Submitted to: Experimental Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 10, 1998
Publication Date: N/A
Interpretive Summary: Three protease activities have been identified from E/S products of Trichinella spiralis L1 infective muscle larvae, and a 4th was identified from E/S products of molting larval parasites. Parasite proteases have been implicated both in vital functions of parasites and in the pathology induced in the host by infection with the parasite. Proteases have been suggested as potential targets for the control of parasitism in human and animal hosts, and recent advances in cloning and molecular modeling of parasite proteases have proven the efficacy of these strategies. Characterization of proteases from T. spiralis may lead to the development of new targets for protease inhibitor-based control of this parasite.
Trichinella spiralis larvae infect their hosts by penetrating small intestinal enterocytes, where they undergo a rapid series of 4 molts to the adult stage in 24-30 hours. The mechanism by which T. spiralis L1 infective muscle larvae accomplish this penetration and rapid molting is unknown, however, proteolytic enzymes released by infective larvae may be involved. Three proteases, 1-62 kDa cysteine protease, and 2 serine proteases, Mr 53 and 44 kDa, have been identified in excretory/secretory (E/S) components of T. spiralis L1 infective muscle larvae. These proteases were capable of hydrolyzing azocoll, a dye linked protein, and gelatin incorporated in PAGE gels, over a broad pH range (4.0-8.5), with maximal activity at pH 5.0. A 4th protease was identified in culture of larvae that had been treated with trypsin and a CO2 pulse to induce ecdysis. This metalloprotease, Mr 49 kDa, was active over a narrower pH range (6.0-8.5), and was temporally associated with larval molting.