-Proteases in helmintic parasites. Proteases catalyse the cleavage of internal peptide bonds within peptides and proteins. They are classified into four major classes and are involved in a broad range of eukaryotic processes. Proteases have also been found to play a number of critical roles in the virulence of pathogenic agents, particularly of nematode parasites. Parasitic proteases are involved in different aspects of host-parasite interactions. They facilitate the invasion of host tissues and allow nutrition as well as the survival of the parasite in its host. Proteases also participate in the parasite's evasion from the host's immune response. The functional diversity and complexity of these enzymes are described in this review, with a particular focus on the principally identified proteases of four helminths: Schistosoma sp., Fasciola sp., Taenia sp. and Haemonchus sp. Some of these proteases, especially the cysteine proteases secreted by the parasitic trematode Fasciola hepatica, have been successfully tested in experimental immunodiagnosis. Proteases identified in different parasites are currently under study for a use as recombinant vaccines. In this respect, proteases are proposed as major potential targets for immunotherapy and chemotherapy against parasitic diseases.
protease / virulence / helminth / therapy / vaccinationRésumé -Les protéases catalysent le clivage de liaisons peptidiques internes au sein de peptides et protéines. Classées en quatre grandes familles, ces enzymes sont impliquées dans de nombreuses fonctions des cellules eucaryotes. De plus, elles jouent un rôle critique dans la virulence des pathogènes et plus particulièrement des parasites. Elles interviennent à différents niveaux de l'interaction hôte-parasite. Elles facilitent la pénétration du parasite au sein de l'hôte et y assurent sa nutrition ; elles participent également à l'échappement du parasite vis à vis du système immunitaire de l'hôte. La diversité et la complexité fonctionnelle de ces molécules sont illustrées dans cette revue qui décrit les principales protéases identifiées chez quatre helminthes : Schistosoma sp., Fasciola sp., Taenia