Parasitology



High expression of a functional cruzipain by a non-infective and non-pathogenic Trypanosoma cruzi clone


C. N. PAIVA a1, T. SOUTO-PADRON a1, D. A. COSTA a1 and C. R. GATTASS a1c1
a1 Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS, Bloco G, Ilha do Fundão, 21949-900, Rio de Janeiro, Brasil

Abstract

We compared a Trypanosoma cruzi clone unable to infect or induce pathology in mice (CL-14), with virulent T. cruzi (Y and CL strains) in terms of cruzipain expression, subcellular distribution and functional activity. Our results showed that (1) intracellular Y amastigotes expressed R1 (carboxy-terminal) and R2 (catalytic) domains concentrated in cytoplasmic vesicles, while CL-14 presented R1 labelling on membrane clusters and R2 in intracellular compartments, (2) CL-14-trypomastigotes presented R1 and R2 staining preferentially on flagellar and cellular membranes, similar to CL, but different from Y strain intracellular labelling pattern, (3) flow-cytometry revealed higher expression of R1 by CL-14-trypomastigotes than virulent strains, but R2 staining similar to CL-trypomastigotes, (4) CL-14-trypomastigotes presented normal cruzipain activity in gelatin gels, but different banding patterns were found in CL-14 versus CL and Y strains. Our data rule out failure in cruzipain expression, activity or subcellular distribution as an explanation for CL-14 biological behaviour, but suggest the expression of a different isoform. These results also cast doubt on the putative role of cruzipain as a target of immunopathological responses, since high levels of functional cruzipain are expressed by a non-pathogenic T. cruzi.

(Received March 4 1998)
(Revised May 27 1998)
(Accepted May 27 1998)


Key Words: Trypanosoma cruzi; cruzipain; cysteine proteinase; infectivity; pathogenicity.

Correspondence:
c1 Corresponding author: Laboratório de Imunoparasitologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS, Bloco G, Ilha do Fundão, 21949-900, Rio de Janeiro, Brasil. Fax: +55 21 280 8193. E-mail: cerli@chagas.biof.ufrj.br


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