High expression of a functional cruzipain by a non-infective and non-pathogenic Trypanosoma cruzi clone
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.
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: firstname.lastname@example.org