Trypanosoma cruzi: strain selection by diferent schedules of mouse passage of an initially mixed infection

From an initial double infection in mice, established by simultaneous and equivalent inocula of bloodstream forms of strains Y and F of Trypanosoma cruzi, two lines were derived by subinoculations: one (W) passaged every week, the other (M) every month. Through biological and biochemical methods only the Y strain was identified at the end of the 10th and 16th passages of line W and only the F strain at the 2nd and 4th passages of line M. The results illustrate strain selection through laboratory manipulation of initially mixed populations of T. cruzi.

Identification of vector species (Diptera: Simuliidae) of human onchocerciasis in the Amazonia focus of Brazil and Venezuela

The taxonomic status of three Amazonian simuliid species, Simulium guianese Wise, S. oyapockense Floch & Abonnenc and S. yarzabali Ramirez Perez is reviewed. Simulium cuasisanguineum Ramirez Perez, Yarzabal & Peterson is synonymized with S. oyapockense, and S. yarzabali is revalidated from its synonymy with S. incrustatum Lutz. The role of these three species in the transmission of human onchocerciasis and mansonelliasis in Amazonia is reviewed.

Trypanosoma cruzi: identification of specific epimastigote antigens by human immune sera

Soluble antigens from epimastigotes of Trypanosoma cruzi were analyzed by western blot in terms of their reactivity with sera from patients with Chagas' disease. In addition, sera from patients with visceral (AVL) and tegumentar leishmaniasis (ATL) were also tested in order to identify cross-reactivities with Trypanosoma cruzy antigens. Twenty eight polypeptides with molecular weights ranging from 14 kDa to 113 kDa were identified with sera from Chagas' disease patients. An extensive cross-reactivity was observed when sera from human visceral leishmaniasis were used, while only a slight cross-reaction was observed with sera from tegumentar leishmaniasis. On the other hand, 10 polypeptidesspecifically reacting with sera from Chagas' disease patients were identified. Among them, the antigens with molecular weights of 46 kDa and 25 kDa reacted with all sera teste and may be good candidates for specific immunodiagnosis of Chagas' disease.

Influence of Trypanosoma cruzi strain on the pathogenesis of chronic myocardiopathy in mice

The murine model of chronic Chaga's myocardiopathy was developed in 201 inbred and outbred mice. The experimental groups consisted of 1st: 73 inbred AKR and A/J mice inoculated with one of the following. Trypanosoma cruzi strains: Peruvian (Type I), 12 SF (Type II) or Colombian (Type III); 2nd: 128 outbred Swiss mice, chronically infected either with Type II or Type III strains isolated from human patients from different geographical areas. All T. cruzi strains were previoulsly characterized by their morphobiological behaviour in mice and by isoenzymatic patterns. For the 1st group the inoculum was 5 x 10**4 for the Peruvian strain and 1 x 10**5 for the 12 SF and Colombian strains. In the 2nd group-Swiss mice the inoculum size varied from 2 x 10**4 to 2 x 10**5. The inbred animals were killed at a 3 time-point scale (90, 180 and 240 days) post-infection. The Swiss mice were killed from 180 to 660 days after infection. The evaluation of parasitemia and serology (xeodiagnosis and indirect immunofluorescent test) was performed. The incidence of macroscopic alterations of the heart and cardiac index were evaluated. Histopathological lesions of the myocardium were graded. The influence of T. cruzi strain on the intensity of cardiac lesions was evaluated by the Chi-square test; the incidence of inflammatory lesions and its relationship to the parasite strain was evaluated by the Fisher test. The influence of the duration of infection was evaluated by using the Gamma Coefficient of Kruskal and Goodman and its measure of significance. Slight to severe microscopic alterations occurred in 85% of the chronically infected nice. There were a clear predominance on the incidence and intensity of inflammatory and fibrotic alterations for the mice infected with Type III strains. Statistical analysis has shown significant differences among the infected groups, in the inflammatory and fibrotic lesions. Macroscopic alterations (right cavities dilatation and apex aneurism of left ventricle), differed in incidence according to mice strains; in Swiss and AKR mice, significant differences were seen in mice infected with different T. cruzi strains, but the A/J mice failed to show significant differences correlated with different parasite strains. The duration of infection, from 90 to 240 days, could not be correlated with the degree of lesions in the several groups.

Strain specific variation of outer membrane proteins of wild Yersinia pestis strains subjected to different growth temperatures

Three Yersinia pestis strains isolated from humans and one laboratory strain (EV76) were grown in rich media at 28§C and 37§C and their outer membrane protein composition compared by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-Page). Several proteins with molecular weights ranging from 34 kDa to 7 kDa were observed to change in relative abundance in samples grown at different temperatures. At least seven Y. pestis outer membrane proteins showed a temperature-dependent and strain-specific behaviour. Some differences between the outer membrane proteins of full-pathogenic wild isolates and the EV76 strain could aldso be detected and the relevance of this finding on the use of laboratory strains as a reference to the study of Y. pestis biological properties is discuted.

Identification and characterization of sex-linked proteins of Schistosoma mansoni

The proteins of adults worms (male and female) of two isolates (BH and RJ) of Shistosoma mansoni were extracted using Triton X-114 phase separation. The SDS-polyacrilamide gel electrophoresis profiles of the three phases (detergent, aqueous and insoluble proteins) obtained were compared after Coomassie blue and silver staining, surface radioiodination and Western blotting. No major differences were detected between the 2 isolates. Of the 25 or more proteins which partitioned into the detergent phase, only about 8 proteins could be surface radiodinated on live adult worms. A comparison was also made between the profiles of mael and females worms, isolated from bisexually infected mice. Two major female-specific and one male-specific band were detected by silver and/or Coomassie staining. The female bands, 32 KDa and 18 KDa, partitioned into the detergent and aqueous phase, respectively. The male-specific band of 42 KDa remained in the insoluble phase. Antigenic differences between male and females protins were detected by Western vlotting using a sera from infected Nectomys squamipes.