contains more paralogs than T. rubrum. About 30 adhesion genes were predicted among dermatophytes. Seventeen adhesins were common between T. rubrum and T. violaceum, while four were specific for the former and eight for the latter. Phylogenetic analysis of secreted proteases reveals considerable expansion and conservation among the analyzed species. Multilocus phylogeny and genome comparison of T. rubrum and T. violaceum underlined their close affinity. The possibility that they represent a single species exhibiting different phenotypes due to different localizations on the human body is discussed.

Towards a rapid identification and a novel proteomic analysis for dermatophytes from human and animal dermatophytosis

“…Fungal cutinases catalyse the esterification and transesterification reactions . Consistent with the detection of cutinase transcription factor 1 alpha in T. rubrum CBS 139224 and T. violaceum CBS 141829, cutinase (C5FSF7_ARTOC) was identified in M. canis . Sulfhydryl oxidases (SOXs) were recently characterised in Aspergillus tubingensis .…”

“…Most probable adhesins detected for dermatophyte species being hypothetical proteins. Likewise, Zhan et al found that most detected adhesins in Trichophyton were hypothetical proteins. Cerato‐platanins (CPPs) small secreted cysteine‐rich moderately hydrophobic proteins and found only in fungi.…”

“…Proteases act as virulence factors since they are essential for nutrients acquisition through host tissue degradation and to escape the host defence . Recently, Arthrodermataceae has been reconsidered based on molecular phylogeny, and the probable virulence factors of secreted proteases and adhesins were anticipated . Overall, the analysed proteins related to pathogenesis are mainly including proteases, adhesins, allergenic cerato‐platanin, immunogenic protein, siderophore iron transporter mirB, protease inhibitors and annexin.…”

“…The secreted subtilisin‐like serine protease is known to have keratinolytic activity that contributes to pathogenicity. Moreover, the analysed exoproteases are aminopeptidases dipeptidyl peptidases and carboxypeptidases . Recently, Muszewska et al suggested that SPs are more pervasive in fungi than anticipated as 21/54 SPs depicted in MEROPS peptidase database are found in fungi.…”

Major challenges and perspectives in the diagnostics and treatment of dermatophyte infections

“…Other factors are associated with patient's characteristics, that is, age, gender, damage or maceration of the epidermis, genetic proneness to diseases, mechanical skin lesions, local lowering of the immunological barrier related to pressure circulatory disorders, possible contacts with dermatophytes, and exposure to a large number of spores due to the socioeconomic or occupational status Zhan et al 2018). There are even more predisposing factors for dermatophytoses associated with the host of infection, and all of them significantly affect the prevalence of these diseases in a given geographical region.…”