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Virulence factors in dermatophytes: screening of SUB genes encoding subtilisin-like proteases

Abstract number: 903_r2213

Lemsaddek A.

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Dermatophytes are a group of closely related filamentous fungi capable to invade keratinised tissues (skin, hair and nails) of humans and animals. Belonging to the genera Trichophyton, Microsporum and Epidermophyton, these fungi are usually grouped in three categories based on their host preference and natural habitat. Members of the anthropophilic (human), zoophilic (animal) and geophilic (soil) ecological groups are potentially able to cause human infections. The colonisation process is assisted by the production of various hydrolytic enzymes, namely subtilisin-like proteases, which are encoded by a family of three genes (SUB1, SUB2 and SUB3). Since their expression is induced during the infection process, they are considered potential virulence factors.

The presence of SUB genes was assayed by PCR with specific primers in a collection of 209 human clinical dermatophytes, representing ten species previously identified phenotypically and genotypically, and 30 reference strains. The results obtained showed that SUB genes are poorly represented among the analysed dermatophytes. SUB1 was only detected for 22 of 29 (75%) M. canis and 22 of 23 (91%) M. audouinii isolates and 1 of 88 (1%) T. mentagrophytes isolates. SUB2 was found in 23 of 29 (79%) isolates of M. canis, 20 of 23 (87%) M. audouinii and 1 of 7 (14%) of M. gypseum isolates. Concerning SUB3 gene, positive results were obtained for two of three (67%) isolates of E. floccosum, 19 of 29 (66%) M. canis, 20 of 23 (87%) M. audouinii, one of seven (14%) M. gypseum, as well as for two of 88 (2%) T. mentagrophytes and two of 46 (4%) T. rubrum isolates. The chi-square analysis of contingency tables was used to test statistical independence among occurrence of virulence traits and origin and species allocation of isolates. Significant associations (P < 0.05) were found between the presence of SUB genes and isolates of the species M. canis and M. audouinii, showing that these virulence factors may have an important role in the infection process for theses two species and a reduced one for the other species.

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Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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