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Secreted dipeptidyl peptidases as potential virulence factors for Microsporum canis

Sandy Vermout1, Aline Baldo, Jérémy Tabart

  • 1Department of Infectious and Parasitic Diseases, Parasitology, Faculty of Veterinary Medicine, University of Liège, Liège, Belgium.

FEMS Immunology and Medical Microbiology
|December 4, 2008
PubMed

Insights

Researchers isolated and characterized two genes, dipeptidyl peptidases IV and V (DppIV and DppV), from Microsporum canis. These proteases, expressed in vivo and in vitro, may play a role in dermatophytosis pathogenesis.

Area of Science:

  • Mycology
  • Molecular Biology
  • Biochemistry

Background:

  • Dermatophytosis, commonly caused by Microsporum canis, is a prevalent zoonotic fungal infection in companion animals and humans.
  • Microsporum canis possesses genes encoding serine proteases, which are implicated in pathogenic processes.

Purpose of the Study:

  • To isolate and characterize two specific genes, dipeptidyl peptidases IV (DppIV) and V (DppV), from Microsporum canis.
  • To investigate the expression and enzymatic activity of DppIV and DppV in relation to fungal pathogenesis.

Main Methods:

  • Gene isolation and characterization of DppIV and DppV.
  • Expression analysis in experimentally infected guinea pigs, naturally infected cats, and in vitro fungal cultures.
  • Production and characterization of recombinant DppIV (rDppIV) and DppV (rDppV) proteases in Pichia pastoris.
  • Enzymatic activity assays, including keratin solubilization and Pro-X bond cleavage.
  • Assessment of DppV's ability to induce delayed-type hypersensitivity (DTH) skin reactions in guinea pigs.

Main Results:

  • DppIV and DppV genes were successfully isolated and characterized, showing homology to S9 family serine proteases.
  • Both genes were expressed in vivo (guinea pigs, cats) and in vitro when the fungus utilized extracellular matrix proteins.
  • Recombinant DppIV exhibited Pro-X bond cleavage activity, while rDppV did not induce DTH skin reactions.
  • rDppIV's activity did not enhance keratin solubilization, suggesting a role in cleaving small soluble peptides.

Conclusions:

  • Dipeptidyl peptidases IV and V are expressed by Microsporum canis during infection and under specific growth conditions.
  • The characterized proteases, particularly rDppIV, possess enzymatic activities that warrant further investigation into their precise role in dermatophytosis.
  • The lack of DTH induction by rDppV suggests a complex immunomodulatory role for these enzymes in host-pathogen interactions.

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