Leishmanolysin-like molecules in Herpetomonas samuelpessoai mediate hydrolysis of protein substrates and interaction with insect.

Herpetomonas samuelpessoai, an insect trypanosomatid, produces a 63-kDa metallopeptidase that has similar biochemical/immunological properties to Leishmania leishmanolysin, a virulence factor that participates in different stages of the parasite life cycle. Herein, we described some biochemical characteristics of the major surface metallopeptidase of H. samuelpessoai that led us to infer some probable functions for this peptidase during the parasite-invertebrate interaction. Gelatin-SDS-PAGE, flow cytometry and confocal fluorescence microscopy provided measurements for the relative levels of surface leishmanolysin-like molecules in H. samuelpessoai. Immunocytochemical analysis demonstrated the presence of leishmanolysin-like molecules on the surface and cytoplasm of the parasite. The surface metallopeptidase was active at a broad spectrum of pH and temperature, showing maximum activity at pH 6.0 at 37 degrees C, and an ability to degrade albumin, hemoglobin, IgG, mucin, casein and gut proteins obtained from Aedes aegypti. This wide substrate utilization might support parasite growth and development. Curiously, H. samuelpessoai cells were able to colonize A. aegypti guts. In an effort to implicate a possible role for the metallopeptidase from H. samuelpessoai, living parasites were treated with different compounds before the interaction with gut cells. The pre-incubation with metallopeptidase inhibitors, phospholipase C or anti-leishmanolysin antibodies promoted a significant reduction in the interaction with guts. Similarly, the pre-treatment of gut cells with purified leishmanolysin-like protein drastically diminished the adhesion process. Furthermore, the expression of surface leishmanolysin in H. samuelpessoai cells was drastically enhanced after passage in A. aegypti. These results suggest the participation of homologues of leishmanolysin in the interaction of H. samuelpessoai with the invertebrate vector.

Molecular characterization of Trypanosoma cruzi sylvatic isolates from Rio de Janeiro, Brazil.

Trypanosoma cruzi, the etiologic agent of Chagas disease, presents considerable heterogeneity between isolated populations within the wild and domestic cycles. By using multiplex polymerase chain reaction based on the mini-exon gene, characterization was performed on seven samples isolated from specimens of Triatoma vitticeps that had been collected from the locality of Triunfo in the municipality of Santa Maria Madalena, state of Rio de Janeiro, Brazil. The samples SMM10, SMM53, SMM88, and SMM98 (area A) and SMM36 and SMM82 (area B) revealed the presence of 150 base pairs, corresponding to the zymodeme III (Z3). Our study suggested that one isolate (SMM1) presents a mixed genotype associated with Z3 and TcII. The typing of isolates of T. cruzi has the main aim of identifying strains with different epidemiological and/or clinical characteristics of Chagas disease. Our results corroborate other descriptions in the literature and contribute towards the knowledge and records of the profile of some additional wild isolates of T. cruzi in regions not yet affected by the disease.