Cysteine proteases of Echinococcus granulosus: identification and preliminary characterization

NAIDICH A; PRADA L; CAMICIA F; CUCHER M; ROSENZVIT M; GUTIERREZ A

Congreso; XXIII International Congress of Hydatidology; 2009

CYSTEINE PROTEASES OF Echinococcus granulosus: IDENTIFICATION AND PRELIMINARY CHARACTERIZATION A. Naidich1ª, L. Prada2, F. Camicia2, M. Cucher2, M. Rosenzvit2, A. Gutierrez1 1 Depto. Parasitología, INEI-ANLIS “Dr. Carlos Malbrán”. Av. Velez Sarsfield 563 (CP1281) 2 Depto. Microbiología. Fac. Medicina. UBA. Buenos Aires. Argentina.ªanaidich@anlis.gov.ar The causative agent of cystic hydatid disease is the cestode Echinococcus granulosus. Several parasitic cysteine proteases have been identified, capable of degrading host molecules, such as extracellular matrix components, participating in tissue penetration and invasion. It is important to determine the role of these proteases in processes like formation of secondary hydatid cysts, as they are possible targets of therapeutic and prophylactic post-surgery treatment. The aim of this study is to identify and characterize cysteine proteases in the larval stage of E. granulosus. RNA was obtained from protoscoleces of porcine hydatid cysts, which was employed in RT-PCR, using primers based on conserved sequences of the active site of cysteine proteases from eukaryotes. The fragments obtained were sequenced. In silico analysis of the translated sequence of the mRNA fragment obtained (Eg-CLP1) showed amino acid identity with cathepsin-L1 in E. multilocularis (Em-CLP1, 93%); Taenia solium, T. asiatica, T. saginata (55%) and Fasciola hepatica (46%). The high identity found with other cysteine proteases from plathyhelminth parasites and the presence of conserved residues in the active site related to substrate specificity, suggests that the protein coded by Eg-CLP1 could be categorized as a cathepsin-L. The molecular phylogenetic analysis showed that it clusters with Em-CLP1. This analysis would suggest that these proteins share substrate specificity and may intervene in the breakup of molecules that form the extracellular matrix of the host. These results will eventually allow designing more specific tools for the analysis of the biochemical function of this protease and for evaluating its potential role in secondary hydatidosis. Keywords: Echinococcus granulosus, Cysteine-peptidases